WorldWideScience

Sample records for fish stock estimates

  1. Size-based estimation of the status of fish stocks: simulation analysis and comparison with age-based estimations

    DEFF Research Database (Denmark)

    Kokkalis, Alexandros; Thygesen, Uffe Høgsbro; Nielsen, Anders

    , were investigated and our estimations were compared to the ICES advice. Only size-specific catch data were used, in order to emulate data limited situations. The simulation analysis reveals that the status of the stock, i.e. F/Fmsy, is estimated more accurately than the fishing mortality F itself....... Specific knowledge of the natural mortality improves the estimation more than having information about all other life history parameters. Our approach gives, at least qualitatively, an estimated stock status which is similar to the results of an age-based assessment. Since our approach only uses size...

  2. The use of coded wire tags to estimate cormorant predation on fish stocks in an estuary

    DEFF Research Database (Denmark)

    Jepsen, Niels; Klenke, Reinhard; Sonnesen, Per Michael

    2010-01-01

    One of the main obstacles to resolving the conflict between an increasing population of cormorants, Phalacrocorax carbo sinensis, and the fishing industry is the lack of documentation of the effect of the birds’ predation on fish stocks. Tagging and releasing fish with coded wire tags followed...

  3. Limits to the reliability of size-based fishing status estimation for data-poor stocks

    DEFF Research Database (Denmark)

    Kokkalis, Alexandros; Thygesen, Uffe Høgsbro; Nielsen, Anders

    2015-01-01

    For stocks which are considered “data-poor” no knowledge exist about growth, mortality or recruitment. The only available information is from catches. Here we examine the ability to assess the level of exploitation of a data-poor stock based only on information of the size of individuals in catches....... The model is a formulation of the classic Beverton–Holt theory in terms of size where stock parameters describing growth, natural mortality, recruitment, etc. are determined from life-history invariants. A simulation study was used to compare the reliability of assessments performed under different...... to a considerable improvement in the assessment. Overall, the simulation study demonstrates that it may be possible to classify a data-poor stock as undergoing over- or under-fishing, while the exact status, i.e., how much the fishing mortality is above or below Fmsy, can only be assessed with a substantial...

  4. Statistical modelling of fish stocks

    DEFF Research Database (Denmark)

    Kvist, Trine

    1999-01-01

    for modelling the dynamics of a fish population is suggested. A new approach is introduced to analyse the sources of variation in age composition data, which is one of the most important sources of information in the cohort based models for estimation of stock abundancies and mortalities. The approach combines...... and it is argued that an approach utilising stochastic differential equations might be advantagous in fish stoch assessments....

  5. Hydroacoustic estimates of fish stocks in temperate reservoirs: day or night surveys?

    Czech Academy of Sciences Publication Activity Database

    Draštík, Vladislav; Kubečka, Jan; Čech, Martin; Frouzová, Jaroslava; Říha, Milan; Jůza, Tomáš; Tušer, Michal; Jarolím, Oldřich; Prchalová, Marie; Peterka, Jiří; Vašek, Mojmír; Kratochvíl, Michal; Matěna, Josef; Mrkvička, Tomáš

    2009-01-01

    Roč. 22, č. 1 (2009), s. 69-77 ISSN 0990-7440 R&D Projects: GA ČR(CZ) GA206/06/1371; GA ČR(CZ) GA206/07/1392; GA AV ČR(CZ) 1QS600170504 Institutional research plan: CEZ:AV0Z60170517 Keywords : hydroacoustics * fish biomass * diel migration * man-made lake Subject RIV: EH - Ecology, Behaviour Impact factor: 1.227, year: 2009

  6. Changing recruitment capacity in global fish stocks.

    Science.gov (United States)

    Britten, Gregory L; Dowd, Michael; Worm, Boris

    2016-01-05

    Marine fish and invertebrates are shifting their regional and global distributions in response to climate change, but it is unclear whether their productivity is being affected as well. Here we tested for time-varying trends in biological productivity parameters across 262 fish stocks of 127 species in 39 large marine ecosystems and high-seas areas (hereafter LMEs). This global meta-analysis revealed widespread changes in the relationship between spawning stock size and the production of juvenile offspring (recruitment), suggesting fundamental biological change in fish stock productivity at early life stages. Across regions, we estimate that average recruitment capacity has declined at a rate approximately equal to 3% of the historical maximum per decade. However, we observed large variability among stocks and regions; for example, highly negative trends in the North Atlantic contrast with more neutral patterns in the North Pacific. The extent of biological change in each LME was significantly related to observed changes in phytoplankton chlorophyll concentration and the intensity of historical overfishing in that ecosystem. We conclude that both environmental changes and chronic overfishing have already affected the productive capacity of many stocks at the recruitment stage of the life cycle. These results provide a baseline for ecosystem-based fisheries management and may help adjust expectations for future food production from the oceans.

  7. Annual trends in catchability and fish stock assessments

    DEFF Research Database (Denmark)

    Marchal, P.; Ulrich, Clara; Korsbrekke, K.

    2003-01-01

    . The performances of the new and traditional XSA assessments are compared using criteria based on the precision of catchability estimates, stationarity of Log-catchability residuals and retrospective patterns relative to fishing mortality, spawning stock biomass and recruitment estimates. The performances....... A range of catchability trends, including values derived from the "Hybrid" method, is then implemented to standardise the fishing effort of some tuning fleets used in the stock assessments performed by XSA (eXtended Survivors Analysis). Stocks being assessed are the North Sea cod, saithe, plaice and sole...

  8. Estimating uncertainty of data limited stock assessments

    DEFF Research Database (Denmark)

    Kokkalis, Alexandros; Eikeset, Anne Maria; Thygesen, Uffe Høgsbro

    2017-01-01

    -limited. Particular emphasis is put on providing uncertainty estimates of the data-limited assessment. We assess four cod stocks in the North-East Atlantic and compare our estimates of stock status (F/Fmsy) with the official assessments. The estimated stock status of all four cod stocks followed the established stock...

  9. Annual trends in catchability and fish stock assessments

    Directory of Open Access Journals (Sweden)

    Marchal Paul

    2003-04-01

    Full Text Available A key assumption of many fish stock assessment models is that catchability is constant over time. We assume here that trends in catchability may occur through fishing power creeping. The tuning fleets, which are prone to fishing power development, may be identified using the Hybrid method. A range of catchability trends, including values derived from the Hybrid method, is then implemented to standardise the fishing effort of some tuning fleets used in the stock assessments performed by XSA (eXtended Survivors Analysis. Stocks being assessed are the North Sea cod, saithe, plaice and sole. The performances of the new and traditional XSA assessments are compared using criteria based on the precision of catchability estimates, stationarity of Log-catchability residuals and retrospective patterns relative to fishing mortality, spawning stock biomass and recruitment estimates. The performances of the North Sea cod, plaice and sole assessments could be enhanced by accounting for an overall annual increase in the catchability of some of the tuning fleets. No significant trends could be detected in the catchability of the tuning fleets relative to the assessment of the North Sea saithe. By contrast with the traditional assessment, the spawning biomass of cod is expected not to have increased between 1997 and 1998, while the fishing mortality of sole is expected to have increased over the same period.

  10. Fish stocking density impacts tank hydrodynamics

    DEFF Research Database (Denmark)

    Rasmussen, Michael R.; Lunger, Angela; Laursen, Jesper

    2006-01-01

    The effect of stocking density upon the hydrodynamics of a circular tank, configured in a recirculation system, was investigated. Red drums Sciaenops ocellatus of approximately 140 g wet weight, were stocked at five rates varying from 0 to 12 kg m-3. The impact of the presence of fish upon tank...... hydrodynamics was established using in-tank-based Rhodamine WT fluorometry at a flow rate of 0.23 l s-1 (tank exchange rate of 1.9 h-1). With increasing numbers of animals, curvilinear relationships were observed for dispersion coefficients and tank mixing times. Stocking densities of 3, 6, 9 and 12 kg m-3...

  11. Performance of maximum likelihood mixture models to estimate nursery habitat contributions to fish stocks: a case study on sea bream Sparus aurata

    Directory of Open Access Journals (Sweden)

    Edwin J. Niklitschek

    2016-10-01

    Full Text Available Background Mixture models (MM can be used to describe mixed stocks considering three sets of parameters: the total number of contributing sources, their chemical baseline signatures and their mixing proportions. When all nursery sources have been previously identified and sampled for juvenile fish to produce baseline nursery-signatures, mixing proportions are the only unknown set of parameters to be estimated from the mixed-stock data. Otherwise, the number of sources, as well as some/all nursery-signatures may need to be also estimated from the mixed-stock data. Our goal was to assess bias and uncertainty in these MM parameters when estimated using unconditional maximum likelihood approaches (ML-MM, under several incomplete sampling and nursery-signature separation scenarios. Methods We used a comprehensive dataset containing otolith elemental signatures of 301 juvenile Sparus aurata, sampled in three contrasting years (2008, 2010, 2011, from four distinct nursery habitats. (Mediterranean lagoons Artificial nursery-source and mixed-stock datasets were produced considering: five different sampling scenarios where 0–4 lagoons were excluded from the nursery-source dataset and six nursery-signature separation scenarios that simulated data separated 0.5, 1.5, 2.5, 3.5, 4.5 and 5.5 standard deviations among nursery-signature centroids. Bias (BI and uncertainty (SE were computed to assess reliability for each of the three sets of MM parameters. Results Both bias and uncertainty in mixing proportion estimates were low (BI ≤ 0.14, SE ≤ 0.06 when all nursery-sources were sampled but exhibited large variability among cohorts and increased with the number of non-sampled sources up to BI = 0.24 and SE = 0.11. Bias and variability in baseline signature estimates also increased with the number of non-sampled sources, but tended to be less biased, and more uncertain than mixing proportion ones, across all sampling scenarios (BI < 0.13, SE < 0

  12. Performance of maximum likelihood mixture models to estimate nursery habitat contributions to fish stocks: a case study on sea bream Sparus aurata

    Science.gov (United States)

    Darnaude, Audrey M.

    2016-01-01

    Background Mixture models (MM) can be used to describe mixed stocks considering three sets of parameters: the total number of contributing sources, their chemical baseline signatures and their mixing proportions. When all nursery sources have been previously identified and sampled for juvenile fish to produce baseline nursery-signatures, mixing proportions are the only unknown set of parameters to be estimated from the mixed-stock data. Otherwise, the number of sources, as well as some/all nursery-signatures may need to be also estimated from the mixed-stock data. Our goal was to assess bias and uncertainty in these MM parameters when estimated using unconditional maximum likelihood approaches (ML-MM), under several incomplete sampling and nursery-signature separation scenarios. Methods We used a comprehensive dataset containing otolith elemental signatures of 301 juvenile Sparus aurata, sampled in three contrasting years (2008, 2010, 2011), from four distinct nursery habitats. (Mediterranean lagoons) Artificial nursery-source and mixed-stock datasets were produced considering: five different sampling scenarios where 0–4 lagoons were excluded from the nursery-source dataset and six nursery-signature separation scenarios that simulated data separated 0.5, 1.5, 2.5, 3.5, 4.5 and 5.5 standard deviations among nursery-signature centroids. Bias (BI) and uncertainty (SE) were computed to assess reliability for each of the three sets of MM parameters. Results Both bias and uncertainty in mixing proportion estimates were low (BI ≤ 0.14, SE ≤ 0.06) when all nursery-sources were sampled but exhibited large variability among cohorts and increased with the number of non-sampled sources up to BI = 0.24 and SE = 0.11. Bias and variability in baseline signature estimates also increased with the number of non-sampled sources, but tended to be less biased, and more uncertain than mixing proportion ones, across all sampling scenarios (BI nursery signatures improved reliability

  13. PIXE analysis of fish otoliths. Application to fish stock discrimination

    International Nuclear Information System (INIS)

    Arai, Nobuaki; Sakamoto, Wataru; Tateno, Koji; Yoshida, Koji.

    1996-01-01

    PIXE was adopted to analyze trace elements in otoliths of Japanese flounder to discriminate among several local fish stocks. The otoliths were removed from samples caught at five different sea areas along with the coast of the Sea of Japan: Akita, Ishikawa, Kyoto (2 stations), and Fukuoka. Besides calcium as main component, strontium, manganese, and zinc were detected. Especially Sr concentrations were different among 4 areas except between 2 stations in Kyoto. It suggested that the fish in the 2 stations in Kyoto were the same stock differed to the others. (author)

  14. Statistical aspects of fish stock assessment

    DEFF Research Database (Denmark)

    Berg, Casper Willestofte

    for stock assessment by application of state-of-the-art statistical methodology. The main contributions are presented in the form of six research papers. The major part of the thesis deals with age-structured assessment models, which is the most common approach. Conversion from length to age distributions...... statistical aspects of fish stocks assessment, which includes topics such as time series analysis, generalized additive models (GAMs), and non-linear state-space/mixed models capable of handling missing data and a high number of latent states and parameters. The aim is to improve the existing methods...

  15. Quantifying relative fishing impact on fish populations based on spatio-temporal overlap of fishing effort and stock density

    DEFF Research Database (Denmark)

    Vinther, Morten; Eero, Margit

    2013-01-01

    Evaluations of the effects of management measures on fish populations are usually based on the analyses of population dynamics and estimates of fishing mortality from stock assessments. However, this approach may not be applicable in all cases, in particular for data-limited stocks, which may...... GAM analyses to predict local cod densities and combine this with spatio-temporal data of fishing effort based on VMS (Vessel Monitoring System). To quantify local fishing impact on the stock, retention probability of the gears is taken into account. The results indicate a substantial decline...... in the impact of the Danish demersal trawl fleet on cod in the Kattegat in recent years, due to a combination of closed areas, introduction of selective gears and changes in overall effort....

  16. POTENTIAL PRODUCTION OF DEMERSAL FISH STOCK IN THE MALACCA STRAIT OF INDONESIA

    Directory of Open Access Journals (Sweden)

    Purwanto Purwanto

    2015-06-01

    Full Text Available Malacca Strait is one of the main fishing areas for demersal fishery in Indonesia. To support the management of that fishery, an assessment of the demersal fish stock was conducted. This study estimated that the maximum sustainable yield and the optimal catch per unit effortof demersal fishery in the Malacca Strait were about 106.8 thousand tons/year and 28.5 tons per unit of Danish seine, respectively, resulting from the operation of 3,752 Danish seines. Unfortunately, fishing effort was higher than its optimum level and the fish stock was over-exploited since 2003. To recover the demersal fish stock to its optimum level and to ensure the optimal fish production from demersal fishery in the Malacca Strait, it was necessary to reduce fishing effort at about 67% from its level in 2011.

  17. Fish otoliths analysis by PIXE: application to stock discrimination

    International Nuclear Information System (INIS)

    Arai, Nobuaki; Takai, Noriyuki; Sakamoto, Wataru; Yoshida, Koji; Maeda, Kuniko.

    1996-01-01

    Fish otoliths are continuously deposited from fish birth to its death along with encoding environmental information. In order to decode the information, PIXE was adopted as trace elemental analysis of the otoliths. Strontium to calcium concentration ratios of red sea bream otoliths varied among rearing stations. The Sr/Ca ratios of Lake Biwa catfishes also varied between male and female and among fishing grounds. The PIXE analysis was applied to the fish stock discrimination. (author)

  18. Protection of Marine Fish Stocks at Risk of Extinction

    Science.gov (United States)

    J.A. Musick; S.A. Berkeley; G.M. Cailliet; M. Camhi; G. Huntsman; M. Nammack; Melvin L. Warren

    2000-01-01

    The American Fisheries Society (AFS) recommends that registory agencies closely scrutinize both marine fish and invertebrate stocks that may be at risk of extinction and take remedial action before populations are threatened or endungered. Initial AFS analyses of marine stocks at risk in North America show at least four primary geographic "hot spots" with...

  19. 75 FR 6058 - Federal Sport Fish Restoration; California Department of Fish and Game Fish Hatchery and Stocking...

    Science.gov (United States)

    2010-02-05

    ...] Federal Sport Fish Restoration; California Department of Fish and Game Fish Hatchery and Stocking Program... (NEPA) of 1969, as amended, for the EIR/EIS jointly prepared with CDFG. Under the Sport Fish Restoration... has authority to grant Federal funds from the Sport Fish Restoration and Boating Trust Fund to support...

  20. Impact of entrainment and impingement on fish populations in the Hudson River estuary. Volume III. An analysis of the validity of the utilities' stock-recruitment curve-fitting exercise and prior estimation of beta technique. Environmental Sciences Division publication No. 1792

    International Nuclear Information System (INIS)

    Christensen, S.W.; Goodyear, C.P.; Kirk, B.L.

    1982-03-01

    This report addresses the validity of the utilities' use of the Ricker stock-recruitment model to extrapolate the combined entrainment-impingement losses of young fish to reductions in the equilibrium population size of adult fish. In our testimony, a methodology was developed and applied to address a single fundamental question: if the Ricker model really did apply to the Hudson River striped bass population, could the utilities' estimates, based on curve-fitting, of the parameter alpha (which controls the impact) be considered reliable. In addition, an analysis is included of the efficacy of an alternative means of estimating alpha, termed the technique of prior estimation of beta (used by the utilities in a report prepared for regulatory hearings on the Cornwall Pumped Storage Project). This validation methodology should also be useful in evaluating inferences drawn in the literature from fits of stock-recruitment models to data obtained from other fish stocks

  1. Available information for estimating reproductive potential of Northwest Atlantic groundfish stocks

    DEFF Research Database (Denmark)

    Tomkiewicz, Jonna; Morgan, M.J.; Burnett, J.

    2003-01-01

    , possibilities for estimating stock potential egg production are constrained by scarcity of fecundity data. Data on fish condition, which can be useful in developing fecundity models, were seldom collected in earlier times, but have increased in recent decades. A data richness index, combining information about...... data quantity and quality, ranked most gadoid stocks as "data comprehensive" with a high proportion of stocks possessing some fecundity information. Flatfish stocks generally were "data moderate" owing to slightly shorter time series of data, while redfish and grenadier stocks in general were "data...

  2. Structural Estimation of Stock Market Participation Costs

    DEFF Research Database (Denmark)

    Khorunzhina, Natalia

    2013-01-01

    education programs can affect consumers' investment decisions. Using household data from the Panel Study of Income Dynamics, I estimate the magnitude of the participation cost, allowing for individual heterogeneity in it. The results show the average stock market participation cost is about 4–6% of labor...

  3. Pelagic fish stock assessment by acoustic methods at Ifremer

    OpenAIRE

    Doray, Mathieu; Masse, Jacques; Petitgas, Pierre; Doray, Mathieu; Masse, Jacques; Petitgas, Pierre

    2010-01-01

    The main objective of Ifremer's pelagic sea surveys (Pelgas in the Bay of Biscay and Pelmed in the Gulf of Lion) is to assess the biomass of anchovy (Engraulis encrasicolus) and sardine (Sardina pilchardus) populations, based on fisheries acoustic data. Complementary data on the whole pelagic ecosystem (hydrology, plankton, fish eggs and larvae, other fish species, seabirds and marine mammals) are also collected during the cruises. This document describes the procedures used to derive stock a...

  4. Competition or cooperation in transboundary fish stocks management: Insight from a dynamical model.

    Science.gov (United States)

    Nguyen, Trong Hieu; Brochier, Timothée; Auger, Pierre; Trinh, Viet Duoc; Brehmer, Patrice

    2018-06-14

    An idealized system of a shared fish stock associated with different exclusive economic zones (EEZ) is modelled. Parameters were estimated for the case of the small pelagic fisheries shared between Southern Morocco, Mauritania and the Senegambia. Two models of fishing effort distribution were explored. The first one considers independent national fisheries in each EEZ, with a cost per unit of fishing effort that depends on local fishery policy. The second one considers the case of a fully cooperative fishery performed by an international fleet freely moving across the borders. Both models are based on a set of six ordinary differential equations describing the time evolution of the fish biomass and the fishing effort. We take advantage of the two time scales to obtain a reduced model governing the total fish biomass of the system and fishing efforts in each zone. At the fast equilibrium, the fish distribution follows the ideal free distribution according to the carrying capacity in each area. Different equilibria can be reached according to management choices. When fishing fleets are independent and national fishery policies are not harmonized, in the general case, competition leads after a few decades to a scenario where only one fishery remains sustainable. In the case of sub-regional agreement acting on the adjustment of cost per unit of fishing effort in each EEZ, we found that a large number of equilibria exists. In this last case the initial distribution of fishing effort strongly impact the optimal equilibrium that can be reached. Lastly, the country with the highest carrying capacity density may get less landings when collaborating with other countries than if it minimises its fishing costs. The second fully cooperative model shows that a single international fishing fleet moving freely in the fishing areas leads to a sustainable equilibrium. Such findings should foster regional fisheries organizations to get potential new ways for neighbouring fish stock

  5. Rapid fish stock depletion in previously unexploited seamounts: the ...

    African Journals Online (AJOL)

    Rapid fish stock depletion in previously unexploited seamounts: the case of Beryx splendens from the Sierra Leone Rise (Gulf of Guinea) ... A spectral analysis and red-noise spectra procedure (REDFIT) algorithm was used to identify the red-noise spectrum from the gaps in the observed time-series of catch per unit effort by ...

  6. Dynamics and management of stage-structured fish stocks.

    Science.gov (United States)

    Meng, Xinzhu; Lundström, Niklas L P; Bodin, Mats; Brännström, Åke

    2013-01-01

    With increasing fishing pressures having brought several stocks to the brink of collapse, there is a need for developing efficient harvesting methods that account for factors beyond merely yield or profit. We consider the dynamics and management of a stage-structured fish stock. Our work is based on a consumer-resource model which De Roos et al. (in Theor. Popul. Biol. 73, 47-62, 2008) have derived as an approximation of a physiologically-structured counterpart. First, we rigorously prove the existence of steady states in both models, that the models share the same steady states, and that there exists at most one positive steady state. Furthermore, we carry out numerical investigations which suggest that a steady state is globally stable if it is locally stable. Second, we consider multiobjective harvesting strategies which account for yield, profit, and the recovery potential of the fish stock. The recovery potential is a measure of how quickly a fish stock can recover from a major disturbance and serves as an indication of the extinction risk associated with a harvesting strategy. Our analysis reveals that a small reduction in yield or profit allows for a disproportional increase in recovery potential. We also show that there exists a harvesting strategy with yield close to the maximum sustainable yield (MSY) and profit close to that associated with the maximum economic yield (MEY). In offering a good compromise between MSY and MEY, we believe that this harvesting strategy is preferable in most instances. Third, we consider the impact of harvesting on population size structure and analytically determine the most and least harmful harvesting strategies. We conclude that the most harmful harvesting strategy consists of harvesting both adults and juveniles, while harvesting only adults is the least harmful strategy. Finally, we find that a high percentage of juvenile biomass indicates elevated extinction risk and might therefore serve as an early-warning signal of

  7. Impact of fishing and stocking practices on Coregonid diversity

    Science.gov (United States)

    Anneville, Orlane; Lasne, Emilien; Guillard, Jean; Eckmann, Reiner; Stockwell, Jason D.; Gillet, Christian; Yule, Daniel

    2015-01-01

    Fish species diversity can be lost through interacting stressors including habitat loss, stocking and overfishing. Although a multitude of stressors have played a role in the global decline of coregonid (Coregonus spp.) diversity, a number of contemporary studies have identified habitat loss stemming from eutrophication as the primary cause. Unfortunately, reconstructing the role of fishing and stocking practices can be difficult, because these records are incomplete or appear only in hard-to-access historic grey literature. Based on an illustrative set of historic and contemporary studies, we describe how fisheries management practices may have contributed to coregonid diversity loss in European and North American lakes. We provide case studies examining how fishing and stocking may reduce coregonid diversity through demographic decline and introgressive hybridization. In some lakes, fisheries management practices may have led to a loss of coregonid diversity well before issues with habitat degradation manifested. Our review suggests that fish conservation policies could beneficially consider the relative importance of all stressors, including management practices, as potential drivers of diversity loss.

  8. Multicriteria assessment in restoring migratory fish stocks in the river Iijoki; Monitavoitearviointi Iijoen vaelluskalakantojen palauttamisen tukena

    Energy Technology Data Exchange (ETDEWEB)

    Karjalainen, T.P.; Rytkoenen, A.-M.; Marttunen, M.; Maeki-Petaeys, A.; Autti, O.

    2011-05-15

    The Iijoki is one of Finland's most important former salmon rivers. Construction of multiple main stem dams on the river in the 1960s effectively blocked the migration corridors of migratory fish. Suitable spawning and nursery habitats above the dams span an estimated 600-800 hectares. With riverside residents are very much in favour of the return of migratory fish, watershed planning for this has been set as a target. Such measures are rendered urgent by the fact that there is still a possibility of replenishing the Iijoki's own salmon stock, thereby restoring the fishes' natural lifecycle and natural selection. This report has been completed as part of the project 'The return of migratory fish to the River Iijoki (2008-2010)', where the main object was reconciling the target of enhancing the natural life cycle of migratory fish with the continued generation of hydropower. Under a multicriteria assessment, various alternatives and measures for improving migratory fish stocks were clarified and their desirability, costs and benefits systematically and transparently evaluated. Furthermore, interest groups' views of the three options and their effects (as distinct from the expert evaluation) were clarified with the help of computer aided interviews. The alternatives were transferring salmon above the main stem dams and two fish-ladder options. The multicriteria assessment viewed the construction of fish ladders, alongside other large-scale support measures, as the best option. Based on all of the criteria applied in a cost-benefit analysis, the stock transfer alternative was the most economically viable, because its net product value was positive in all cases. The fish ladder options were the most expensive due to the construction costs involved, but they also provided the greatest benefits. Above all, fish ladder construction is supported by the fact that it would return migratory fish to their natural lifecycle and attain the EU

  9. Decision making under uncertainty in fisheries management: capital adjustment, fishermen behavior and stochasticity in fish stocks

    NARCIS (Netherlands)

    Dijk, van D.

    2013-01-01

    The world’s marine fisheries are characterized by declining global catch, an increasing number of overexploited stocks and high natural variability in fish stocks. Policy makers are becoming more aware that effective management systems have to be implemented to rebuild overexploited fish stocks. The

  10. Effects of changes in stock productivity and mixing on sustainable fishing and economic viability

    DEFF Research Database (Denmark)

    Bastardie, Francois; Nielsen, J. Rasmus; Eero, Margit

    2017-01-01

    Within the new FMSY European paradigm, this paper shows how a combination of changes in fish stock mixing, non-stationarity in productivity, and constraints on unit stock concepts undermine the effective management of fisheries, especially when management reference points are not adjusted...... accordingly. Recent changes in stock structures, conditions and stock mixing between eastern and western Baltic cod can jeopardize the reliability of stock assessments and of the fishery economy. We modelled how different management, individual vessel decision-making, and stock growth and mixing scenarios...... have induced alternative individual vessel spatial effort allocation and economic performance by affecting fishing costs and by changing the relative stock abundance and size distribution. Stock mixing heavily influences profit and stock abundance for stocks that have experienced increased fishing...

  11. Fish stock assessment under data limitations developing a new method based on a size-structured theoretical ecology framework

    DEFF Research Database (Denmark)

    Kokkalis, Alexandros

    catch is known, important quantities about the stock (e.g. biomass of spawners, recruitment) can be quantified. The method is tested using simulated data and validated using a subset of available data from data-rich fish stocks. The implementation of the method as a software package in the R programming......Fish stock assessment is an integral part of every fisheries management system. Modern assessment methods require data about the fishery and the stock, such as catches, survey estimates, aging information and life history parameters, all of which is difficult and expensive to gather. However......, the majority of global fish catches comes from species that lack an official assessment due to lack of data. That is true especially for small scale fisheries and fisheries in developing countries. New methods are in need that require little amount of easily attainable data and provide scientific advice...

  12. Experimental stocking of sport fish in the regulated Tallapoosa River to determine critical periods for recruitment

    Science.gov (United States)

    Lloyd, M. Clint; Lai, Quan; Sammons, Steve; Irwin, Elise R.

    2017-01-01

    The stocking of fish in riverine systems to re-establish stocks for conservation and management appears limited to a few species and often occurs in reaches impacted by impoundments. Stocking of sport fish species such as centrarchids and ictalurids is often restricted to lentic environments, although stocking in lotic environments is feasible with variable success. R. L. Harris Dam on the Tallapoosa River, Alabama is the newest and uppermost dam facility on the river (operating since 1983); flows from the dam have been managed adaptively for multiple stakeholder objectives since 2005. One of the stakeholders’ primary objectives is to provide quality sport fisheries in the Tallapoosa River in the managed area below the dam. Historically, ictalurids and cyprinids dominated the river above Lake Martin. However, investigations after Harris Dam closed have detected a shift in community structure to domination by centrarchids. Flow management (termed the Green Plan) has been occurring since March 2005; however, sport fish populations as measured by recruitment of age-1 sport fishes below the dam has not responded adequately to flow management. The objectives of this research were to: (1) determine if stocking Channel Catfish Ictalurus punctatus and Redbreast Sunfish Lepomis auritus influences year-class strength; (2) estimate vital rates (i.e. growth, mortality, and recruitment) for Channel Catfish populations for use in an age-based population model; and (3) identify age-specific survivorship and fecundity rates contributing to Channel Catfish population stability. No marked Redbreast Sunfish were recaptured due to poor marking efficacy and therefore no further analysis was conducted with this species. Stocked Channel Catfish, similarly, were not recaptured, leaving reasons for non-recapture unknown. Matrix models exploring vital rates illustrated survival to age-1 for Channel Catfish to be less than 0.03% and that survival through ages 2 – 4 had equal contribution

  13. Single and multispecies reference points for Baltic fish stocks

    DEFF Research Database (Denmark)

    Gislason, Henrik

    1999-01-01

    reference points. Management advice based on biomass reference points will also differ. In the single species situation the combinations of cod and pelagic fishing effort for which the equilibrium spawning- stock biomass of the three species is above the biomass reference points forms a rectangular area......Single and multispecies models are used to examine the effect of species interaction on biological reference points for cod, herring, and sprat in the Baltic. The results demonstrate that reference points are different in single and multispecies contexts. Reference points for fishing mortality...... based on single-species yield and SSB calculations are difficult to use when natural mortality depends on the absolute abundance of the predators and their alternative prey. Reference points based on maximizing total yield from the system may lead to impractical results when species interact...

  14. Stock price estimation using ensemble Kalman Filter square root method

    Science.gov (United States)

    Karya, D. F.; Katias, P.; Herlambang, T.

    2018-04-01

    Shares are securities as the possession or equity evidence of an individual or corporation over an enterprise, especially public companies whose activity is stock trading. Investment in stocks trading is most likely to be the option of investors as stocks trading offers attractive profits. In determining a choice of safe investment in the stocks, the investors require a way of assessing the stock prices to buy so as to help optimize their profits. An effective method of analysis which will reduce the risk the investors may bear is by predicting or estimating the stock price. Estimation is carried out as a problem sometimes can be solved by using previous information or data related or relevant to the problem. The contribution of this paper is that the estimates of stock prices in high, low, and close categorycan be utilized as investors’ consideration for decision making in investment. In this paper, stock price estimation was made by using the Ensemble Kalman Filter Square Root method (EnKF-SR) and Ensemble Kalman Filter method (EnKF). The simulation results showed that the resulted estimation by applying EnKF method was more accurate than that by the EnKF-SR, with an estimation error of about 0.2 % by EnKF and an estimation error of 2.6 % by EnKF-SR.

  15. Changes in the fish community and water quality during seven years of stocking piscivorous fish in a shallow lake

    DEFF Research Database (Denmark)

    Skov, Christian; Perrow, M.R.; Berg, Søren

    2002-01-01

    evaluated between predatory fish and potential prey and between zooplanktivorous or benthivorous fish and water quality parameters. In addition, potential consumption of piscivorous fishes was calculated. 3. The density of fish feeding on larger zooplankton or benthos (roach >15 cm, crucian carp >15 cm......1. Piscivores (annual stocking of 1000 individuals ha(-1) of 0+ pike and a single stocking of 30 kg ha(-1) of large 20-30 cm perch) were stocked in seven consecutive years in a shallow eutrophic lake in Denmark. The stocking programme aimed at changing food-web structure by reducing...... zooplanktivorous and benthivorous fish, with resultant effects on lower trophic levels and ultimately water quality. 2. The fish community and water quality parameters (Secchi depth, concentrations of total phosphorus, chlorophyll a and suspended solids) were monitored between 1996 and 2000 and relationships were...

  16. Exploitation dynamics of small fish stocks like Arctic cisco

    Science.gov (United States)

    Nielsen, Jennifer L.

    2004-01-01

    population within the Colville River other than only the Mackenzie River population. This needs further exploration. By examining otolith microchemistry, unique transitions from freshwater to sea can be identified for these stocks. This may shed light on why some fish arrive at the mouth of the Colville River, while others don’t.

  17. Is age structure a relevant criterion for the health of fish stocks?

    NARCIS (Netherlands)

    Brunel, T.P.A.; Piet, G.J.

    2013-01-01

    The age and size structure of exploited fish stocks is one of the criteria for Good Environmental Status of commercial fish. However, two underlying assumptions to this criterion remain to be tested: first, that a well-balanced age structure is indeed indicative of a “healthier” stock, and second,

  18. InterCatch - a tool for fish stock assessment, status and methods

    DEFF Research Database (Denmark)

    Kjems-Nielsen, Henrik; Larsen, Lena Inger; Zarecki, Maria

    2006-01-01

    InterCatch is a web-based system for handling fish stock assessment data focusing on documenting characteristics of the catches. These national fish stock data are uploaded to InterCatch by national data submitters. After all data are uploaded the stock coordinators (working for the fish stock as...... assessment group) can then check and set up allocation schemes for unsampled catches. After applying the best allocation scheme to the unsampled catches, the catch data are aggregated as required and exported for analysis, e.g. XSA or ICA....

  19. The effect of fish impingement at Sizewell 'A' Power Station, Suffolk, on North Sea fish stocks

    International Nuclear Information System (INIS)

    Turnpenny, A.W.H.; Utting, N.J.; Millner, R.S.; Riley, J.D.

    1988-04-01

    Samples collected from the cooling water intake screens of Sizewell 'A' power station over a 12 month period contained 73 species of fish. Of these, only 20 species were present on more than 50% of sampling dates and only 7 commercially exploited species were caught in quantities of more than a few hundred over the year; namely sprat, herring, cod, whiting, sole, dab and plaice. These species formed the basis of analysis of the impact of the Power Station on commercial species. Commercial species found in the Sizewell area are part of major North Sea stocks. The impact of the losses due to the Power Station is spread over these stocks, hence the effect is minimal. The mortality rate caused by the Power Station is one thousandth to one hundred-thousandth, depending on species, of that caused by commercial fishing and the effect is less than that of a small, inefficient commercial trawler. (author)

  20. Hydroacoustic estimates of fish biomass and spatial distributions in shallow lakes

    Science.gov (United States)

    Lian, Yuxi; Huang, Geng; Godlewska, Małgorzata; Cai, Xingwei; Li, Chang; Ye, Shaowen; Liu, Jiashou; Li, Zhongjie

    2018-03-01

    We conducted acoustical surveys with a horizontal beam transducer to detect fish and with a vertical beam transducer to detect depth and macrophytes in two typical shallow lakes along the middle and lower reaches of the Changjiang (Yangtze) River in November 2013. Both lakes are subject to active fish management with annual stocking and removal of large fish. The purpose of the study was to compare hydroacoustic horizontal beam estimates with fish landings. The preliminary results show that the fish distribution patterns differed in the two lakes and were affected by water depth and macrophyte coverage. The hydroacoustically estimated fish biomass matched the commercial catch very well in Niushan Lake, but it was two times higher in Kuilei Lake. However, acoustic estimates included all fish, whereas the catch included only fish >45 cm (smaller ones were released). We were unable to determine the proper regression between acoustic target strength and fish length for the dominant fish species in the two lakes.

  1. Chinook Bycatch - Contemporary Salmon Genetic Stock Composition Estimates

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The purpose of this project is to measure and monitor impacts on ESA-listed populations and to estimate overall Chinook salmon stock composition in bycatch...

  2. Applying Moving Objects Patterns towards Estimating Future Stocks Direction

    Directory of Open Access Journals (Sweden)

    Galal Dahab

    2016-01-01

    Full Text Available Stock is gaining vast popularity as a strategic investment tool not just by investor bankers, but also by the average worker. Large capitals are being traded within the stock market all around the world, making its impact not only macro economically focused, but also greatly valued taking into consideration its direct social impact. As a result, almost 66% of all American citizens are striving in their respective fields every day, trying to come up with better ways to predict and find patterns in stocks that could enhance their estimation and visualization so as to have the opportunity to take better investment decisions. Given the amount of effort that has been put into enhancing stock prediction techniques, there is still a factor that is almost completely neglected when handling stocks. The factor that has been obsolete for so long is in fact the effect of a correlation existing between stocks of the same index or parent company. This paper proposes a distinct approach for studying the correlation between stocks that belong to the same index by modelling stocks as moving objects to be able to track their movements while considering their relationships. Furthermore, it studies one of the movement techniques applied to moving objects to predict stock movement. The results yielded that both the movement technique and correlation coefficient technique are consistent in directions, with minor variations in values. The variations are attributed to the fact that the movement technique takes into consideration the sibling relationship

  3. Fish stock assessments in the Mediterranean: state of the art

    Directory of Open Access Journals (Sweden)

    Jordi Lleonart

    2003-04-01

    Full Text Available The Mediterranean fisheries are characterised by fragmented fleets, usually composed by relatively small vessels, use of a large number of landing sites, multi-species catches and low CPUEs. Fish are commercialised mainly fresh and the prices are relatively high. These factors make it difficult and expensive to get extensive and reliable data time series and to get biological samples. Most of the fish caught in the Mediterranean are the recruits (0-1 year old of the main target species. Since the recruitment is much more uncertain than the abundance of the adult stages, the assessments are also more uncertain. Furthermore, no TAC or adaptive management is in place, so the administrations do not require monitoring in order to manage the fisheries. The continental shelf is narrow (with some exceptions and there are few stocks shared between two or more countries. Consequently, the international management structures have not been sufficiently enforced, and until recently no regular assessments were made by international working groups. These characteristics have led to a situation in which most of the assessments have been done in the framework of scientific projects, and therefore do not have continuity in time. The results of these assessments have rarely been incorporated in management.

  4. State-Space Estimation of Soil Organic Carbon Stock

    Science.gov (United States)

    Ogunwole, Joshua O.; Timm, Luis C.; Obidike-Ugwu, Evelyn O.; Gabriels, Donald M.

    2014-04-01

    Understanding soil spatial variability and identifying soil parameters most determinant to soil organic carbon stock is pivotal to precision in ecological modelling, prediction, estimation and management of soil within a landscape. This study investigates and describes field soil variability and its structural pattern for agricultural management decisions. The main aim was to relate variation in soil organic carbon stock to soil properties and to estimate soil organic carbon stock from the soil properties. A transect sampling of 100 points at 3 m intervals was carried out. Soils were sampled and analyzed for soil organic carbon and other selected soil properties along with determination of dry aggregate and water-stable aggregate fractions. Principal component analysis, geostatistics, and state-space analysis were conducted on the analyzed soil properties. The first three principal components explained 53.2% of the total variation; Principal Component 1 was dominated by soil exchange complex and dry sieved macroaggregates clusters. Exponential semivariogram model described the structure of soil organic carbon stock with a strong dependence indicating that soil organic carbon values were correlated up to 10.8m.Neighbouring values of soil organic carbon stock, all waterstable aggregate fractions, and dithionite and pyrophosphate iron gave reliable estimate of soil organic carbon stock by state-space.

  5. Effects of marine protected areas on overfished fishing stocks with multiple stable states.

    Science.gov (United States)

    Takashina, Nao; Mougi, Akihiko

    2014-01-21

    Marine protected areas (MPAs) have attracted much attention as a tool for sustainable fisheries management, restoring depleted fisheries stocks and maintaining ecosystems. However, even with total exclusion of fishing effort, depleted stocks sometimes show little or no recovery over a long time period. Here, using a mathematical model, we show that multiple stable states may hold the key to understanding the tendency for fisheries stocks to recover because of MPAs. We find that MPAs can have either a positive effect or almost no effect on the recovery of depleted fishing stocks, depending on the fish migration patterns and the fishing policies. MPAs also reinforce ecological resilience, particularly for migratory species. In contrast to previous reports, our results show that MPAs have small or sometimes negative effects on the recovery of sedentary species. Unsuitable MPA planning might result in low effectiveness or even deterioration of the existing condition. © 2013 Elsevier Ltd. All rights reserved.

  6. Effects of fish density and river fertilization on algal standing stocks, invertebrates communities, and fish production in an Arctic River

    Science.gov (United States)

    Deegan, Linda A.; Peterson, B.J.; Golden, H.; McIvor, C.C.; Miller, M.C.

    1997-01-01

    This study examined the relative importance of bottom-up and top-down controls of an arctic stream food web by simultaneous manipulation of the top predator and nutrient availability. We created a two-step trophic system (algae to insects) by removal of the top predator (Arctic grayling, Thymallus arcticus) in fertilized and control stream reaches. Fish abundance was also increased 10 times to examine the effect of high fish density on stream ecosystem dynamics and fish. We measured the response of epilithic algae, benthic and drifting insects, and fish to nutrient enrichment and to changes in fish density. Insect grazers had little effect on algae and fish had little effect on insects. In both the control and fertilized reaches, fish growth, energy storage, and reproductive response of females declined with increased fish density. Fish growth and energy storage were more closely correlated with per capita insect availability than with per capita algal standing stock

  7. Assessing effects of stocked trout on nongame fish assemblages in southern Appalachian Mountain streams

    Science.gov (United States)

    Weaver, D.; Kwak, Thomas J.

    2013-01-01

    Fisheries managers are faced with the challenge of balancing the management of recreational fisheries with that of conserving native species and preserving ecological integrity. The negative effects that nonnative trout species exert on native trout are well documented and include alteration of competitive interactions, habitat use, and production. However, the effects that nonnative trout may exert on nongame fish assemblages are poorly understood. Our objectives were to quantify the effects of trout stocking on native nongame fish assemblages intensively on one newly stocked river, the North Toe River, North Carolina, and extensively on other southern Appalachian Mountain streams that are annually stocked with trout. In the intensive study, we adopted a before-after, control-impact (BACI) experimental design to detect short-term effects on the nongame fish assemblage and found no significant differences in fish density, species richness, species diversity, or fish microhabitat use associated with trout stocking. We observed differences in fish microhabitat use between years, however, which suggests there is a response to environmental changes, such as the flow regime, which influence available habitat. In the extensive study, we sampled paired stocked and unstocked stream reaches to detect long-term effects from trout stocking; however, we detected no differences in nongame fish density, species richness, species diversity, or population size structure between paired sites. Our results revealed high inherent system variation caused by natural and anthropogenic factors that appear to overwhelm any acute or chronic effect of stocked trout. Furthermore, hatchery-reared trout may be poor competitors in a natural setting and exert a minimal or undetectable impact on native fish assemblages in these streams. These findings provide quantitative results necessary to assist agencies in strategic planning and decision making associated with trout fisheries, stream

  8. Estimating carbon stock in secondary forests

    DEFF Research Database (Denmark)

    Breugel, Michiel van; Ransijn, Johannes; Craven, Dylan

    2011-01-01

    of trees and species for destructive biomass measurements. We assess uncertainties associated with these decisions using data from 94 secondary forest plots in central Panama and 244 harvested trees belonging to 26 locally abundant species. AGB estimates from species-specific models were used to assess...... is the use of allometric regression models to convert forest inventory data to estimates of aboveground biomass (AGB). The use of allometric models implies decisions on the selection of extant models or the development of a local model, the predictor variables included in the selected model, and the number...... relative errors of estimates from multispecies models. To reduce uncertainty in the estimation of plot AGB, including wood specific gravity (WSG) in the model was more important than the number of trees used for model fitting. However, decreasing the number of trees increased uncertainty of landscape...

  9. Estimating forest carbon stocks in tropical dry forests of Zimbabwe ...

    African Journals Online (AJOL)

    Estimation and mapping of forest dendrometric characteristics such as carbon stocks using remote sensing techniques is fundamental for improved understanding of the role of forests in the carbon cycle and climate change. In this study, we tested whether and to what extent spectral transforms, i.e. vegetation indices ...

  10. An alternative method for estimating the status of resident reef fish ...

    African Journals Online (AJOL)

    The stock status of roman Chrysoblephus laticeps was estimated in the Goukamma, a temperate South African marine protected area (MPA). Standardised catch per unit effort (CPUE) from a controlled angling survey on both sides of the MPA border was employed to extrapolate the CPUE at zero fishing mortality. Converted ...

  11. Biological reference points for fish stocks in a multispecies context

    DEFF Research Database (Denmark)

    Collie, J.S.; Gislason, Henrik

    2001-01-01

    Biological reference points (BRPs) are widely used to define safe levels of harvesting for marine fish populations. Most BRPs are either minimum acceptable biomass levels or maximum fishing mortality rates. The values of BRPs are determined from historical abundance data and the life...

  12. Status and trends of the major roundfish, flatfish, and pelagic fish stocks in the North Sea: thirty- year overview

    NARCIS (Netherlands)

    Serchuk, F.M.; Kirkegaard, E.; Daan, N.

    1996-01-01

    Changes in the status of the major roundfish, flatfish, and pelagic stocks in the North Sea over the past 30 years are reviewed. Synopses are presented on trends in catches, fishing mortality, spawning-stock biomass, and recruitment for eight stocks (cod, haddock, whitting, saithe, plaice, sole,

  13. Fishing impact and environmental status in European seas: A diagnosis from stock assessments and ecosystem indicators

    DEFF Research Database (Denmark)

    Gascuel, Didier; Coll, Marta; Fox, Clive

    2016-01-01

    Stock-based and ecosystem-based indicators are used to provide a new diagnosis of the fishing impact and environmental status of European seas. In the seven European marine ecosystems covering the Baltic and the North-east Atlantic, (i) trends in landings since 1950 were examined; (ii) syntheses...

  14. Duck Valley Reservoirs Fish Stocking and Operation and Maintenance, 2006-2007 Annual Progress Report.

    Energy Technology Data Exchange (ETDEWEB)

    Sellman, Jake; Dykstra, Tim [Shoshone-Paiute Tribes

    2009-05-11

    The Duck Valley Reservoirs Fish Stocking and Operations and Maintenance (DV Fisheries) project is an ongoing resident fish program that serves to partially mitigate the loss of anadromous fish that resulted from downstream construction of the hydropower system. The project's goals are to enhance subsistence fishing and educational opportunities for Tribal members of the Shoshone-Paiute Tribes and provide resident fishing opportunities for non-Tribal members. In addition to stocking rainbow trout (Oncorhynchus mykiss) in Mountain View, Lake Billy Shaw, and Sheep Creek Reservoirs, the program is also designed to maintain healthy aquatic conditions for fish growth and survival, to provide superior facilities with wilderness qualities to attract non-Tribal angler use, and to offer clear, consistent communication with the Tribal community about this project as well as outreach and education within the region and the local community. Tasks for this performance period are divided into operations and maintenance plus monitoring and evaluation. Operation and maintenance of the three reservoirs include fences, roads, dams and all reservoir structures, feeder canals, water troughs and stock ponds, educational signs, vehicles and equipment, and outhouses. Monitoring and evaluation activities included creel, gillnet, wildlife, and bird surveys, water quality and reservoir structures monitoring, native vegetation planting, photo point documentation, control of encroaching exotic vegetation, and community outreach and education. The three reservoirs are monitored in terms of water quality and fishery success. Sheep Creek Reservoir was very unproductive this year as a fishery. Fish morphometric and water quality data indicate that the turbidity is severely impacting trout survival. Lake Billy Shaw was very productive as a fishery and received good ratings from anglers. Mountain View was also productive and anglers reported a high number of quality sized fish. Water quality

  15. A Benchmark Estimate for the Capital Stock. An Optimal Consistency Method

    OpenAIRE

    Jose Miguel Albala-Bertrand

    2001-01-01

    There are alternative methods to estimate a capital stock for a benchmark year. These methods, however, do not allow for an independent check, which could establish whether the estimated benchmark level is too high or too low. I propose here an optimal consistency method (OCM), which may allow estimating a capital stock level for a benchmark year and/or checking the consistency of alternative estimates of a benchmark capital stock.

  16. Impact of metal pollution, food availability, and excessive fishing on Rhabdosargus haffara stock (family: Sparidae) in Timsah lake.

    Science.gov (United States)

    Mehanna, Sahar F; Abd El-Azim, Hoda; Belal, Aisha A

    2016-08-01

    The lakes' fisheries play an important role in Egyptian economy. In 1980s, they provided more than 50 % of harvested fish in Egypt but now their contribution to the Egypt fish production decreased to only 12.5 % in 2012. Lake Timsah, one of the Suez Canal lakes, faced many challenges that lead to serious changes in its water and fish quality, fish production, as well as the catch composition. The present work investigated the impact of pollution, food availability, and excessive fishing mortality on the haffara production in lake Timsah. The distribution of four heavy metals (Pb, Zn, Ni, and Fe) was detected seasonally in water and in muscles, gills, and livers of Rhabdosargus haffara, during 2012 through 2013. Fe and Zn were presented by high values in liver, while Pb and Ni in gills. Generally, the lowest concentrations of all metals were found in muscles. The recorded crustacean organisms (the main food of haffara) decreased from 12 species and 32,079 organisms⁄m(2) in 2012 to only 7 species and 7290 organisms⁄m(2) in 2013 while the amphipods completely disappeared. This serious change was due to the severe pollution in the lake. A logistic surplus production model was fitted to the catch per unit effort indices, to estimate the maximum sustainable yield and the optimum level of fishing effort. The results revealed that haffara stock at lake Timsah is overfished, and the estimated precautionary target reference points advised the reduction of fishing effort by about 30-50 %.

  17. Responsible genetic approach to stock restoration, sea ranching and stock enhancement of marine fishes and invertebrates

    DEFF Research Database (Denmark)

    Grant, W. Stewart; Jasper, James; Bekkevold, Dorte

    2017-01-01

    of marine fishes and invertebrates have been implemented with various outcomes. A review of the literature indicates that considerable effort has been directed toward culture technologies to maximize production, but scant attention has been given to genetic risks to wild populations. Genetic risks from...

  18. Targeting Abundant Fish Stocks while Avoiding Overfished Species: Video and Fishing Surveys to Inform Management after Long-Term Fishery Closures

    Science.gov (United States)

    2016-01-01

    Historically, it has been difficult to balance conservation goals and yield objectives when managing multispecies fisheries that include stocks with various vulnerabilities to fishing. As managers try to maximize yield in mixed-stock fisheries, exploitation rates can lead to less productive stocks becoming overfished. In the late 1990s, population declines of several U.S. West Coast groundfish species caused the U.S. Pacific Fishery Management Council to create coast-wide fishery closures, known as Rockfish Conservation Areas, to rebuild overfished species. The fishery closures and other management measures successfully reduced fishing mortality of these species, but constrained fishing opportunities on abundant stocks. Restrictive regulations also caused the unintended consequence of reducing fishery-dependent data available to assess population status of fished species. As stocks rebuild, managers are faced with the challenge of increasing fishing opportunities while minimizing fishing mortality on rebuilding species. We designed a camera system to evaluate fishes in coastal habitats and used experimental gear and fishing techniques paired with video surveys to determine if abundant species could be caught in rocky habitats with minimal catches of co-occurring rebuilding species. We fished a total of 58 days and completed 741 sets with vertical hook-and-line fishing gear. We also conducted 299 video surveys in the same locations where fishing occurred. Comparison of fishing and stereo-video surveys indicated that fishermen could fish with modified hook-and-line gear to catch abundant species while limiting bycatch of rebuilding species. As populations of overfished species continue to recover along the U.S. West Coast, it is important to improve data collection, and video and fishing surveys may be key to assessing species that occur in rocky habitats. PMID:28002499

  19. What kinds of fish stock predictions do we need and what kinds of information will help us to make better predictions?

    Directory of Open Access Journals (Sweden)

    Keith Brander

    2003-04-01

    Full Text Available Fish stock predictions are used to guide fisheries management, but stocks continue to be over-exploited. Traditional single-species age-structured stock assessment models, which became an operational component of fisheries management in the 1950s, ignore biological and environmental effects. As our knowledge of the marine environment improves and our concern about the state of the marine ecosystem and about global change increases, the scope of our models needs to be widened. We need different kinds of predictions as well as better predictions. Population characteristics (rates of mortality, growth, recruitment of 61 stocks of 17 species of NE Atlantic fish are reviewed in order to consider the implications for the time-scale and quality of stock predictions. Short life expectancy limits the time horizon for predictability based on the current fishable stock and predictions are therefore more dependent on estimates or assumptions about future rates. Evidence is presented that rates of growth and recruitment are influenced by environmental factors and possibilities for including new information are explored in order to improve predictions.

  20. An Individual-based Probabilistic Model for Fish Stock Simulation

    Directory of Open Access Journals (Sweden)

    Federico Buti

    2010-08-01

    Full Text Available We define an individual-based probabilistic model of a sole (Solea solea behaviour. The individual model is given in terms of an Extended Probabilistic Discrete Timed Automaton (EPDTA, a new formalism that is introduced in the paper and that is shown to be interpretable as a Markov decision process. A given EPDTA model can be probabilistically model-checked by giving a suitable translation into syntax accepted by existing model-checkers. In order to simulate the dynamics of a given population of soles in different environmental scenarios, an agent-based simulation environment is defined in which each agent implements the behaviour of the given EPDTA model. By varying the probabilities and the characteristic functions embedded in the EPDTA model it is possible to represent different scenarios and to tune the model itself by comparing the results of the simulations with real data about the sole stock in the North Adriatic sea, available from the recent project SoleMon. The simulator is presented and made available for its adaptation to other species.

  1. Duck Valley Reservoirs Fish Stocking and O&M, Annual Progress Report 2007-2008.

    Energy Technology Data Exchange (ETDEWEB)

    Sellman, Jake; Perugini, Carol [Department of Fish, Wildlife, and Parks, Shoshone-Paiute Tribes

    2009-02-20

    The Duck Valley Reservoirs Fish Stocking and Operations and Maintenance Project (DV Fisheries) is an ongoing resident fish program that serves to partially mitigate the loss of anadromous fish that resulted from downstream construction of the federal hydropower system. The project's goals are to enhance subsistence fishing and educational opportunities for Tribal members of the Shoshone-Paiute Tribes and provide fishing opportunities for non-Tribal members. In addition to stocking rainbow trout (Oncorhynchus mykiss) in Mountain View (MVR), Lake Billy Shaw (LBS), and Sheep Creek Reservoirs (SCR), the program is also designed to: maintain healthy aquatic conditions for fish growth and survival, provide superior facilities with wilderness qualities to attract non-Tribal angler use, and offer clear, consistent communication with the Tribal community about this project as well as outreach and education within the region and the local community. Tasks for this performance period fall into three categories: operations and maintenance, monitoring and evaluation, and public outreach. Operation and maintenance of the three reservoirs include maintaining fences, roads, dams and all reservoir structures, feeder canals, water troughs, stock ponds, educational signs, vehicles, equipment, and restroom facilities. Monitoring and evaluation activities include creel, gillnet, wildlife, and bird surveys, water quality and reservoir structures monitoring, native vegetation planting, photo point documentation, and control of encroaching exotic vegetation. Public outreach activities include providing environmental education to school children, providing fishing reports to local newspapers and vendors, updating the website, hosting community environmental events, and fielding numerous phone calls from anglers. The reservoir monitoring program focuses on water quality and fishery success. Sheep Creek Reservoir and Lake Billy Shaw had less than productive trout growth due to water

  2. Duck Valley Reservoirs Fish Stocking and Operation and Maintenance, 2005-2006 Annual Progress Report.

    Energy Technology Data Exchange (ETDEWEB)

    Sellman, Jake; Dykstra, Tim [Shoshone-Paiute Tribes

    2009-05-11

    The Duck Valley Reservoirs Fish Stocking and Operations and Maintenance (DV Fisheries) project is an ongoing resident fish program designed to enhance both subsistence fishing, educational opportunities for Tribal members of the Shoshone-Paiute Tribes, and recreational fishing facilities for non-Tribal members. In addition to stocking rainbow trout (Oncorhynchus mykiss) in Mountain View, Lake Billy Shaw, and Sheep Creek Reservoirs, the program also intends to afford and maintain healthy aquatic conditions for fish growth and survival, to provide superior facilities with wilderness qualities to attract non-Tribal angler use, and to offer clear, consistent communication with the Tribal community about this project as well as outreach and education within the region and the local community. Tasks for this performance period are divided into operations and maintenance plus monitoring and evaluation. Operation and maintenance of the three reservoirs include fences, roads, dams and all reservoir structures, feeder canals, water troughs and stock ponds, educational signs, vehicles and equipment, and outhouses. Monitoring and evaluation activities included creel, gillnet, wildlife, and bird surveys, water quality and reservoir structures monitoring, native vegetation planting, photo point documentation, control of encroaching exotic vegetation, and community outreach and education. The three reservoirs are monitored in terms of water quality and fishery success. Sheep Creek Reservoir was the least productive as a result of high turbidity levels and constraining water quality parameters. Lake Billy Shaw trout were in poorer condition than in previous years potentially as a result of water quality or other factors. Mountain View Reservoir trout exhibit the best health of the three reservoirs and was the only reservoir to receive constant flows of water.

  3. The reliability of fishing statistics as a source for catches and fish stocks in antiquity

    DEFF Research Database (Denmark)

    Jacobsen, A. Lif Lund

    2005-01-01

    In 1985, T.W. Gallant published an influential essay on the potential productivity of fishing in the ancient world. He concluded that: ”the role of fishing in the diet and economy would have been, on the whole, subordinate and supplementary…” His methodological approach was original in using modern...

  4. Estimating fish exploitation and aquatic habitat loss across diffuse inland recreational fisheries.

    Science.gov (United States)

    de Kerckhove, Derrick Tupper; Minns, Charles Kenneth; Chu, Cindy

    2015-01-01

    The current state of many freshwater fish stocks worldwide is largely unknown but suspected to be vulnerable to exploitation from recreational fisheries and habitat degradation. Both these factors, combined with complex ecological dynamics and the diffuse nature of inland fisheries could lead to an invisible collapse: the drastic decline in fish stocks without great public or management awareness. In this study we provide a method to address the pervasive knowledge gaps in regional rates of exploitation and habitat degradation, and demonstrate its use in one of North America's largest and most diffuse recreational freshwater fisheries (Ontario, Canada). We estimated that (1) fish stocks were highly exploited and in apparent danger of collapse in management zones close to large population centres, and (2) fish habitat was under a low but constant threat of degradation at rates comparable to deforestation in Ontario and throughout Canada. These findings confirm some commonly held, but difficult to quantify, beliefs in inland fisheries management but also provide some further insights including (1) large anthropogenic projects greater than one hectare could contribute much more to fish habitat loss on an area basis than the cumulative effect of smaller projects within one year, (2) hooking mortality from catch-and-release fisheries is likely a greater source of mortality than the harvest itself, and (3) in most northern management zones over 50% of the fisheries resources are not yet accessible to anglers. While this model primarily provides a framework to prioritize management decisions and further targeted stock assessments, we note that our regional estimates of fisheries productivity and exploitation were similar to broadscale monitoring efforts by the Province of Ontario. We discuss the policy implications from our results and extending the model to other jurisdictions and countries.

  5. Biomass models to estimate carbon stocks for hardwood tree species

    Energy Technology Data Exchange (ETDEWEB)

    Ruiz-Peinado, R.; Montero, G.; Rio, M. del

    2012-11-01

    To estimate forest carbon pools from forest inventories it is necessary to have biomass models or biomass expansion factors. In this study, tree biomass models were developed for the main hardwood forest species in Spain: Alnus glutinosa, Castanea sativa, Ceratonia siliqua, Eucalyptus globulus, Fagus sylvatica, Fraxinus angustifolia, Olea europaea var. sylvestris, Populus x euramericana, Quercus canariensis, Quercus faginea, Quercus ilex, Quercus pyrenaica and Quercus suber. Different tree biomass components were considered: stem with bark, branches of different sizes, above and belowground biomass. For each species, a system of equations was fitted using seemingly unrelated regression, fulfilling the additivity property between biomass components. Diameter and total height were explored as independent variables. All models included tree diameter whereas for the majority of species, total height was only considered in the stem biomass models and in some of the branch models. The comparison of the new biomass models with previous models fitted separately for each tree component indicated an improvement in the accuracy of the models. A mean reduction of 20% in the root mean square error and a mean increase in the model efficiency of 7% in comparison with recently published models. So, the fitted models allow estimating more accurately the biomass stock in hardwood species from the Spanish National Forest Inventory data. (Author) 45 refs.

  6. How systematic age underestimation can impede understanding of fish population dynamics: Lessons learned from a Lake Superior cisco stock

    Science.gov (United States)

    Yule, D.L.; Stockwell, J.D.; Black, J.A.; Cullis, K.I.; Cholwek, G.A.; Myers, J.T.

    2008-01-01

    Systematic underestimation of fish age can impede understanding of recruitment variability and adaptive strategies (like longevity) and can bias estimates of survivorship. We suspected that previous estimates of annual survival (S; range = 0.20-0.44) for Lake Superior ciscoes Coregonus artedi developed from scale ages were biased low. To test this hypothesis, we estimated the total instantaneous mortality rate of adult ciscoes from the Thunder Bay, Ontario, stock by use of cohort-based catch curves developed from commercial gill-net catches and otolith-aged fish. Mean S based on otolith ages was greater for adult females (0.80) than for adult males (0.75), but these differences were not significant. Applying the results of a study of agreement between scale and otolith ages, we modeled a scale age for each otolith-aged fish to reconstruct catch curves. Using modeled scale ages, estimates of S (0.42 for females, 0.36 for males) were comparable with those reported in past studies. We conducted a November 2005 acoustic and midwater trawl survey to estimate the abundance of ciscoes when the fish were being harvested for roe. Estimated exploitation rates were 0.085 for females and 0.025 for males, and the instantaneous rates of fishing mortality were 0.089 for females and 0.025 for males. The instantaneous rates of natural mortality were 0.131 and 0.265 for females and males, respectively. Using otolith ages, we found that strong year-classes at large during November 2005 were caught in high numbers as age-1 fish in previous annual bottom trawl surveys, whereas weak or absent year-classes were not. For decades, large-scale fisheries on the Great Lakes were allowed to operate because ciscoes were assumed to be short lived and to have regular recruitment. We postulate that the collapse of these fisheries was linked in part to a misunderstanding of cisco biology driven by scale-ageing error. ?? Copyright by the American Fisheries Society 2008.

  7. Implications of fisheries during the spawning season for the sustainable management and recovery of depleted fish stocks: a conceptual framework

    NARCIS (Netherlands)

    Rijnsdorp, A.D.

    2009-01-01

    Fishing during the spawning season may negatively affects the reproductive potential and reproductive dynamics of exploited fish stocks due to a variety of mechanisms such as the disturbance of the natural spawning behaviour, effects on the age, size and sex composition of the spawning population

  8. Lessons learned from practical approaches to reconcile mismatches between biological population structure and stock units of marine fish

    DEFF Research Database (Denmark)

    Kerr, Lisa A.; Hintzen, Niels T.; Cadrin, Steven X.

    2017-01-01

    for overexploitation of unique spawning components, which can lead to loss of productivity and reduced biodiversity along with destabilization of local and regional stock dynamics. Furthermore, ignoring complex population structure and stock connectivity can lead to misperception of the magnitude of fish productivity......, which can translate to suboptimal utilization of the resource. We describe approaches that are currently being applied to improve the assessment and management process for marine fish in situations where complex spatial structure has led to an observed mismatch between the scale of biological...... and resilience of fish species....

  9. Portfolio theory as a management tool to guide conservation and restoration of multi-stock fish populations

    Science.gov (United States)

    DuFour, Mark R.; May, Cassandra J.; Roseman, Edward F.; Ludsin, Stuart A.; Vandergoot, Christopher S.; Pritt, Jeremy J.; Fraker, Michael E.; Davis, Jeremiah J.; Tyson, Jeffery T.; Miner, Jeffery G.; Marschall, Elizabeth A.; Mayer, Christine M.

    2015-01-01

    Habitat degradation and harvest have upset the natural buffering mechanism (i.e., portfolio effects) of many large-scale multi-stock fisheries by reducing spawning stock diversity that is vital for generating population stability and resilience. The application of portfolio theory offers a means to guide management activities by quantifying the importance of multi-stock dynamics and suggesting conservation and restoration strategies to improve naturally occurring portfolio effects. Our application of portfolio theory to Lake Erie Sander vitreus (walleye), a large population that is supported by riverine and open-lake reef spawning stocks, has shown that portfolio effects generated by annual inter-stock larval fish production are currently suboptimal when compared to potential buffering capacity. Reduced production from riverine stocks has resulted in a single open-lake reef stock dominating larval production, and in turn, high inter-annual recruitment variability during recent years. Our analyses have shown (1) a weak average correlation between annual river and reef larval production (ρ̄ = 0.24), suggesting that a natural buffering capacity exists in the population, and (2) expanded annual production of larvae (potential recruits) from riverine stocks could stabilize the fishery by dampening inter-annual recruitment variation. Ultimately, our results demonstrate how portfolio theory can be used to quantify the importance of spawning stock diversity and guide management on ecologically relevant scales (i.e., spawning stocks) leading to greater stability and resilience of multi-stock populations and fisheries.

  10. Measurement Error Affects Risk Estimates for Recruitment to the Hudson River Stock of Striped Bass

    Directory of Open Access Journals (Sweden)

    Dennis J. Dunning

    2002-01-01

    Full Text Available We examined the consequences of ignoring the distinction between measurement error and natural variability in an assessment of risk to the Hudson River stock of striped bass posed by entrainment at the Bowline Point, Indian Point, and Roseton power plants. Risk was defined as the probability that recruitment of age-1+ striped bass would decline by 80% or more, relative to the equilibrium value, at least once during the time periods examined (1, 5, 10, and 15 years. Measurement error, estimated using two abundance indices from independent beach seine surveys conducted on the Hudson River, accounted for 50% of the variability in one index and 56% of the variability in the other. If a measurement error of 50% was ignored and all of the variability in abundance was attributed to natural causes, the risk that recruitment of age-1+ striped bass would decline by 80% or more after 15 years was 0.308 at the current level of entrainment mortality (11%. However, the risk decreased almost tenfold (0.032 if a measurement error of 50% was considered. The change in risk attributable to decreasing the entrainment mortality rate from 11 to 0% was very small (0.009 and similar in magnitude to the change in risk associated with an action proposed in Amendment #5 to the Interstate Fishery Management Plan for Atlantic striped bass (0.006— an increase in the instantaneous fishing mortality rate from 0.33 to 0.4. The proposed increase in fishing mortality was not considered an adverse environmental impact, which suggests that potentially costly efforts to reduce entrainment mortality on the Hudson River stock of striped bass are not warranted.

  11. The Use of Indicators in Modified Historical Model to Estimate the Intrinsic Value of a Stock

    Directory of Open Access Journals (Sweden)

    Gottwald Radim

    2012-06-01

    Full Text Available The article mentions several methods of a fundamental analysis used to value stocks. It primarily focuses on the historical model. This model enables undervalued, correctly valued and overvalued stocks to be identified. The model is further modified in the article, using selected accounting indicators. The modified model versions are applied to selected stocks in the SPAD segment, Prague Stock Exchange, within the 2005-2010 period. Empirical analysis is applied to a comparison of accuracy of the accounting indicator value estimates and accuracy of stock intrinsic value estimates, both separately for each stock and accounting indicator. The comparisons of accuracy of the accounting indicator value estimates and the accuracy of the stock intrinsic value estimates are also done based on the length of applied time period. With respect to the obvious fierce competition between stock issuers within the financial markets, the model enables potential investors, who are to select from an extensive offer of stocks, to make better informed investment decisions.

  12. Parasites as biological tags of fish stocks: a meta-analysis of their discriminatory power.

    Science.gov (United States)

    Poulin, Robert; Kamiya, Tsukushi

    2015-01-01

    The use of parasites as biological tags to discriminate among marine fish stocks has become a widely accepted method in fisheries management. Here, we first link this approach to its unstated ecological foundation, the decay in the similarity of the species composition of assemblages as a function of increasing distance between them, a phenomenon almost universal in nature. We explain how distance decay of similarity can influence the use of parasites as biological tags. Then, we perform a meta-analysis of 61 uses of parasites as tags of marine fish populations in multivariate discriminant analyses, obtained from 29 articles. Our main finding is that across all studies, the observed overall probability of correct classification of fish based on parasite data was about 71%. This corresponds to a two-fold improvement over the rate of correct classification expected by chance alone, and the average effect size (Zr = 0·463) computed from the original values was also indicative of a medium-to-large effect. However, none of the moderator variables included in the meta-analysis had a significant effect on the proportion of correct classification; these moderators included the total number of fish sampled, the number of parasite species used in the discriminant analysis, the number of localities from which fish were sampled, the minimum and maximum distance between any pair of sampling localities, etc. Therefore, there are no clear-cut situations in which the use of parasites as tags is more useful than others. Finally, we provide recommendations for the future usage of parasites as tags for stock discrimination, to ensure that future applications of the method achieve statistical rigour and a high discriminatory power.

  13. Micro-PIXE analysis of fish otoliths. Methodology and evaluation of first results for stock discrimination

    International Nuclear Information System (INIS)

    Sie, S.H.; Thresher, R.E.

    1992-01-01

    Micro-PIXE has been used to measure the trace element distribution in otoliths from several species of ocean fish, in order to investigate its possible use in stock discrimination. Trace elements detected include Sr, Fe, Mn, Ni, Zn, Cu, Se, Cd, Br, Hg and Pb. Trace elements Na, K, Cl, S and Cl were detected with the electron microprobe. The high sensitivity of PIXE demands a meticulous sample preparation procedure to avoid contamination problems. Practical problems associated with the application of the technique were investigated in detail. Preliminary results indicate that most trace elements except Sr, are present at close to the limits of detection at few ppm, but biologically significant data can be obtained for stock discrimination applications. (author)

  14. Optimal harvesting of fish stocks under a time-varying discount rate.

    Science.gov (United States)

    Duncan, Stephen; Hepburn, Cameron; Papachristodoulou, Antonis

    2011-01-21

    Optimal control theory has been extensively used to determine the optimal harvesting policy for renewable resources such as fish stocks. In such optimisations, it is common to maximise the discounted utility of harvesting over time, employing a constant time discount rate. However, evidence from human and animal behaviour suggests that we have evolved to employ discount rates which fall over time, often referred to as "hyperbolic discounting". This increases the weight on benefits in the distant future, which may appear to provide greater protection of resources for future generations, but also creates challenges of time-inconsistent plans. This paper examines harvesting plans when the discount rate declines over time. With a declining discount rate, the planner reduces stock levels in the early stages (when the discount rate is high) and intends to compensate by allowing the stock level to recover later (when the discount rate will be lower). Such a plan may be feasible and optimal, provided that the planner remains committed throughout. However, in practice there is a danger that such plans will be re-optimized and adjusted in the future. It is shown that repeatedly restarting the optimization can drive the stock level down to the point where the optimal policy is to harvest the stock to extinction. In short, a key contribution of this paper is to identify the surprising severity of the consequences flowing from incorporating a rather trivial, and widely prevalent, "non-rational" aspect of human behaviour into renewable resource management models. These ideas are related to the collapse of the Peruvian anchovy fishery in the 1970's. Copyright © 2010 Elsevier Ltd. All rights reserved.

  15. ESTIMATING THE STOCK OF GLASS EELS IN AN ESTUARY BY MARK-RECAPTURE EXPERIMENTS USING VITAL DYES

    Directory of Open Access Journals (Sweden)

    BRIAND C.

    2005-10-01

    Full Text Available Glass eels (Anguilla anguilla arriving after the fishing season in the Vilaine estuary (France were caught by boat and at a trapping ladder located at a blocking dam upstream in the estuary. They were marked with Bismarck brown, rhodamine B or neutral red, and released into the estuary. The effect of marking on behaviour, mortality and recapture differed according to the dye and concentration used. The glass eels also differed in response to marking according to their origin. Estuarine glass eels were clearly desynchronized in their selective tidal stream transport and left the release area after a few tidal cycles. Trapped glass eels were less sensitive to marking. They remained in the release area and were recaptured in larger number both in the trapping ladder and in the estuary. These results supported a model of two behavioral fractions in the estuary: flow-carried migrants and active glass eels with stronger rheotactic behaviour. The proportion of active glass eels in the estuary shifted from none for the two weeks after the fishery closure, to 10% value of the total stock. At the trapping ladder, the migration ended in June each year, while a large stock was still present in the estuary. These observations favour the interpretation of a short duration of the active phase at this site followed by the transition towards a more benthic behavior. The daily efficiency of the trapping ladder was calculated as 4% of the active stock from both stock estimations and average recapture rate. This value was consistent with the low annual efficiency of the trapping ladder, calculated as 30% of the estuarine stock of glass eels that arrived after the fishing season.

  16. Forecasting fish stock dynamics under climate change: Baltic herring (Clupea harengus) as a case study

    DEFF Research Database (Denmark)

    Bartolino, V.; Margonski, P.; Lindegren, Martin

    2014-01-01

    Climate change and anthropogenic disturbances may affect marine populations and ecosystems through multiple pathways. In this study we present a framework in which we integrate existing models and knowledge on basic regulatory processes to investigate the potential impact of future scenarios...... of fisheries exploitation and climate change on the temporal dynamics of the central Baltic herring stock. Alternative scenarios of increasing sea surface temperature and decreasing salinity of the Baltic Sea from a global climate model were combined with two alternative fishing scenarios, and their direct......-term fish dynamics can be an informative tool to derive expectations of the potential long-term impact of alternative future scenarios of exploitation and climate change...

  17. An Economical Approach to Estimate a Benchmark Capital Stock. An Optimal Consistency Method

    OpenAIRE

    Jose Miguel Albala-Bertrand

    2003-01-01

    There are alternative methods of estimating capital stock for a benchmark year. However, these methods are costly and time-consuming, requiring the gathering of much basic information as well as the use of some convenient assumptions and guesses. In addition, a way is needed of checking whether the estimated benchmark is at the correct level. This paper proposes an optimal consistency method (OCM), which enables a capital stock to be estimated for a benchmark year, and which can also be used ...

  18. The statistical properties of recreational catch rate data for some fish stocks off the northeast U.S. coast

    OpenAIRE

    Terceiro, Mark

    2003-01-01

    Recreational fisheries in the waters off the northeast U.S. target a variety of pelagic and demersal fish species, and catch and effort data sampled from recreational fisheries are a critical component of the information used in resource evaluation and management. Standardized indices of stock abundance developed from recreational fishery catch rates are routinely used in stock assessments. The statistical properties of both simulated and empirical recreational fishery catch-rate data such...

  19. Estimating the size of juvenile fish populations in southeastern coastal-plain estuaries

    International Nuclear Information System (INIS)

    Kjelson, M.A.

    1977-01-01

    Understanding the ecological significance of man's activities upon fishery resources requires information on the size of affected fish stocks. The objective of this paper is to provide information to evaluate and plan sampling programs designed to obtain accurate and precise estimates of fish abundance. Nursery habitats, as marsh--tidal creeks and submerged grass beds, offer the optimal conditions for estimating natural mortality rates for young-of-the-year fish in Atlantic and Gulf of Mexico coast estuaries. The area-density method of abundance estimation using quantitative gears is more feasible than either mark-recapture or direct-count techniques. The blockage method provides the most accurate estimates, while encircling devices enable highly mobile species found in open water to be captured. Drop nets and lift nets allow samples to be taken in obstructed sites, but trawls and seines are the most economical gears. Replicate samples are necessary to improve the precision of density estimates, while evaluation and use of gear-catch efficiencies is feasible and required to improve the accuracy of density estimates. Coefficients of variation for replicate trawl samples range from 50 to 150 percent, while catch efficiencies for both trawls and seines for many juvenile fishes range from approximately 30 to 70 percent

  20. Inference for lidar-assisted estimation of forest growing stock volume

    Science.gov (United States)

    Ronald E. McRoberts; Erik Næsset; Terje. Gobakken

    2013-01-01

    Estimates of growing stock volume are reported by the national forest inventories (NFI) of most countries and may serve as the basis for aboveground biomass and carbon estimates as required by an increasing number of international agreements. The probability-based (design-based) statistical estimators traditionally used by NFIs to calculate estimates are generally...

  1. Status and trends of the major roundfish, flatfish, and pelagic fish stocks in the North Sea : Thirty-year overview

    DEFF Research Database (Denmark)

    Serchuk, F.M.; Kirkegaard, Eskild; Daan, N.

    1996-01-01

    Changes in the status of the major roundfish, flatfish, and pelagic stocks in the North Sea over the past 30 years are reviewed. Synopses are presented on trends in catches, fishing mortality, spawning-stock biomass, and recruitment for eight stocks (cod, haddock, whiting, saithe, plaice, sole......, herring, and mackerel), together with an evaluation of the current state of these resources and the most resent management advice provided by the ICES Advisory, Committee on Fishery Management. (C) 1996 International Council for the Exploration of the Sea...

  2. Quantifying the uncertainty of regional and national estimates of soil carbon stocks

    Science.gov (United States)

    Papritz, Andreas

    2013-04-01

    At regional and national scales, carbon (C) stocks are frequently estimated by means of regression models. Such statistical models link measurements of carbons stocks, recorded for a set of soil profiles or soil cores, to covariates that characterize soil formation conditions and land management. A prerequisite is that these covariates are available for any location within a region of interest G because they are used along with the fitted regression coefficients to predict the carbon stocks at the nodes of a fine-meshed grid that is laid over G. The mean C stock in G is then estimated by the arithmetic mean of the stock predictions for the grid nodes. Apart from the mean stock, the precision of the estimate is often also of interest, for example to judge whether the mean C stock has changed significantly between two inventories. The standard error of the estimated mean stock in G can be computed from the regression results as well. Two issues are thereby important: (i) How large is the area of G relative to the support of the measurements? (ii) Are the residuals of the regression model spatially auto-correlated or is the assumption of statistical independence tenable? Both issues are correctly handled if one adopts a geostatistical block kriging approach for estimating the mean C stock within a region and its standard error. In the presentation I shall summarize the main ideas of external drift block kriging. To compute the standard error of the mean stock, one has in principle to sum the elements a potentially very large covariance matrix of point prediction errors, but I shall show that the required term can be approximated very well by Monte Carlo techniques. I shall further illustrated with a few examples how the standard error of the mean stock estimate changes with the size of G and with the strenght of the auto-correlation of the regression residuals. As an application a robust variant of block kriging is used to quantify the mean carbon stock stored in the

  3. Resident Fish Stock Status above Chief Joseph and Grand Coulee Dams; 2001 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Connor, Jason M. (Kalispell Department of Natural Resources, Usk, WA); McLellan, Jason G. (Washington Department of Fish and Wildlife, Spokane, WA); O' Connor, Dick (Washington Department of Fish and Wildlife, Olympia, WA)

    2003-01-01

    In 1980, the United States Congress enacted the Northwest Power Planning and Conservation Act (PL 96-501, 1980), which established the Northwest Power Planning Council (NPPC). The NPPC was directed by Congress to develop a regional Power Plan and also the Columbia River Basin Fish and Wildlife Program (FWP) to restore or replace losses of fish caused by construction and operation of hydroelectric dams in the Columbia River Basin. In developing the FWP, Congress specifically directed NPPC to solicit recommendations for measures to be included in the Program from the region's fish and wildlife agencies and Indian tribes. All measures adopted by the Council were also required to be consistent with the management objectives of the agencies and tribes [Section 4.(h)(6)(A)], the legal rights of Indian tribes in the region [Section 4.(h)(6)(D)] and be based upon and supported by the best available scientific knowledge [Section 4.(h)(6)(B)]. The Resident Fish Stock Status above Chief Joseph and Grand Coulee Dams Project, also known as the Joint Stock Assessment Project (JSAP) specifically addresses NPPC Council measure 10.8B.26 of the 1994 program. The Joint Stock Assessment Project is a management tool using ecosystem principles to manage artificial fish assemblages and native fish in altered environments existing in the Columbia River System above Chief Joseph and Grand Coulee Dams (Blocked Area). A three-phase approach of this project will enhance the fisheries resources of the Blocked Area by identifying data gaps, filling data gaps with research, and implementing management recommendations based on research results. The Blocked Area fisheries information is housed in a central location, allowing managers to view the entire system while making decisions, rather than basing management decisions on isolated portions of the system. The JSAP is designed and guided jointly by fisheries managers in the Blocked Area and the Columbia Basin Blocked Area Management Plan

  4. Resident Fish Stock above Chief Joseph and Grand Coulee Dams; 2002 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Connor, Jason M. (Kalispel Department of Natural Resources, Usk, WA); McLellan, Jason G. (Washington Department of Fish and Wildlife, Spokane, WA); Butler, Chris (Spokane Tribe of Indians, Department of Natural Resources, Wellpinit, WA)

    2003-09-01

    In 1980, the United States Congress enacted the Northwest Power Planning and Conservation Act (PL 96-501, 1980), which established the Northwest Power and Conservation Council (NPCC), formerly the Northwest Power Planning Council. The NPCC was directed by Congress to develop a regional Power Plan and also the Columbia River Basin Fish and Wildlife Program (FWP) to restore or replace losses of fish caused by construction and operation of hydroelectric dams in the Columbia River Basin. In developing the FWP, Congress specifically directed NPCC to solicit recommendations for measures to be included in the Program from the region's fish and wildlife agencies and Indian tribes. All measures adopted by the Council were also required to be consistent with the management objectives of the agencies and tribes [Section 4.(h)(6)(A)], the legal rights of Indian tribes in the region [Section 4.(h)(6)(D)] and be based upon and supported by the best available scientific knowledge [Section 4.(h)(6)(B)]. The Resident Fish Stock Status above Chief Joseph and Grand Coulee Dams Project, also known as the Joint Stock Assessment Project (JSAP) specifically addresses NPPC Council measure 10.8B.26 of the 1994 program. The Joint Stock Assessment Project is a management tool using ecosystem principles to manage artificial fish assemblages and native fish in altered environments existing in the Columbia River System above Chief Joseph and Grand Coulee Dams (Blocked Area). A three-phase approach of this project will enhance the fisheries resources of the Blocked Area by identifying data gaps, filling data gaps with research, and implementing management recommendations based on research results. The Blocked Area fisheries information is housed in a central location, allowing managers to view the entire system while making decisions, rather than basing management decisions on isolated portions of the system. The JSAP is designed and guided jointly by fisheries managers in the Blocked Area

  5. Above Ground Carbon Stock Estimates of Mangrove Forest Using Worldview-2 Imagery in Teluk Benoa, Bali

    Science.gov (United States)

    Candra, E. D.; Hartono; Wicaksono, P.

    2016-11-01

    Mangrove forests have a role as an absorbent and a carbon sink to a reduction CO2 in the atmosphere. Based on the previous studies found that mangrove forests have the ability to sequestering carbon through photosynthesis and carbon burial of sediment effectively. The value and distribution of carbon stock are important to understand through remote sensing technology. In this study, will estimate the carbon stock using WorldView-2 imagery with and without distinction mangrove species. Worldview-2 is a high resolution image with 2 meters spatial resolution and eight spectral bands. Worldview-2 potential to estimate carbon stock in detail. Vegetation indices such as DVI (Difference Vegetation Index), EVI (Enhanced Vegetation Index), and MRE-SR (Modified Red Edge-Simple Ratio) and field data were modeled to determine the best vegetation indices to estimate carbon stocks. Carbon stock estimated by allometric equation approach specific to each species of mangrove. Worldview-2 imagery to map mangrove species with an accuracy of 80.95%. Total carbon stock estimation results in the study area of 35.349,87 tons of dominant species Rhizophora apiculata, Rhizophora mucronata and Sonneratia alba.

  6. Admixture analysis and stocking impact assessment in brown trout ( Salmo trutta ), estimated with incomplete baseline data

    DEFF Research Database (Denmark)

    Hansen, Michael Møller; Eg Nielsen, Einar; Bekkevold, Dorte

    2001-01-01

    the populations contributing to admixture. We applied the method to analyse the genetic contribution of domesticated brown trout (Salmo trutta) in samples of anadromous trout from two stocked populations with no genetic data available before stocking. Further, we estimated population level admixture proportions...... by the mean of individual admixture coefficients. This method proved more informative than a multidimensional scaling analysis of individual-based genetic distances and assignment tests. The results showed almost complete absence of stocked, domesticated trout in samples of trout from the rivers. Consequently......, stocking had little effect on improving fisheries. In one population, the genetic contribution by domesticated trout was small, whereas in the other population, some genetic impact was suggested. Admixture in this sample of anadromous trout despite absence of stocked domesticated trout could be because...

  7. Resident Fish Stock above Chief Joseph and Grand Coulee Dams; 2003-2004 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Connor, Jason M. (Kalispel Tribe of Indians, Usk, WA); McLellan, Jason G. (Washington Department of Fish and Wildlife, Olympia, WA); Butler, Chris (Spokane Tribe of Indians, Wellpinit, WA)

    2005-11-01

    In 1980, the United States Congress enacted the Northwest Power Planning and Conservation Act (PL 96-501, 1980), which established the Northwest Power and Conservation Council (NPCC), formerly the Northwest Power Planning Council. The NPCC was directed by Congress to develop a regional Power Plan and also the Columbia River Basin Fish and Wildlife Program (FWP) to restore or replace losses of fish caused by construction and operation of hydroelectric dams in the Columbia River Basin. In developing the FWP, Congress specifically directed NPCC to solicit recommendations for measures to be included in the Program from the region's fish and wildlife agencies and Indian tribes. All measures adopted by the Council were also required to be consistent with the management objectives of the agencies and tribes [Section 4.(h)(6)(A)], the legal rights of Indian tribes in the region [Section 4.(h)(6)(D)] and be based upon and supported by the best available scientific knowledge [Section 4.(h)(6)(B)]. The Resident Fish Stock Status above Chief Joseph and Grand Coulee Dams Project, also known as the Joint Stock Assessment Project (JSAP) specifically addresses NPPC Council measure 10.8B.26 of the 1994 program. The Joint Stock Assessment Project is a management tool using ecosystem principles to manage artificial and native fish assemblages in altered environments existing in the Columbia River System above Chief Joseph and Grand Coulee Dams (Blocked Area). A three-phase approach of this project will enhance the fisheries resources of the Blocked Area by identifying data gaps, filling data gaps with research, and implementing management recommendations based on research results. The Blocked Area fisheries information is housed in a central location, allowing managers to view the entire system while making decisions, rather than basing management decisions on isolated portions of the system. The JSAP is designed and guided jointly by fisheries managers in the Blocked Area. The

  8. Resident Fish Stock Status above Chief Joseph and Grand Coulee Dams; 2002-2003 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Connor, Jason M. (Kalispel Tribe of Indians, Usk, WA); McLellan, Jason G. (Washington Department of Fish and Wildlife); Butler, Chris (Spokane Tribe of Indians, Wellpinit, WA)

    2006-02-01

    In 1980, the United States Congress enacted the Northwest Power Planning and Conservation Act (PL 96-501, 1980), which established the Northwest Power and Conservation Council (NPCC), formerly the Northwest Power Planning Council. The NPCC was directed by Congress to develop a regional Power Plan and also the Columbia River Basin Fish and Wildlife Program (FWP) to restore or replace losses of fish caused by construction and operation of hydroelectric dams in the Columbia River Basin. In developing the FWP, Congress specifically directed NPCC to solicit recommendations for measures to be included in the Program from the region's fish and wildlife agencies and Indian tribes. All measures adopted by the Council were also required to be consistent with the management objectives of the agencies and tribes [Section 4.(h)(6)(A)], the legal rights of Indian tribes in the region [Section 4.(h)(6)(D)] and be based upon and supported by the best available scientific knowledge [Section 4.(h)(6)(B)]. The Resident Fish Stock Status above Chief Joseph and Grand Coulee Dams Project, also known as the Joint Stock Assessment Project (JSAP) specifically addresses NPPC Council measure 10.8B.26 of the 1994 program. The Joint Stock Assessment Project is a management tool using ecosystem principles to manage artificial and native fish assemblages in altered environments existing in the Columbia River System above Chief Joseph and Grand Coulee Dams (Blocked Area). A three-phase approach of this project will enhance the fisheries resources of the Blocked Area by identifying data gaps, filling data gaps with research, and implementing management recommendations based on research results. The Blocked Area fisheries information is housed in a central location, allowing managers to view the entire system while making decisions, rather than basing management decisions on isolated portions of the system. The JSAP is designed and guided jointly by fisheries managers in the Blocked Area. The

  9. Managing a fish stock without knowledge of its mag- nitude and the ...

    African Journals Online (AJOL)

    denise

    The best estimate was some 134 tons, a value also proposed as the limit reference point. Current depletion .... where M∞ is 0.208 year-1 and t is the age of the fish. This mortality value ..... ever, point to a slightly different situation. For example,.

  10. Agonistic behavior among three stocked trout species in a novel reservoir fish community

    Science.gov (United States)

    Budy, Phaedra; Hafen, Konrad

    2015-01-01

    The popularity of reservoirs to support sport fisheries has led to the stocking of species that did not co-evolve, creating novel reservoir fish communities. In Utah, the Bear Lake strain of Bonneville Cutthroat Trout Oncorhynchus clarkii utah and tiger trout (female Brown Trout Salmo trutta × male Brook Trout Salvelinus fontinalis) are being more frequently added to a traditional stocking regimen consisting primarily of Rainbow TroutO. mykiss. Interactions between these three predatory species are not well understood, and studies evaluating community interactions have raised concern for an overall decrease of trout condition. To evaluate the potential for negative interactions among these species, we tested aggression in laboratory aquaria using three-species and pairwise combinations at three densities. Treatments were replicated before and after feeding. During the three-species trials Rainbow Trout initiated 24.8 times more aggressive interactions than Cutthroat Trout and 10.2 times more aggressive interactions than tiger trout, and tiger trout exhibited slightly (1.9 times) more aggressive initiations than Cutthroat Trout. There was no significant difference in behavior before versus after feeding for any species, and no indication of increased aggression at higher densities. Although Rainbow Trout in aquaria may benefit from their bold, aggressive behavior, given observations of decreased relative survival in the field, these benefits may be outweighed in reservoirs, possibly through unnecessary energy expenditure and exposure to predators.

  11. Estimating the risk-return tradeoff in MENA Stock Markets

    Directory of Open Access Journals (Sweden)

    Salim Lahmiri

    2013-04-01

    Full Text Available This study employs the generalized autoregressive conditionally heteroskedastic in the mean (GARCH-M methodology to investigate the return generating process of Jordan, Kingdom of Saudi Arabia (KSA, Kuwait, and Morocco stock market indices. The tradeoff between returns and the conditional variance is found to be positive in all markets. In other words, the empirical findings show that investors are rewarded for their exposure to more risk in these financial markets. This result is consistent with both financial theory and empirical finance.

  12. APPLYING ARTIFICIAL NEURAL NETWORK OPTIMIZED BY FIREWORKS ALGORITHM FOR STOCK PRICE ESTIMATION

    Directory of Open Access Journals (Sweden)

    Khuat Thanh Tung

    2016-04-01

    Full Text Available Stock prediction is to determine the future value of a company stock dealt on an exchange. It plays a crucial role to raise the profit gained by firms and investors. Over the past few years, many methods have been developed in which plenty of efforts focus on the machine learning framework achieving the promising results. In this paper, an approach based on Artificial Neural Network (ANN optimized by Fireworks algorithm and data preprocessing by Haar Wavelet is applied to estimate the stock prices. The system was trained and tested with real data of various companies collected from Yahoo Finance. The obtained results are encouraging.

  13. Do lake littoral benthic invertebrates respond differently to eutrophication, hydromorphological alteration, land use and fish stocking?

    Directory of Open Access Journals (Sweden)

    Šiling Rebeka

    2016-01-01

    Full Text Available In order to provide adequate guidelines in freshwater management, managers need reliable bioindicators that can respond differently to varied stressors. Managers also have to consider hierarchical structure of environmental factors. Thus, our research aims to test the independence of taxa responses along environmental gradients and to examine in what order natural and anthropogenic factors constrain the structure of littoral benthic assemblages. The rank of explained variance of littoral benthic assemblage's variable group hierarchy was: land use > landscape characteristics > eutrophication > fish stocking > hydromorphological alteration. We determined nine gradients (two natural and seven stressor gradients, separated into five groups based on statistically significant differences in responsiveness of taxa. Apart from responsiveness to natural factors, littoral benthic invertebrates could be used as bioindicators for stressors reflecting urbanization, eutrophication, hydromorphological alteration and fish stocking. The taxonomical composition of littoral benthic invertebrates, especially when taxa with preference for certain relatively narrow environmental conditions along gradients are present, can be used to identify effects of key stressors. Our findings have profound implications for ecological assessment and management of lakes, as they indicate that benthic invertebrates can be used when the effects of multiple stressors need to be disentangled.

  14. Recovery And Valorization Of Snakehead Fish Channa Striata Surimi Wash Water As Stock Albumin Tablet

    Directory of Open Access Journals (Sweden)

    Ikbal Syukroni

    2017-11-01

    Full Text Available Surimi washing process is aimed to concentrate the myofibril protein by removing catepsin enzyme fat pigment blood and sarcoplasmic protein which is soluble in wash water. The soluble subtances cause trouble environment if it was untreated. In addition recovery protein will give benefit both in reducing trouble environment and utilizing soluble protein as sources of albumin protein. The objectives of research were to recover albumin from snakehead fish surimi wash water and to valorize as stock albumin tablet. Recovery of albumin use 0.05 m ultrafiltration membrane and the valorization of albumin tablets was by direct compression. The protein band with molecular weight of 67.741 kDa on the retentate was detected as albumin. Concentration of protein recover by ultrafiltration membrane increased 89.98 and the albumin content 3.50.4 gdl. Based on the result of chemical composition and microbiology analysis albumin of snakehead surimi wash water appropriate with Indonesia National Standard SNI quality requirement about snakehead fish albumin extract. The best formulation in the preparation of surimi wash water albumin tablet was by using corn starch excipients with uniformity weight value 410.39 0.09 g hardness value 7.65 0.8 Kp uniformity size of tablet with diameter 1 cm and thickness 0.59 cm friability value 2.3 and disintregation time of the tablet is 2 minutes 16 second.

  15. Addressing catch mechanisms in gillnets improves modeling of selectivity and estimates of mortality rates: a case study using survey data on an endangered stock of Arctic char

    DEFF Research Database (Denmark)

    Jonsson, T.; Setzer, M.; Pope, John George

    2013-01-01

    Estimation of fish stock size distributions from survey data requires knowledge about gear selectivity. However, selectivity models rest on assumptions that seldom are analyzed. Departures from these can lead to misinterpretations and biased management recommendations. Here, we use survey data...... and asymmetric, with poor model fits. Removing potentially nonmeshed fish had the greatest positive effect on model fit, resulting in much narrower and less asymmetric selection curves, while attempting to take nonisometric growth into account, by using girth rather than length, improved model fit...

  16. Does predation by grey seals (Halichoerus grypus) affect Bothnian Sea herring stock estimates?

    DEFF Research Database (Denmark)

    Gårdmark, Anna; Östman, Örjan; Nielsen, Anders

    2012-01-01

    when accounting for seal predation, this did not change the conclusions about drivers of herring dynamics. Accounting for grey seal predation is important for abundance estimates of old herring, but currently not for SSB estimates, given the great uncertainties in the standard assessment. The grey seal...... fivefold since 1985. Its main prey, herring (Clupea harrengus), is a key species for fisheries in the region. Yet, current stock assessments assume constant natural mortality, leading to a risk of biased stock estimates with increasing predation and misleading analyses of herring population dynamics. We...... estimated grey seal predation from diet data and reanalysed herring spawning stock biomass (SSB) during 1973–2009. Accounting for predation increased the herring SSB 16% (maximum 19%), but this was within the confidence intervals when ignoring predation. Although mortality in older individuals was inflated...

  17. Implementing ecosystem-based fisheries management: from single-species to integrated ecosystem assessment and advice for Baltic Sea fish stocks

    DEFF Research Database (Denmark)

    Möllmann, Christian; Lindegren, Martin; Blenckner, Thorsten

    2014-01-01

    -economic factors, in relation to specified management objectives. Here, we focus on implementing the IEA approach for Baltic Sea fish stocks. We combine both tactical and strategic management aspects into a single strategy that supports the present Baltic Sea fish stock advice, conducted by the International...... Council for the Exploration of the Sea (ICES). We first review the state of the art in the development of IEA within the current management framework. We then outline and discuss an approach that integrates fish stock advice and IEAs for the Baltic Sea. We intentionally focus on the central Baltic Sea...... and its three major fish stocks cod (Gadus morhua), herring (Clupea harengus), and sprat (Sprattus sprattus), but emphasize that our approach may be applied to other parts and stocks of the Baltic, as well as other ocean areas...

  18. Resident fish stock status above Chief Joseph and Grand Coulee dams : 2000 annual report; ANNUAL

    International Nuclear Information System (INIS)

    Lockwood, N.; McLellan, J.; Crossley, B.

    2001-01-01

    The Resident Fish Stock Status above Chief Joseph and Grand Coulee Dams Project, commonly known as the Joint Stock Assessment Project (JSAP) is a management tool using ecosystem principles to manage artificial fish assemblages and native fish in altered environments existing in the Columbia River System above Chief Joseph and Grand Coulee Dams (blocked area). The three-phase approach of this project will enhance the fisheries resources of the blocked area by identifying data gaps, filling data gaps with research, and implementing management recommendations based on research results. The Blocked Area fisheries information housed in a central location will allow managers to view the entire system while making decisions, rather than basing management decisions on isolated portions of the system. The JSAP (NWPPC program measure 10.8B.26) is designed and guided jointly by fisheries managers in the blocked area and the Columbia Basin blocked area management plan (1998). The initial year of the project (1997) identified the need for a central data storage and analysis facility, coordination with the StreamNet project, compilation of blocked area fisheries information, and a report on the ecological condition of the Spokane River System. These needs were addressed in 1998 by acquiring a central location with a data storage and analysis system, coordinating a pilot project with StreamNet, compiling fisheries distribution data throughout the blocked area, identifying data gaps based on compiled information, and researching the ecological condition of the Spokane River. In order to ensure that any additional information collected throughout the life of this project will be easily stored and manipulated by the central storage facility, it was necessary to develop standardized methodologies between the JSAP fisheries managers. The use of common collection and analytical tools is essential to the process of streamlining joint management decisions. In 1999 and 2000 the project

  19. Resident Fish Stock Status above Chief Joseph and Grand Coulee Dams; 2000 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Lockwood, Jr., Neil [Kalispel Tribe of Indians, Usk, WA (United States); McLellan, Jason G [Washington Department of Fish and Wildlife, Spokane, WA (United States); Crossley, Brian [Spokane Tribe of Indians, Department of Natural Resources, Wellpinit, WA (United States); O' Connor, Dick

    2001-01-01

    The Resident Fish Stock Status above Chief Joseph and Grand Coulee Dams Project, commonly known as the Joint Stock Assessment Project (JSAP) is a management tool using ecosystem principles to manage artificial fish assemblages and native fish in altered environments existing in the Columbia River System above Chief Joseph and Grand Coulee Dams (blocked area). The three-phase approach of this project will enhance the fisheries resources of the blocked area by identifying data gaps, filling data gaps with research, and implementing management recommendations based on research results. The Blocked Area fisheries information housed in a central location will allow managers to view the entire system while making decisions, rather than basing management decisions on isolated portions of the system. The JSAP (NWPPC program measure 10.8B.26) is designed and guided jointly by fisheries managers in the blocked area and the Columbia Basin blocked area management plan (1998). The initial year of the project (1997) identified the need for a central data storage and analysis facility, coordination with the StreamNet project, compilation of blocked area fisheries information, and a report on the ecological condition of the Spokane River System. These needs were addressed in 1998 by acquiring a central location with a data storage and analysis system, coordinating a pilot project with StreamNet, compiling fisheries distribution data throughout the blocked area, identifying data gaps based on compiled information, and researching the ecological condition of the Spokane River. In order to ensure that any additional information collected throughout the life of this project will be easily stored and manipulated by the central storage facility, it was necessary to develop standardized methodologies between the JSAP fisheries managers. The use of common collection and analytical tools is essential to the process of streamlining joint management decisions. In 1999 and 2000 the project

  20. Inventory-based estimates of forest biomass carbon stocks in China: A comparison of three methods

    Science.gov (United States)

    Zhaodi Guo; Jingyun Fang; Yude Pan; Richard. Birdsey

    2010-01-01

    Several studies have reported different estimates for forest biomass carbon (C) stocks in China. The discrepancy among these estimates may be largely attributed to the methods used. In this study, we used three methods [mean biomass density method (MBM), mean ratio method (MRM), and continuous biomass expansion factor (BEF) method (abbreviated as CBM)] applied to...

  1. Life history inhomogeneity in Baltic Sea whitefish populations revealed by otolith strontium signatures – identification of stocked fish

    Directory of Open Access Journals (Sweden)

    Henry Hägerstrand

    2015-11-01

    The strontium concentrations in the otolith cores of whitefish from River Tornionjoki were higher than that of the four otoliths with low core strontium from fishes caught at sea (Table 1. Supposing that this latter group represent stocked fish raised in freshwater ponds, the vast majority of River Tornionjoki whitefish is naturally reproduced fish. This is plausible because in River Tornionjoki, the major whitefish spawning river in Finland, no larger stocking have been made since 1990s (Jokikokko and Huhmarniemi 2014. In conclusion, the concentration of otolith core strontium differs in whitefish hatched in fresh-water and in whitefish hatched in river water or in brackish Baltic Sea water. This difference can be used to reveal stocked whitefish. Barium concentration may be an even better indicator in this respect than strontium, as previous results indicate (Hägerstrand et al., 2015. Stocked river spawning whitefish appear in large amount at the southern feeding grounds around the Åland Islands, as already indicated by e.g. Leskelä et al. (2009.

  2. Estimating the long-term effects of stocking domesticated trout into wild brown trout ( Salmo trutta ) populations : an approach using microsatellite DNA analysis of historical and contemporary samples

    DEFF Research Database (Denmark)

    Hansen, Michael Møller

    2002-01-01

    . The study was based on analysis of two historical samples (194556), represented by old scale collections, and seven contemporary samples (1986-2000). In one population historical and contemporary samples were remarkably genetically similar despite more than a decade of intense stocking. Estimation...... of admixture proportions showed a small genetic contribution from domesticated trout (approximately 6%), and individual admixture analysis demonstrated a majority of nonadmixed individuals. The expected genetic contribution by domesticated trout was 64%, assessed from the number of stocked trout and assuming...... in samples from a broodstock thought to represent the indigenous population and in a sample of wild spawners. Survival of domesticated trout and admixture with indigenous fish in the broodstock and subsequent stocking into the river, combined with a low population size of native trout relative to the number...

  3. Satellite telemetry reveals higher fishing mortality rates than previously estimated, suggesting overfishing of an apex marine predator.

    Science.gov (United States)

    Byrne, Michael E; Cortés, Enric; Vaudo, Jeremy J; Harvey, Guy C McN; Sampson, Mark; Wetherbee, Bradley M; Shivji, Mahmood

    2017-08-16

    Overfishing is a primary cause of population declines for many shark species of conservation concern. However, means of obtaining information on fishery interactions and mortality, necessary for the development of successful conservation strategies, are often fisheries-dependent and of questionable quality for many species of commercially exploited pelagic sharks. We used satellite telemetry as a fisheries-independent tool to document fisheries interactions, and quantify fishing mortality of the highly migratory shortfin mako shark ( Isurus oxyrinchus ) in the western North Atlantic Ocean. Forty satellite-tagged shortfin mako sharks tracked over 3 years entered the Exclusive Economic Zones of 19 countries and were harvested in fisheries of five countries, with 30% of tagged sharks harvested. Our tagging-derived estimates of instantaneous fishing mortality rates ( F = 0.19-0.56) were 10-fold higher than previous estimates from fisheries-dependent data (approx. 0.015-0.024), suggesting data used in stock assessments may considerably underestimate fishing mortality. Additionally, our estimates of F were greater than those associated with maximum sustainable yield, suggesting a state of overfishing. This information has direct application to evaluations of stock status and for effective management of populations, and thus satellite tagging studies have potential to provide more accurate estimates of fishing mortality and survival than traditional fisheries-dependent methodology. © 2017 The Author(s).

  4. CURRENT STATE OF FISHERIES AND ASSESSMENT OF FISH STOCKS IN THE WESTERN MIDDLE OF THE CASPIAN SEA. PROSPECTS FOR THE USE OF THE FISH RESOURCES

    Directory of Open Access Journals (Sweden)

    A. S. Abdusamadov

    2016-01-01

    Full Text Available Aim. To aim is to assess stocks and the fisheries of aquatic biological resources in the western part of the middle Caspian Sea and perspectives for the use of their resource potential.Methods. On the basis of the literature sources and our own data on the fish inventory in the western part of the Middle Caspian, we discuss possible reasons for emerging environmental, economic and other problems in the use of biological resources.Results. The main negative factors are the large-scale poaching, resulting in a catastrophic reduction in stocks of sturgeon and other valuable fish species of the Caspian Sea, a natural penetration of alien organisms (Mnemiopsis and overfishing of some species. The potential danger is large-scale development of oil and gas fields in the Caspian Sea, which can lead to even worse situation for the biological resources of the sea.Conclusions. In order to preserve the biological resources of the sea it is necessary to create conditions for steadily developing fishing and fish processing enterprises, thus ensuring the satisfaction of the constant demand for fish products and an increase in the revenue base of the budget and the well-being of the Russian population.

  5. Monitoring and estimating tropical forest carbon stocks: making REDD a reality

    International Nuclear Information System (INIS)

    Gibbs, Holly K; Brown, Sandra; Niles, John O; Foley, Jonathan A

    2007-01-01

    Reducing carbon emissions from deforestation and degradation in developing countries is of central importance in efforts to combat climate change. Key scientific challenges must be addressed to prevent any policy roadblocks. Foremost among the challenges is quantifying nations' carbon emissions from deforestation and forest degradation, which requires information on forest clearing and carbon storage. Here we review a range of methods available to estimate national-level forest carbon stocks in developing countries. While there are no practical methods to directly measure all forest carbon stocks across a country, both ground-based and remote-sensing measurements of forest attributes can be converted into estimates of national carbon stocks using allometric relationships. Here we synthesize, map and update prominent forest biomass carbon databases to create the first complete set of national-level forest carbon stock estimates. These forest carbon estimates expand on the default values recommended by the Intergovernmental Panel on Climate Change's National Greenhouse Gas Inventory Guidelines and provide a range of globally consistent estimates

  6. Impacts of the local environment on recruitment: a comparative study of North Sea and Baltic Sea fish stocks

    DEFF Research Database (Denmark)

    Pécuchet, Lauréne; Nielsen, J. Rasmus; Christensen, Asbjørn

    2015-01-01

    of the local environmental variability on the recruitment strength. Hence, the prerecruits' survival variability is studied according to geographically disaggregated and potentially impacting abiotic or biotic variables. Time series (1990-2009) of nine environmental variables consistent with the spawning...... of other fish stocks are regularly significant in the models. This study shows the importance of the local environment on the dynamics of SR. The results provide evidence of the necessity of including environmental variables in stock assessment for a realistic and efficient management of fisheries.......While the impact of environmental forcing on recruitment variability in marine populations remains largely elusive, studies spanning large spatial areas and many stocks are able to identify patterns common to different regions and species. In this study, we investigate the effects...

  7. Consequences of alternative tree-level biomass estimation procedures on U.S. forest carbon stock estimates

    Science.gov (United States)

    Grant M. Domke; Christopher W. Woodall; James E. Smith; James A. Westfall; Ronald E. McRoberts

    2012-01-01

    Forest ecosystems are the largest terrestrial carbon sink on earth and their management has been recognized as a relatively cost-effective strategy for offsetting greenhouse gas emissions. Forest carbon stocks in the U.S. are estimated using data from the USDA Forest Service, Forest Inventory and Analysis (FIA) program. In an attempt to balance accuracy with...

  8. AFSC/REFM: Isolation by distance (IBD) Alaskan fish stock structure modeling

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — There is no established management protocol for stocks subject to isolation-by-distance (IBD) stock structure. This study examines several management strategies for...

  9. Fish stock surveys from 41 sites on the islands of Oahu and Hawaii from September 11, 1952 to December 28, 2000 (NODC Accession 0002754)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data are from underwater visual surveys of fish stocks from 41 survey sites on the islands of Oahu and Hawaii, conducted by biologists and technicians of Hawaii's...

  10. Using basal area to estimate aboveground carbon stocks in forests: La Primavera Biosphere's Reserve, Mexico

    NARCIS (Netherlands)

    Balderas Torres, Arturo; Lovett, Jonathan Cranidge

    2012-01-01

    Increasing use of woody plants for greenhouse gas mitigation has led to demand for rapid, cost-effective estimation of forest carbon stocks. Bole diameter is readily measured and basal area can be correlated to biomass and carbon through application of allometric equations. We explore different

  11. Gear and seasonal bias associated with abundance and size structure estimates for lentic freshwater fishes

    Science.gov (United States)

    Fischer, Jesse R.; Quist, Michael C.

    2014-01-01

    All freshwater fish sampling methods are biased toward particular species, sizes, and sexes and are further influenced by season, habitat, and fish behavior changes over time. However, little is known about gear-specific biases for many common fish species because few multiple-gear comparison studies exist that have incorporated seasonal dynamics. We sampled six lakes and impoundments representing a diversity of trophic and physical conditions in Iowa, USA, using multiple gear types (i.e., standard modified fyke net, mini-modified fyke net, sinking experimental gill net, bag seine, benthic trawl, boat-mounted electrofisher used diurnally and nocturnally) to determine the influence of sampling methodology and season on fisheries assessments. Specifically, we describe the influence of season on catch per unit effort, proportional size distribution, and the number of samples required to obtain 125 stock-length individuals for 12 species of recreational and ecological importance. Mean catch per unit effort generally peaked in the spring and fall as a result of increased sampling effectiveness in shallow areas and seasonal changes in habitat use (e.g., movement offshore during summer). Mean proportional size distribution decreased from spring to fall for white bass Morone chrysops, largemouth bass Micropterus salmoides, bluegill Lepomis macrochirus, and black crappie Pomoxis nigromaculatus, suggesting selectivity for large and presumably sexually mature individuals in the spring and summer. Overall, the mean number of samples required to sample 125 stock-length individuals was minimized in the fall with sinking experimental gill nets, a boat-mounted electrofisher used at night, and standard modified nets for 11 of the 12 species evaluated. Our results provide fisheries scientists with relative comparisons between several recommended standard sampling methods and illustrate the effects of seasonal variation on estimates of population indices that will be critical to

  12. FISH PRODUCTION ESTIMATES FOR GBEDIKERE LAKE, BASSA, KOGI STATE, NIGERIA

    Directory of Open Access Journals (Sweden)

    Samuel Olusegun Adeyemi

    2013-10-01

    Full Text Available Annual estimates of the fish caught by local fishermen in randomly selected fishing villages adjacent to Gbedikere Lake were determined using Catch Assessment (CAS. The studies were carried out within two seasons of low water (February and high water (September periods between 2006 to 2008. Annual fish catch varied from 537.4 mts to 576.9 mts at high water. Mean catch per boat ranged from 7.40 kg to 10.60 kg among the landing sites. A total of 12 fish species were identified belonging to ten families. The catches were dominated by the cichlids with Orechromis niloticus dominating the overall catch compositions. Production estimate was compared with the catches obtained through experimental gill-net sampling and potential fish yield estimates using Ryder’s Morpho - Edaphic Index (MEI as modified by Henderson and Welcomme (1974. Contributions of the gears in use were also done with cast nets ranking above others (29%, followed by the set net (25%, hook and lines (16.6%, traps (16.6%, clap net (8.3%. Management measures were suggested.

  13. Effects of changing nutrient inputs on the ratio of small pelagic fish stock and phytoplankton biomass in the Black Sea

    Science.gov (United States)

    Yunev, Oleg A.; Velikova, Violeta; Carstensen, Jacob

    2017-10-01

    Significant increases in nitrogen and phosphorus inputs to the Black Sea in the second half of the 20th century caused eutrophication and drastically decreasing Si:N and Si:P ratios. Combined with climate change, overfishing of top predators and a huge outbreak of the non-indigenous ctenophore Mnemiopsis, the pelagic food web was strongly modified and its efficiency for channeling primary production to higher trophic levels substantially reduced. We used the ratio between small pelagic fish stock and phytoplankton biomass on the Danube shelf and in the open Black Sea to investigate long-term changes in food web functioning. The ratio had 1) highest values for the pre-eutrophication period when diatoms and copepods dominated the pelagic food web ('muscle food chain'), 2) decreased during the eutrophication period with stronger prevalence of autotrophic pico- and nanophytoplankton, bacteria, heterotrophic nanoflagellates, microzooplankton, Noctiluca and jellyfish ('jelly food chain' with increased importance of the microbial loop), 3) lowest values during the ecological crisis (1989-1992), when small pelagic fish stocks collapsed, and 4) increased after 1993, indicating that the ecosystem went out of the crisis and exhibited a trend of recovery. However, in the last period (1993-2008) the ratio remained close to values observed in the middle eutrophication phase, suggesting that the ecosystem was far from fully recovered. Since early 2000s, fluctuating pelagic fish stocks, with a tendency to decreasing fish landing again, have been observed in the Black Sea. Additionally, the quality of food for the small pelagic fish has deteriorated due to warming trends and the legacy of eutrophication, giving support for the 'jelly food chain', exhibiting low energy transfer and prevalence of organisms with high respiration rate and low nutritional value.

  14. Effect of stress on turbine fish passage mortality estimates

    International Nuclear Information System (INIS)

    Ruggles, C.P.

    1993-01-01

    Tests were conducted with juvenile alewife to determine the effects of four experimental protocols upon turbine fish passage mortality estimates. Three protocols determined the effect of cumulative stresses upon fish, while the fourth determined the effect of long range truck transportation prior to release into the penstock or tailrace. The wide range in results were attributed to the presence or absence of additional stress factors associated with the experiments. For instance, fish may survive passage through a turbine, or non-turbine related stresses imposed by the investigator; however, when both are imposed, the cumulative stresses may be lethal. The impact of protocol stress on turbine mortality estimates becomes almost exponential after control mortality exceeds 10%. Valid turbine related mortalities may be determined only after stresses associated with experimental protocol are adequately reduced. This is usually indicated by a control mortality of less than 10%. 14 refs., 5 figs., 6 tabs

  15. Comparisons of allometric and climate-derived estimates of tree coarse root carbon stocks in forests of the United States

    Science.gov (United States)

    Matthew B. Russell; Grant M. Domke; Christopher W. Woodall; Anthony W. D' Amato

    2015-01-01

    Background: Refined estimation of carbon (C) stocks within forest ecosystems is a critical component of efforts to reduce greenhouse gas emissions and mitigate the effects of projected climate change through forest C management. Specifically, belowground C stocks are currently estimated in the United States' national greenhouse gas inventory (US NGHGI) using...

  16. 329 Diversité végétale urbaine et estimation du stock de carbone ...

    African Journals Online (AJOL)

    TOSHIBA

    Diversité végétale urbaine et estimation du stock de carbone : cas de la commune du Plateau ... Urban plants diversity and carbon stock estimation: the case of Plateau district. Abidjan, Côte d'Ivoire ..... [15] - R. HOME; C. KELLER; P. NAGEL; N. BAUER et M. HUNZIKER, Selection criteria for flagship species by conservation ...

  17. Estimating time-varying conditional correlations between stock and foreign exchange markets

    Science.gov (United States)

    Tastan, Hüseyin

    2006-02-01

    This study explores the dynamic interaction between stock market returns and changes in nominal exchange rates. Many financial variables are known to exhibit fat tails and autoregressive variance structure. It is well-known that unconditional covariance and correlation coefficients also vary significantly over time and multivariate generalized autoregressive model (MGARCH) is able to capture the time-varying variance-covariance matrix for stock market returns and changes in exchange rates. The model is applied to daily Euro-Dollar exchange rates and two stock market indexes from the US economy: Dow-Jones Industrial Average Index and S&P500 Index. The news impact surfaces are also drawn based on the model estimates to see the effects of idiosyncratic shocks in respective markets.

  18. Rapid diagnostic test supply chain and consumption study in Cabo Delgado, Mozambique: estimating stock shortages and identifying drivers of stock-outs.

    Science.gov (United States)

    Hasselback, Leah; Crawford, Jessica; Chaluco, Timoteo; Rajagopal, Sharanya; Prosser, Wendy; Watson, Noel

    2014-08-02

    Malaria rapid diagnostic tests (RDTs) are particularly useful in low-resource settings where follow-through on traditional laboratory diagnosis is challenging or lacking. The availability of these tests depends on supply chain processes within the distribution system. In Mozambique, stock-outs of malaria RDTs are fairly common at health facilities. A longitudinal cross-sectional study was conducted to evaluate drivers of stock shortages in the Cabo Delgado province. Data were collected from purposively sampled health facilities, using monthly cross-sectional surveys between October 2011 and May 2012. Estimates of lost consumption (consumption not met due to stock-outs) served as the primary quantitative indicator of stock shortages. This is a better measure of the magnitude of stock-outs than binary indicators that only measure frequency of stock-outs at a given facility. Using a case study based methodology, distribution system characteristics were qualitatively analysed to examine causes of stock-outs at the provincial, district and health centre levels. 15 health facilities were surveyed over 120 time points. Stock-out patterns varied by data source; average monthly proportions of 59%, 17% and 17% of health centres reported a stock-out on stock cards, laboratory and pharmacy forms, respectively. Estimates of lost consumption percentage were significantly high; ranging from 0% to 149%; with a weighted average of 78%. Each ten-unit increase in monthly-observed consumption was associated with a nine-unit increase in lost consumption percentage indicating that higher rates of stock-outs occurred at higher levels of observed consumption. Causes of stock-outs included inaccurate tracking of lost consumption, insufficient sophistication in inventory management and replenishment, and poor process compliance by facility workers, all arguably stemming from inadequate attention to the design and implementation of the distribution system. Substantially high levels of RDT

  19. Sectoral Differences in the Choice of the Time Horizon during Estimation of the Unconditional Stock Beta

    Directory of Open Access Journals (Sweden)

    Dimitrios Dadakas

    2016-12-01

    Full Text Available The stock beta coefficient literature extensively discusses the proper methods for the estimation of beta as well as its use in asset valuation. However, there are fewer references with respect to the appropriate time horizon that investors should utilize when evaluating the risk-return relationship of a stock. We examine the appropriate time horizon for beta estimation, differentiating our results by sector according to the Industry Classification Benchmark. We employ data from the NYSE and estimate varying lengths of beta employing data from 30 to 250 trading days. The constructed beta series is then examined for the presence of breaks using the endogenous structural break literature. Results show evidence against the use of betas that employ more than 90 trading days of data provisional to the sector under study.

  20. Estimating Stocks Return with Decomposition of the Book-to-Market Ratio: Evidences from Bovespa

    Directory of Open Access Journals (Sweden)

    Juliano Ribeiro de Almeida

    2010-12-01

    Full Text Available The book-to-market (BM ratio differs across stocks because to differences in expected cashflows and expected returns. The central hypothesis is that the evolution of BM, in terms of past changes in price and book equity, contains information about future cashflows that can be used to improve estimates of expected returns. This article used a database of Economática to extract a sample of non-financial companies shares listed on BOVESPA and test this hypothesis. The estimated regressions were performed monthly during the period July 1996 to June 2008. Both for large and mid caps as for small caps, the results do not favor this hypothesis and show that only the most recent BM is important to predict the assets returns. Furthermore, stock issues and repurchases are also related to future cashflows and it is expected to improve estimates of expected returns. However, the results provide no evidence favoring that.

  1. Reliability of fish size estimates obtained from multibeam imaging sonar

    Science.gov (United States)

    Hightower, Joseph E.; Magowan, Kevin J.; Brown, Lori M.; Fox, Dewayne A.

    2013-01-01

    Multibeam imaging sonars have considerable potential for use in fisheries surveys because the video-like images are easy to interpret, and they contain information about fish size, shape, and swimming behavior, as well as characteristics of occupied habitats. We examined images obtained using a dual-frequency identification sonar (DIDSON) multibeam sonar for Atlantic sturgeon Acipenser oxyrinchus oxyrinchus, striped bass Morone saxatilis, white perch M. americana, and channel catfish Ictalurus punctatus of known size (20–141 cm) to determine the reliability of length estimates. For ranges up to 11 m, percent measurement error (sonar estimate – total length)/total length × 100 varied by species but was not related to the fish's range or aspect angle (orientation relative to the sonar beam). Least-square mean percent error was significantly different from 0.0 for Atlantic sturgeon (x̄  =  −8.34, SE  =  2.39) and white perch (x̄  = 14.48, SE  =  3.99) but not striped bass (x̄  =  3.71, SE  =  2.58) or channel catfish (x̄  = 3.97, SE  =  5.16). Underestimating lengths of Atlantic sturgeon may be due to difficulty in detecting the snout or the longer dorsal lobe of the heterocercal tail. White perch was the smallest species tested, and it had the largest percent measurement errors (both positive and negative) and the lowest percentage of images classified as good or acceptable. Automated length estimates for the four species using Echoview software varied with position in the view-field. Estimates tended to be low at more extreme azimuthal angles (fish's angle off-axis within the view-field), but mean and maximum estimates were highly correlated with total length. Software estimates also were biased by fish images partially outside the view-field and when acoustic crosstalk occurred (when a fish perpendicular to the sonar and at relatively close range is detected in the side lobes of adjacent beams). These sources of

  2. THE STOCKS ACCOUNTING EVALUATION AND ESTIMATION INFLUENCE ON THE ENTITY PERFORMANCE

    Directory of Open Access Journals (Sweden)

    TULVINSCHI MIHAELA

    2015-12-01

    Full Text Available Improving the performance of a company involves an operative and accurate measurement of the efforts and effects, the efficient use of the company resources and also identifying ways to reduce consumption, a category in which stocks occupy a significant position. The purpose of this article is to demonstrate that the accounting information on stocks can not rely only on the accuracy assessment of past and current events, but must take into account estimations of future events, even if these involve uncertainty and risk taking. Different methods for evaluating stocks at the exit of the entity lead to different results but does not affect the entity performance. Opposed to the evaluation, when we speak about the accounting estimation, there is a significant freedom of action when choosing methods. The economic entity is always in the present, and for this reason it must take into consideration both the evaluation accuracy and the accounting estimations uncertainty. Estimating the net achievable value is influenced by the purpose for which the inventory is held. Accounting estimations are influenced by the judgment which is sometimes subjected to inherent bias, but this bias should not turn into a form of manipulating the entity's performance.

  3. Insights into fisheries management practices: using the theory of planned behavior to explain fish stocking among a sample of Swiss anglers.

    Directory of Open Access Journals (Sweden)

    Eike von Lindern

    Full Text Available Using inadequate management tools often threatens the natural environment. This study focuses on the example of Swiss recreational fishermen (hereafter called "anglers" as recreational fisheries management stakeholders. In recreational fisheries, fish stocking conducted by anglers has been identified as one important factor associated with declining fish catches. We therefore aimed to a gain insights into why anglers want to maintain fish stocking and b identify entry points for interventions to promote more pro-ecological management practices. Results (N = 349 showed that the majority of anglers think very uncritically about stocking and that they frequently engage in it. We conclude that outcome expectancies and beliefs about risks, in combination with a lack of stocking success controls are the main reasons that anglers retain stocking measures. We suggest that providing anglers with direct experience and feedback about stocking success is suitable to change their intentions regarding stocking and their actual stocking behavior, and thus, to promote more pro-ecological management methods. From a more general perspective, the results of this study are likely to help improve pro-ecological ecosystem management in other domains where problems similar to those in recreational fisheries management might exist.

  4. EVALUATION OF FISH FAUNA STOCKS IN DAMS IN SOSSEGO MIME IN CANAÃ OF CARAJÁS (EASTERN AMAZON, CAPTURED WITH THE USE OF CAST NET BEFORE THE DEPOSIT OF TAILINGS

    Directory of Open Access Journals (Sweden)

    Ivan Furtado Junior

    2016-12-01

    Full Text Available This study aims to estimate the biomass of fish stocks in the area of the dam formed by tailings of Sossego mine in Canaã dos Carajás, captured with the use of cast nets for fish. The prospecting work was carried out during the period from 29 February to 6 March 2004, 6 months after closing the dam and immediately before the disposal of waste. The average values estimated for the capture per unit area covered by cast nets (CPUA and biomass were 8.4 g m-² and 16,922.7 kg, respectively. The most representative groups of fish were minnows, with 67.7% and discus with 24.8% of the total estimated biomass. The species caught were: Moenkhausia cf. sanctaefilomenae (redeye tetra fish, Tetragonopterus cf. argenteus (white tetra fish, Tetragonopterus chalceus (red tetra fish, Aequidens viridis (cichlasoma bimaculatum Crenicichla cincta (jacunda Hoplerythrinus unitaeniatus (jeju Curimata inornata (branquinha and Hoplias malabaricus (trahira. Keywords: fishing survey; yield per unit area; biomass; tailings dam.

  5. Hankin and Reeves' approach to estimating fish abundance in small streams: limitations and alternatives

    Science.gov (United States)

    William L. Thompson

    2003-01-01

    Hankin and Reeves' (1988) approach to estimating fish abundance in small streams has been applied in stream fish studies across North America. However, their population estimator relies on two key assumptions: (1) removal estimates are equal to the true numbers of fish, and (2) removal estimates are highly correlated with snorkel counts within a subset of sampled...

  6. Mercury content in Chilean fish and estimated intake levels.

    Science.gov (United States)

    Cortes, Sandra; Fortt, Antonia

    2007-09-01

    The intake of fish products is a major public health concern due to possible methyl mercury exposure, which is especially toxic to the human nervous system. This pilot study (n = 46) was designed to determine mercury concentrations in fish products for national consumption (Chilean jack mackerel, hake, Chilean mussel, tuna) and for export (salmon, Patagonian toothfish, swordfish, southern hake), and to estimate the exposure of the general population. The fish products were collected from markets in Talcahuano, Puerto Montt and Santiago. Samples were analyzed at the National Environmental Center by cold vapor atomic absorption spectrophotometry. Mercury levels in swordfish and one canned tuna sample exceeded levels prescribed by national and international standards. The remaining two export products (Patagonian toothfish, also known as Chilean sea bass, and salmon) complied with international limits, which are more demanding than Chilean regulations. Theoretical estimates of mercury intake varied from 0.08 to 3.8 microg kg(-1) bw day(-1) for high fish consumers, exceeding the provisional tolerable intake for tuna, Chilean seabass, Chilean jack mackerel and swordfish. This group appears to be at the greatest risk from mercury contamination among the Chilean population.

  7. Estimating temporal changes in soil carbon stocks at ecoregional scale in Madagascar using remote-sensing

    Science.gov (United States)

    Grinand, C.; Maire, G. Le; Vieilledent, G.; Razakamanarivo, H.; Razafimbelo, T.; Bernoux, M.

    2017-02-01

    Soil organic carbon (SOC) plays an important role in climate change regulation notably through release of CO2 following land use change such a deforestation, but data on stock change levels are lacking. This study aims to empirically assess SOC stocks change between 1991 and 2011 at the landscape scale using easy-to-access spatially-explicit environmental factors. The study area was located in southeast Madagascar, in a region that exhibits very high rate of deforestation and which is characterized by both humid and dry climates. We estimated SOC stock on 0.1 ha plots for 95 different locations in a 43,000 ha reference area covering both dry and humid conditions and representing different land cover including natural forest, cropland, pasture and fallows. We used the Random Forest algorithm to find out the environmental factors explaining the spatial distribution of SOC. We then predicted SOC stocks for two soil layers at 30 cm and 100 cm over a wider area of 395,000 ha. By changing the soil and vegetation indices derived from remote sensing images we were able to produce SOC maps for 1991 and 2011. Those estimates and their related uncertainties where combined in a post-processing step to map estimates of significant SOC variations and we finally compared the SOC change map with published deforestation maps. Results show that the geologic variables, precipitation, temperature, and soil-vegetation status were strong predictors of SOC distribution at regional scale. We estimated an average net loss of 10.7% and 5.2% for the 30 cm and the 100 cm layers respectively for deforested areas in the humid area. Our results also suggest that these losses occur within the first five years following deforestation. No significant variations were observed for the dry region. This study provides new solutions and knowledge for a better integration of soil threats and opportunities in land management policies.

  8. [Regional and global estimates of carbon stocks and carbon sequestration capacity in forest ecosystems: A review].

    Science.gov (United States)

    Liu, Wei-wei; Wang, Xiao-ke; Lu, Fei; Ouyang, Zhi-yun

    2015-09-01

    As a dominant part of terrestrial ecosystems, forest ecosystem plays an important role in absorbing atmospheric CO2 and global climate change mitigation. From the aspects of zonal climate and geographical distribution, the present carbon stocks and carbon sequestration capacity of forest ecosystem were comprehensively examined based on the review of the latest literatures. The influences of land use change on forest carbon sequestration were analyzed, and factors that leading to the uncertainty of carbon sequestration assessment in forest ecosystem were also discussed. It was estimated that the current forest carbon stock was in the range of 652 to 927 Pg C and the carbon sequestration capacity was approximately 4.02 Pg C · a(-1). In terms of zonal climate, the carbon stock and carbon sequestration capacity of tropical forest were the maximum, about 471 Pg C and 1.02-1.3 Pg C · a(-1) respectively; then the carbon stock of boreal forest was about 272 Pg C, while its carbon sequestration capacity was the minimum, approximately 0.5 Pg C · a(-1); for temperate forest, the carbon stock was minimal, around 113 to 159 Pg C and its carbon sequestration capacity was 0.8 Pg C · a(-1). From the aspect of geographical distribution, the carbon stock of forest ecosystem in South America was the largest (187.7-290 Pg C), then followed by European (162.6 Pg C), North America (106.7 Pg C), Africa (98.2 Pg C) and Asia (74.5 Pg C), and Oceania (21.7 Pg C). In addition, carbon sequestration capacity of regional forest ecosystem was summed up as listed below: Tropical South America forest was the maximum (1276 Tg C · a(-1)), then were Tropical Africa (753 Tg C · a(-1)), North America (248 Tg C · a(-1)) and European (239 Tg C · a(-1)), and East Asia (98.8-136.5 Tg C · a(-1)) was minimum. To further reduce the uncertainty in the estimations of the carbon stock and carbon sequestration capacity of forest ecosystem, comprehensive application of long-term observation, inventories

  9. Temporally stratified sampling programs for estimation of fish impingement

    International Nuclear Information System (INIS)

    Kumar, K.D.; Griffith, J.S.

    1977-01-01

    Impingement monitoring programs often expend valuable and limited resources and fail to provide a dependable estimate of either total annual impingement or those biological and physicochemical factors affecting impingement. In situations where initial monitoring has identified ''problem'' fish species and the periodicity of their impingement, intensive sampling during periods of high impingement will maximize information obtained. We use data gathered at two nuclear generating facilities in the southeastern United States to discuss techniques of designing such temporally stratified monitoring programs and their benefits and drawbacks. Of the possible temporal patterns in environmental factors within a calendar year, differences among seasons are most influential in the impingement of freshwater fishes in the Southeast. Data on the threadfin shad (Dorosoma petenense) and the role of seasonal temperature changes are utilized as an example to demonstrate ways of most efficiently and accurately estimating impingement of the species

  10. The soil classification and the subsurface carbon stock estimation with a ground-penetrating radar

    International Nuclear Information System (INIS)

    Onishi, K.; Rokugawa, S.; Kato, Y.

    2002-01-01

    One of the serious problems of the Kyoto Protocol is that we have no effective method to estimate the carbon stock of the subsurface. To solve this problem, we propose the application of ground-penetrating radar (GPR) to the subsurface soil survey. As a result, it is shown that GPR can detect the soil horizons, stones and roots. The fluctuations of the soil horizons in the forest are cleanly indicated as the reflection pattern of the microwaves. Considering the fact that the physical, chemical, and biological characteristics of each soil layer is almost unique, GPR results can be used to estimate the carbon stock in soil by combining with the vertical soil sample survey at one site. Then as a trial, we demonstrate to estimate the carbon content fixed in soil layers based on the soil samples and GPR survey data. we also compare this result with the carbon stock for the flat horizon case. The advantages of GPR usage for this object are not only the reduction of uncertainty and the cost, but also the environmental friendliness of survey manner. Finally, we summarize the adaptabilities of various antennas having different predominant frequencies for the shallow subsurface zone. (author)

  11. Evaluation of different estimating techniques to generate best possible total return on investing on individual stocks on Oslo Stock Exchange

    OpenAIRE

    Larikka, Jyri Egil

    2010-01-01

    Master's thesis in Finance My intension with this thesis is to present three different kinds of models to analyze stock market and to find good buy candidates. They use different methodology as the first is using pair-trading, the second is using technical analysis and the third is using regression analysis. The first model uses momentum strategy and adaptive market hypothesis in a pair trading context to dynamically generate good pairs of stocks based on their log return and correlatio...

  12. Identification of fish populations with particular reference to the pelagic fish stocks of the Indian Ocean region

    Digital Repository Service at National Institute of Oceanography (India)

    Dwivedi, S.N.

    The most essential step in any fishery management is the identification of discrete fish populations. This is particularly important for the development of Indian Ocean pelagic fisheries. The simple signal character analysis of meristic or metric...

  13. Otolith shape and size: The importance of age when determining indices for fish-stock separation

    OpenAIRE

    Mapp, James; Hunter, Ewan; Van Der Kooij, Jeroen; Songer, Sally; Fisher, Mark

    2017-01-01

    Stock-separation of highly mobile Clupeids (sprat – Sprattus sprattus and herring – Clupea harengus) using otolith morphometrics was explored. Analysis focused on three stock discrimination problems with the aim of reassigning individual otoliths to source populations using experiments undertaken using a machine learning environment known as \\{WEKA\\} (Waikato Environment for Knowledge Analysis). Six feature sets encoding combinations of size and shape together with nine learning algorithms we...

  14. Using interview-based recall surveys to estimate cod Gadus morhua and eel Anguilla anguilla harvest in Danish recreational fishing

    DEFF Research Database (Denmark)

    Sparrevohn, Claus Reedtz; Storr-Paulsen, Marie

    2012-01-01

    Using interview-based recall surveys to estimate cod Gadus morhua and eel Anguilla anguilla harvest in Danish recreational fishing. – ICES Journal of Marine Science, 69: 323–330.Marine recreational fishing is a popular outdoor activity in Denmark, practised by both anglers and passive gear fishers....... However, the impact on the targeted stocks is unknown, so to estimate the 2009 harvest of cod Gadus morhua and eel Anguilla anguilla, two separate interview-based surveys were initiated and carried out in 2009/2010. The first recall survey exclusively targeted fishers who had been issued......, in certain areas, the recreational harvest of cod accounted for more than 30% of the total yield. The majority (81%) of the recreational cod harvest was taken by anglers. Eels, however, are almost exclusively caught with passive gear (fykenets) and a total of 104 t year−1 was harvested, which corresponds...

  15. Spatially-Resolved Influence of Temperature and Salinity on Stock and Recruitment Variability of Commercially Important Fishes in the North Sea.

    Directory of Open Access Journals (Sweden)

    Anna Akimova

    Full Text Available Understanding of the processes affecting recruitment of commercially important fish species is one of the major challenges in fisheries science. Towards this aim, we investigated the relation between North Sea hydrography (temperature and salinity and fish stock variables (recruitment, spawning stock biomass and pre-recruitment survival index for 9 commercially important fishes using spatially-resolved cross-correlation analysis. We used high-resolution (0.2° × 0.2° hydrographic data fields matching the maximal temporal extent of the fish population assessments (1948-2013. Our approach allowed for the identification of regions in the North Sea where environmental variables seem to be more influential on the fish stocks, as well as the regions of a lesser or nil influence. Our results confirmed previously demonstrated negative correlations between temperature and recruitment of cod and plaice and identified regions of the strongest correlations (German Bight for plaice and north-western North Sea for cod. We also revealed a positive correlation between herring spawning stock biomass and temperature in the Orkney-Shetland area, as well as a negative correlation between sole pre-recruitment survival index and temperature in the German Bight. A strong positive correlation between sprat stock variables and salinity in the central North Sea was also found. To our knowledge the results concerning correlations between North Sea hydrography and stocks' dynamics of herring, sole and sprat are novel. The new information about spatial distribution of the correlation provides an additional help to identify mechanisms underlying these correlations. As an illustration of the utility of these results for fishery management, an example is provided that incorporates the identified environmental covariates in stock-recruitment models.

  16. The Dynamics, Ecological Variability and Estimated Carbon Stocks of Mangroves in Mahajamba Bay, Madagascar

    Directory of Open Access Journals (Sweden)

    Trevor G. Jones

    2015-08-01

    Full Text Available Mangroves are found throughout the tropics, providing critical ecosystem goods and services to coastal communities and supporting rich biodiversity. Globally, mangroves are being rapidly degraded and deforested at rates exceeding loss in many tropical inland forests. Madagascar contains around 2% of the global distribution, >20% of which has been deforested since 1990, primarily from over-harvest for forest products and conversion for agriculture and aquaculture. While historically not prominent, mangrove loss in Madagascar’s Mahajamba Bay is increasing. Here, we focus on Mahajamba Bay, presenting long-term dynamics calculated using United States Geological Survey (USGS national-level mangrove maps contextualized with socio-economic research and ground observations, and the results of contemporary (circa 2011 mapping of dominant mangrove types. The analysis of the USGS data indicated 1050 hectares (3.8% lost from 2000 to 2010, which socio-economic research suggests is increasingly driven by commercial timber extraction. Contemporary mapping results permitted stratified sampling based on spectrally distinct and ecologically meaningful mangrove types, allowing for the first-ever vegetation carbon stock estimates for Mahajamba Bay. The overall mean carbon stock across all mangrove classes was estimated to be 100.97 ± 10.49 Mg C ha−1. High stature closed-canopy mangroves had the highest average carbon stock estimate (i.e., 166.82 ± 15.28 Mg C ha−1. These estimates are comparable to other published values in Madagascar and elsewhere in the Western Indian Ocean and demonstrate the ecological variability of Mahajamba Bay’s mangroves and their value towards climate change mitigation.

  17. Estimation of the annual flow and stock of marine debris in South Korea for management purposes.

    Science.gov (United States)

    Jang, Yong Chang; Lee, Jongmyoung; Hong, Sunwook; Mok, Jin Yong; Kim, Kyoung Shin; Lee, Yun Jeong; Choi, Hyun-Woo; Kang, Hongmook; Lee, Sukhui

    2014-09-15

    The annual flow and stock of marine debris in the Sea of Korea was estimated by summarizing previous survey results and integrating them with other relevant information to underpin the national marine debris management plan. The annual inflow of marine debris was estimated to be 91,195 tons [32,825 tons (36% of the total) from sources on land and 58,370 tons (64%) from ocean sources]. As of the end of 2012, the total stock of marine debris on all South Korean coasts (12,029 tons), the seabed (137,761 tons), and in the water column (2451 tons) was estimated to be 152,241 tons. In 2012, 42,595 tons of marine debris was collected from coasts, seabeds, and the water column. This is a very rare case study that estimated the amount of marine debris at a national level, the results of which provide essential information for the development of efficient marine debris management policies. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. Development of an evolutionary fuzzy expert system for estimating future behavior of stock price

    Science.gov (United States)

    Mehmanpazir, Farhad; Asadi, Shahrokh

    2017-03-01

    The stock market has always been an attractive area for researchers since no method has been found yet to predict the stock price behavior precisely. Due to its high rate of uncertainty and volatility, it carries a higher risk than any other investment area, thus the stock price behavior is difficult to simulation. This paper presents a "data mining-based evolutionary fuzzy expert system" (DEFES) approach to estimate the behavior of stock price. This tool is developed in seven-stage architecture. Data mining is used in three stages to reduce the complexity of the whole data space. The first stage, noise filtering, is used to make our raw data clean and smooth. Variable selection is second stage; we use stepwise regression analysis to choose the key variables been considered in the model. In the third stage, K-means is used to divide the data into sub-populations to decrease the effects of noise and rebate complexity of the patterns. At next stage, extraction of Mamdani type fuzzy rule-based system will be carried out for each cluster by means of genetic algorithm and evolutionary strategy. In the fifth stage, we use binary genetic algorithm to rule filtering to remove the redundant rules in order to solve over learning phenomenon. In the sixth stage, we utilize the genetic tuning process to slightly adjust the shape of the membership functions. Last stage is the testing performance of tool and adjusts parameters. This is the first study on using an approximate fuzzy rule base system and evolutionary strategy with the ability of extracting the whole knowledge base of fuzzy expert system for stock price forecasting problems. The superiority and applicability of DEFES are shown for International Business Machines Corporation and compared the outcome with the results of the other methods. Results with MAPE metric and Wilcoxon signed ranks test indicate that DEFES provides more accuracy and outperforms all previous methods, so it can be considered as a superior tool for

  19. Dynamic Estimation on Output Elasticity of Highway Capital Stock in China

    Science.gov (United States)

    Li, W. J.; Zuo, Q. L.; Bai, Y. F.

    2017-12-01

    By using the Perpetual Inventory Method to calculate the capital stock of highway in China from 1988 to 2016, the paper builds the State Space Model based on Translog Production Function, according to the Ridge Regression and Kalman Filter Method, the dynamic estimation results of output elasticity are measured continuously and analyzed. The conclusions show that: Firstly, China’s growth speed on highway industry capital stock are divided into three stages which are respectively from 1988 to 2000, from 2001 to 2009 and from 2010 to 2016, during which shows steady growth, between which reflect rapid growth; Secondly, the output elasticity of highway capital stock, being between 0.154 and 0.248, is slightly larger than the output elasticity of human input factor, lower than the output elasticity of the technical level, shows positive effect on transport economy and rises steadily, but the output efficiency is low on the whole; Thirdly, around the year of 2010, the scale pay on highway industry begins to highlight the characteristic of increase.

  20. The Stock Potency of Demersal Fish Resource at The Coastal Zone, East Kutai District in East Kalimantan

    Directory of Open Access Journals (Sweden)

    Juliani Juliani

    2014-04-01

    Full Text Available The objective of this research was to estimate the potency of demersal fish resource spread over three sub-districts i.e. Sangkulirang, Sandaran and Kaliorang in Kutai district, East Kalimantan province. The result showed that the highest total biomass was produced by aquatic zone of Sandaran sub-district with 1,763,713.6 ton/zone and the density stock was 13,566.5 kg/km2. It was followed by Sangkulirang sub-district with 264,653.3 ton/zone and 6,640.4 kg/km2, respectively and then by Kaliorang sub-district with 58.086,5 ton/zone and 2,768.0 kg/km2, respectively. In term of species particularly from crustaseaae family, the most economic aquatic zone was found in Sangkulirang sub-district. The export product species Penaeus sp was obtained from Penaeus monodon, Metapenaeus monoceros, Metapenaeus sp, Parapenaeopsis sculptilis, Penaeus sp, and lobster which was accounted by 3,381.6 tons/zone, 83,199 tons/zone, 14,492.7 tons/zone, 24,691.3 tons/zone, 41,331.1 tons/zone, and 1,073.5 tons/zone, respectively. It was followed by Sandaran sub-district with export product species was Penaeus merguensis 33,495.7 tons/zone and non-export products were Parapenaeopsis sculptilis 63,641.7 tons/zone, Penaeus sp 16,747.8 tons/zone, Metapenaeus sp 1.674,8 tons/zone, Caridina sp 1.562.572,2 tons/zone, and Scylla serrata 3,349.6 tons/zone. Next was Kaliorang sub-district which accounted by Penaeus merguensis 62.2 tons/zone and Metapenaeus monoceros 49.7 tons/zone. In situ measurement on seven physical-chemical quality parameters of water which compared to the standardized of sea water showed that water quality found in coastal zone of Kaliorang, Sangkulirang and Sandaran sub-district, East Kutai province was suitable and feasible for the aquatic and living of marine habitats Normal 0 false false false IN X-NONE X-NONE

  1. [Remote sensing estimation of urban forest carbon stocks based on QuickBird images].

    Science.gov (United States)

    Xu, Li-Hua; Zhang, Jie-Cun; Huang, Bo; Wang, Huan-Huan; Yue, Wen-Ze

    2014-10-01

    Urban forest is one of the positive factors that increase urban carbon sequestration, which makes great contribution to the global carbon cycle. Based on the high spatial resolution imagery of QuickBird in the study area within the ring road in Yiwu, Zhejiang, the forests in the area were divided into four types, i. e., park-forest, shelter-forest, company-forest and others. With the carbon stock from sample plot as dependent variable, at the significance level of 0.01, the stepwise linear regression method was used to select independent variables from 50 factors such as band grayscale values, vegetation index, texture information and so on. Finally, the remote sensing based forest carbon stock estimation models for the four types of forest were established. The estimation accuracies for all the models were around 70%, with the total carbon reserve of each forest type in the area being estimated as 3623. 80, 5245.78, 5284.84, 5343.65 t, respectively. From the carbon density map, it was found that the carbon reserves were mainly in the range of 25-35 t · hm(-2). In the future, urban forest planners could further improve the ability of forest carbon sequestration through afforestation and interplanting of trees and low shrubs.

  2. Parasites as biological tags for the discrimination of marine fish stocks in Brazil: current status and perspectives

    Directory of Open Access Journals (Sweden)

    Iris Aparecida Soares

    2016-11-01

    Full Text Available ABSTRACT. Soares I.A. & Luque J.L. [Parasites as biological tags for the discrimination of marine fish stocks in Brazil: current status and perspectives.] Parasitos como marcadores biológicos para discriminação de estoques de peixes marinhos no Brasil: estado atual e perspectivas. Revista Brasileira de Medicina Veterinária, 38(supl. 3:99-113, 2016. Programa de Pós-Graduação em Ciências Veterinárias, Universidade Federal Rural do Rio de Janeiro, BR 465 Km 7, Seropédica, RJ 23890-000, Brasil. E-mail: luqueufrrj@gmail.com The global state of marine fisheries and its effects endanger the future of fishery resources, which may result in extinction of several species as well as threatening the overall integrity of the ecosystems. As the fish consumption growths, marine fishing and related market activities are stimulated increasing the incidence of threatened or exploited species. Aiming the future sustainability, fishery inventories need to be properly identified as a tool for implementation of more efficient policies on the management and conservation of the natural resources. Thus, by the high heterogeneity observed in the Atlantic coast of Brazil as well as the lack of related studies using this tool, the country represents great potential for the use of this technique, to improve our knowledge of local fishing resources. Therefore, the present study highlights the use of parasites as biological markers on identifying fish populations through robust statistical analysis, which represents an efficient and low cost approach and the lack of similar studies in Brazil showing the need of more research efforts on this subject in Brazil.

  3. Stocking up on Fish Mox: a Systematic Analysis of Cultural Narratives about Self-medicating in Online Forums

    Directory of Open Access Journals (Sweden)

    Rebecca Howes-Mischel

    2017-09-01

    Full Text Available This study is a systematic review of cultural narratives that drive American belief in the value and efficacy of stocking up on fish antibiotics for human consumption. Popularized by “doomsday prepper” forums and survivalist medical professionals’ online videos, this narrative suggests that in some scenarios humans may benefit from such treatments—even as they note its contraindication to mainstream public health advice. Discussions in crowd-sourcing forums however, reveal that in practice Americans are using them as a form of home remedy to treat routine infections without missing work or to make up for gaps in insurance coverage. This article argues for greater attention to what makes it plausible and reasonable to treat human conditions with animal medications. It suggests that public health initiatives should address such decisions as emerging from a rational analysis of social and economic conditions rather than dismissing such practices as dangerous to population and individual health outcomes. As social scientists of medicine have long argued, collective narratives about health and medicine illustrate deeply the broader contexts in which communities understand and experience bodily state and shape how communities interact with public health institutions and respond to medical expertise. This study surveys online discussions about “fish mox” to show how participants contest medical expertise and promote a more distributed form of populist expertise. As such, consuming fish mox is both panacea for health inequality and a critique of health institutions for perpetrating such stratification.

  4. Mixed-species allometric equations and estimation of aboveground biomass and carbon stocks in restoring degraded landscape in northern Ethiopia

    Science.gov (United States)

    Mokria, Mulugeta; Mekuria, Wolde; Gebrekirstos, Aster; Aynekulu, Ermias; Belay, Beyene; Gashaw, Tadesse; Bräuning, Achim

    2018-02-01

    Accurate biomass estimation is critical to quantify the changes in biomass and carbon stocks following the restoration of degraded landscapes. However, there is lack of site-specific allometric equations for the estimation of aboveground biomass (AGB), which consequently limits our understanding of the contributions of restoration efforts in mitigating climate change. This study was conducted in northwestern Ethiopia to develop a multi-species allometric equation and investigate the spatial and temporal variation of C-stocks following the restoration of degraded landscapes. We harvested and weighed 84 trees from eleven dominant species from six grazing exclosures and adjacent communal grazing land. We observed that AGB correlates significantly with diameter at stump height D 30 (R 2 = 0.78 P < 0.01), and tree height H (R 2 = 0.41, P < 0.05). Our best model, which includes D 30 and H as predictors explained 82% of the variations in AGB. This model produced the lowest bias with narrow ranges of errors across different diameter classes. Estimated C-stock showed a significant positive correlation with stem density (R 2 = 0.80, P < 0.01) and basal area (R 2 = 0.84, P < 0.01). At the watershed level, the mean C-stock was 3.8 (±0.5) Mg C ha-1. Plot-level C-stocks varied between 0.1 and 13.7 Mg C ha-1. Estimated C-stocks in three- and seven-year-old exclosures exceeded estimated C-stock in the communal grazing land by 50%. The species that contribute most to C-stocks were Leucaena sp. (28%), Calpurnia aurea (21%), Euclea racemosa (20.9%), and Dodonaea angustifolia (15.8%). The equations developed in this study allow monitoring changes in C-stocks and C-sequestration following the implementation of restoration practices in northern Ethiopia over space and time. The estimated C-stocks can be used as a reference against which future changes in C-stocks can be compared.

  5. AFSC/REFM: Isolation by distance (IBD) Alaskan fish stock structure modeling (NCEI Accession 0130929)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This model study examines several management strategies for two marine fish species subject to isolation-by-distance (IBD): Pacific cod in the Aleutian Islands (AI)...

  6. Fish stock assessment of piraputanga Brycon microlepis in the Cuiabá River basin, Pantanal of Mato Grosso, Brazil

    Directory of Open Access Journals (Sweden)

    L. A. de F. MATEUS

    Full Text Available Fork length measurements of individuals of Brycon microlepis landed and commercialized at the Porto Market in Cuiabá, MT, from May-October 1996 to May-October 1997 were used to estimate growth and mortality parameters for this species. The average estimated populational parameters were: L¥ = 705 mm, k = 0.275 year--1, C = 0.775, WP = 0.465, Lc = 164 mm, M = 0.585 year--1, Z = 0.822 year--1, with F = 0.237 year--1. Yield per recruit analysis suggests that the stock is not yet overexploited.

  7. Fish stock assessment of piraputanga Brycon microlepis in the Cuiabá River Basin, Pantanal of Mato Grosso, Brazil.

    Science.gov (United States)

    Mateus, L A de F; Estupiñán, G M B

    2002-02-01

    Fork length measurements of individuals of Brycon microlepis landed and commercialized at the Porto Market in Cuiabá, MT, from May-October 1996 to May-October 1997 were used to estimate growth and mortality parameters for this species. The average estimated populational parameters were: L infinity = 705 mm, k = 0.275 year-1, C = 0.775, WP = 0.465, Lc = 164 mm, M = 0.585 year-1, Z = 0.822 year-1, with F = 0.237 year-1. Yield per recruit analysis suggests that the stock is not yet overexploited.

  8. Estimating national forest carbon stocks and dynamics: combining models and remotely sensed information

    Science.gov (United States)

    Smallman, Thomas Luke; Exbrayat, Jean-François; Bloom, Anthony; Williams, Mathew

    2017-04-01

    Forests are a critical component of the global carbon cycle, storing significant amounts of carbon, split between living biomass and dead organic matter. The carbon budget of forests is the most uncertain component of the global carbon cycle - it is currently impossible to quantify accurately the carbon source/sink strength of forest biomes due to their heterogeneity and complex dynamics. It has been a major challenge to generate robust carbon budgets across landscapes due to data scarcity. Models have been used for estimating carbon budgets, but outputs have lacked an assessment of uncertainty, making a robust assessment of their reliability and accuracy challenging. Here a Metropolis Hastings - Markov Chain Monte Carlo (MH-MCMC) data assimilation framework has been used to combine remotely sensed leaf area index (MODIS), biomass (where available) and deforestation estimates, in addition to forest planting information from the UK's national forest inventory, an estimate of soil carbon from the Harmonized World Database (HWSD) and plant trait information with a process model (DALEC) to produce a constrained analysis with a robust estimate of uncertainty of the UK forestry carbon budget between 2000 and 2010. Our analysis estimates the mean annual UK forest carbon sink at -3.9 MgC ha-1 yr-1 with a 95 % confidence interval between -4.0 and -3.1 MgC ha-1yr-1. The UK national forest inventory (NFI) estimates the mean UK forest carbon sink to be between -1.4 and -5.5 MgC ha-1 yr-1. The analysis estimate for total forest biomass stock in 2010 is estimated at 229 (177/232) TgC, while the NFI an estimated total forest biomass carbon stock of 216 TgC. Leaf carbon area (LCA) is a key plant trait which we are able to estimate using our analysis. Comparison of median estimates for (LCA) retrieved from the analysis and a UK land cover map show higher and lower values for LCA are estimated areas dominated by needle leaf and broad leaf forests forest respectively, consistent with

  9. A model of a fishery with fish stock involving delay equations.

    Science.gov (United States)

    Auger, P; Ducrot, Arnaud

    2009-12-13

    The aim of this paper is to provide a new mathematical model for a fishery by including a stock variable for the resource. This model takes the form of an infinite delay differential equation. It is mathematically studied and a bifurcation analysis of the steady states is fulfilled. Depending on the different parameters of the problem, we show that Hopf bifurcation may occur leading to oscillating behaviours of the system. The mathematical results are finally discussed.

  10. Indirect manifestation of cormorant (Phalacrocorax carbo sinensis (L. predation on pond fish stock

    Directory of Open Access Journals (Sweden)

    J. Kortan

    2008-10-01

    Full Text Available The damage to fisheries caused by cormorant predation pressure consists of losses due to direct predation and subsequent indirect losses elicited by cormorant feeding activities resulting in fish wounding and stress. Healed wounds reduce the commercial value of afflicted fish and stress may impact fish body and health condition. Fulton´s condition coefficient (FCC was calculated for wounded and healthy two-year old carp originating from five South Moravian (Czech Republic fishponds. Significant (P = 0.0011 differences in FCC (mean ± s.d., were found between non-wounded (1.48 ± 0.11, n = 19 and wounded mirror common carp, Cyprinus carpio (1.33 ± 0.14, n = 19. However no differences (P > 0.05 were recorded in scaly common carp between non-wounded (FCC 1.41 ± 0.25, n = 33 and wounded (FCC 1.46 ± 0.47, n = 33 fish of the same age and size category. A computer assisted image analysis was applied to describe the extent of such injuries. In the case of two-year old mirror, scaly and bighead carp (Aristichthys nobilis, signs of serious injuries (necroses were recorded on 1.93, 0.89 and 1.61% of body surface, respectively. Fish with deep wounds and scars, often accompanied with progressive necroses, were subject to parasitological examination. The percentage of wounded fish from total fish harvested was evaluated as ranging between < 1 and 47.4% in five ponds under study.

  11. From models to measurements: comparing downed dead wood carbon stock estimates in the U.S. forest inventory.

    Directory of Open Access Journals (Sweden)

    Grant M Domke

    Full Text Available The inventory and monitoring of coarse woody debris (CWD carbon (C stocks is an essential component of any comprehensive National Greenhouse Gas Inventory (NGHGI. Due to the expense and difficulty associated with conducting field inventories of CWD pools, CWD C stocks are often modeled as a function of more commonly measured stand attributes such as live tree C density. In order to assess potential benefits of adopting a field-based inventory of CWD C stocks in lieu of the current model-based approach, a national inventory of downed dead wood C across the U.S. was compared to estimates calculated from models associated with the U.S.'s NGHGI and used in the USDA Forest Service, Forest Inventory and Analysis program. The model-based population estimate of C stocks for CWD (i.e., pieces and slash piles in the conterminous U.S. was 9 percent (145.1 Tg greater than the field-based estimate. The relatively small absolute difference was driven by contrasting results for each CWD component. The model-based population estimate of C stocks from CWD pieces was 17 percent (230.3 Tg greater than the field-based estimate, while the model-based estimate of C stocks from CWD slash piles was 27 percent (85.2 Tg smaller than the field-based estimate. In general, models overestimated the C density per-unit-area from slash piles early in stand development and underestimated the C density from CWD pieces in young stands. This resulted in significant differences in CWD C stocks by region and ownership. The disparity in estimates across spatial scales illustrates the complexity in estimating CWD C in a NGHGI. Based on the results of this study, it is suggested that the U.S. adopt field-based estimates of CWD C stocks as a component of its NGHGI to both reduce the uncertainty within the inventory and improve the sensitivity to potential management and climate change events.

  12. From models to measurements: comparing downed dead wood carbon stock estimates in the U.S. forest inventory.

    Science.gov (United States)

    Domke, Grant M; Woodall, Christopher W; Walters, Brian F; Smith, James E

    2013-01-01

    The inventory and monitoring of coarse woody debris (CWD) carbon (C) stocks is an essential component of any comprehensive National Greenhouse Gas Inventory (NGHGI). Due to the expense and difficulty associated with conducting field inventories of CWD pools, CWD C stocks are often modeled as a function of more commonly measured stand attributes such as live tree C density. In order to assess potential benefits of adopting a field-based inventory of CWD C stocks in lieu of the current model-based approach, a national inventory of downed dead wood C across the U.S. was compared to estimates calculated from models associated with the U.S.'s NGHGI and used in the USDA Forest Service, Forest Inventory and Analysis program. The model-based population estimate of C stocks for CWD (i.e., pieces and slash piles) in the conterminous U.S. was 9 percent (145.1 Tg) greater than the field-based estimate. The relatively small absolute difference was driven by contrasting results for each CWD component. The model-based population estimate of C stocks from CWD pieces was 17 percent (230.3 Tg) greater than the field-based estimate, while the model-based estimate of C stocks from CWD slash piles was 27 percent (85.2 Tg) smaller than the field-based estimate. In general, models overestimated the C density per-unit-area from slash piles early in stand development and underestimated the C density from CWD pieces in young stands. This resulted in significant differences in CWD C stocks by region and ownership. The disparity in estimates across spatial scales illustrates the complexity in estimating CWD C in a NGHGI. Based on the results of this study, it is suggested that the U.S. adopt field-based estimates of CWD C stocks as a component of its NGHGI to both reduce the uncertainty within the inventory and improve the sensitivity to potential management and climate change events.

  13. A national scale estimation of soil carbon stocks of Pinus densiflora forests in Korea: a modelling approach

    Science.gov (United States)

    Yi, K.; Park, C.; Ryu, S.; Lee, K.; Yi, M.; Kim, C.; Park, G.; Kim, R.; Son, Y.

    2011-12-01

    Soil carbon (C) stocks of Pinus densiflora forests in Korea were estimated using a generic forest soil C dynamics model based on the process of dead organic matter input and decomposition. Annual input of dead organic matter to the soil was determined by stand biomass and turnover rates of tree components (stem, branch, twig, foliage, coarse root, and fine root). The model was designed to have a simplified structure consisting of three dead organic matter C (DOC) pools (aboveground woody debris (AWD), belowground woody debris (BWD), and litter (LTR) pool) and one soil organic C (SOC) pool. C flows in the model were regulated by six turnover rates of stem, branch, twig, foliage, coarse root, and fine root, and four decay rates of AWD, BWD, LTR, and SOC. To simulate the soil C stocks of P. densiflora forests, statistical data of forest land area (1,339,791 ha) and growing stock (191,896,089 m3) sorted by region (nine provinces and seven metropolitan cities) and stand age class (11 to 20- (II), 21 to 30- (III), 31 to 40- (IV), 41 to 50- (V), and 51 to 60-year-old (VI)) were used. The growing stock of each stand age class was calculated for every region and representable site index was also determined by consulting the yield table. Other model parameters related to the stand biomass, annual input of dead organic matter and decomposition were estimated from previous studies conducted on P. densiflora forests in Korea, which were also applied for model validation. As a result of simulation, total soil C stock of P. densiflora forests were estimated as 53.9 MtC and soil C stocks per unit area ranged from 28.71 to 47.81 tC ha-1 within the soil depth of 30 cm. Also, soil C stocks in the P. densiflora forests of age class II, III, IV, V, and VI were 16,780,818, 21,450,812, 12,677,872, 2,366,939, and 578,623 tC, respectively, and highly related to the distribution of age classes. Soil C stocks per unit area initially decreased with stand age class and started to increase

  14. The estimation of beta coefficient for shares quoted on the Belgrade Stock Exchange

    Directory of Open Access Journals (Sweden)

    Lastić Ljiljana

    2017-01-01

    Full Text Available The paper contains an estimate of the Beta coefficient for the shares listed on the Prime Listing of the Belgrade Stock Exchange. The companies chosen for analysis are "NIS j.s.c.", The "Nikola Tesla" Airport, "Energoprojekt holding" and "Sojaprotein". The main aim of this paper is to evaluate the Beta coefficients for the mentioned companies in order to make it easier for investors to bring investment decisions. During the calculation of Beta coefficients, quite similar results were obtained, which was later analyzed and presented. One of the reasons for similar results is that the analysis was based on a single and incomplete financial market of the Republic of Serbia.

  15. Imputing forest carbon stock estimates from inventory plots to a nationally continuous coverage

    Directory of Open Access Journals (Sweden)

    Wilson Barry Tyler

    2013-01-01

    Full Text Available Abstract The U.S. has been providing national-scale estimates of forest carbon (C stocks and stock change to meet United Nations Framework Convention on Climate Change (UNFCCC reporting requirements for years. Although these currently are provided as national estimates by pool and year to meet greenhouse gas monitoring requirements, there is growing need to disaggregate these estimates to finer scales to enable strategic forest management and monitoring activities focused on various ecosystem services such as C storage enhancement. Through application of a nearest-neighbor imputation approach, spatially extant estimates of forest C density were developed for the conterminous U.S. using the U.S.’s annual forest inventory. Results suggest that an existing forest inventory plot imputation approach can be readily modified to provide raster maps of C density across a range of pools (e.g., live tree to soil organic carbon and spatial scales (e.g., sub-county to biome. Comparisons among imputed maps indicate strong regional differences across C pools. The C density of pools closely related to detrital input (e.g., dead wood is often highest in forests suffering from recent mortality events such as those in the northern Rocky Mountains (e.g., beetle infestations. In contrast, live tree carbon density is often highest on the highest quality forest sites such as those found in the Pacific Northwest. Validation results suggest strong agreement between the estimates produced from the forest inventory plots and those from the imputed maps, particularly when the C pool is closely associated with the imputation model (e.g., aboveground live biomass and live tree basal area, with weaker agreement for detrital pools (e.g., standing dead trees. Forest inventory imputed plot maps provide an efficient and flexible approach to monitoring diverse C pools at national (e.g., UNFCCC and regional scales (e.g., Reducing Emissions from Deforestation and Forest

  16. Estimation of sport fish harvest for risk and hazard assessment of environmental contaminants

    International Nuclear Information System (INIS)

    Poston, T.M.; Strenge, D.L.

    1989-01-01

    Consumption of contaminated fish flesh can be a significant route of human exposure to hazardous chemicals. Estimation of exposure resulting from the consumption of fish requires knowledge of fish consumption and contaminant levels in the edible portion of fish. Realistic figures of sport fish harvest are needed to estimate consumption. Estimates of freshwater sport fish harvest were developed from a review of 72 articles and reports. Descriptive statistics based on fishing pressure were derived from harvest data for four distinct groups of freshwater sport fish in three water types: streams, lakes, and reservoirs. Regression equations were developed to relate harvest to surface area fished where data bases were sufficiently large. Other aspects of estimating human exposure to contaminants in fish flesh that are discussed include use of bioaccumulation factors for trace metals and organic compounds. Using the bioaccumulation factor and the concentration of contaminants in water as variables in the exposure equation may also lead to less precise estimates of tissue concentration. For instance, muscle levels of contaminants may not increase proportionately with increases in water concentrations, leading to overestimation of risk. In addition, estimates of water concentration may be variable or expressed in a manner that does not truly represent biological availability of the contaminant. These factors are discussed. 45 refs., 1 fig., 7 tabs

  17. MORPHOMETRIC CHARACTERISTICS OF THE REPLACEMENT-BROOD STOCK OF RAINBOW TROUT (ONCORHYNCHUS MYKISS (WALBAUM, 1792 REARED IN THE CONDITIONS OF THE INDUSTRIAL FISH FARM "SLOBODA-BANYLIV”

    Directory of Open Access Journals (Sweden)

    P. Mendrishora

    2017-09-01

    Full Text Available Purpose. To analyze the results of morphometric measurements and dates of aquaculture-biological characteristics of the young-of-the-year and age-1+ rainbow trout reared under industrial technology at instable conditions of the fish farm “Sloboda-Banyliv”. Methodology. The study has been performed at the industrial fish farm “Sloboda-Banyliv”, Chernivtsi region. The materials for the study were young-of-the-year and age-1+ rainbow trout obtained from the eggs of autumn-spawning form rainbow trout. The young-of-the-year were reared in a 216 m2 tank with stocking density of 255 ind./m2, age-1+ fish were reared in 108 m2 tank with a stocking density of 33 ind./m2 according to generally accepted methods in trout culture. Morphometric measurements of fish were performed according to I.F. Pravdin. Statistical processing of data was carried out in Microsoft Office Excel (2003. The analysis of values was done in the system of absolute values. The analyzed criteria of the measured parameters were their mean values and standard errors (M±m, deviation (σ, variability coefficient (Cv. Fish were fed with the artificial feed with high protein content manufactured by “Biomar” (Denmark. Findings. The studies on rainbow trout rearing under industrial conditions showed that fish body proportions did not change with age, however, the length of their fins decreased. The slenderness coefficient in age-1+ fish decreased insignificantly that is typical with increasing body depth. Despite instable rearing conditions, both young-of-the-year and age-1+ fish were characterized by moderate growth rate and high feed-conversion efficiency. Originality. For the first time, in conditions of Ukraine, a study on the formation of rainbow trout brood stocks in a fish farm with instable rearing conditions was performed with the use of the analysis of phenotypical and productive features. Practical value. The results of the performed work will provide an opportunity to

  18. Simplifying ART cohort monitoring: Can pharmacy stocks provide accurate estimates of patients retained on antiretroviral therapy in Malawi?

    Directory of Open Access Journals (Sweden)

    Tweya Hannock

    2012-07-01

    Full Text Available Abstract Background Routine monitoring of patients on antiretroviral therapy (ART is crucial for measuring program success and accurate drug forecasting. However, compiling data from patient registers to measure retention in ART is labour-intensive. To address this challenge, we conducted a pilot study in Malawi to assess whether patient ART retention could be determined using pharmacy records as compared to estimates of retention based on standardized paper- or electronic based cohort reports. Methods Twelve ART facilities were included in the study: six used paper-based registers and six used electronic data systems. One ART facility implemented an electronic data system in quarter three and was included as a paper-based system facility in quarter two only. Routine patient retention cohort reports, paper or electronic, were collected from facilities for both quarter two [April–June] and quarter three [July–September], 2010. Pharmacy stock data were also collected from the 12 ART facilities over the same period. Numbers of ART continuation bottles recorded on pharmacy stock cards at the beginning and end of each quarter were documented. These pharmacy data were used to calculate the total bottles dispensed to patients in each quarter with intent to estimate the number of patients retained on ART. Information for time required to determine ART retention was gathered through interviews with clinicians tasked with compiling the data. Results Among ART clinics with paper-based systems, three of six facilities in quarter two and four of five facilities in quarter three had similar numbers of patients retained on ART comparing cohort reports to pharmacy stock records. In ART clinics with electronic systems, five of six facilities in quarter two and five of seven facilities in quarter three had similar numbers of patients retained on ART when comparing retention numbers from electronically generated cohort reports to pharmacy stock records. Among

  19. Estimating Forest Carbon Stock in Alpine and Arctic Ecotones of the Urals

    Directory of Open Access Journals (Sweden)

    V. A. Usoltsev

    2014-10-01

    Full Text Available This paper reports on measured carbon stocks in the forests of two tree line ecotones of the Ural region where climate change might improve growing conditions. The first is an alpine ecotone that is represented by an altitudinal gradient of the spruce-dominated forests on the Western slope of the Tylaiskii Kamen Mountain (Western part of the Konzhakovskii-Tylaiskii-Serebryanskii Mountain system, 59°30′N, 59°00′E, at the alpine timber line that has risen from 864 to 960 m above sea level in the course of the last 100 years. The second is an arctic ecotone in larch-dominated forests at the lower course of the Pur river (67°N, 78°E, at the transition zone between closed floodplain forests and open or island-like communities of upland forests on tundra permafrost. According to our results, there are large differences in the carbon of the aboveground biomass of both ecotones across environmental gradients. In the alpine tree line ecotone, a 19-fold drop of the carbon stocks was detected between the lower and higher altitudinal levels. In the arctic ecotone the aboveground biomass carbon stock of forests of similar densities (1300 to 1700 trees per ha was 7 times as much in the river flood bed, and 5 times as much in mature, dense forests as the low density forests at higher elevations. Twelve regression equations describing dependencies of the aboveground tree biomass (stems, branches, foliage, total aboveground part upon stem diameter of the tree are proposed, which can be used to estimating the biological productivity (carbon of spruce and larch forests on Tylaiskii Kamen Mountain and the lower Pur river and on surrounding areas on the base of traditional forest mensuration have been proposed. In order to reduce the labor intensity of a coming determination of forest biomass the average values of density and dry matter content in the biomass fractions are given that were obtained by taking our sample trees.The results can be useful in

  20. Stakeholder participation in the management of North East Atlantic pelagic fish stocks

    DEFF Research Database (Denmark)

    Coers, Aukje; Raakjær, Jesper; Olesen, Christian

    2012-01-01

    When the Regional Advisory Councils (RACs) were created during the last reform of the Common Fisheries Policy (CFP) in 2002, it was recognised that in addition to the five geographically orientated stakeholder lead advisory bodies, a separate RAC dedicated exclusively to pelagic fisheries...... floor. For this reason, as well as the fact that they are usually widely distributed, researching and managing this dynamic group of fishes across the borders of many countries requires a unique approach. Fortunately, despite these complexities, policy makers have succeeded to establish a reasonably...

  1. Annual dynamics of the fish stock in a backwater of the River Dyje

    Czech Academy of Sciences Publication Activity Database

    Lusk, Stanislav; Halačka, Karel; Lusková, Věra; Horák, Václav

    2001-01-01

    Roč. 17, 4-5 (2001), s. 571-581 ISSN 0886-9375. [International Symposium on Regulated Streams /8./. Toulouse, 17.07.2000-21.07.2000] R&D Projects: GA ČR GA206/99/1519; GA ČR GA206/00/0668; GA AV ČR IBS6093007; GA AV ČR KSK6005114 Institutional research plan: CEZ:AV0Z6093917 Keywords : backwater * fish communities * River Dyje Subject RIV: EF - Botanics Impact factor: 1.169, year: 2001

  2. The effect of hydropower on fish stocks: comparison between cascade and non-cascade reservoirs

    Czech Academy of Sciences Publication Activity Database

    Draštík, Vladislav; Kubečka, Jan; Tušer, Michal; Čech, Martin; Frouzová, Jaroslava; Jarolím, Oldřich; Prchalová, Marie

    2008-01-01

    Roč. 609, č. 1 (2008), s. 25-36 ISSN 0018-8158. [EIFAC Symposium on hydropower , flood control and water abstraction: implications for fish and fisheries. Mondsee, 14.06.2006-17.06.2006] R&D Projects: GA ČR(CZ) GA206/06/1371; GA ČR(CZ) GA206/02/0520; GA ČR(CZ) GA206/07/1392; GA AV ČR(CZ) 1QS600170504 Institutional research plan: CEZ:AV0Z60170517 Keywords : abundance * biomass * longitudinal gradient * vertical and horizontal distribution * cascade Subject RIV: EH - Ecology, Behaviour Impact factor: 1.449, year: 2008

  3. Brood stock formation of the hermaphrodite finfish species Pagellus erythrinus (common Pandora from fish reared in captivity

    Directory of Open Access Journals (Sweden)

    S.D. KLAOUDATOS

    2004-06-01

    Full Text Available Formation of brood stock is considered to be one of the most important operations in order to acquire eggs and fry from any promising candidate finfish species for aquaculture production. The sex reversal observed in hermaphrodite species adds to confusion and creates additional complications in forming a brood stock. The present study describes the efforts and the results of the brood stock formation of the hermaphrodite finfish species Pagellus erythrinus (common Pandora from individuals aged between 4 and 5 years (TL>300mm reared in floating cages. Six groups were formed (50 fish/group in all of which females were present comprising 20 to 40% of the population. The presence of females was in contrast to the literature, which reported that sex reversal of the common Pandora is complete in naturally occurring populations with the absence of females in sizes of a total length greater than 220mm, indicating that in captivity sex reversal is not complete for this species. Four of the groups formed spawned under natural environmental conditions without hormonal treatment and the other two groups were administered a different dosage (250 and 500 IU/kg of Human Chorionic Gonadotropin (HCG to induce spawning. The reproductive period started in the middle of May and ended at the beginning of July and spontaneous spawning occurred in all groups. Egg release lasted for a mean period of one month for the groups that spawned without hormonal treatment with no significant difference in the number of viable eggs between groups. The groups that spawned under hormonal treatment released eggs for a period of six and seven days, for the group that spawned under the high and low hormonal treatment, respectively, with no significant difference in the number of viable eggs between them. The hormonal induced spawning resulted in egg release within a short period of time ideal for a hatchery. However, the number of viable eggs produced was significantly lower

  4. ABOUT ESTIMATION OF THE OPTIMAL PARAMETERS OF MESH IN FISHING GEAR FOR FISHERY IN UKRAINE

    Directory of Open Access Journals (Sweden)

    A. Chuklin

    2013-06-01

    Full Text Available The analysis of biometric exterior indicators of haarder (Liza haematocheilus in the Azov Sea is given and by example of use of these indicators the calculations for optimization of the parameters of mesh in fishing gear for fish catching in the Ukraine is complete. The calculations show that the minimum mesh size which provides selective catch capacity concerning haarder of commercial measure (more than 38 cm should be increased in size from 30 mm to 40 mm. In this case, the probability to continue catching of juveniles from 26.8 cm to 38 cm remains, but its share will be significantly less than in case of using adopted now mesh size of 30 mm. The proposed method is recommended for engineering and biological calculations for the design of new gear and improvement of commercial fishing regulations in order to optimize and improve the effectiveness of management of fish stocks.

  5. Estimating temporary and permanent stock price innovations on Croatian capital market

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    Tihana Škrinjarić

    2014-03-01

    Full Text Available This paper evaluates the size and duration of temporary and permanent stock price innovations on Croatian capital market in the structural VAR (vector autoregression framework with Blanchard and Quah (1989 decomposition. The purpose is to identify the effects of temporary price innovations in order to determine to which extent future stock prices can be predicted. Temporary components present in stock prices are explained throughout the mean-reversion hypothesis. This means that stock prices deviate from the fundamental values, but they will revert to their mean. In that way, to some extent, it is possible to predict future price movements. The results show that for the observed period from January 2000 to September 2013, temporary innovations account for only 2.62% of price variability over a two-year horizon. This means that forecasting the future movements of stock prices on Zagreb Stock Exchange is a difficult task.

  6. Value-at-Risk analysis using ARMAX GARCHX approach for estimating risk of banking subsector stock return’s

    Science.gov (United States)

    Dewi Ratih, Iis; Sutijo Supri Ulama, Brodjol; Prastuti, Mike

    2018-03-01

    Value at Risk (VaR) is one of the statistical methods used to measure market risk by estimating the worst losses in a given time period and level of confidence. The accuracy of this measuring tool is very important in determining the amount of capital that must be provided by the company to cope with possible losses. Because there is a greater losses to be faced with a certain degree of probability by the greater risk. Based on this, VaR calculation analysis is of particular concern to researchers and practitioners of the stock market to be developed, thus getting more accurate measurement estimates. In this research, risk analysis of stocks in four banking sub-sector, Bank Rakyat Indonesia, Bank Mandiri, Bank Central Asia and Bank Negara Indonesia will be done. Stock returns are expected to be influenced by exogenous variables, namely ICI and exchange rate. Therefore, in this research, stock risk estimation are done by using VaR ARMAX-GARCHX method. Calculating the VaR value with the ARMAX-GARCHX approach using window 500 gives more accurate results. Overall, Bank Central Asia is the only bank had the estimated maximum loss in the 5% quantile.

  7. Measuring and modeling carbon stock change estimates for US forests and uncertainties from apparent inter-annual variability

    Science.gov (United States)

    James E. Smith; Linda S. Heath

    2015-01-01

    Our approach is based on a collection of models that convert or augment the USDA Forest Inventory and Analysis program survey data to estimate all forest carbon component stocks, including live and standing dead tree aboveground and belowground biomass, forest floor (litter), down deadwood, and soil organic carbon, for each inventory plot. The data, which include...

  8. Estimating Aboveground Biomass and Carbon Stocks in Periurban Andean Secondary Forests Using Very High Resolution Imagery

    Directory of Open Access Journals (Sweden)

    Nicola Clerici

    2016-07-01

    Full Text Available Periurban forests are key to offsetting anthropogenic carbon emissions, but they are under constant threat from urbanization. In particular, secondary Neotropical forest types in Andean periurban areas have a high potential to store carbon, but are currently poorly characterized. To address this lack of information, we developed a method to estimate periurban aboveground biomass (AGB—a proxy for multiple ecosystem services—of secondary Andean forests near Bogotá, Colombia, based on very high resolution (VHR GeoEye-1, Pleiades-1A imagery and field-measured plot data. Specifically, we tested a series of different pre-processing workflows to derive six vegetation indices that were regressed against in situ estimates of AGB. Overall, the coupling of linear models and the Ratio Vegetation Index produced the most satisfactory results. Atmospheric and topographic correction proved to be key in improving model fit, especially in high aerosol and rugged terrain such as the Andes. Methods and findings provide baseline AGB and carbon stock information for little studied periurban Andean secondary forests. The methodological approach can also be used for integrating limited forest monitoring plot AGB data with very high resolution imagery for cost-effective modelling of ecosystem service provision from forests, monitoring reforestation and forest cover change, and for carbon offset assessments.

  9. Ecological Variability and Carbon Stock Estimates of Mangrove Ecosystems in Northwestern Madagascar

    Directory of Open Access Journals (Sweden)

    Trevor G. Jones

    2014-01-01

    Full Text Available Mangroves are found throughout the tropics, providing critical ecosystem goods and services to coastal communities and supporting rich biodiversity. Despite their value, world-wide, mangroves are being rapidly degraded and deforested. Madagascar contains approximately 2% of the world’s mangroves, >20% of which has been deforested since 1990 from increased extraction for charcoal and timber and conversion to small to large-scale agriculture and aquaculture. Loss is particularly prominent in the northwestern Ambaro and Ambanja bays. Here, we focus on Ambaro and Ambanja bays, presenting dynamics calculated using United States Geological Survey (USGS national-level mangrove maps and the first localized satellite imagery derived map of dominant land-cover types. The analysis of USGS data indicated a loss of 7659 ha (23.7% and a gain of 995 ha (3.1% from 1990–2010. Contemporary mapping results were 93.4% accurate overall (Kappa 0.9, with producer’s and user’s accuracies ≥85%. Classification results allowed partitioning mangroves in to ecologically meaningful, spectrally distinct strata, wherein field measurements facilitated estimating the first total carbon stocks for mangroves in Madagascar. Estimates suggest that higher stature closed-canopy mangroves have average total vegetation carbon values of 146.8 Mg/ha (±10.2 and soil organic carbon of 446.2 (±36.9, supporting a growing body of studies that mangroves are amongst the most carbon-dense tropical forests.

  10. Coded-Wire Tag Expansion Factors for Chinook Salmon Carcass Surveys in California: Estimating the Numbers and Proportions of Hatchery-Origin Fish

    Directory of Open Access Journals (Sweden)

    Michael S. Mohr

    2013-12-01

    Full Text Available Recovery of fish with adipose fin clips (adc and coded-wire tags (cwt in escapement surveys allows calculation of expansion factors used in estimation of the total number of fish from each adc,cwt release group, allowing escapement to be resolved by age and stock of origin. Expanded recoveries are used to derive important estimates such as the total number and proportion of hatchery-origin fish present. The standard estimation scheme assumes accurate visual classification of adc status, which can be problematic for decomposing carcasses. Failure to account for this potential misclassification can lead to significant estimation bias. We reviewed sample expansion factors used for the California Central Valley Chinook salmon 2010 carcass surveys in this context. For upper Sacramento River fall-run and late fall-run carcass surveys, the estimated proportions of adc,cwt fish for fresh and non-fresh carcasses differed substantially, likely from the under-recognition of adc fish in non-fresh carcasses. The resulting estimated proportions of hatchery-origin fish in the upper Sacramento River fall-run and late fall-run carcass surveys were 2.33 to 2.89 times higher if only fresh carcasses are considered. Similar biases can be avoided by consideration of only fresh carcasses for which determination of adc status is relatively straightforward; however, restricting the analysis entirely to fresh carcasses may limit precision because of reduced sample size, and is only possible if protocols for sampling and recording data ensure that the sample data and results for fresh carcasses can be extracted. Thus we recommend sampling protocols that are clearly documented and separately track fresh versus non-fresh carcasses, either collecting only definitively adc fish or that carefully track non-fresh carcasses that are definitively adc versus those that are possibly adc. This would allow judicious use of non-fresh carcass data when sample sizes are otherwise

  11. Estimating rainforest biomass stocks and carbon loss from deforestation and degradation in Papua New Guinea 1972-2002: Best estimates, uncertainties and research needs.

    Science.gov (United States)

    Bryan, Jane; Shearman, Phil; Ash, Julian; Kirkpatrick, J B

    2010-01-01

    Reduction of carbon emissions from tropical deforestation and forest degradation is being considered a cost-effective way of mitigating the impacts of global warming. If such reductions are to be implemented, accurate and repeatable measurements of forest cover change and biomass will be required. In Papua New Guinea (PNG), which has one of the world's largest remaining areas of tropical forest, we used the best available data to estimate rainforest carbon stocks, and emissions from deforestation and degradation. We collated all available PNG field measurements which could be used to estimate carbon stocks in logged and unlogged forest. We extrapolated these plot-level estimates across the forested landscape using high-resolution forest mapping. We found the best estimate of forest carbon stocks contained in logged and unlogged forest in 2002 to be 4770 Mt (+/-13%). Our best estimate of gross forest carbon released through deforestation and degradation between 1972 and 2002 was 1178 Mt (+/-18%). By applying a long-term forest change model, we estimated that the carbon loss resulting from deforestation and degradation in 2001 was 53 Mt (+/-18%), rising from 24 Mt (+/-15%) in 1972. Forty-one percent of 2001 emissions resulted from logging, rising from 21% in 1972. Reducing emissions from logging is therefore a priority for PNG. The large uncertainty in our estimates of carbon stocks and fluxes is primarily due to the dearth of field measurements in both logged and unlogged forest, and the lack of PNG logging damage studies. Research priorities for PNG to increase the accuracy of forest carbon stock assessments are the collection of field measurements in unlogged forest and more spatially explicit logging damage studies. Copyright 2009 Elsevier Ltd. All rights reserved.

  12. Identification and phylogenetic inferences on stocks of sharks affected by the fishing industry off the Northern coast of Brazil

    Directory of Open Access Journals (Sweden)

    Luis Fernando da Silva Rodrigues-Filho

    2009-01-01

    Full Text Available The ongoing decline in abundance and diversity of shark stocks, primarily due to uncontrolled fishery exploitation, is a worldwide problem. An additional problem for the development of conservation and management programmes is the identification of species diversity within a given area, given the morphological similarities among shark species, and the typical disembarkation of processed carcasses which are almost impossible to differentiate. The main aim of the present study was to identify those shark species being exploited off northern Brazil, by using the 12S-16S molecular marker. For this, DNA sequences were obtained from 122 specimens collected on the docks and the fish market in Bragança, in the Brazilian state of Pará. We identified at least 11 species. Three-quarters of the specimens collected were either Carcharhinus porosus or Rhizoprionodon sp, while a notable absence was the daggernose shark, Isogomphodon oxyrhyncus, previously one of the most common species in local catches. The study emphasises the value of molecular techniques for the identification of cryptic shark species, and the potential of the 12S-16S marker as a tool for phylogenetic inferences in a study of elasmobranchs.

  13. Division of Aquatic Resources (DAR), Division of Lands and Natural Resources (DLNR) of the State of Hawaii Fish Stock Surveys from 41 sites on Oahu and Island of Hawaii from 1952-2000 (NODC Accession 0002754)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data are from underwater visual surveys of fish stocks from 41 survey sites on the islands of Oahu and Hawaii, conducted by biologists and technicians of Hawaii's...

  14. Report of the second joint meeting of the Working Party on Assessment of Fish Resources and the Working Party on Stock Assessment of Shrimp and Lobster Resources, Mexico City, Mexico, 26-29 November 1979

    National Research Council Canada - National Science Library

    1981-01-01

    The final formal report of the WECAFC Working Parties on Assessment of Fish Resources and on Stock Assessment of Shrimp and Lobster Resources, held in Mexico City, Mexico, 26-29 November 1979 is presented...

  15. Comparison of regression coefficient and GIS-based methodologies for regional estimates of forest soil carbon stocks

    International Nuclear Information System (INIS)

    Elliott Campbell, J.; Moen, Jeremie C.; Ney, Richard A.; Schnoor, Jerald L.

    2008-01-01

    Estimates of forest soil organic carbon (SOC) have applications in carbon science, soil quality studies, carbon sequestration technologies, and carbon trading. Forest SOC has been modeled using a regression coefficient methodology that applies mean SOC densities (mass/area) to broad forest regions. A higher resolution model is based on an approach that employs a geographic information system (GIS) with soil databases and satellite-derived landcover images. Despite this advancement, the regression approach remains the basis of current state and federal level greenhouse gas inventories. Both approaches are analyzed in detail for Wisconsin forest soils from 1983 to 2001, applying rigorous error-fixing algorithms to soil databases. Resulting SOC stock estimates are 20% larger when determined using the GIS method rather than the regression approach. Average annual rates of increase in SOC stocks are 3.6 and 1.0 million metric tons of carbon per year for the GIS and regression approaches respectively. - Large differences in estimates of soil organic carbon stocks and annual changes in stocks for Wisconsin forestlands indicate a need for validation from forthcoming forest surveys

  16. Compatible above-ground biomass equations and carbon stock estimation for small diameter Turkish pine (Pinus brutia Ten.).

    Science.gov (United States)

    Sakici, Oytun Emre; Kucuk, Omer; Ashraf, Muhammad Irfan

    2018-04-15

    Small trees and saplings are important for forest management, carbon stock estimation, ecological modeling, and fire management planning. Turkish pine (Pinus brutia Ten.) is a common coniferous species and comprises 25.1% of total forest area of Turkey. Turkish pine is also important due to its flammable fuel characteristics. In this study, compatible above-ground biomass equations were developed to predict needle, branch, stem wood, and above-ground total biomass, and carbon stock assessment was also described for Turkish pine which is smaller than 8 cm diameter at breast height or shorter than breast height. Compatible biomass equations are useful for biomass prediction of small diameter individuals of Turkish pine. These equations will also be helpful in determining fire behavior characteristics and calculating their carbon stock. Overall, present study will be useful for developing ecological models, forest management plans, silvicultural plans, and fire management plans.

  17. Lessons learned from practical approaches to reconcile mismatches between biological population structure and stock units of marine fish

    NARCIS (Netherlands)

    Kerr, Lisa A.; Hintzen, Niels T.; Cadrin, Steven X.; Clausen, Lotte Worsøe; Dickey-Collas, Mark; Goethel, Daniel R.; Hatfield, Emma M.C.; Kritzer, Jacob P.; Nash, Richard D.M.

    2016-01-01

    Recent advances in the application of stock identification methods have revealed inconsistencies between the spatial structure of biological populations and the definition of stock units used in assessment and management. From a fisheries management perspective, stocks are typically assumed to be

  18. Hydroacoustic Estimates of Fish Density Distributions in Cougar Reservoir, 2011

    Energy Technology Data Exchange (ETDEWEB)

    Ploskey, Gene R.; Zimmerman, Shon A.; Hennen, Matthew J.; Batten, George W.; Mitchell, T. D.

    2012-09-01

    Day and night mobile hydroacoustic surveys were conducted once each month from April through December 2011 to quantify the horizontal and vertical distributions of fish throughout Cougar Reservoir, Lane County, Oregon.

  19. [Tree above-ground biomass allometries for carbon stocks estimation in the Caribbean mangroves in Colombia].

    Science.gov (United States)

    Yepes, Adriana; Zapata, Mauricio; Bolivar, Jhoanata; Monsalve, Alejandra; Espinosa, Sandra Milena; Sierra-Correa, Paula Cristina; Sierra, Andrés

    2016-06-01

    The distribution of carbon in “Blue Carbon” ecosystems such as mangroves is little known, when compared with the highly known terrestrial forests, despite its particular and recognized high productivity and carbon storage capacity. The objective of this study was to analyze the above ground biomass (AGB) of the species Rhizophora mangle and Avicennia germinans from the Marine Protected Area of Distrito de Manejo Integrado (DMI), Cispatá-Tinajones-La Balsa, Caribbean Colombian coast. With official authorization, we harvested and studied 30 individuals of each species, and built allometric models in order to estimate AGB. Our AGB results indicated that the studied mangrove forests of the DMI Colombian Caribbean was of 129.69 ± 20.24 Mg/ha, equivalent to 64.85 ± 10.12 MgC/ha. The DMI has an area of 8 570.9 ha in mangrove forests, and we estimated that the total carbon potential stored was about 555 795.93 Mg C. The equations generated in this study can be considered as an alternative for the assessment of carbon stocks in AGB of mangrove forests in Colombia; as other available AGB allometric models do not discriminate mangrove forests, despite being particular ecosystems. They can be used for analysis at a more detailed scale and are considered useful to determine the carbon storage potential of mangrove forests, as a country alternative to support forest conservation and emission reduction strategies. In general, the potential of carbon storage from Colombian Caribbean mangrove forests is important and could promote the country leadership of the “blue carbon” stored.

  20. Global estimates of carbon stock changes in living forest biomass: EDGARv4.3 - time series from 1990 to 2010

    Science.gov (United States)

    Petrescu, A. M. R.; Abad-Viñas, R.; Janssens-Maenhout, G.; Blujdea, V. N. B.; Grassi, G.

    2012-08-01

    While the Emissions Database for Global Atmospheric Research (EDGAR) focuses on global estimates for the full set of anthropogenic activities, the Land Use, Land-Use Change and Forestry (LULUCF) sector might be the most diverse and most challenging to cover consistently for all countries of the world. Parties to United Nations Framework Convention on Climate Change (UNFCCC) are required to provide periodic estimates of greenhouse gas (GHG) emissions, following the latest approved methodological guidance by the International Panel on Climate Change (IPCC). The current study aims to consistently estimate the carbon (C) stock changes from living forest biomass for all countries of the world, in order to complete the LULUCF sector in EDGAR. In order to derive comparable estimates for developing and developed countries, it is crucial to use a single methodology with global applicability. Data for developing countries are generally poor, such that only the Tier 1 methods from either the IPCC Good Practice Guide for Land Use, Land-Use Change and Forestry (GPG-LULUCF) 2003 or the IPCC 2006 Guidelines can be applied to these countries. For this purpose, we applied the IPCC Tier 1 method at global level following both IPCC GPG-LULUCF 2003 and IPCC 2006, using spatially coarse activity data (i.e. area, obtained combining two different global forest maps: the Global Land Cover map and the eco-zones subdivision of the Global Ecological Zone (GEZ) map) in combination with the IPCC default C stocks and C stock change factors. Results for the C stock changes were calculated separately for gains, harvest, fires (Global Fire Emissions Database version 3, GFEDv.3) and net deforestation for the years 1990, 2000, 2005 and 2010. At the global level, results obtained with the two sets of IPCC guidance differed by about 40 %, due to different assumptions and default factors. The IPCC Tier 1 method unavoidably introduced high uncertainties due to the "globalization" of parameters. When the

  1. Statistical evaluation of a project to estimate fish trajectories through the intakes of Kaplan hydropower turbines

    Science.gov (United States)

    Sutton, Virginia Kay

    This paper examines statistical issues associated with estimating paths of juvenile salmon through the intakes of Kaplan turbines. Passive sensors, hydrophones, detecting signals from ultrasonic transmitters implanted in individual fish released into the preturbine region were used to obtain the information to estimate fish paths through the intake. Aim and location of the sensors affects the spatial region in which the transmitters can be detected, and formulas relating this region to sensor aiming directions are derived. Cramer-Rao lower bounds for the variance of estimators of fish location are used to optimize placement of each sensor. Finally, a statistical methodology is developed for analyzing angular data collected from optimally placed sensors.

  2. Estimating Soil Organic Carbon stocks and uncertainties for the National inventory Report - a study case in Southern Belgium

    Science.gov (United States)

    Chartin, Caroline; Stevens, Antoine; Kruger, Inken; Esther, Goidts; Carnol, Monique; van Wesemael, Bas

    2016-04-01

    As many other countries, Belgium complies with Annex I of the United Nations Framework Convention on Climate Change (UNFCCC). Belgium thus reports its annual greenhouse gas emissions in its national inventory report (NIR), with a distinction between emissions/sequestration in cropland and grassland (EU decision 529/2013). The CO2 fluxes are then based on changes in SOC stocks computed for each of these two types of landuse. These stocks are specified for each of the agricultural regions which correspond to areas with similar agricultural practices (rotations and/or livestock) and yield potentials. For Southern Belgium (Wallonia) consisting of ten agricultural regions, the Soil Monitoring Network (SMN) 'CARBOSOL' has been developed this last decade to survey the state of agricultural soils by quantifying SOC stocks and their evolution in a reasonable number of locations complying with the time and funds allocated. Unfortunately, the 592 points of the CARBOSOL network do not allow a representative and a sound estimation of SOC stocks and its uncertainties for the 20 possible combinations of land use/agricultural regions. Moreover, the SMN CARBIOSOL is based on a legacy database following a convenience scheme sampling strategy rather than a statistical scheme defined by design-based or model-based strategies. Here, we aim to both quantify SOC budgets (i.e., How much?) and spatialize SOC stocks (i.e., Where?) at regional scale (Southern Belgium) based on data from the SMN described above. To this end, we developed a computation procedure based on Digital Soil Mapping techniques and stochastic simulations (Monte-Carlo) allowing the estimation of multiple (10,000) independent spatialized datasets. This procedure accounts for the uncertainties associated to estimations of both i) SOC stock at the pixelscale and ii) parameters of the models. Based on these 10,000 individual realizations of the spatial model, mean SOC stocks and confidence intervals can be then computed at

  3. SRKW summer prey - Prey species and stock specific consumption estimates for SRKW in their summer range

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Southern Resident Killer Whales (SRKW) are listed as a Distinct Population Segment under the Endangered Species Act. Data concerning their prey species and stock...

  4. Estimation of a simple agent-based model of financial markets: An application to Australian stock and foreign exchange data

    Science.gov (United States)

    Alfarano, Simone; Lux, Thomas; Wagner, Friedrich

    2006-10-01

    Following Alfarano et al. [Estimation of agent-based models: the case of an asymmetric herding model, Comput. Econ. 26 (2005) 19-49; Excess volatility and herding in an artificial financial market: analytical approach and estimation, in: W. Franz, H. Ramser, M. Stadler (Eds.), Funktionsfähigkeit und Stabilität von Finanzmärkten, Mohr Siebeck, Tübingen, 2005, pp. 241-254], we consider a simple agent-based model of a highly stylized financial market. The model takes Kirman's ant process [A. Kirman, Epidemics of opinion and speculative bubbles in financial markets, in: M.P. Taylor (Ed.), Money and Financial Markets, Blackwell, Cambridge, 1991, pp. 354-368; A. Kirman, Ants, rationality, and recruitment, Q. J. Econ. 108 (1993) 137-156] of mimetic contagion as its starting point, but allows for asymmetry in the attractiveness of both groups. Embedding the contagion process into a standard asset-pricing framework, and identifying the abstract groups of the herding model as chartists and fundamentalist traders, a market with periodic bubbles and bursts is obtained. Taking stock of the availability of a closed-form solution for the stationary distribution of returns for this model, we can estimate its parameters via maximum likelihood. Expanding our earlier work, this paper presents pertinent estimates for the Australian dollar/US dollar exchange rate and the Australian stock market index. As it turns out, our model indicates dominance of fundamentalist behavior in both the stock and foreign exchange market.

  5. Sampling designs and methods for estimating fish-impingement losses at cooling-water intakes

    International Nuclear Information System (INIS)

    Murarka, I.P.; Bodeau, D.J.

    1977-01-01

    Several systems for estimating fish impingement at power plant cooling-water intakes are compared to determine the most statistically efficient sampling designs and methods. Compared to a simple random sampling scheme the stratified systematic random sampling scheme, the systematic random sampling scheme, and the stratified random sampling scheme yield higher efficiencies and better estimators for the parameters in two models of fish impingement as a time-series process. Mathematical results and illustrative examples of the applications of the sampling schemes to simulated and real data are given. Some sampling designs applicable to fish-impingement studies are presented in appendixes

  6. Modelling the Carbon Stocks Estimation of the Tropical Lowland Dipterocarp Forest Using LIDAR and Remotely Sensed Data

    Science.gov (United States)

    Zaki, N. A. M.; Latif, Z. A.; Suratman, M. N.; Zainal, M. Z.

    2016-06-01

    Tropical forest embraces a large stock of carbon in the global carbon cycle and contributes to the enormous amount of above and below ground biomass. The carbon kept in the aboveground living biomass of trees is typically the largest pool and the most directly impacted by the anthropogenic factor such as deforestation and forest degradation. However, fewer studies had been proposed to model the carbon for tropical rain forest and the quantification still remain uncertainties. A multiple linear regression (MLR) is one of the methods to define the relationship between the field inventory measurements and the statistical extracted from the remotely sensed data which is LiDAR and WorldView-3 imagery (WV-3). This paper highlight the model development from fusion of multispectral WV-3 with the LIDAR metrics to model the carbon estimation of the tropical lowland Dipterocarp forest of the study area. The result shown the over segmentation and under segmentation value for this output is 0.19 and 0.11 respectively, thus D-value for the classification is 0.19 which is 81%. Overall, this study produce a significant correlation coefficient (r) between Crown projection area (CPA) and Carbon stocks (CS); height from LiDAR (H_LDR) and Carbon stocks (CS); and Crown projection area (CPA) and height from LiDAR (H_LDR) were shown 0.671, 0.709 and 0.549 respectively. The CPA of the segmentation found to be representative spatially with higher correlation of relationship between diameter at the breast height (DBH) and carbon stocks which is Pearson Correlation p = 0.000 (p using multiple linear regression method. The study concluded that the integration of WV-3 imagery with the CHM raster based LiDAR were useful in order to quantify the AGB and carbon stocks for a larger sample area of the Lowland Dipterocarp forest.

  7. The Importance of Parameter Estimates for Stock-REIT-Bond Optimal Asset Allocation

    OpenAIRE

    Lin, Lisa; Lo, Jonathan

    2012-01-01

    This study is an extension of the research done by Waggle & Agrrawal (2006), which assesses the marginal effects of changes in optimal portfolio weights with respect to changes in the REIT-stock risk premium and correlation coefficients under a three-asset setting. We also consider two time periods from 1988-2011 and from 2000-2011. The results show that the sensitivity of changes in the REIT-stock risk premium on optimal portfolio weights is significantly higher than the effect of change...

  8. LIMNOLOGICAL CONDITION AND ESTIMATION OF POTENTIAL FISH PRODUCTION OF KERINCI LAKE JAMBI, SUMATRA

    Directory of Open Access Journals (Sweden)

    Samuel Samuel

    2015-06-01

    Full Text Available Kerinci Lake is a type of tectonic lakes located in a protected forest area of National Park of Kerinci Sebelat and a source of various fish species important for local people for their dayly food comsumption and income. However, few information is available on limnological condition and fish resources. Field research observing the limnological condition and estimating the potential fish production was conducted four times in April, June, August and October 2013. The research is aimed to describe the condition of limnology and estimate the potential fish production of the lake. Limnological aspect included the physico-chemical and biological parameters, namely: temperature, water transparency, depth, substrate, conductivity, pH, dissolved oxygen, alkalinity, ammonia, nitrate, phosphate, total phosphorus, chlorophyll-a and trophic state. Potential fish production was calculated by using the biological parameter levels of chlorophyll-a. The results show that the euphotic layer of the lake waters was still feasible for fish life. Water condition of the bottom layer was less supportable for fish life due to low dissolved oxygen content. Trophic state index (TSI values, either measured by temporal and spatial ways, had TSI with an average of 61.75. From these index, the lake is classified as a lake at the high productivity level (eutrophic. Annual fish production was an average of 307 kg/ha/year. By taking account the average of fish production and the total area of lake of around 4,200 ha, the potential fish production of Kerinci Lake is estimated about ± 1,287 tons/year.

  9. Ability of LANDSAT-8 Oli Derived Texture Metrics in Estimating Aboveground Carbon Stocks of Coppice Oak Forests

    Science.gov (United States)

    Safari, A.; Sohrabi, H.

    2016-06-01

    The role of forests as a reservoir for carbon has prompted the need for timely and reliable estimation of aboveground carbon stocks. Since measurement of aboveground carbon stocks of forests is a destructive, costly and time-consuming activity, aerial and satellite remote sensing techniques have gained many attentions in this field. Despite the fact that using aerial data for predicting aboveground carbon stocks has been proved as a highly accurate method, there are challenges related to high acquisition costs, small area coverage, and limited availability of these data. These challenges are more critical for non-commercial forests located in low-income countries. Landsat program provides repetitive acquisition of high-resolution multispectral data, which are freely available. The aim of this study was to assess the potential of multispectral Landsat 8 Operational Land Imager (OLI) derived texture metrics in quantifying aboveground carbon stocks of coppice Oak forests in Zagros Mountains, Iran. We used four different window sizes (3×3, 5×5, 7×7, and 9×9), and four different offsets ([0,1], [1,1], [1,0], and [1,-1]) to derive nine texture metrics (angular second moment, contrast, correlation, dissimilar, entropy, homogeneity, inverse difference, mean, and variance) from four bands (blue, green, red, and infrared). Totally, 124 sample plots in two different forests were measured and carbon was calculated using species-specific allometric models. Stepwise regression analysis was applied to estimate biomass from derived metrics. Results showed that, in general, larger size of window for deriving texture metrics resulted models with better fitting parameters. In addition, the correlation of the spectral bands for deriving texture metrics in regression models was ranked as b4>b3>b2>b5. The best offset was [1,-1]. Amongst the different metrics, mean and entropy were entered in most of the regression models. Overall, different models based on derived texture metrics

  10. Fish freshness estimation using eye image processing under white and UV lightings

    Science.gov (United States)

    Kanamori, Katsuhiro; Shirataki, Yuri; Liao, Qiuhong; Ogawa, Yuichi; Suzuki, Tetsuhito; Kondo, Naoshi

    2017-05-01

    A non-destructive method of estimating the freshness of fish is required for appropriate price setting and food safety. In particular, for determining the possibility of eating raw fish (sashimi), freshness estimation is critical. We studied such an estimation method by capturing images of fish eyes and performing image processing using the temporal changes of the luminance of pupil and iris. To detect subtle non-visible changes of these features, we used UV (375 nm) light illumination in addition to visible white light illumination. Polarization and two-channel LED techniques were used to remove strong specular reflection from the cornea of the eye and from clear-plastic wrap used to cover the fish to maintain humidity. Pupil and iris regions were automatically detected separately by image processing after the specular reflection removal process, and two types of eye contrast were defined as the ratio of mean and median pixel values of each region. Experiments using 16 Japanese dace (Tribolodon hakonensis) at 23° and 85% humidity for 24 hours were performed. The eye contrast of raw fish increase non-linearly in the initial period and then decreased; however, that of frozen-thawed fish decreased linearly throughout 24 hours, regardless of the lighting. Interestingly, the eye contrast using UV light showed a higher correlation with time than that using white light only in the case of raw fish within the early 6- hour period postmortem. These results show the possibility of estimating fish freshness in the initial stage when fish are eaten raw using white and UV lightings.

  11. Applying a new ensemble approach to estimating stock status of marine fisheries around the world

    DEFF Research Database (Denmark)

    Rosenberg, Andrew A.; Kleisner, Kristin M.; Afflerbach, Jamie

    2018-01-01

    The exploitation status of marine fisheries stocks worldwide is of critical importance for food security, ecosystem conservation, and fishery sustainability. Applying a suite of data-limited methods to global catch data, combined through an ensemble modeling approach, we provide quantitative esti...

  12. Predictability of Stock Returns

    Directory of Open Access Journals (Sweden)

    Ahmet Sekreter

    2017-06-01

    Full Text Available Predictability of stock returns has been shown by empirical studies over time. This article collects the most important theories on forecasting stock returns and investigates the factors that affecting behavior of the stocks’ prices and the market as a whole. Estimation of the factors and the way of estimation are the key issues of predictability of stock returns.

  13. Application of a multistate model to estimate culvert effects on movement of small fishes

    Science.gov (United States)

    Norman, J.R.; Hagler, M.M.; Freeman, Mary C.; Freeman, B.J.

    2009-01-01

    While it is widely acknowledged that culverted road-stream crossings may impede fish passage, effects of culverts on movement of nongame and small-bodied fishes have not been extensively studied and studies generally have not accounted for spatial variation in capture probabilities. We estimated probabilities for upstream and downstream movement of small (30-120 mm standard length) benthic and water column fishes across stream reaches with and without culverts at four road-stream crossings over a 4-6-week period. Movement and reach-specific capture probabilities were estimated using multistate capture-recapture models. Although none of the culverts were complete barriers to passage, only a bottomless-box culvert appeared to permit unrestricted upstream and downstream movements by benthic fishes based on model estimates of movement probabilities. At two box culverts that were perched above the water surface at base flow, observed movements were limited to water column fishes and to intervals when runoff from storm events raised water levels above the perched level. Only a single fish was observed to move through a partially embedded pipe culvert. Estimates for probabilities of movement over distances equal to at least the length of one culvert were low (e.g., generally ???0.03, estimated for 1-2-week intervals) and had wide 95% confidence intervals as a consequence of few observed movements to nonadjacent reaches. Estimates of capture probabilities varied among reaches by a factor of 2 to over 10, illustrating the importance of accounting for spatially variable capture rates when estimating movement probabilities with capture-recapture data. Longer-term studies are needed to evaluate temporal variability in stream fish passage at culverts (e.g., in relation to streamflow variability) and to thereby better quantify the degree of population fragmentation caused by road-stream crossings with culverts. ?? American Fisheries Society 2009.

  14. A combined telemetry - tag return approach to estimate fishing and natural mortality rates of an estuarine fish

    Science.gov (United States)

    Bacheler, N.M.; Buckel, J.A.; Hightower, J.E.; Paramore, L.M.; Pollock, K.H.

    2009-01-01

    A joint analysis of tag return and telemetry data should improve estimates of mortality rates for exploited fishes; however, the combined approach has thus far only been tested in terrestrial systems. We tagged subadult red drum (Sciaenops ocellatus) with conventional tags and ultrasonic transmitters over 3 years in coastal North Carolina, USA, to test the efficacy of the combined telemetry - tag return approach. There was a strong seasonal pattern to monthly fishing mortality rate (F) estimates from both conventional and telemetry tags; highest F values occurred in fall months and lowest levels occurred during winter. Although monthly F values were similar in pattern and magnitude between conventional tagging and telemetry, information on F in the combined model came primarily from conventional tags. The estimated natural mortality rate (M) in the combined model was low (estimated annual rate ?? standard error: 0.04 ?? 0.04) and was based primarily upon the telemetry approach. Using high-reward tagging, we estimated different tag reporting rates for state agency and university tagging programs. The combined telemetry - tag return approach can be an effective approach for estimating F and M as long as several key assumptions of the model are met.

  15. [Phylogeny and divergence time estimation of Schizothoracinae fishes in Xinjiang].

    Science.gov (United States)

    Ayelhan, Haysa; Guo, Yan; Meng, Wei; Yang, Tianyan; Ma, Yanwu

    2014-10-01

    Based on combined data of mitochondrial COI, ND4 and 16S RNA genes, molecular phylogeny of 4 genera, 10 species or subspecies of Schizothoracinae fishes distributed in Xinjiang were analyzed. The molecular clock was calibrated by divergence time of Cyprininae and geological segregation event between the upper Yellow River and Qinghai Lake. Divergence time of Schizothoracinae fishes was calculated, and its relationship with the major geological events and the climate changes in surrounding areas of Tarim Basin was discussed. The results showed that genus Aspiorhynchus did not form an independent clade, but clustered with Schizothorax biddulphi and S. irregularis. Kimura 2-parameter model was used to calculate the genetic distance of COI gene, the genetic distance between genus Aspiorhynchus and Schizothorax did not reach genus level, and Aspiorhynchus laticeps might be a specialized species of genus Schizothorax. Cluster analysis showed a different result with morphological classification method, and it did not support the subgenus division of Schizothorax fishes. Divergence of two groups of primitive Schizothoracinae (8.18Ma) and divergence of Gymnodiptychus dybowskii and Diptychus maculates (7.67Ma) occurred in late Miocene, which might be related with the separation of Kunlun Mountain and north Tianshan Mountain River system that was caused by the uplift of Qinghai-Tibet Plateau and Tianshan Mountain, and the aridification of Tarim Basin. The terrain of Tarim Basin that was affected by Quaternary Himalayan movement was high in west but low in east, as a result, Lop Nor became the center of surrounding mountain rivers in Tarim Basin, which shaped the distribution pattern of genus Schizothorax.

  16. Impacts of Airborne Lidar Pulse Density on Estimating Biomass Stocks and Changes in a Selectively Logged Tropical Forest

    Directory of Open Access Journals (Sweden)

    Carlos Alberto Silva

    2017-10-01

    Full Text Available Airborne lidar is a technology well-suited for mapping many forest attributes, including aboveground biomass (AGB stocks and changes in selective logging in tropical forests. However, trade-offs still exist between lidar pulse density and accuracy of AGB estimates. We assessed the impacts of lidar pulse density on the estimation of AGB stocks and changes using airborne lidar and field plot data in a selectively logged tropical forest located near Paragominas, Pará, Brazil. Field-derived AGB was computed at 85 square 50 × 50 m plots in 2014. Lidar data were acquired in 2012 and 2014, and for each dataset the pulse density was subsampled from its original density of 13.8 and 37.5 pulses·m−2 to lower densities of 12, 10, 8, 6, 4, 2, 0.8, 0.6, 0.4 and 0.2 pulses·m−2. For each pulse density dataset, a power-law model was developed to estimate AGB stocks from lidar-derived mean height and corresponding changes between the years 2012 and 2014. We found that AGB change estimates at the plot level were only slightly affected by pulse density. However, at the landscape level we observed differences in estimated AGB change of >20 Mg·ha−1 when pulse density decreased from 12 to 0.2 pulses·m−2. The effects of pulse density were more pronounced in areas of steep slope, especially when the digital terrain models (DTMs used in the lidar derived forest height were created from reduced pulse density data. In particular, when the DTM from high pulse density in 2014 was used to derive the forest height from both years, the effects on forest height and the estimated AGB stock and changes did not exceed 20 Mg·ha−1. The results suggest that AGB change can be monitored in selective logging in tropical forests with reasonable accuracy and low cost with low pulse density lidar surveys if a baseline high-quality DTM is available from at least one lidar survey. We recommend the results of this study to be considered in developing projects and national

  17. Estimating Carbon Stocks Along Depressional Wetlands Using Ground Penetrating Radar (GPR) in the Disney Wilderness Preserve (Orlando, Florida)

    Science.gov (United States)

    McClellan, M. D.; Comas, X.; Wright, W. J.; Mount, G. J.

    2014-12-01

    Peat soils store a large fraction of the global carbon (C) in soil. It is estimated that 95% of carbon in peatlands is stored in the peat soil, while less than 5% occurs in the vegetation. The majority of studies related to C stocks in peatlands have taken place in northern latitudes leaving the tropical and subtropical latitudes clearly understudied. In this study we use a combination of indirect non-invasive geophysical methods (mainly ground penetrating radar, GPR) as well as direct measurements (direct coring) to calculate total C stocks within subtropical depressional wetlands in the Disney Wilderness Preserve (DWP, Orlando, FL). A set of three-dimensional (3D) GPR surveys were used to detect variability of the peat layer thickness and the underlying peat-sand mix layer across several depressional wetlands. Direct samples collected at selected locations were used to confirm depth of each interface and to estimate C content in the laboratory. Layer thickness estimated from GPR and direct C content were used to estimate total peat volume and C content for the entire depressional wetland. Through the use of aerial photos a relationship between surface area along the depressional wetlands and total peat thickness (and thus C content) was established for the depressions surveyed and applied throughout the entire preserve. This work shows the importance of depressional wetlands as critical contributors of the C budget at the DWP.

  18. Greenland Halibut in Upernavik: a preliminary study of the importance of the stock for the fishing populace

    DEFF Research Database (Denmark)

    Delaney, Alyne E.; Becker Jakobsen, Rikke; Hendriksen, Kåre

    for Greenland halibut in Upernavik. There are up to an additional 75 who also fish, however, without paying the license fee. This means that almost half of working age men fish for halibut in the Upernavik district. Fishing is extremely important in Upernavik for its role in the local, mixed economy. Fishing...... often provides the cash needed for materials needed for work (hunting and fishing equipment such as bullets, nets, snowmobiles, etc.) and daily living (housing, transport, television, food, etc). Fishing also supports the important local cultural practice of meeting social obligations and reciprocity...... of Greenland is currently in the midst of proposing changes to the Halibut management structure, the report focuses specifically on potential social impacts of the fishery management plan to coastal fishers. The degree and consequence of any impact is a function of the characteristics of the fishing community...

  19. [Estimation of spur dike-affected fish habitat area].

    Science.gov (United States)

    Ray-Shyan, Wu; Yan-Ru, Chen; Yi-Liang, Ge

    2012-04-01

    Based on the HEC-RAS and River 2D modes, and taking 5% change rate of weighted usable area (WUA) as the threshold to define the spur dike- affected area of target fish species Acrossocheilus paradoxus in Fazi River in Taiwan, this paper studied the affected area of the fish habitat by spur dike, and, in combining with the references about the installations of spur dikes in Taiwan in recent 10 years, analyzed the relative importance of related affecting factors such as dike height, dike length (water block rate), average slope gradient of river way, single or double spur dike, and flow discharge. In spite of the length of the dike, the affected area in downstream was farther, and was about 2-6 times as large as that in upstream. The ratio of the affected area in downstream / upstream decreased with increasing slope gradient, but increased with increasing dike length and flow discharge. When the discharge was approximate to 10 years return periods, the ratio of the affected area would be close to a constant of 2. Building double spur dike would produce a better WUA than building single spur dike.

  20. An investigation on how to estimate future cash flows: Evidence from Tehran Stock Exchange

    Directory of Open Access Journals (Sweden)

    Roghayeh Ahmdi Panah Banad Koki

    2014-03-01

    Full Text Available This paper presents an empirical investigation to predict future cash flows using present cash flow and accruals using the information of 96 selected firms listed on Tehran Stock Exchange over the period 2007-2011. The proposed study uses linear regression techniques to forecast future cash flow and the results indicate that cash flow and accruals together could provide more power to forecast cash flow. In addition, accrual provides future cash flow better than cash flow. The survey also performs an investigation on discretionary accrual and finds that the firms with higher accruals maintain lower return compared with firms with lower return. This means there is a clear evidence of discretionary accruals on Tehran Stock Exchange.

  1. An investigation on how to estimate future cash flows: Evidence from Tehran Stock Exchange

    OpenAIRE

    Roghayeh Ahmdi Panah Banad Koki; Iman Jokar

    2014-01-01

    This paper presents an empirical investigation to predict future cash flows using present cash flow and accruals using the information of 96 selected firms listed on Tehran Stock Exchange over the period 2007-2011. The proposed study uses linear regression techniques to forecast future cash flow and the results indicate that cash flow and accruals together could provide more power to forecast cash flow. In addition, accrual provides future cash flow better than cash flow. The survey also perf...

  2. CONTRIBUTION OF TROUT YOLK-SAC FRY (SALMO TRUTTA L. ORIGINATING FROM WILD STOCK TO FISHING IN THE MOSELOTTE RIVER, FRANCE

    Directory of Open Access Journals (Sweden)

    GERDEAUX D.

    2006-07-01

    Full Text Available The Moselotte River has been severely affected by human activity and in some of its stretches this has impaired reproduction of trout, which has added to an adverse effect on the trout population arising from a high fishing pressure by local anglers. To offset this problem, the local anglers annually release about 50,000 yolk-sac fry that have been derived from wild native breeding stock. It was possible to monitor the fry released in 1999 and 2000 using a method of mass marking by immersion in a fluoromarking agent (Alizarin Red S. The trout enter the fishery at 3 years and about 90% of the trout caught are three or four years old. Fish that had been released represented 25.5% and 36.7% of the catches respectively in 2002 and 2003, two percentages that do not differ significantly. This proportion varied according to the location in the river. The age structure of the marked fish that were caught was similar to that of fish hatched in the wild.

  3. MODELLING THE CARBON STOCKS ESTIMATION OF THE TROPICAL LOWLAND DIPTEROCARP FOREST USING LIDAR AND REMOTELY SENSED DATA

    Directory of Open Access Journals (Sweden)

    N. A. M. Zaki

    2016-06-01

    Full Text Available Tropical forest embraces a large stock of carbon in the global carbon cycle and contributes to the enormous amount of above and below ground biomass. The carbon kept in the aboveground living biomass of trees is typically the largest pool and the most directly impacted by the anthropogenic factor such as deforestation and forest degradation. However, fewer studies had been proposed to model the carbon for tropical rain forest and the quantification still remain uncertainties. A multiple linear regression (MLR is one of the methods to define the relationship between the field inventory measurements and the statistical extracted from the remotely sensed data which is LiDAR and WorldView-3 imagery (WV-3. This paper highlight the model development from fusion of multispectral WV-3 with the LIDAR metrics to model the carbon estimation of the tropical lowland Dipterocarp forest of the study area. The result shown the over segmentation and under segmentation value for this output is 0.19 and 0.11 respectively, thus D-value for the classification is 0.19 which is 81%. Overall, this study produce a significant correlation coefficient (r between Crown projection area (CPA and Carbon stocks (CS; height from LiDAR (H_LDR and Carbon stocks (CS; and Crown projection area (CPA and height from LiDAR (H_LDR were shown 0.671, 0.709 and 0.549 respectively. The CPA of the segmentation found to be representative spatially with higher correlation of relationship between diameter at the breast height (DBH and carbon stocks which is Pearson Correlation p = 0.000 (p Dipterocarp forest.

  4. Hankin and Reeves' approach to estimating fish abundance in small streams: limitations and potential options; TOPICAL

    International Nuclear Information System (INIS)

    Thompson, William L.

    2000-01-01

    Hankin and Reeves' (1988) approach to estimating fish abundance in small streams has been applied in stream-fish studies across North America. However, as with any method of population estimation, there are important assumptions that must be met for estimates to be minimally biased and reasonably precise. Consequently, I investigated effects of various levels of departure from these assumptions via simulation based on results from an example application in Hankin and Reeves (1988) and a spatially clustered population. Coverage of 95% confidence intervals averaged about 5% less than nominal when removal estimates equaled true numbers within sampling units, but averaged 62% - 86% less than nominal when they did not, with the exception where detection probabilities of individuals were and gt;0.85 and constant across sampling units (95% confidence interval coverage= 90%). True total abundances averaged far (20% - 41%) below the lower confidence limit when not included within intervals, which implies large negative bias. Further, average coefficient of variation was about 1.5 times higher when removal estimates did not equal true numbers within sampling units (C(bar V)0.27[SE= 0.0004]) than when they did (C(bar V)= 0.19[SE= 0.0002]). A potential modification to Hankin and Reeves' approach is to include environmental covariates that affect detection rates of fish into the removal model or other mark-recapture model. A potential alternative is to use snorkeling in combination with line transect sampling to estimate fish densities. Regardless of the method of population estimation, a pilot study should be conducted to validate the enumeration method, which requires a known (or nearly so) population of fish to serve as a benchmark to evaluate bias and precision of population estimates

  5. An analytical method of estimating Value-at-Risk on the Belgrade Stock Exchange

    Directory of Open Access Journals (Sweden)

    Obadović Milica D.

    2009-01-01

    Full Text Available This paper presents market risk evaluation for a portfolio consisting of shares that are continuously traded on the Belgrade Stock Exchange, by applying the Value-at-Risk model - the analytical method. It describes the manner of analytical method application and compares the results obtained by implementing this method at different confidence levels. Method verification was carried out on the basis of the failure rate that demonstrated the confidence level for which this method was acceptable in view of the given conditions.

  6. Pike ( Esox lucius L.) stocking as a biomanipulation tool .1. Effects on the fish population in Lake Lyng, Denmark

    DEFF Research Database (Denmark)

    Berg, Søren; Jeppesen, E.; Søndergaard, M.

    1997-01-01

    significantly by 64 to 97%. In 1991 ruffe disappeared completely. The pike stocking did not affect the density of perch significantly. The growth of pike was high and also the growth of perch increased significantly from 1990 to 1991 (p ... of the piscivorous perch increased due to increased Secchi depth and a continuous high density of 0+ planktivores in the pelagic zone of the lake during the years of pike stocking, possibly caused by behaviourial changes and the forcing of the 0+ planktivores into the pelagic zone...

  7. Allometric Equations for Estimating Biomass and Carbon Stocks in the Temperate Forests of North-Western Mexico

    Directory of Open Access Journals (Sweden)

    Benedicto Vargas-Larreta

    2017-07-01

    Full Text Available This paper presents new equations for estimating above-ground biomass (AGB and biomass components of seventeen forest species in the temperate forests of northwestern Mexico. A data set corresponding to 1336 destructively sampled oak and pine trees was used to fit the models. The generalized method of moments was used to simultaneously fit systems of equations for biomass components and AGB, to ensure additivity. In addition, the carbon content of each tree component was calculated by the dry combustion method, in a TOC analyser. The results of cross-validation indicated that the fitted equations accounted for on average 91%, 82%, 83% and 76% of the observed variance in stem wood and stem bark, branch and foliage biomass, respectively, whereas the total AGB equations explained on average 93% of the total observed variance in AGB. The inclusion of total height (h or diameter at breast height2 × total height (d2h as a predictor in the d-only based equations systems slightly improved estimates for stem wood, stem bark and total above-ground biomass, and greatly improved the estimates produced by the branch and foliage biomass equations. The predictive power of the proposed equations is higher than that of existing models for the study area. The fitted equations were used to estimate stand level AGB stocks from data on growing stock in 429 permanent sampling plots. Three machine-learning techniques were used to model the estimated stand level AGB and carbon contents; the selected models were used to map the AGB and carbon distributions in the study area, for which mean values of respectively 129.84 Mg ha−1 and 63.80 Mg ha−1 were obtained.

  8. Measuring Ucrit and endurance: equipment choice influences estimates of fish swimming performance.

    Science.gov (United States)

    Kern, P; Cramp, R L; Gordos, M A; Watson, J R; Franklin, C E

    2018-01-01

    This study compared the critical swimming speed (U crit ) and endurance performance of three Australian freshwater fish species in different swim-test apparatus. Estimates of U crit measured in a large recirculating flume were greater for all species compared with estimates from a smaller model of the same recirculating flume. Large differences were also observed for estimates of endurance swimming performance between these recirculating flumes and a free-surface swim tunnel. Differences in estimates of performance may be attributable to variation in flow conditions within different types of swim chambers. Variation in estimates of swimming performance between different types of flumes complicates the application of laboratory-based measures to the design of fish passage infrastructure. © 2017 The Fisheries Society of the British Isles.

  9. An overall estimation of losses caused by diseases in the Brazilian fish farms.

    Science.gov (United States)

    Tavares-Dias, Marcos; Martins, Maurício Laterça

    2017-12-01

    Parasitic and infectious diseases are common in finfish, but are difficult to accurately estimate the economic impacts on the production in a country with large dimensions like Brazil. The aim of this study was to estimate the costs caused by economic losses of finfish due to mortality by diseases in Brazil. A model for estimating the costs related to parasitic and bacterial diseases in farmed fish and an estimative of these economic impacts are presented. We used official data of production and mortality of finfish for rough estimation of economic losses. The losses herein presented are related to direct and indirect economic costs for freshwater farmed fish, which were estimated in US$ 84 million per year. Finally, it was possible to establish by the first time an estimative of overall losses in finfish production in Brazil using data available from production. Therefore, this current estimative must help researchers and policy makers to approximate the economic costs of diseases for fish farming industry, as well as for developing of public policies on the control measures of diseases and priority research lines.

  10. Differences on soil organic carbon stock estimation according to sampling type in Mediterranean areas

    Science.gov (United States)

    Parras-Alcántara, Luis; Lozano-García, Beatriz

    2016-04-01

    Soil organic carbon (SOC) is an important part of the global carbon (C) cycle. In addition, SOC is a soil property subject to changes and highly variable in space and time. Consequently, the scientific community is researching the fate of the organic carbon in the ecosystems. In this line, soil organic matter configuration plays an important role in the Soil System (Parras-Alcántara and Lozano García, 2014). Internationally it is known that soil C sequestration is a strategy to mitigate climate change. In this sense, many soil researchers have studied this parameter (SOC). However, many of these studies were carried out arbitrarily using entire soil profiles (ESP) by pedogenetic horizons or soil control sections (SCS) (edaphic controls to different thickness). As a result, the indiscriminate use of both methodologies implies differences with respect to SOC stock (SOCS) quantification. This scenario has been indicated and warned for different researchers (Parras-Alcántara et al., 2015a; Parras-Alcántara et al., 2015b). This research sought to analyze the SOC stock (SOCS) variability using both methods (ESP and SCS) in the Cardeña and Montoro Natural Park (Spain). This nature reserve is a forested area with 385 km2 in southern Spain. Thirty-seven sampling points were selected in the study zone. Each sampling point was analyzed in two different ways, as ESP (by horizons) and as SCS with different depth increments (0-25, 25-50, 50-75 and 75-100 cm). The major goal of this research was to study the SOCS variability at regional scale. The studied soils were classified as Phaeozems, Cambisols, Regosols and Leptosols. The results obtained show an overestimation of SOCS when SCS sampling approach is used compared to ESP. This supports that methodology selection is very important to SOCS quantification. This research is an assessment for modeling SOCS at the regional level in Mediterranean natural areas. References Parras-Alcántara, L., Lozano-García, B., 2014

  11. Accounting for escape mortality in fisheries: implications for stock productivity and optimal management.

    Science.gov (United States)

    Baker, Matthew R; Schindler, Daniel E; Essington, Timothy E; Hilborn, Ray

    2014-01-01

    Few studies have considered the management implications of mortality to target fish stocks caused by non-retention in commercial harvest gear (escape mortality). We demonstrate the magnitude of this previously unquantified source of mortality and its implications for the population dynamics of exploited stocks, biological metrics, stock productivity, and optimal management. Non-retention in commercial gillnet fisheries for Pacific salmon (Oncorhynchus spp.) is common and often leads to delayed mortality in spawning populations. This represents losses, not only to fishery harvest, but also in future recruitment to exploited stocks. We estimated incidence of non-retention in Alaskan gillnet fisheries for sockeye salmon (O. nerka) and found disentanglement injuries to be extensive and highly variable between years. Injuries related to non-retention were noted in all spawning populations, and incidence of injury ranged from 6% to 44% of escaped salmon across nine river systems over five years. We also demonstrate that non-retention rates strongly correlate with fishing effort. We applied maximum likelihood and Bayesian approaches to stock-recruitment analyses, discounting estimates of spawning salmon to account for fishery-related mortality in escaped fish. Discounting spawning stock estimates as a function of annual fishing effort improved model fits to historical stock-recruitment data in most modeled systems. This suggests the productivity of exploited stocks has been systematically underestimated. It also suggests that indices of fishing effort may be used to predict escape mortality and correct for losses. Our results illustrate how explicitly accounting for collateral effects of fishery extraction may improve estimates of productivity and better inform management metrics derived from estimates of stock-recruitment analyses.

  12. Estimating belowground carbon stocks in isolated wetlands of the Northern Everglades Watershed, central Florida, using ground penetrating radar (GPR) and aerial imagery

    Science.gov (United States)

    McClellan, Matthew; Comas, Xavier; Hinkle, Ross; Sumner, David M.

    2017-01-01

    Peat soils store a large fraction of the global soil carbon (C) pool and comprise 95% of wetland C stocks. While isolated freshwater wetlands in temperate and tropical biomes account for more than 20% of the global peatland C stock, most studies of wetland soil C have occurred in expansive peatlands in northern boreal and subarctic biomes. Furthermore, the contribution of small depressional wetlands in comparison to larger wetland systems in these environments is very uncertain. Given the fact that these wetlands are numerous and variable in terms of their internal geometry, innovative methods are needed for properly estimating belowground C stocks and their overall C contribution to the landscape. In this study, we use a combination of ground penetrating radar (GPR), aerial imagery, and direct measurements (coring) in conjunction with C core analysis to develop a relation between C stock and surface area, and estimate the contribution of subtropical depressional wetlands to the total C stock of pine flatwoods at the Disney Wilderness Preserve (DWP), Florida. Additionally, GPR surveys were able to image collapse structures underneath the peat basin of depressional wetlands, depicting lithological controls on the formation of depressional wetlands at the DWP. Results indicate the importance of depressional wetlands as critical contributors to the landscape C budget at the DWP and the potential of GPR-based approaches for (1) rapidly and noninvasively estimating the contribution of depressional wetlands to regional C stocks and (2) evaluating the formational processes of depressional wetlands.

  13. Estimating Belowground Carbon Stocks in Isolated Wetlands of the Northern Everglades Watershed, Central Florida, Using Ground Penetrating Radar and Aerial Imagery

    Science.gov (United States)

    McClellan, Matthew; Comas, Xavier; Benscoter, Brian; Hinkle, Ross; Sumner, David

    2017-11-01

    Peat soils store a large fraction of the global soil carbon (C) pool and comprise 95% of wetland C stocks. While isolated freshwater wetlands in temperate and tropical biomes account for more than 20% of the global peatland C stock, most studies of wetland soil C have occurred in expansive peatlands in northern boreal and subarctic biomes. Furthermore, the contribution of small depressional wetlands in comparison to larger wetland systems in these environments is very uncertain. Given the fact that these wetlands are numerous and variable in terms of their internal geometry, innovative methods are needed for properly estimating belowground C stocks and their overall C contribution to the landscape. In this study, we use a combination of ground penetrating radar (GPR), aerial imagery, and direct measurements (coring) in conjunction with C core analysis to develop a relation between C stock and surface area, and estimate the contribution of subtropical depressional wetlands to the total C stock of pine flatwoods at the Disney Wilderness Preserve (DWP), Florida. Additionally, GPR surveys were able to image collapse structures underneath the peat basin of depressional wetlands, depicting lithological controls on the formation of depressional wetlands at the DWP. Results indicate the importance of depressional wetlands as critical contributors to the landscape C budget at the DWP and the potential of GPR-based approaches for (1) rapidly and noninvasively estimating the contribution of depressional wetlands to regional C stocks and (2) evaluating the formational processes of depressional wetlands.

  14. Bayesian Estimation of Fish Disease Prevalence from Pooled Samples Incorporating Sensitivity and Specificity

    Science.gov (United States)

    Williams, Christopher J.; Moffitt, Christine M.

    2003-03-01

    An important emerging issue in fisheries biology is the health of free-ranging populations of fish, particularly with respect to the prevalence of certain pathogens. For many years, pathologists focused on captive populations and interest was in the presence or absence of certain pathogens, so it was economically attractive to test pooled samples of fish. Recently, investigators have begun to study individual fish prevalence from pooled samples. Estimation of disease prevalence from pooled samples is straightforward when assay sensitivity and specificity are perfect, but this assumption is unrealistic. Here we illustrate the use of a Bayesian approach for estimating disease prevalence from pooled samples when sensitivity and specificity are not perfect. We also focus on diagnostic plots to monitor the convergence of the Gibbs-sampling-based Bayesian analysis. The methods are illustrated with a sample data set.

  15. Temporal Decorrelation Effect in Carbon Stocks Estimation Using Polarimetric Interferometry Synthetic Aperture Radar (PolInSAR (Case Study: Southeast Sulawesi Tropical Forest

    Directory of Open Access Journals (Sweden)

    Laode M Golok Jaya

    2017-07-01

    Full Text Available This paper was aimed to analyse the effect of temporal decorrelation in carbon stocks estimation. Estimation of carbon stocks plays important roles particularly to understand the global carbon cycle in the atmosphere regarding with climate change mitigation effort. PolInSAR technique combines the advantages of Polarimetric Synthetic Aperture Radar (PolSAR and Interferometry Synthetic Aperture Radar (InSAR technique, which is evidenced to have significant contribution in radar mapping technology in the last few years. In carbon stocks estimation, PolInSAR provides information about vertical vegetation structure to estimate carbon stocks in the forest layers. Two coherence Synthetic Aperture Radar (SAR images of ALOS PALSAR full-polarimetric with 46 days temporal baseline were used in this research. The study was carried out in Southeast Sulawesi tropical forest. The research method was by comparing three interferometric phase coherence images affected by temporal decorrelation and their impacts on Random Volume over Ground (RvoG model. This research showed that 46 days temporal baseline has a significant impact to estimate tree heights of the forest cover where the accuracy decrease from R2=0.7525 (standard deviation of tree heights is 2.75 meters to R2=0.4435 (standard deviation 4.68 meters and R2=0.3772 (standard deviation 3.15 meters respectively. However, coherence optimisation can provide the best coherence image to produce a good accuracy of carbon stocks.

  16. Estimating the Value-at-Risk for some stocks at the capital market in Indonesia based on ARMA-FIGARCH models

    Science.gov (United States)

    Sukono; Lesmana, E.; Susanti, D.; Napitupulu, H.; Hidayat, Y.

    2017-11-01

    Value-at-Risk has already become a standard measurement that must be carried out by the financial institution for both internal interest and regulatory. In this paper, the estimation of Value-at-Risk of some stocks with econometric models approach is analyzed. In this research, we assume that the stock return follows the time series model. To do the estimation of mean value we are using ARMA models, while to estimate the variance value we are using FIGARCH models. Furthermore, the mean value estimator and the variance are used to estimate the Value-at-Risk. The result of the analysis shows that from five stock PRUF, BBRI, MPPA, BMRI, and INDF, the Value-at-Risk obtained are 0.01791, 0.06037, 0.02550, 0.06030, and 0.02585 respectively. Since Value-at-Risk represents the maximum risk size of each stock at a 95% level of significance, then it can be taken into consideration in determining the investment policy on stocks.

  17. Stereological estimation of surface area and barrier thickness of fish gills in vertical sections.

    Science.gov (United States)

    Da Costa, Oscar T F; Pedretti, Ana Carolina E; Schmitz, Anke; Perry, Steven F; Fernandes, Marisa N

    2007-01-01

    Previous morphometric methods for estimation of the volume of components, surface area and thickness of the diffusion barrier in fish gills have taken advantage of the highly ordered structure of these organs for sampling and surface area estimations, whereas the thickness of the diffusion barrier has been measured orthogonally on perpendicularly sectioned material at subjectively selected sites. Although intuitively logical, these procedures do not have a demonstrated mathematical basis, do not involve random sampling and measurement techniques, and are not applicable to the gills of all fish. The present stereological methods apply the principles of surface area estimation in vertical uniform random sections to the gills of the Brazilian teleost Arapaima gigas. The tissue was taken from the entire gill apparatus of the right-hand or left-hand side (selected at random) of the fish by systematic random sampling and embedded in glycol methacrylate for light microscopy. Arches from the other side were embedded in Epoxy resin. Reference volume was estimated by the Cavalieri method in the same vertical sections that were used for surface density and volume density measurements. The harmonic mean barrier thickness of the water-blood diffusion barrier was calculated from measurements taken along randomly selected orientation lines that were sine-weighted relative to the vertical axis. The values thus obtained for the anatomical diffusion factor (surface area divided by barrier thickness) compare favourably with those obtained for other sluggish fish using existing methods.

  18. Allometric Equations for Estimating Carbon Stocks in Natural Forest in New Zealand

    Directory of Open Access Journals (Sweden)

    Andrea Brandon

    2012-09-01

    Full Text Available Species-specific and mixed-species volume and above ground biomass allometric equations were developed for 15 indigenous tree species and four tree fern species in New Zealand. A mixed-species tree equation based on breast height diameter (DBH and tree height (H provided acceptable estimates of stem plus branch (>10 cm in diameter over bark volume, which was multiplied by live tree density to estimate dry matter. For dead standing spars, DBH, estimated original height, actual spar height and compatible volume/taper functions provided estimates of dead stem volume, which was multiplied by live tree density and a density modifier based on log decay class from field assessments to estimate dry matter. Live tree density was estimated using ratio estimators. Ratio estimators were based on biomass sample trees, and utilized density data from outerwood basic density surveys which were available for 35 tree species sampled throughout New Zealand. Foliage and branch ( < 10 cm in diameter over bark dry matter were estimated directly from tree DBH. Tree fern above ground dry matter was estimated using allometric equations based on DBH and H. Due to insufficient data, below ground carbon for trees was estimated using the default IPCC root/shoot ratio of 25%, but for tree ferns it was estimated using measured root/shoot ratios which averaged 20%.

  19. Mobile sailing robot for automatic estimation of fish density and monitoring water quality.

    Science.gov (United States)

    Koprowski, Robert; Wróbel, Zygmunt; Kleszcz, Agnieszka; Wilczyński, Sławomir; Woźnica, Andrzej; Łozowski, Bartosz; Pilarczyk, Maciej; Karczewski, Jerzy; Migula, Paweł

    2013-07-01

    The paper presents the methodology and the algorithm developed to analyze sonar images focused on fish detection in small water bodies and measurement of their parameters: volume, depth and the GPS location. The final results are stored in a table and can be exported to any numerical environment for further analysis. The measurement method for estimating the number of fish using the automatic robot is based on a sequential calculation of the number of occurrences of fish on the set trajectory. The data analysis from the sonar concerned automatic recognition of fish using the methods of image analysis and processing. Image analysis algorithm, a mobile robot together with its control in the 2.4 GHz band and full cryptographic communication with the data archiving station was developed as part of this study. For the three model fish ponds where verification of fish catches was carried out (548, 171 and 226 individuals), the measurement error for the described method was not exceeded 8%. Created robot together with the developed software has features for remote work also in the variety of harsh weather and environmental conditions, is fully automated and can be remotely controlled using Internet. Designed system enables fish spatial location (GPS coordinates and the depth). The purpose of the robot is a non-invasive measurement of the number of fish in water reservoirs and a measurement of the quality of drinking water consumed by humans, especially in situations where local sources of pollution could have a significant impact on the quality of water collected for water treatment for people and when getting to these places is difficult. The systematically used robot equipped with the appropriate sensors, can be part of early warning system against the pollution of water used by humans (drinking water, natural swimming pools) which can be dangerous for their health.

  20. Genetic composition of laboratory stocks of the self-fertilizing fish Kryptolebias marmoratus: a valuable resource for experimental research.

    Directory of Open Access Journals (Sweden)

    Andrey Tatarenkov

    2010-09-01

    Full Text Available The hermaphroditic Mangrove Killifish, Kryptolebias marmoratus, is the world's only vertebrate that routinely self-fertilizes. As such, highly inbred and presumably isogenic "clonal" lineages of this androdioecious species have long been maintained in several laboratories and used in a wide variety of experiments that require genetically uniform vertebrate specimens. Here we conduct a genetic inventory of essentially all laboratory stocks of the Mangrove Killifish held worldwide. At 32 microsatellite loci, these stocks proved to show extensive interline differentiation as well as some intraline variation, much of which can be attributed to post-origin de novo mutations and/or to the segregation of polymorphisms from wild progenitors. Our genetic findings also document that many of the surveyed laboratory strains are not what they have been labeled, apparently due to the rather frequent mishandling or unintended mixing of various laboratory stocks over the years. Our genetic inventory should help to clarify much of this confusion about the clonal identities and genetic relationships of laboratory lines, and thereby help to rejuvenate interest in K. marmoratus as a reliable vertebrate model for experimental research that requires or can capitalize upon "clonal" replicate specimens.

  1. Effect of stocking densities on growth, production and survival rate of red tilapia in hapa at fish hatchery Chilya Thatta, Sindh, Pakistan

    Directory of Open Access Journals (Sweden)

    Abdul Malik Daudpota

    2014-12-01

    Full Text Available Effect of stocking density on growth, production and survival of red tilapia (Oreochromis mossambicus × O. niloticus were conducted in hapa for 60 days at Chilya Thatta. Tilapia fry (4.5±0.02 cm, 2.0±0.01 g were stocked into hapa (4.5x2.4x1 m. Three treatments with two replicates were used: T1-200; T2-250 and T3-300 fry/hapa. Fry were fed twice a daily with pelleted feed containing 35% protein, 5% of total biomass. After 60 days, the highest growth were determined in T1 (49.8±0.0 g while in T3 lowest growth (29.09±0.0 g was recorded. Production (9.56, 10.13 and 8.12 kg/m3/60days in T1, T2 and T3 respectively were significantly different (P0.05. Survival was significantly different among treatments (P<0.01. Highest survival (100% was attained in T1 with lower stocking density, followed by T2 (98% and T3 (95%. Water quality parameters recorded throughout the study period were found within the ranges for fish culture such as temperature 27.2 to 28.5 °C, dissolved oxygen 5.8 to 6.4 mg/l, pH 6.9 to 7.6, ammonia from 0.45 to 0.51 mg/l, hardness 106 to 110 ppm and nitrite 0.151 to 0.162 mg/l.

  2. Connecting single-stock assessment models through correlated survival

    DEFF Research Database (Denmark)

    Albertsen, Christoffer Moesgaard; Nielsen, Anders; Thygesen, Uffe Høgsbro

    2017-01-01

    times. We propose a simple alternative. In three case studies each with two stocks, we improve the single-stock models, as measured by Akaike information criterion, by adding correlation in the cohort survival. To limit the number of parameters, the correlations are parameterized through...... the corresponding partial correlations. We consider six models where the partial correlation matrix between stocks follows a band structure ranging from independent assessments to complex correlation structures. Further, a simulation study illustrates the importance of handling correlated data sufficiently...... by investigating the coverage of confidence intervals for estimated fishing mortality. The results presented will allow managers to evaluate stock statuses based on a more accurate evaluation of model output uncertainty. The methods are directly implementable for stocks with an analytical assessment and do...

  3. Stock Identification of Columbia River Chinook Salmon and Steelhead Trout, 1984-1985 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Schreck, Carl B.; Sharpe, Cameron; Li, Hiram W. (Oregon State University, Oregon Cooperative Fishery Research Unit, Corvallis, OR)

    1985-09-21

    Fish were collected from 60 stocks of chinook salmon and 62 stocks of steelhead trout. Electrophoretic analyses were completed on 43 stocks of chinook salmon and 41 stocks of steelhead trout and meristic counts were completed on 43 stocks of chinook and 41 stocks of steelhead. Statistical comparisons between year classes of our electrophoretic data indicate that most enzyme systems are stable over time but some may be dynamic and should be used with caution in our analyses. We also compared neighboring stocks of both spring chinook and steelhead trout. These comparisons were between stocks of the same race from adjacent stream systems and/or hatcheries. Differences in isozyme gene frequencies can be used to estimate genetic segregation between pairs of stocks. Analysis of the chinook data suggests that, as expected, the number of statistically significant differences in isozyme gene frequencies increases as the geographic distance between stocks increases. The results from comparisons between adjacent steelhead stocks were inconclusive and must await final analysis with more data. Cluster analyses using either isozyme gene frequencies or meristic characters both tended to group the chinook and steelhead stocks by geographic areas and by race and both methods resulted in generally similar grouping patterns. However, cluster analyses using isozyme gene frequencies produced more clusters than the analyses using meristic characters probably because of the greater number of electrophoretic characters compared to the number of meristic characters. Heterozygosity values for each stock were computed using the isozyme gene frequencies. The highest heterozygosity values for chinook were observed in summer chinook and the hatchery stocks while the lowest values were observed in the spring chinook and wild stocks. The results of comparisons of heterozygosity values among areas were inconclusive. The steelhead heterozygosity values were higher in the winter stocks than in the

  4. Equivalence among three alternative approaches to estimating live tree carbon stocks in the eastern United States

    Science.gov (United States)

    Coeli M. Hoover; James E. Smith

    2017-01-01

    Assessments of forest carbon are available via multiple alternate tools or applications and are in use to address various regulatory and reporting requirements. The various approaches to making such estimates may or may not be entirely comparable. Knowing how the estimates produced by some commonly used approaches vary across forest types and regions allows users of...

  5. Forest inventory-based estimation of carbon stocks and flux in California forests in 1990.

    Science.gov (United States)

    Jeremy S. Fried; Xiaoping. Zhou

    2008-01-01

    Estimates of forest carbon stores and flux for California circa 1990 were modeled from forest inventory data in support of California’s legislatively mandated greenhouse gas inventory. Reliable estimates of live-tree carbon stores and flux on timberlands outside of national forest could be calculated from periodic inventory data collected in the 1980s and 1990s;...

  6. Estimating Carbon Stocks and Atmospheric Exchange of Depressional Marshes on the Central Florida Landscape

    Science.gov (United States)

    Benscoter, B.; McClellan, M. D.; Benavides, V.; Harshbarger, D.; Comas, X.

    2014-12-01

    Depressional marshes are ubiquitous throughout central and south Florida. Often distributed within a matrix of sandy pine flatwoods and hammocks, these wetlands have a seasonally variable water table, alternating between inundation and complete drydown. Though these landforms are typically small individually, they comprise a substantial component of the landscape and provide vital habitat for an array of flora and fauna. Given their fluctuating hydrology, conditions for soil and plant carbon (C) exchange mechanisms can vary greatly both spatially and temporally. In this study, we are developing a C budget for depressional marsh landforms by assessing ecosystem carbon exchange along an ecotone gradient and quantifying belowground C stocks using non-invasive geophysical methods (ground penetrating radar, GPR) at the Disney Wilderness Preserve (DWP) in Kissimmee, FL, USA. Using a series of closed chambers transecting the marsh from the center outward into the surrounding flatwoods, we are quantifying the effects of seasonal water table change on the magnitude of C exchange. Three dimensional GPR surveys were used to quantify peat layer thickness, and were constrained with direct core sampling to verify subsurface lithology and to assess peat C content. Using the relationship between landform surface area and belowground C volume, we assessed the cumulative C storage in depressional marshes across the DWP landscape. In conjunction with a nearby eddy covariance tower and seasonal hydrologic data, these response functions will help to evaluate the contribution of these small but widespread landscape features on regional C cycling.

  7. Accounting for density reduction and structural loss in standing dead trees: Implications for forest biomass and carbon stock estimates in the United States

    Directory of Open Access Journals (Sweden)

    Domke Grant M

    2011-11-01

    Full Text Available Abstract Background Standing dead trees are one component of forest ecosystem dead wood carbon (C pools, whose national stock is estimated by the U.S. as required by the United Nations Framework Convention on Climate Change. Historically, standing dead tree C has been estimated as a function of live tree growing stock volume in the U.S.'s National Greenhouse Gas Inventory. Initiated in 1998, the USDA Forest Service's Forest Inventory and Analysis program (responsible for compiling the Nation's forest C estimates began consistent nationwide sampling of standing dead trees, which may now supplant previous purely model-based approaches to standing dead biomass and C stock estimation. A substantial hurdle to estimating standing dead tree biomass and C attributes is that traditional estimation procedures are based on merchantability paradigms that may not reflect density reductions or structural loss due to decomposition common in standing dead trees. The goal of this study was to incorporate standing dead tree adjustments into the current estimation procedures and assess how biomass and C stocks change at multiple spatial scales. Results Accounting for decay and structural loss in standing dead trees significantly decreased tree- and plot-level C stock estimates (and subsequent C stocks by decay class and tree component. At a regional scale, incorporating adjustment factors decreased standing dead quaking aspen biomass estimates by almost 50 percent in the Lake States and Douglas-fir estimates by more than 36 percent in the Pacific Northwest. Conclusions Substantial overestimates of standing dead tree biomass and C stocks occur when one does not account for density reductions or structural loss. Forest inventory estimation procedures that are descended from merchantability standards may need to be revised toward a more holistic approach to determining standing dead tree biomass and C attributes (i.e., attributes of tree biomass outside of sawlog

  8. Pollution Problem in River Kabul: Accumulation Estimates of Heavy Metals in Native Fish Species.

    Science.gov (United States)

    Ahmad, Habib; Yousafzai, Ali Muhammad; Siraj, Muhammad; Ahmad, Rashid; Ahmad, Israr; Nadeem, Muhammad Shahid; Ahmad, Waqar; Akbar, Nazia; Muhammad, Khushi

    2015-01-01

    The contamination of aquatic systems with heavy metals is affecting the fish population and hence results in a decline of productivity rate. River Kabul is a transcountry river originating at Paghman province in Afghanistan and inters in Khyber Pakhtunkhwa province of Pakistan and it is the major source of irrigation and more than 54 fish species have been reported in the river. Present study aimed at the estimation of heavy metals load in the fish living in River Kabul. Heavy metals including chromium, nickel, copper, zinc, cadmium, and lead were determined through atomic absorption spectrophotometer after tissue digestion by adopting standard procedures. Concentrations of these metals were recorded in muscles and liver of five native fish species, namely, Wallago attu, Aorichthys seenghala, Cyprinus carpio, Labeo dyocheilus, and Ompok bimaculatus. The concentrations of chromium, nickel, copper, zinc, and lead were higher in both of the tissues, whereas the concentration of cadmium was comparatively low. However, the concentration of metals was exceeding the RDA (Recommended Dietary Allowance of USA) limits. Hence, continuous fish consumption may create health problems for the consumers. The results of the present study are alarming and suggest implementing environmental laws and initiation of a biomonitoring program of the river.

  9. Estimating stock parameters from trawl cpue-at-age series using year-class curves

    NARCIS (Netherlands)

    Cotter, A.J.R.; Mesnil, B.; Piet, G.J.

    2007-01-01

    A year-class curve is a plot of log cpue (catch per unit effort) over age for a single year class of a species (in contrast to the better known catch curve, fitted to multiple year classes at one time). When linear, the intercept and slope estimate the log cpue at age 0 and the average rate of total

  10. Challenging ICES age estimation protocols: lessons learned from the eastern Baltic cod stock

    DEFF Research Database (Denmark)

    Hüssy, Karin; Radtke, Krzysztof; Plikshs, Maris

    2016-01-01

    Over the recent decades, the International Council for the Exploration of the Sea (ICES) has set guidelines for best practise quality control of age estimation procedures. The applicability of these guidelines is assessed by reviewing the ageing issues of eastern Baltic cod (EBC) as a case study....

  11. Pricing stock options under stochastic volatility and interest rates with efficient method of moments estimation

    NARCIS (Netherlands)

    Jiang, George J.; Sluis, Pieter J. van der

    1999-01-01

    While the stochastic volatility (SV) generalization has been shown to improve the explanatory power over the Black-Scholes model, empirical implications of SV models on option pricing have not yet been adequately tested. The purpose of this paper is to first estimate a multivariate SV model using

  12. Software documentation and user's manual for fish-impingement sampling design and estimation method computer programs

    International Nuclear Information System (INIS)

    Murarka, I.P.; Bodeau, D.J.

    1977-11-01

    This report contains a description of three computer programs that implement the theory of sampling designs and the methods for estimating fish-impingement at the cooling-water intakes of nuclear power plants as described in companion report ANL/ES-60. Complete FORTRAN listings of these programs, named SAMPLE, ESTIMA, and SIZECO, are given and augmented with examples of how they are used

  13. Inter-annual cascade effect on marine food web: A benthic pathway lagging nutrient supply to pelagic fish stock.

    Directory of Open Access Journals (Sweden)

    Lohengrin Dias de Almeida Fernandes

    Full Text Available Currently, spatial and temporal changes in nutrients availability, marine planktonic, and fish communities are best described on a shorter than inter-annual (seasonal scale, primarily because the simultaneous year-to-year variations in physical, chemical, and biological parameters are very complex. The limited availability of time series datasets furnishing simultaneous evaluations of temperature, nutrients, plankton, and fish have limited our ability to describe and to predict variability related to short-term process, as species-specific phenology and environmental seasonality. In the present study, we combine a computational time series analysis on a 15-year (1995-2009 weekly-sampled time series (high-resolution long-term time series, 780 weeks with an Autoregressive Distributed Lag Model to track non-seasonal changes in 10 potentially related parameters: sea surface temperature, nutrient concentrations (NO2, NO3, NH4 and PO4, phytoplankton biomass (as in situ chlorophyll a biomass, meroplankton (barnacle and mussel larvae, and fish abundance (Mugil liza and Caranx latus. Our data demonstrate for the first time that highly intense and frequent upwelling years initiate a huge energy flux that is not fully transmitted through classical size-structured food web by bottom-up stimulus but through additional ontogenetic steps. A delayed inter-annual sequential effect from phytoplankton up to top predators as carnivorous fishes is expected if most of energy is trapped into benthic filter feeding organisms and their larval forms. These sequential events can explain major changes in ecosystem food web that were not predicted in previous short-term models.

  14. Bias in estimating food consumption of fish from stomach-content analysis

    DEFF Research Database (Denmark)

    Rindorf, Anna; Lewy, Peter

    2004-01-01

    This study presents an analysis of the bias introduced by using simplified methods to calculate food intake of fish from stomach contents. Three sources of bias were considered: (1) the effect of estimating consumption based on a limited number of stomach samples, (2) the effect of using average......, a serious positive bias was introduced by estimating food intake from the contents of pooled stomach samples. An expression is given that can be used to correct analytically for this bias. A new method, which takes into account the distribution and evacuation of individual prey types as well as the effect...... of other food in the stomach on evacuation, is suggested for estimating the intake of separate prey types. Simplifying the estimation by ignoring these factors biased estimates of consumption of individual prey types by up to 150% in a data example....

  15. Using river distance and existing hydrography data can improve the geostatistical estimation of fish tissue mercury at unsampled locations.

    Science.gov (United States)

    Money, Eric S; Sackett, Dana K; Aday, D Derek; Serre, Marc L

    2011-09-15

    Mercury in fish tissue is a major human health concern. Consumption of mercury-contaminated fish poses risks to the general population, including potentially serious developmental defects and neurological damage in young children. Therefore, it is important to accurately identify areas that have the potential for high levels of bioaccumulated mercury. However, due to time and resource constraints, it is difficult to adequately assess fish tissue mercury on a basin wide scale. We hypothesized that, given the nature of fish movement along streams, an analytical approach that takes into account distance traveled along these streams would improve the estimation accuracy for fish tissue mercury in unsampled streams. Therefore, we used a river-based Bayesian Maximum Entropy framework (river-BME) for modern space/time geostatistics to estimate fish tissue mercury at unsampled locations in the Cape Fear and Lumber Basins in eastern North Carolina. We also compared the space/time geostatistical estimation using river-BME to the more traditional Euclidean-based BME approach, with and without the inclusion of a secondary variable. Results showed that this river-based approach reduced the estimation error of fish tissue mercury by more than 13% and that the median estimate of fish tissue mercury exceeded the EPA action level of 0.3 ppm in more than 90% of river miles for the study domain.

  16. Estimation of age structure of fish populations from length-frequency data

    International Nuclear Information System (INIS)

    Kumar, K.D.; Adams, S.M.

    1977-01-01

    A probability model is presented to determine the age structure of a fish population from length-frequency data. It is shown that when the age-length key is available, maximum-likelihood estimates of the age structure can be obtained. When the key is not available, approximate estimates of the age structure can be obtained. The model is used for determination of the age structure of populations of channel catfish and white crappie. Practical applications of the model to impact assessment are discussed

  17. TropFishR: an R package for fisheries analysis with length-frequency data

    DEFF Research Database (Denmark)

    Mildenberger, Tobias; Taylor, M. H.; Wolff, A.M.

    2017-01-01

    1. The R package TropFishR is a new analysis toolbox compiling single-species stock assessment methods specifically designed for data-limited fisheries analysis using length-frequency data. 2. It includes methods for (i) estimating biological stock characteristics such as growth and mortality par...... introduces the package and demonstrates the functionality of a selection of its core methods. 4. TropFishR modernises traditional stock assessment methods by easing application and development and by combining it with advanced statistical approaches......1. The R package TropFishR is a new analysis toolbox compiling single-species stock assessment methods specifically designed for data-limited fisheries analysis using length-frequency data. 2. It includes methods for (i) estimating biological stock characteristics such as growth and mortality...

  18. Impact of entrainment and impingement on fish populations in the Hudson River Estuary. Volume II. Impingement impact analyses, evaluations of alternative screening devices, and critiques of utility testimony relating to density-dependent growth, the age-composition of the striped bass spawning stock, and the LMS real-time life cycle model

    International Nuclear Information System (INIS)

    Barnthouse, L.W.; Van Winkle, W.; Golumbek, J.; Cada, G.F.; Goodyear, C.P.; Christensen, S.W.; Cannon, J.B.; Lee, D.W.

    1982-04-01

    This volume includes a series of four exhibits relating to impacts of impingement on fish populations, together with a collection of critical evaluations of testimony prepared for the utilities by their consultants. The first exhibit is a quantitative evaluation of four sources of bias (collection efficiency, reimpingement, impingement on inoperative screens, and impingement survival) affecting estimates of the number of fish killed at Hudson River power plants. The two following exhibits contain, respectively, a detailed assessment of the impact of impingement on the Hudson River white perch population and estimates of conditional impingement mortality rates for seven Hudson River fish populations. The fourth exhibit is an evaluation of the engineering feasibility and potential biological effectiveness of several types of modified intake structures proposed as alternatives to cooling towers for reducing impingement impacts. The remainder of Volume II consists of critical evaluations of the utilities' empirical evidence for the existence of density-dependent growth in young-of-the-year striped bass and white perch, of their estimate of the age-composition of the striped bass spawning stock in the Hudson River, and of their use of the Lawler, Matusky, and Skelly (LMS) Real-Time Life Cycle Model to estimate the impact of entrainment and impingement on the Hudson River striped bass population

  19. The Use of Mixed Effects Models for Obtaining Low-Cost Ecosystem Carbon Stock Estimates in Mangroves of the Asia-Pacific

    Science.gov (United States)

    Bukoski, J. J.; Broadhead, J. S.; Donato, D.; Murdiyarso, D.; Gregoire, T. G.

    2016-12-01

    Mangroves provide extensive ecosystem services that support both local livelihoods and international environmental goals, including coastal protection, water filtration, biodiversity conservation and the sequestration of carbon (C). While voluntary C market projects that seek to preserve and enhance forest C stocks offer a potential means of generating finance for mangrove conservation, their implementation faces barriers due to the high costs of quantifying C stocks through measurement, reporting and verification (MRV) activities. To streamline MRV activities in mangrove C forestry projects, we develop predictive models for (i) biomass-based C stocks, and (ii) soil-based C stocks for the mangroves of the Asia-Pacific. We use linear mixed effect models to account for spatial correlation in modeling the expected C as a function of stand attributes. The most parsimonious biomass model predicts total biomass C stocks as a function of both basal area and the interaction between latitude and basal area, whereas the most parsimonious soil C model predicts soil C stocks as a function of the logarithmic transformations of both latitude and basal area. Random effects are specified by site for both models, and are found to explain a substantial proportion of variance within the estimation datasets. The root mean square error (RMSE) of the biomass C model is approximated at 24.6 Mg/ha (18.4% of mean biomass C in the dataset), whereas the RMSE of the soil C model is estimated at 4.9 mg C/cm 3 (14.1% of mean soil C). A substantial proportion of the variation in soil C, however, is explained by the random effects and thus the use of the SOC model may be most valuable for sites in which field measurements of soil C exist.

  20. Estimating fish swimming metrics and metabolic rates with accelerometers: the influence of sampling frequency.

    Science.gov (United States)

    Brownscombe, J W; Lennox, R J; Danylchuk, A J; Cooke, S J

    2018-06-21

    Accelerometry is growing in popularity for remotely measuring fish swimming metrics, but appropriate sampling frequencies for accurately measuring these metrics are not well studied. This research examined the influence of sampling frequency (1-25 Hz) with tri-axial accelerometer biologgers on estimates of overall dynamic body acceleration (ODBA), tail-beat frequency, swimming speed and metabolic rate of bonefish Albula vulpes in a swim-tunnel respirometer and free-swimming in a wetland mesocosm. In the swim tunnel, sampling frequencies of ≥ 5 Hz were sufficient to establish strong relationships between ODBA, swimming speed and metabolic rate. However, in free-swimming bonefish, estimates of metabolic rate were more variable below 10 Hz. Sampling frequencies should be at least twice the maximum tail-beat frequency to estimate this metric effectively, which is generally higher than those required to estimate ODBA, swimming speed and metabolic rate. While optimal sampling frequency probably varies among species due to tail-beat frequency and swimming style, this study provides a reference point with a medium body-sized sub-carangiform teleost fish, enabling researchers to measure these metrics effectively and maximize study duration. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  1. Improving estimation of tree carbon stocks by harvesting aboveground woody biomass within airborne LiDAR flight areas

    Science.gov (United States)

    Colgan, M.; Asner, G. P.; Swemmer, A. M.

    2011-12-01

    The accurate estimation of carbon stored in a tree is essential to accounting for the carbon emissions due to deforestation and degradation. Airborne LiDAR (Light Detection and Ranging) has been successful in estimating aboveground carbon density (ACD) by correlating airborne metrics, such as canopy height, to field-estimated biomass. This latter step is reliant on field allometry which is applied to forest inventory quantities, such as stem diameter and height, to predict the biomass of a given tree stem. Constructing such allometry is expensive, time consuming, and requires destructive sampling. Consequently, the sample sizes used to construct such allometry are often small, and the largest tree sampled is often much smaller than the largest in the forest population. The uncertainty resulting from these sampling errors can lead to severe biases when the allometry is applied to stems larger than those harvested to construct the allometry, which is then subsequently propagated to airborne ACD estimates. The Kruger National Park (KNP) mission of maintaining biodiversity coincides with preserving ecosystem carbon stocks. However, one hurdle to accurately quantifying carbon density in savannas is that small stems are typically harvested to construct woody biomass allometry, yet they are not representative of Kruger's distribution of biomass. Consequently, these equations inadequately capture large tree variation in sapwood/hardwood composition, root/shoot/leaf allocation, branch fall, and stem rot. This study eliminates the "middleman" of field allometry by directly measuring, or harvesting, tree biomass within the extent of airborne LiDAR. This enables comparisons of field and airborne ACD estimates, and also enables creation of new airborne algorithms to estimate biomass at the scale of individual trees. A field campaign was conducted at Pompey Silica Mine 5km outside Kruger National Park, South Africa, in Mar-Aug 2010 to harvest and weigh tree mass. Since

  2. A comparison of fisheries biological reference points estimated from temperature-specific multi-species and single-species climate-enhanced stock assessment models

    Science.gov (United States)

    Holsman, Kirstin K.; Ianelli, James; Aydin, Kerim; Punt, André E.; Moffitt, Elizabeth A.

    2016-12-01

    Multi-species statistical catch at age models (MSCAA) can quantify interacting effects of climate and fisheries harvest on species populations, and evaluate management trade-offs for fisheries that target several species in a food web. We modified an existing MSCAA model to include temperature-specific growth and predation rates and applied the modified model to three fish species, walleye pollock (Gadus chalcogrammus), Pacific cod (Gadus macrocephalus) and arrowtooth flounder (Atheresthes stomias), from the eastern Bering Sea (USA). We fit the model to data from 1979 through 2012, with and without trophic interactions and temperature effects, and use projections to derive single- and multi-species biological reference points (BRP and MBRP, respectively) for fisheries management. The multi-species model achieved a higher over-all goodness of fit to the data (i.e. lower negative log-likelihood) for pollock and Pacific cod. Variability from water temperature typically resulted in 5-15% changes in spawning, survey, and total biomasses, but did not strongly impact recruitment estimates or mortality. Despite this, inclusion of temperature in projections did have a strong effect on BRPs, including recommended yield, which were higher in single-species models for Pacific cod and arrowtooth flounder that included temperature compared to the same models without temperature effects. While the temperature-driven multi-species model resulted in higher yield MBPRs for arrowtooth flounder than the same model without temperature, we did not observe the same patterns in multi-species models for pollock and Pacific cod, where variability between harvest scenarios and predation greatly exceeded temperature-driven variability in yield MBRPs. Annual predation on juvenile pollock (primarily cannibalism) in the multi-species model was 2-5 times the annual harvest of adult fish in the system, thus predation represents a strong control on population dynamics that exceeds temperature

  3. Recreational sea fishing in Europe in a global context-Participation rates, fishing effort, expenditure, and implications for monitoring and assessment

    NARCIS (Netherlands)

    Hyder, Kieran; Weltersbach, Marc Simon; Armstrong, Mike; Ferter, Keno; Townhill, Bryony; Ahvonen, Anssi; Arlinghaus, Robert; Baikov, Andrei; Bellanger, Manuel; Birzaks, Janis; Borch, Trude; Cambie, Giulia; Graaf, De Martin; Diogo, Hugo M.C.; Dziemian, Łukasz; Gordoa, Ana; Grzebielec, Ryszard; Hartill, Bruce; Kagervall, Anders; Kapiris, Kostas; Karlsson, Martin; Kleiven, Alf Ring; Lejk, Adam M.; Levrel, Harold; Lovell, Sabrina; Lyle, Jeremy; Moilanen, Pentti; Monkman, Graham; Morales-Nin, Beatriz; Mugerza, Estanis; Martinez, Roi; O'Reilly, Paul; Olesen, Hans Jakob; Papadopoulos, Anastasios; Pita, Pablo; Radford, Zachary; Radtke, Krzysztof; Roche, William; Rocklin, Delphine; Ruiz, Jon; Scougal, Callum; Silvestri, Roberto; Skov, Christian; Steinback, Scott; Sundelöf, Andreas; Svagzdys, Arvydas; Turnbull, David; Hammen, Van Der Tessa; Voorhees, Van David; Winsen, Van Frankwin; Verleye, Thomas; Veiga, Pedro; Vølstad, Jon-Helge; Zarauz, Lucia; Zolubas, Tomas; Strehlow, Harry V.

    2018-01-01

    Marine recreational fishing (MRF) is a high-participation activity with large economic value and social benefits globally, and it impacts on some fish stocks. Although reporting MRF catches is a European Union legislative requirement, estimates are only available for some countries. Here, data on

  4. Recreational sea fishing in Europe in a global context—Participation rates, fishing effort, expenditure, and implications for monitoring and assessment

    DEFF Research Database (Denmark)

    Hyder, Kieran; Weltersbach, Marc Simon; Armstrong, Mike

    2018-01-01

    Marine recreational fishing (MRF) is a high‐participation activity with large economic value and social benefits globally, and it impacts on some fish stocks. Although reporting MRF catches is a European Union legislative requirement, estimates are only available for some countries. Here, data on...

  5. Comparison of sampling methodologies and estimation of population parameters for a temporary fish ectoparasite

    Directory of Open Access Journals (Sweden)

    J.M. Artim

    2016-08-01

    Full Text Available Characterizing spatio-temporal variation in the density of organisms in a community is a crucial part of ecological study. However, doing so for small, motile, cryptic species presents multiple challenges, especially where multiple life history stages are involved. Gnathiid isopods are ecologically important marine ectoparasites, micropredators that live in substrate for most of their lives, emerging only once during each juvenile stage to feed on fish blood. Many gnathiid species are nocturnal and most have distinct substrate preferences. Studies of gnathiid use of habitat, exploitation of hosts, and population dynamics have used various trap designs to estimate rates of gnathiid emergence, study sensory ecology, and identify host susceptibility. In the studies reported here, we compare and contrast the performance of emergence, fish-baited and light trap designs, outline the key features of these traps, and determine some life cycle parameters derived from trap counts for the Eastern Caribbean coral-reef gnathiid, Gnathia marleyi. We also used counts from large emergence traps and light traps to estimate additional life cycle parameters, emergence rates, and total gnathiid density on substrate, and to calibrate the light trap design to provide estimates of rate of emergence and total gnathiid density in habitat not amenable to emergence trap deployment.

  6. N-mix for fish: estimating riverine salmonid habitat selection via N-mixture models

    Science.gov (United States)

    Som, Nicholas A.; Perry, Russell W.; Jones, Edward C.; De Juilio, Kyle; Petros, Paul; Pinnix, William D.; Rupert, Derek L.

    2018-01-01

    Models that formulate mathematical linkages between fish use and habitat characteristics are applied for many purposes. For riverine fish, these linkages are often cast as resource selection functions with variables including depth and velocity of water and distance to nearest cover. Ecologists are now recognizing the role that detection plays in observing organisms, and failure to account for imperfect detection can lead to spurious inference. Herein, we present a flexible N-mixture model to associate habitat characteristics with the abundance of riverine salmonids that simultaneously estimates detection probability. Our formulation has the added benefits of accounting for demographics variation and can generate probabilistic statements regarding intensity of habitat use. In addition to the conceptual benefits, model application to data from the Trinity River, California, yields interesting results. Detection was estimated to vary among surveyors, but there was little spatial or temporal variation. Additionally, a weaker effect of water depth on resource selection is estimated than that reported by previous studies not accounting for detection probability. N-mixture models show great promise for applications to riverine resource selection.

  7. Developing alternative indices of reproductive potential for use in fisheries management : Case studies for stocks spanning an information gradient

    DEFF Research Database (Denmark)

    Marshall, C.T.; O'Brien, L.; Tomkiewicz, Jonna

    2003-01-01

    There is accumulating evidence to suggest that spawning stock biomass (SSB) may not bedirectly proportional to reproductive potential. The wide-ranging implications of this conclu-sion necessitate that it be tested for as many stocks as possible. Undertaking such tests iscomplicated by the fact...... that fish stocks vary in the amount and type of information that isavailable to estimate reproductive potential. In this review, nine stocks illustrate the range of approaches that are being taken to developing alternative indices of reproductive potential fromexisting data resources. Three stocks had...... sufficient data to reconstruct a time series of total eggproduction (TEP), whereas, the remaining stocks were limited to estimating proxies for stockreproductive potential. For some of the case studies the alternative indices explained a higheramount of recruitment variation than did SSB. Other case studies...

  8. Methylmercury determination in fish and seafood products and estimated daily intake for the Spanish population.

    Science.gov (United States)

    Sahuquillo, I; Lagarda, M J; Silvestre, M D; Farré, R

    2007-08-01

    The mercury content of 25 samples of fish and seafood products most frequently consumed in Spain was determined. A simple method comprising cold vapour and atomic absorption spectrometry was used to determine separately inorganic and organic mercury. In all samples inorganic mercury content was below 50 microg kg(-1). There was wide variability, among not only the mercury levels of different fish species, but also for different samples of the same species - with the methylmercury content ranging from below 54 to 662 microg kg(-1). The highest mean methylmercury content was found in fresh tuna. Based on an average total fish consumption of 363 g/person week(-1), the methylmercury intake was estimated to be 46.2 microg/person week(-1). Therefore, the mercury intake of Spanish people with a body weight Food Additives (JECFA) provisional tolerable weekly intake (PTWI) of 1.6 microg kg(-1) body weight, but exceeds the US National Research Council (NRC) limit of 0.7 microg kg(-1) body weight week(-1) based on a benchmark dose.

  9. Genetic diversity of Prochilodus lineatus stocks using in the stocking program of Tietê River, Brazil

    Directory of Open Access Journals (Sweden)

    Ricardo Ribeiro

    2013-11-01

    Full Text Available Objective. Assess the genetic diversity in four brood stocks and one juvenile stock of curimba Prochilodus lineatus in a Hydropower plant in São Paulo - Brazil, using the Tietê River stocking program. Materials and methods. Five RAPD primers were used to amplify the extracted DNA from 150 fin-clip samples. Results. Fifty-nine fragments were polymorphic, 52 had frequencies with significant differences (p<0.05, 45 had low frequencies, 54 were excluded, and two were fixed fragments. High values for polymorphic fragments (71.19% to 91.53% and Shannon index (0.327 to 0.428 were observed. The genetic divergence values within each stock were greater than 50%. Most of the genetic variation was found within the groups through the AMOVA analysis, which was confirmed by the results of the identity and genetic distance. High ancestry levels (FST among the groups value indicated high and moderate genetic differentiation. The estimates of number of migrants by generation (Nm indicated low levels of gene flow. High and moderate genetic divergence between groups (0.58 to 0.83 was observed. Conclusions. The results indicate high variability within the stocks, and genetic differentiation among them. The fish stocks analyzed represent a large genetic base that will allow the fish technicians to release juveniles without genetic risks to wild populations present in the river. These genetic procedures may be used as models for other migratory species, including those threatened by extinction.

  10. Historical Population Estimates For Several Fish Species At Offshore Oil and Gas Structures in the US Gulf of Mexico

    Science.gov (United States)

    Gitschlag, G.

    2016-02-01

    Population estimates were calculated for four fish species occurring at offshore oil and gas structures in water depths of 14-32 m off the Louisiana and upper Texas coasts in the US Gulf of Mexico. From 1993-1999 sampling was conducted at eight offshore platforms in conjunction with explosive salvage of the structures. To estimate fish population size prior to detonation of explosives, a fish mark-recapture study was conducted. Fish were captured on rod and reel using assorted hook sizes. Traps were occasionally used to supplement catches. Fish were tagged below the dorsal fin with plastic t-bar tags using tagging guns. Only fish that were alive and in good condition were released. Recapture sampling was conducted after explosives were detonated during salvage operations. Personnel operating from inflatable boats used dip nets to collect all dead fish that floated to the surface. Divers collected representative samples of dead fish that sank to the sea floor. Data provided estimates for red snapper (Lutjanus campechanus), Atlantic spadefish (Chaetodipterus faber), gray triggerfish (Balistes capriscus), and blue runner (Caranx crysos) at one or more of the eight platforms studied. At seven platforms, population size for red snapper was calculated at 503-1,943 with a 95% CI of 478. Abundance estimates for Atlantic spadefish at three platforms ranged from 1,432-1,782 with a 95% CI of 473. At three platforms, population size of gray triggerfish was 63-129 with a 95% CI of 82. Blue runner abundance at one platform was 558. Unlike the other three species which occur close to the platforms, blue runner range widely and recapture of this species was dependent on fish schools being in close proximity to the platform at the time explosives were detonated. Tag recapture was as high as 73% for red snapper at one structure studied.

  11. Distribution, stock composition and timing, and tagging response of wild Chinook Salmon returning to a large, free-flowing river basin

    Science.gov (United States)

    Eiler, John H.; Masuda, Michele; Spencer, Ted R.; Driscoll, Richard J.; Schreck, Carl B.

    2014-01-01

    Chinook Salmon Oncorhynchus tshawytscha returns to the Yukon River basin have declined dramatically since the late 1990s, and detailed information on the spawning distribution, stock structure, and stock timing is needed to better manage the run and facilitate conservation efforts. A total of 2,860 fish were radio-tagged in the lower basin during 2002–2004 and tracked upriver. Fish traveled to spawning areas throughout the basin, ranging from several hundred to over 3,000 km from the tagging site. Similar distribution patterns were observed across years, suggesting that the major components of the run were identified. Daily and seasonal composition estimates were calculated for the component stocks. The run was dominated by two regional components comprising over 70% of the return. Substantially fewer fish returned to other areas, ranging from 2% to 9% of the return, but their collective contribution was appreciable. Most regional components consisted of several principal stocks and a number of small, spatially isolated populations. Regional and stock composition estimates were similar across years even though differences in run abundance were reported, suggesting that the differences in abundance were not related to regional or stock-specific variability. Run timing was relatively compressed compared with that in rivers in the southern portion of the species’ range. Most stocks passed through the lower river over a 6-week period, ranging in duration from 16 to 38 d. Run timing was similar for middle- and upper-basin stocks, limiting the use of timing information for management. The lower-basin stocks were primarily later-run fish. Although differences were observed, there was general agreement between our composition and timing estimates and those from other assessment projects within the basin, suggesting that the telemetry-based estimates provided a plausible approximation of the return. However, the short duration of the run, complex stock structure, and

  12. A surplus production model including environmental effects: Application to the Senegalese white shrimp stocks

    Science.gov (United States)

    Thiaw, Modou; Gascuel, Didier; Jouffre, Didier; Thiaw, Omar Thiom

    2009-12-01

    In Senegal, two stocks of white shrimp ( Penaeusnotialis) are intensively exploited, one in the north and another in the south. We used surplus production models including environmental effects to analyse their changes in abundance over the past 10 years and to estimate their Maximum Sustainable Yield (MSY) and the related fishing effort ( EMSY). First, yearly abundance indices were estimated from commercial statistics using GLM techniques. Then, two environmental indices were alternatively tested in the model: the coastal upwelling intensity from wind speeds provided by the SeaWifs database and the primary production derived from satellite infrared images of chlorophyll a. Models were fitted, with or without the environmental effect, to the 1996-2005 time series. They express stock abundance and catches as functions of the fishing effort and the environmental index (when considered). For the northern stock, fishing effort and abundance fluctuate over the period without any clear trends. The model based on the upwelling index explains 64.9% of the year-to-year variability. It shows that the stock was slightly overexploited in 2002-2003 and is now close to full exploitation. Stock abundance strongly depends on environmental conditions; consequently, the MSY estimate varies from 300 to 900 tons according to the upwelling intensity. For the southern stock, fishing effort has strongly increased over the past 10 years, while abundance has been reduced 4-fold. The environment has a significant effect on abundance but only explains a small part of the year-to-year variability. The best fit is obtained using the primary production index ( R2 = 0.75), and the stock is now significantly overfished regardless of environmental conditions. MSY varies from 1200 to 1800 tons according to environmental conditions. Finally, in northern Senegal, the upwelling is highly variable from year to year and constitutes the major factor determining productivity. In the south, hydrodynamic

  13. Variability in abundance of temperate reef fishes estimated by visual census.

    Directory of Open Access Journals (Sweden)

    Alejo J Irigoyen

    Full Text Available Identifying sources of sampling variation and quantifying their magnitude is critical to the interpretation of ecological field data. Yet, most monitoring programs of reef fish populations based on underwater visual censuses (UVC consider only a few of the factors that may influence fish counts, such as the diver or census methodology. Recent studies, however, have drawn attention to a broader range of processes that introduce variability at different temporal scales. This study analyzes the magnitude of different sources of variation in UVCs of temperate reef fishes off Patagonia (Argentina. The variability associated with time-of-day, tidal state, and time elapsed between censuses (minutes, days, weeks and months was quantified for censuses conducted on the five most conspicuous and common species: Pinguipes brasilianus, Pseudopercis semifasciata, Sebastes oculatus, Acanthistius patachonicus and Nemadactylus bergi. Variance components corresponding to spatial heterogeneity and to the different temporal scales were estimated using nested random models. The levels of variability estimated for the different species were related to their life history attributes and behavior. Neither time-of-day nor tidal state had a significant effect on counts, except for the influence of tide on P. brasilianus. Spatial heterogeneity was the dominant source of variance in all but one species. Among the temporal scales, the intra-annual variation was the highest component for most species due to marked seasonal fluctuations in abundance, followed by the weekly and the instantaneous variation; the daily component was not significant. The variability between censuses conducted at different tidal levels and time-of-day was similar in magnitude to the instantaneous variation, reinforcing the conclusion that stochastic variation at very short time scales is non-negligible and should be taken into account in the design of monitoring programs and experiments. The present

  14. Inter-calibration of three electric fishing techniques to estimate 0+ juvenile fish densities on sandy river beaches

    Czech Academy of Sciences Publication Activity Database

    Janáč, Michal; Jurajda, Pavel

    2005-01-01

    Roč. 12, č. 3 (2005), s. 161-167 ISSN 0969-997X R&D Projects: GA AV ČR(CZ) IAB6093106; GA ČR(CZ) GA524/02/0924 Institutional research plan: CEZ:AV0Z60930519 Keywords : electric fishing * 0+ juvenile fish * point abundance sampling Subject RIV: EH - Ecology, Behaviour Impact factor: 1.031, year: 2005

  15. Participatory boat tracking reveals spatial fishing patterns in an Indonesian artisanal fishery

    DEFF Research Database (Denmark)

    Forero, Gabriela Navarrete; Miñarro, Sara; Mildenberger, Tobias

    2017-01-01

    for the coral reef ecosystem, contributing to its overall degradation. Estimations on the ecological impacts of different levels of fishing pressure, as well as fisheries stock assessments and marine resource management require precise information of the spatial distribution of fishing effort, which involves...

  16. Hydroacoustic estimation of fish biomass in the Gulf of Nicoya, Costa Rica

    Directory of Open Access Journals (Sweden)

    John Hedgepeth

    2000-06-01

    Full Text Available A stratified sampling design was used for a hydroacoustic survey of the inner parts of the Gulf of Nicoya in 1987 and 1988. The bottom topography of the inner Gulf was modeled by introducing the concept of a topographical basin model, as the basis for the projection of the sample survey estimates to the entire inner gulf. The bottom depth contours and volumes for the basin model were constructed from nautical charts. The estimates of sample abundance were made for the fish in the inner Gulf using the acoustic methods, EMS (Expectation Maximization and Smoothing and echo integration. The estimates of population were made by the multiplication of the topographic model's estimate of water volume and a model of fish density dependent on bottom depth. The results showed a general decrease in fish density biomass with bottom depth, and a simultaneous tendency for maximum concentrations over bottom depths of about four meters. The four meter bottom depth includes a broad expanse of the inner Gulf located south of Isla Chira. Overall estimates of volumetric density (0.269 fish/m³ and of areal densities (1.88 fish/m² are comparable to other estuarine shallow water environments.Se utilizó un diseño muestral estratificado para llevar a cabo una evaluación hidroacústica de la sección interior del Golfo de Nicoya. La topografía submarina fue modelada introduciendo el concepto topográfico de la cuenca, como una forma de proyectar los estimados del muestreo a todo el Golfo interno. Las isobatas y volúmenes de la cuenca del Golfo fueron construidos a partir de cartas náuticas. Los estimados de abundancia en las muestras se hicieron para los peces en la parte interna del Golfo utilizando los métodos acústicos conocidos como EMS (Expectation, Maximitation and Smoothing y ecointegración. Los estimados de población se obtuvieron a partir de la multiplicación de los estimados del modelo topográfico de volúmen acuático y un modelo de densidad de

  17. Fixed-location hydroacoustic monitoring designs for estimating fish passage using stratified random and systematic sampling

    International Nuclear Information System (INIS)

    Skalski, J.R.; Hoffman, A.; Ransom, B.H.; Steig, T.W.

    1993-01-01

    Five alternate sampling designs are compared using 15 d of 24-h continuous hydroacoustic data to identify the most favorable approach to fixed-location hydroacoustic monitoring of salmonid outmigrants. Four alternative aproaches to systematic sampling are compared among themselves and with stratified random sampling (STRS). Stratifying systematic sampling (STSYS) on a daily basis is found to reduce sampling error in multiday monitoring studies. Although sampling precision was predictable with varying levels of effort in STRS, neither magnitude nor direction of change in precision was predictable when effort was varied in systematic sampling (SYS). Furthermore, modifying systematic sampling to include replicated (e.g., nested) sampling (RSYS) is further shown to provide unbiased point and variance estimates as does STRS. Numerous short sampling intervals (e.g., 12 samples of 1-min duration per hour) must be monitored hourly using RSYS to provide efficient, unbiased point and interval estimates. For equal levels of effort, STRS outperformed all variations of SYS examined. Parametric approaches to confidence interval estimates are found to be superior to nonparametric interval estimates (i.e., bootstrap and jackknife) in estimating total fish passage. 10 refs., 1 fig., 8 tabs

  18. Fishing for MSY: using “pretty good yield” ranges without impairing recruitment

    DEFF Research Database (Denmark)

    Rindorf, Anna; Cardinale, Massimiliano; Shephard, Samuel

    2017-01-01

    to impairing recruitment. An FMSY range was calculated for each stock as the range of fishing mortalities (F) that lead to an average catch of at least 95% of MSY in long-term simulations. Further, a precautionary reference point for each stock (FP.05) was defined as the F resulting in a 5% probability...... of the spawning-stock biomass falling below an agreed biomass limit below which recruitment is impaired (Blim) in long-term simulations. For the majority of the stocks analysed, the upper bound of the FMSY range exceeded the estimated FP.05. However, larger fish species had higher precautionary limits to fishing...... mortality, and species with larger asymptotic length were less likely to have FMSY ranges impairing recruitment. Our study shows that fishing at FMSY generally is precautionary with respect to impairing recruitment for highly exploited teleost species in northern European waters, whereas the upper part...

  19. Evaluation of methods to estimate the essential amino acids requirements of fish from the muscle amino acid profile

    Directory of Open Access Journals (Sweden)

    Álvaro José de Almeida Bicudo

    2014-03-01

    Full Text Available Many methods to estimate amino acid requirement based on amino acid profile of fish have been proposed. This study evaluates the methodology proposed by Meyer & Fracalossi (2005 and by Tacon (1989 to estimate amino acids requirement of fish, which do exempt knowledge on previous nutritional requirement of reference amino acid. Data on amino acid requirement of pacu, Piaractus mesopotamicus, were used to validate de accuracy of those methods. Meyer & Fracalossi's and Tacon's methodology estimated the lysine requirement of pacu, respectively, at 13 and 23% above requirement determined using dose-response method. The values estimated by both methods lie within the range of requirements determined for other omnivorous fish species, the Meyer & Fracalossi (2005 method showing better accuracy.

  20. Model to Estimate Monthly Time Horizons for Application of DEA in Selection of Stock Portfolio and for Maintenance of the Selected Portfolio

    Directory of Open Access Journals (Sweden)

    José Claudio Isaias

    2015-01-01

    Full Text Available In the selecting of stock portfolios, one type of analysis that has shown good results is Data Envelopment Analysis (DEA. It, however, has been shown to have gaps regarding its estimates of monthly time horizons of data collection for the selection of stock portfolios and of monthly time horizons for the maintenance of a selected portfolio. To better estimate these horizons, this study proposes a model of mathematical programming binary of minimization of square errors. This model is the paper’s main contribution. The model’s results are validated by simulating the estimated annual return indexes of a portfolio that uses both horizons estimated and of other portfolios that do not use these horizons. The simulation shows that portfolios with both horizons estimated have higher indexes, on average 6.99% per year. The hypothesis tests confirm the statistically significant superiority of the results of the proposed mathematical model’s indexes. The model’s indexes are also compared with portfolios that use just one of the horizons estimated; here the indexes of the dual-horizon portfolios outperform the single-horizon portfolios, though with a decrease in percentage of statistically significant superiority.

  1. Evaluation of otolith shape as a tool for stock discrimination in marine fishes using Baltic Sea cod as a case study

    DEFF Research Database (Denmark)

    Hüssy, Karin; Mosegaard, Henrik; Albertsen, Christoffer Moesgaard

    2016-01-01

    demonstrate theinterplay of environmental, ontogenetic and genetic influences on otolith shape, which complicates theapplication of otolith shape for stock discrimination in mixed-stock scenarios. Rigours genetic validationand further studies on the temporal dynamics of shape formation are necessary.......In the Western Baltic Sea two genetically distinct cod stocks “Eastern Baltic cod” and “Western Balticcod” occur with considerable mixing of stocks. In this study we evaluated the applicability of otolithshape analysis for classification of individuals caught in the mixed stock cod fishery, using...... SNP (singlenucleotide polymorphism) based genetic assignment of otolith shape baselines. We further developeda management aimed approach for mixed stock assignment by robust stochastic baseline selection andposterior bias correction by individual reassignment of the least likely classifications...

  2. An Iterated GMM Procedure for Estimating the Campbell-Cochrane Habit Formation Model, with an Application to Danish Stock and Bond Returns

    DEFF Research Database (Denmark)

    Engsted, Tom; Møller, Stig Vinther

    2010-01-01

    We suggest an iterated GMM approach to estimate and test the consumption based habit persistence model of Campbell and Cochrane, and we apply the approach on annual and quarterly Danish stock and bond returns. For comparative purposes we also estimate and test the standard constant relative risk...... covering more than 80 years there is absolutely no evidence of superior performance of the Campbell-Cochrane model. For the shorter and more recent quarterly data over a 20-30 year period, there is some evidence of counter-cyclical time-variation in the degree of risk-aversion, in accordance...

  3. An iterated GMM procedure for estimating the Campbell-Cochrane habit formation model, with an application to Danish stock and bond returns

    DEFF Research Database (Denmark)

    Engsted, Tom; Møller, Stig V.

    We suggest an iterated GMM approach to estimate and test the consumption based habit persistence model of Campbell and Cochrane (1999), and we apply the approach on annual and quarterly Danish stock and bond returns. For comparative purposes we also estimate and test the standard CRRA model...... than 80 years there is absolutely no evidence of superior performance of the Campbell-Cochrane model. For the shorter and more recent quarterly data over a 20-30 year period, there is some evidence of counter-cyclical time-variation in the degree of risk-aversion, in accordance with the Campbell...

  4. Seasonal estimates of DOC standing stocks in Apalachicola Bay estuary: Towards a better understanding using field, ocean color and model data

    Science.gov (United States)

    D'Sa, E. J.; Joshi, I.; Osburn, C. L.; Bianchi, T. S.; Ko, D. S.; Oviedo-Vargas, D.; Arellano, A.; Ward, N.

    2016-12-01

    Apalachicola Bay, a semi-enclosed estuary located in Florida's panhandle, is well known for its water quality and oyster yields. We present the use of combined field and ocean color satellite observations and the outputs of a high-resolution hydrodynamic model to study the influence of physical processes on the distribution and the transport of terrestrially derived CDOM and DOC to shelf waters during the spring and fall of 2015. Determination of DOC stocks were based on the development of a CDOM algorithm (R2 = 0.87, N = 9) for the VIIRS ocean color sensor, and the assessment of CDOM - DOC relationships (R2 = 0.88, N = 13 in March; R2 = 0.83, N = 24 in November) for the Apalachicola Bay. Satellite-derived CDOM and DOC maps together with model-based salinity distributions revealed their spatial extent, sources and transport to the shelf water. Furthermore, strong seasonal influence on DOM distribution in the bay was associated with inputs from Apalachicola and Carrabelle Rivers and the surrounding marshes. Estimates of DOC standing stocks in the bay obtained using ocean color data and high-resolution bathymetry showed relatively higher stocks in November ( 3.71 × 106 kg C, 560 km2) than in March ( 4.07 × 106 kg C, 560 km2) despite lower river discharge in dry season. Results of DOC flux estimates from the bay to coastal waters will also be presented.

  5. A reliable method for ageing of whiting (Merlangius merlangus) for use in stock assessment and management

    DEFF Research Database (Denmark)

    Ross, Stine Dalmann; Hüssy, Karin

    2013-01-01

    Accurate age estimation is important for stock assessment and management. The importance of reliable ageing is emphasized by the impending analytical assessment of whiting (Merlangius merlangus) in the Baltic Sea. Whiting is a top predator in the western Baltic Sea, where it is fished commercially...

  6. Do North Sea cod (Gadus morhua) fisheries maintain high catch rates at low stock size?

    DEFF Research Database (Denmark)

    Rindorf, Anna; Andersen, Bo Sølgaard

    2008-01-01

    This study presents all investigation of the relationship between stock size of North Sea cod (Gadus morhua) and catch rates in seven commercial fishing fleets. The shape of the relationship was estimated using a model allowing both density-dependent changes in catchability and bias...

  7. Compression stockings

    Science.gov (United States)

    Call your health insurance or prescription plan: Find out if they pay for compression stockings. Ask if your durable medical equipment benefit pays for compression stockings. Get a prescription from your doctor. Find a medical equipment store where they can ...

  8. Stock Status

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These data inform the public of the most recent stock status for all stocks (FSSI and non-FSSI) in the fishery management unit contained in a fishery managment plan....

  9. Effects of mapped variation in soil conditions on estimates of soil carbon and nitrogen stocks for South America

    NARCIS (Netherlands)

    Batjes, N.H.

    2000-01-01

    Organic carbon and total nitrogen stocks for South America are computed using four 1:5,000,000 scale soil data sets of different spatial resolution. These are the 60' by 60' resolution Zobler soil data file, the 30' by 30' resolution World Inventory of Soil Emission Potentials (WISE) database, a 5'

  10. Hankin and Reeves' Approach to Estimating Fish Abundance in Small Streams : Limitations and Potential Options.

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, William L. [Bonneville Power Administration, Portland, OR (US). Environment, Fish and Wildlife

    2000-11-01

    Hankin and Reeves' (1988) approach to estimating fish abundance in small streams has been applied in stream-fish studies across North America. However, as with any method of population estimation, there are important assumptions that must be met for estimates to be minimally biased and reasonably precise. Consequently, I investigated effects of various levels of departure from these assumptions via simulation based on results from an example application in Hankin and Reeves (1988) and a spatially clustered population. Coverage of 95% confidence intervals averaged about 5% less than nominal when removal estimates equaled true numbers within sampling units, but averaged 62% - 86% less than nominal when they did not, with the exception where detection probabilities of individuals were >0.85 and constant across sampling units (95% confidence interval coverage = 90%). True total abundances averaged far (20% - 41%) below the lower confidence limit when not included within intervals, which implies large negative bias. Further, average coefficient of variation was about 1.5 times higher when removal estimates did not equal true numbers within sampling units (C{bar V} = 0.27 [SE = 0.0004]) than when they did (C{bar V} = 0.19 [SE = 0.0002]). A potential modification to Hankin and Reeves' approach is to include environmental covariates that affect detection rates of fish into the removal model or other mark-recapture model. A potential alternative is to use snorkeling in combination with line transect sampling to estimate fish densities. Regardless of the method of population estimation, a pilot study should be conducted to validate the enumeration method, which requires a known (or nearly so) population of fish to serve as a benchmark to evaluate bias and precision of population estimates.

  11. A two-step approach to estimating selectivity and fishing power of research gill nets used in Greenland waters

    DEFF Research Database (Denmark)

    Hovgård, Holger

    1996-01-01

    by normal distributions and could be related to mesh size in accordance with the principle of geometrical similarity. In the second step the selection parameters were estimated by a nonlinear least squares fit. The model also estimated the relative efficiency of the two capture processes and the fishing......Catches of Atlantic cod (Gadus morhua) from Greenland gill-net surveys were analyzed by a two-step approach. In the initial step the form of the selection curve was identified as binormal, which was caused by fish being gilled or caught by the maxillae. Both capture processes could be described...

  12. Stream fishes and desirable fish stocks

    DEFF Research Database (Denmark)

    Dieperink, C.; Sand-Jensen, K.

    2006-01-01

    Freshwater fi sh communities have always been valuable resources for society, particularly the species that migrate between freshwater and the sea. Historically, eel, salmon and trout were so abundant that good fi shing luck could turn a capable fi sherman into a wealthy person. Unfortunately......, illustrates this historical decline and also the diffi culty of re-establishing healthy fi sh communities once the original populations have deteriorated or, in the case of salmon, become extinct. Efforts are currently needed to be made to effectively restore and manage fi sh communities in streams....

  13. An analysis of genetic stock identification on a small geographical scale using microsatellite markers, and its application in the management of a mixed-stock fishery for Atlantic salmon Salmo salar in Ireland.

    Science.gov (United States)

    Ensing, D; Crozier, W W; Boylan, P; O'Maoiléidigh, N; McGinnity, P

    2013-06-01

    A genetic stock identification (GSI) study was undertaken in a fishery for Atlantic salmon Salmo salar to determine the effects of restrictive fishery management measures on the stock composition of the fishery, and if accurate and precise stock composition estimates could be achieved on the small geographical scale where this fishery operates, using a suite of only seven microsatellite loci. The stock composition of the Foyle fishery was shown to comprise almost exclusively of Foyle origin fish in the 3 years after restrictive measures were introduced in 2007, compared to 85% the year before. This showed that the restrictive measures resulted in the Foyle fishery being transformed from a mixed-stock fishery to an almost exclusively single-stock fishery, and showed how GSI studies can guide and evaluate management decisions to successfully manage these fisheries. Highly accurate and precise stock composition estimates were achieved in this study, using both cBAYES and ONCOR genetic software packages. This suggests accurate and precise stock composition is possible even on small geographical scales. © 2013 AFBINI. Journal of Fish Biology © 2013 The Fisheries Society of the British Isles.

  14. Exploiting Growing Stock Volume Maps for Large Scale Forest Resource Assessment: Cross-Comparisons of ASAR- and PALSAR-Based GSV Estimates with Forest Inventory in Central Siberia

    Directory of Open Access Journals (Sweden)

    Christian Hüttich

    2014-07-01

    Full Text Available Growing stock volume is an important biophysical parameter describing the state and dynamics of the Boreal zone. Validation of growing stock volume (GSV maps based on satellite remote sensing is challenging due to the lack of consistent ground reference data. The monitoring and assessment of the remote Russian forest resources of Siberia can only be done by integrating remote sensing techniques and interdisciplinary collaboration. In this paper, we assess the information content of GSV estimates in Central Siberian forests obtained at 25 m from ALOS-PALSAR and 1 km from ENVISAT-ASAR backscatter data. The estimates have been cross-compared with respect to forest inventory data showing 34% relative RMSE for the ASAR-based GSV retrievals and 39.4% for the PALSAR-based estimates of GSV. Fragmentation analyses using a MODIS-based land cover dataset revealed an increase of retrieval error with increasing fragmentation of the landscape. Cross-comparisons of multiple SAR-based GSV estimates helped to detect inconsistencies in the forest inventory data and can support an update of outdated forest inventory stands.

  15. Does bioelectrical impedance analysis accurately estimate the condition of threatened and endangered desert fish species?

    Science.gov (United States)

    Dibble, Kimberly L.; Yard, Micheal D.; Ward, David L.; Yackulic, Charles B.

    2017-01-01

    Bioelectrical impedance analysis (BIA) is a nonlethal tool with which to estimate the physiological condition of animals that has potential value in research on endangered species. However, the effectiveness of BIA varies by species, the methodology continues to be refined, and incidental mortality rates are unknown. Under laboratory conditions we tested the value of using BIA in addition to morphological measurements such as total length and wet mass to estimate proximate composition (lipid, protein, ash, water, dry mass, energy density) in the endangered Humpback Chub Gila cypha and Bonytail G. elegans and the species of concern Roundtail Chub G. robusta and conducted separate trials to estimate the mortality rates of these sensitive species. Although Humpback and Roundtail Chub exhibited no or low mortality in response to taking BIA measurements versus handling for length and wet-mass measurements, Bonytails exhibited 14% and 47% mortality in the BIA and handling experiments, respectively, indicating that survival following stress is species specific. Derived BIA measurements were included in the best models for most proximate components; however, the added value of BIA as a predictor was marginal except in the absence of accurate wet-mass data. Bioelectrical impedance analysis improved the R2 of the best percentage-based models by no more than 4% relative to models based on morphology. Simulated field conditions indicated that BIA models became increasingly better than morphometric models at estimating proximate composition as the observation error around wet-mass measurements increased. However, since the overall proportion of variance explained by percentage-based models was low and BIA was mostly a redundant predictor, we caution against the use of BIA in field applications for these sensitive fish species.

  16. Estimates of entrainment mortality for striped bass and other fish species inhabiting the Hudson River estuary

    International Nuclear Information System (INIS)

    Boreman, J.; Goodyear, C.P.

    1988-01-01

    An empirically derived age-, time-, and space-variant equation was used to estimate entrainment mortality at power plants for seven fish species inhabiting the Hudson River estuary. Entrainment mortality is expressed as a conditional rate, which is the fractional reduction in year-class strength due to entrainment if other sources of mortality are density-independent. Estimates of the conditional entrainment mortality, based on historical and projected once-through cooling operation of five power plants, were 11-22% for striped bass, 11-17% for white perch, 5-7% for Atlantic tomcod, 14-21% for American shad, 4-11% for river herring (alewife and blueback herring combined), and 35-79% for bay anchovy. Closed-cycle cooling (natural-draft cooling towers) at three of the power plants (Indian Point, Bowline Point, and Roseton) would reduce entrainment mortality of striped bass by 50-80%, of white perch by 75-80%, of Atlantic tocod by 65-70%, of American shad by 80%, of river herring by 30-90%, and of bay anchovy by 45-80%. The life stages most vulnerable to entrainment mortality were post-yolk-sac larva and entrainable size juvenile. 18 refs., 7 tabs

  17. The contingent behavior of charter fishing participants on the Chesapeake Bay: Welfare estimates associated with water quality improvements

    Science.gov (United States)

    Poor, P.J.; Breece, M.

    2006-01-01

    Water quality in the Chesapeake Bay has deteriorated over recent years. Historically, fishing has contributed to the region's local economy in terms of commercial and recreational harvests. A contingent behavior model is used to estimate welfare measures for charter fishing participants with regard to a hypothetical improvement in water quality. Using a truncated Poisson count model corrected for endogenous stratification, it was found that charter fishers not only contribute to the local market economy, but they also place positive non-market value on preserving the Bay's water quality. Using two estimates for travels costs it is estimated that the individual consumer surplus is $200 and $117 per trip, and the average individual consumer surplus values for an improvement in water quality is $75 and $44 for two models estimated. ?? 2006 University of Newcastle upon Tyne.

  18. Estimation of uncertainty of a reference material for proficiency testing for the determination of total mercury in fish in nature

    International Nuclear Information System (INIS)

    Santana, L V; Sarkis, J E S; Ulrich, J C; Hortellani, M A

    2015-01-01

    We provide an uncertainty estimates for homogeneity and stability studies of reference material used in proficiency test for determination of total mercury in fish fresh muscle tissue. Stability was estimated by linear regression and homogeneity by ANOVA. The results indicate that the reference material is both homogeneous and chemically stable over the short term. Total mercury concentration of the muscle tissue, with expanded uncertainty, was 0.294 ± 0.089 μg g −1

  19. Assessments of the lesser sandeel ( Ammodytes marinus ) in the North Sea based on revised stock divisions

    DEFF Research Database (Denmark)

    Pedersen, S.A.; Lewy, Peter; Wright, P.

    1999-01-01

    effort, catch per unit effort, yield, fishing and natural mortality. A better understanding of sandeel growth is important for stock and catch predictions because previous studies indicate that the variability of mean weight-at-age is one of the most important factors influencing the precision......Recent investigations suggest that the current treatment of North Sea sandeel (Ammodytes marinus) as a single unit stock may have little biological basis. In order to study regional effects of the fishery on North Sea lesser sandeel it may therefore be important to assess stock dynamics...... of predictions. The Danish weight-at-age data of sandeel are re- analysed to estimate the mean weight-at-age in the catch and the stock and the precision of the estimates. The reliability of the sandeel assessments is discussed in relation to the data sources available and to the knowledge of sandeel biology...

  20. Proceedings of the International Workshop on age determination of oceanic pelagic fishes: Tunas, billfishes, and sharks, Miami, Florida, February 15-18,1982

    OpenAIRE

    1983-01-01

    Accurate and precise estimates of age and growth rates are essential parameters in understanding the population dynamics of fishes. Some of the more sophisticated stock assessment models, such as virtual population analysis, require age and growth information to partition catch data by age. Stock assessment efforts by regulatory agencies are usually directed at specific fisheries which are being heavily exploited and are suspected of being overfished. Interest in stock assessment of som...

  1. Seasonal and diel effects on acoustic fish biomass estimates: application to a shallow reservoir with untargeted common carp (Cyprinus carpio)

    Science.gov (United States)

    Djemali, Imed; Yule, Daniel; Guillard, Jean

    2016-01-01

    The aim of the present study was to understand how seasonal fish distributions affect acoustically derived fish biomass estimates in a shallow reservoir in a semi-arid country (Tunisia). To that end, sampling events were performed during four seasons (spring (June), summer (September), autumn (December) and winter (March)) that included day and night surveys. A Simrad EK60 echosounder, equipped with two 120-kHz split-beam transducers for simultaneous horizontal and vertical beaming, was used to sample the entire water column. Surveys during spring and summer and daytime hours of winter were deemed unusable owing to high methane flux from the sediment, and during the day survey of autumn, fish were close to the reservoir bottom leading to low detectability. It follows that acoustic surveys should be conducted only at night during the cold season (December–March) for shallow reservoirs having carp Cyprinus carpio (L.) as the dominant species. Further, night-time biomass estimates during the cold season declined significantly (P < 0.001) from autumn to winter. Based on our autumn night-time survey, overall fish biomass in the Bir-Mcherga Reservoir was high (mean (± s.d.) 185 ± 98 tonnes (Mg)), but annual fishery exploitation is low (19.3–24.1 Mg) because the fish biomass is likely dominated by invasive carp not targeted by fishers. The results suggest that controlling carp would help improve the fishery.

  2. Evaluating the predictive performance of empirical estimators of natural mortality rate using information on over 200 fish species

    Science.gov (United States)

    Then, Amy Y.; Hoenig, John M; Hall, Norman G.; Hewitt, David A.

    2015-01-01

    Many methods have been developed in the last 70 years to predict the natural mortality rate, M, of a stock based on empirical evidence from comparative life history studies. These indirect or empirical methods are used in most stock assessments to (i) obtain estimates of M in the absence of direct information, (ii) check on the reasonableness of a direct estimate of M, (iii) examine the range of plausible M estimates for the stock under consideration, and (iv) define prior distributions for Bayesian analyses. The two most cited empirical methods have appeared in the literature over 2500 times to date. Despite the importance of these methods, there is no consensus in the literature on how well these methods work in terms of prediction error or how their performance may be ranked. We evaluate estimators based on various combinations of maximum age (tmax), growth parameters, and water temperature by seeing how well they reproduce >200 independent, direct estimates of M. We use tenfold cross-validation to estimate the prediction error of the estimators and to rank their performance. With updated and carefully reviewed data, we conclude that a tmax-based estimator performs the best among all estimators evaluated. The tmax-based estimators in turn perform better than the Alverson–Carney method based on tmax and the von Bertalanffy K coefficient, Pauly’s method based on growth parameters and water temperature and methods based just on K. It is possible to combine two independent methods by computing a weighted mean but the improvement over the tmax-based methods is slight. Based on cross-validation prediction error, model residual patterns, model parsimony, and biological considerations, we recommend the use of a tmax-based estimator (M=4.899tmax−0.916">M=4.899t−0.916maxM=4.899tmax−0.916, prediction error = 0.32) when possible and a growth-based method (M=4.118K0.73L∞−0.33">M=4.118K0.73L−0.33∞M=4.118K0.73L∞−0.33 , prediction error

  3. Assessment of Sustainable Yield and Optimum Fishing Effort for the ...

    African Journals Online (AJOL)

    Bheema

    length based models are suitable for tropical fish stock assessment work as they do not .... A value of Z/F = 0.5 have been used as the starting value based on the ..... Similarly, estimates of annual recruitment rate of O.niloticus obtained in the ...

  4. The Application of Traits-Based Assessment Approaches to Estimate the Effects of Hydroelectric Turbine Passage on Fish Populations

    Energy Technology Data Exchange (ETDEWEB)

    Cada, Glenn F [ORNL; Schweizer, Peter E [ORNL

    2012-04-01

    One of the most important environmental issues facing the hydropower industry is the adverse impact of hydroelectric projects on downstream fish passage. Fish that migrate long distances as part of their life cycle include not only important diadromous species (such as salmon, shads, and eels) but also strictly freshwater species. The hydropower reservoirs that downstream-moving fish encounter differ greatly from free-flowing rivers. Many of the environmental changes that occur in a reservoir (altered water temperature and transparency, decreased flow velocities, increased predation) can reduce survival. Upon reaching the dam, downstream-migrating fish may suffer increased mortality as they pass through the turbines, spillways and other bypasses, or turbulent tailraces. Downstream from the dam, insufficient environmental flow releases may slow downstream fish passage rates or decrease survival. There is a need to refine our understanding of the relative importance of causative factors that contribute to turbine passage mortality (e.g., strike, pressure changes, turbulence) so that turbine design efforts can focus on mitigating the most damaging components. Further, present knowledge of the effectiveness of turbine improvements is based on studies of only a few species (mainly salmon and American shad). These data may not be representative of turbine passage effects for the hundreds of other fish species that are susceptible to downstream passage at hydroelectric projects. For example, there are over 900 species of fish in the United States. In Brazil there are an estimated 3,000 freshwater fish species, of which 30% are believed to be migratory (Viana et al. 2011). Worldwide, there are some 14,000 freshwater fish species (Magurran 2009), of which significant numbers are susceptible to hydropower impacts. By comparison, in a compilation of fish entrainment and turbine survival studies from over 100 hydroelectric projects in the United States, Winchell et al. (2000

  5. A statistical model for estimation of fish density including correlation in size, space, time and between species from research survey data

    DEFF Research Database (Denmark)

    Nielsen, J. Rasmus; Kristensen, Kasper; Lewy, Peter

    2014-01-01

    Trawl survey data with high spatial and seasonal coverage were analysed using a variant of the Log Gaussian Cox Process (LGCP) statistical model to estimate unbiased relative fish densities. The model estimates correlations between observations according to time, space, and fish size and includes...

  6. Development of software and modification of Q-FISH protocol for estimation of individual telomere length in immunopathology.

    Science.gov (United States)

    Barkovskaya, M Sh; Bogomolov, A G; Knauer, N Yu; Rubtsov, N B; Kozlov, V A

    2017-04-01

    Telomere length is an important indicator of proliferative cell history and potential. Decreasing telomere length in the cells of an immune system can indicate immune aging in immune-mediated and chronic inflammatory diseases. Quantitative fluorescent in situ hybridization (Q-FISH) of a labeled (C 3 TA[Formula: see text] peptide nucleic acid probe onto fixed metaphase cells followed by digital image microscopy allows the evaluation of telomere length in the arms of individual chromosomes. Computer-assisted analysis of microscopic images can provide quantitative information on the number of telomeric repeats in individual telomeres. We developed new software to estimate telomere length. The MeTeLen software contains new options that can be used to solve some Q-FISH and microscopy problems, including correction of irregular light effects and elimination of background fluorescence. The identification and description of chromosomes and chromosome regions are essential to the Q-FISH technique. To improve the quality of cytogenetic analysis after Q-FISH, we optimized the temperature and time of DNA-denaturation to get better DAPI-banding of metaphase chromosomes. MeTeLen was tested by comparing telomere length estimations for sister chromatids, background fluorescence estimations, and correction of nonuniform light effects. The application of the developed software for analysis of telomere length in patients with rheumatoid arthritis was demonstrated.

  7. Computing ordinary least-squares parameter estimates for the National Descriptive Model of Mercury in Fish

    Science.gov (United States)

    Donato, David I.

    2013-01-01

    A specialized technique is used to compute weighted ordinary least-squares (OLS) estimates of the parameters of the National Descriptive Model of Mercury in Fish (NDMMF) in less time using less computer memory than general methods. The characteristics of the NDMMF allow the two products X'X and X'y in the normal equations to be filled out in a second or two of computer time during a single pass through the N data observations. As a result, the matrix X does not have to be stored in computer memory and the computationally expensive matrix multiplications generally required to produce X'X and X'y do not have to be carried out. The normal equations may then be solved to determine the best-fit parameters in the OLS sense. The computational solution based on this specialized technique requires O(8p2+16p) bytes of computer memory for p parameters on a machine with 8-byte double-precision numbers. This publication includes a reference implementation of this technique and a Gaussian-elimination solver in preliminary custom software.

  8. Valuing the Unmarketable: An Ecological Approach to the Externalities Estimate in Fishing Activities

    Directory of Open Access Journals (Sweden)

    Piero Franzoi

    2013-02-01

    Full Text Available In a rapidly changing world, sustainability, if it can be said to exist at all, is concept that has attained mythic status, often pursued and rarely reached. In order to improve our capability to cope with environmental problems, adopting an Ecosystem Approach has been suggested. One of the major challenges in the implementation of this new paradigm relates to control of externalities. The recognition and quantification of externalities is often cast as valuing the unmarketable, and there are several approaches that have been proposed. Here, we analyze the opportunity to “feed” the economic valuation with ecological concepts. From an ecological perspective, the energy required to sustain a biomass unit at a given trophic level (TL is the same, whatever the species. We build on this central tenet of ecology to assess the value of a TL unit for each trophic position using fish market data. The results obtained were then used to assign a value to each species living in a given habitat, together with consideration of their ecological role within the community. Estimates of both natural capital and functional value were applied to assess the ecological impacts of mechanical clam harvesting versus the multi-species artisanal fishery in the Venice lagoon. Results are discussed in relation to possible contribution to the implementation of a different management strategy.

  9. Contribution to the risk characterization of ciguatoxins: LOAEL estimated from eight ciguatera fish poisoning events in Guadeloupe (French West Indies).

    Science.gov (United States)

    Hossen, Virginie; Soliño, Lucia; Leroy, Patricia; David, Eric; Velge, Pierre; Dragacci, Sylviane; Krys, Sophie; Flores Quintana, Harold; Diogène, Jorge

    2015-11-01

    From 2010 to 2012, 35 ciguatera fish poisoning (CFP) events involving 87 individuals who consumed locally-caught fish were reported in Guadeloupe (French West Indies). For 12 of these events, the presence of ciguatoxins (CTXs) was indicated in meal remnants and in uncooked fish by the mouse bioassay (MBA). Caribbean ciguatoxins (C-CTXs) were confirmed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. Using a cell-based assay (CBA), and the only available standard Pacific ciguatoxin-1 (P-CTX-1), the lowest toxins level detected in fish samples causing CFP was 0.022 µg P-CTX-1 equivalent (eq.)·kg(-1) fish. Epidemiological and consumption data were compiled for most of the individuals afflicted, and complete data for establishing the lowest observable adverse effects level (LOAEL) were obtained from 8 CFP events involving 21 individuals. Based on toxin intakes, the LOAEL was estimated at 4.2 ng P-CTX-1 eq./individual corresponding to 48. 4 pg P-CTX-1 eq.kg(-1) body weight (bw). Although based on limited data, these results are consistent with the conclusions of the European Food Safety Authority (EFSA) opinion which indicates that a level of 0.01 µg P-CTX-1 eq.kg(-1) fish, regardless of source, should not exert effects in sensitive individuals when consuming a single meal. The calculated LOAEL is also consistent with the U.S. Food and Drug Administration guidance levels for CTXs (0.1 µg C-CTX-1 eq.kg(-1) and 0.01 µg P-CTX-1 eq.kg(-1) fish). Copyright © 2015 Elsevier Inc. All rights reserved.

  10. Estimating Common Growth Patterns in Juvenile Chinook Salmon (Oncorhynchus tshawytscha from Diverse Genetic Stocks and a Large Spatial Extent.

    Directory of Open Access Journals (Sweden)

    Pascale A L Goertler

    Full Text Available Life history variation in Pacific salmon (Oncorhynchus spp. supports species resilience to natural disturbances and fishery exploitation. Within salmon species, life-history variation often manifests during freshwater and estuarine rearing, as variation in growth. To date, however, characterizing variability in growth patterns within and among individuals has been difficult via conventional sampling methods because of the inability to obtain repeated size measurements. In this study we related otolith microstructures to growth rates of individual juvenile Chinook salmon (O. tshawytscha from the Columbia River estuary over a two-year period (2010-2012. We used dynamic factor analysis to determine whether there were common patterns in growth rates within juveniles based on their natal region, capture location habitat type, and whether they were wild or of hatchery origin. We identified up to five large-scale trends in juvenile growth rates depending on month and year of capture. We also found that hatchery fish had a narrower range of trend loadings for some capture groups, suggesting that hatchery fish do not express the same breadth of growth variability as wild fish. However, we were unable to resolve a relationship between specific growth patterns and habitat transitions. Our study exemplifies how a relatively new statistical analysis can be applied to dating or aging techniques to summarize individual variation, and characterize aspects of life history diversity.

  11. Research Fishing

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Accurate and precise stock assessments are predicated on accurate and precise estimates of life history parameters, abundance, and catch across the range of the...

  12. 78 FR 32179 - Fisheries of the Caribbean, Gulf of Mexico, and South Atlantic; Reef Fish Fishery of the Gulf of...

    Science.gov (United States)

    2013-05-29

    ... snapper stock is still overfished and under a rebuilding plan through 2032. The next SEDAR benchmark stock..., weekend fishing, peak season fishing, increases in stock abundance, potentially significant levels of...

  13. Patterns in the spatial distribution of Peruvian anchovy ( Engraulis ringens) revealed by spatially explicit fishing data

    Science.gov (United States)

    Bertrand, Sophie; Díaz, Erich; Lengaigne, Matthieu

    2008-10-01

    Peruvian anchovy ( Engraulis ringens) stock abundance is tightly driven by the high and unpredictable variability of the Humboldt Current Ecosystem. Management of the fishery therefore cannot rely on mid- or long-term management policy alone but needs to be adaptive at relatively short time scales. Regular acoustic surveys are performed on the stock at intervals of 2 to 4 times a year, but there is a need for more time continuous monitoring indicators to ensure that management can respond at suitable time scales. Existing literature suggests that spatially explicit data on the location of fishing activities could be used as a proxy for target stock distribution. Spatially explicit commercial fishing data could therefore guide adaptive management decisions at shorter time scales than is possible through scientific stock surveys. In this study we therefore aim to (1) estimate the position of fishing operations for the entire fleet of Peruvian anchovy purse-seiners using the Peruvian satellite vessel monitoring system (VMS), and (2) quantify the extent to which the distribution of purse-seine sets describes anchovy distribution. To estimate fishing set positions from vessel tracks derived from VMS data we developed a methodology based on artificial neural networks (ANN) trained on a sample of fishing trips with known fishing set positions (exact fishing positions are known for approximately 1.5% of the fleet from an at-sea observer program). The ANN correctly identified 83% of the real fishing sets and largely outperformed comparative linear models. This network is then used to forecast fishing operations for those trips where no observers were onboard. To quantify the extent to which fishing set distribution was correlated to stock distribution we compared three metrics describing features of the distributions (the mean distance to the coast, the total area of distribution, and a clustering index) for concomitant acoustic survey observations and fishing set positions

  14. Bioenergetics modeling of the annual consumption of zooplankton by pelagic fish feeding in the Northeast Atlantic

    DEFF Research Database (Denmark)

    Bachiller, Eneko; Utne, Kjell Rong; Jansen, Teunis

    2018-01-01

    The present study uses bioenergetics modeling to estimate the annual consumption of the main zooplankton groups by some of the most commercially important planktivorous fish stocks in the Northeast Atlantic, namely Norwegian spring-spawning (NSS) herring (Clupea harengus), blue whiting (Micromesi......The present study uses bioenergetics modeling to estimate the annual consumption of the main zooplankton groups by some of the most commercially important planktivorous fish stocks in the Northeast Atlantic, namely Norwegian spring-spawning (NSS) herring (Clupea harengus), blue whiting...

  15. Coupling age-structured stock assessment and fish bioenergetics models: a system of time-varying models for quantifying piscivory patterns during the rapid trophic shift in the main basin of Lake Huron

    Science.gov (United States)

    He, Ji X.; Bence, James R.; Madenjian, Charles P.; Pothoven, Steven A.; Dobiesz, Norine E.; Fielder, David G.; Johnson, James E.; Ebener, Mark P.; Cottrill, Adam R.; Mohr, Lloyd C.; Koproski, Scott R.

    2015-01-01

    We quantified piscivory patterns in the main basin of Lake Huron during 1984–2010 and found that the biomass transfer from prey fish to piscivores remained consistently high despite the rapid major trophic shift in the food webs. We coupled age-structured stock assessment models and fish bioenergetics models for lake trout (Salvelinus namaycush), Chinook salmon (Oncorhynchus tshawytscha), walleye (Sander vitreus), and lake whitefish (Coregonus clupeaformis). The model system also included time-varying parameters or variables of growth, length–mass relations, maturity schedules, energy density, and diets. These time-varying models reflected the dynamic connections that a fish cohort responded to year-to-year ecosystem changes at different ages and body sizes. We found that the ratio of annual predation by lake trout, Chinook salmon, and walleye combined with the biomass indices of age-1 and older alewives (Alosa pseudoharengus) and rainbow smelt (Osmerus mordax) increased more than tenfold during 1987–2010, and such increases in predation pressure were structured by relatively stable biomass of the three piscivores and stepwise declines in the biomass of alewives and rainbow smelt. The piscivore stability was supported by the use of alternative energy pathways and changes in relative composition of the three piscivores. In addition, lake whitefish became a new piscivore by feeding on round goby (Neogobius melanostomus). Their total fish consumption rivaled that of the other piscivores combined, although fish were still a modest proportion of their diet. Overall, the use of alternative energy pathways by piscivores allowed the increases in predation pressure on dominant diet species.

  16. Estimating movement and survival rates of a small saltwater fish using autonomous antenna receiver arrays and passive integrated transponder tags

    Science.gov (United States)

    Rudershausen, Paul J.; Buckel, Jeffery A.; Dubreuil, Todd; O'Donnell, Matthew J.; Hightower, Joseph E.; Poland, Steven J.; Letcher, Benjamin H.

    2014-01-01

    We evaluated the performance of small (12.5 mm long) passive integrated transponder (PIT) tags and custom detection antennas for obtaining fine-scale movement and demographic data of mummichog Fundulus heteroclitus in a salt marsh creek. Apparent survival and detection probability were estimated using a Cormack Jolly Seber (CJS) model fitted to detection data collected by an array of 3 vertical antennas from November 2010 to March 2011 and by a single horizontal antenna from April to August 2011. Movement of mummichogs was monitored during the period when the array of vertical antennas was used. Antenna performance was examined in situ using tags placed in wooden dowels (drones) and in live mummichogs. Of the 44 tagged fish, 42 were resighted over the 9 mo monitoring period. The in situ detection probabilities of the drone and live mummichogs were high (~80-100%) when the ambient water depth was less than ~0.8 m. Upstream and downstream movement of mummichogs was related to hourly water depth and direction of tidal current in a way that maximized time periods over which mummichogs utilized the intertidal vegetated marsh. Apparent survival was lower during periods of colder water temperatures in December 2010 and early January 2011 (median estimate of daily apparent survival = 0.979) than during other periods of the study (median estimate of daily apparent survival = 0.992). During late fall and winter, temperature had a positive effect on the CJS detection probability of a tagged mummichog, likely due to greater fish activity over warmer periods. During the spring and summer, this pattern reversed possibly due to mummichogs having reduced activity during the hottest periods. This study demonstrates the utility of PIT tags and continuously operating autonomous detection systems for tracking fish at fine temporal scales, and improving estimates of demographic parameters in salt marsh creeks that are difficult or impractical to sample with active fishing gear.

  17. Estimating escapement of fish and invertebrates in a Danish anchor seine

    DEFF Research Database (Denmark)

    Noack, Thomas; Madsen, Niels; Mieske, Bernd

    2017-01-01

    The codend is generally presumed to be the place where the main selectivity of fish occurs in towed fishing gears, but other parts of the net have been found to contribute to the selectivity process of several invertebrate species. This means that conventional selectivity or survival studies may......) invertebrates from the forward parts of the seine net. For seven species of demersal fish, most fish escaped through the lower panel close to the codend. All invertebrate species were found in higher numbers in the collecting bags than in the codend where many organisms escaped in the lower panel of the wings...... or the belly. Mean levels of visible damage ranged from 1.00 to 3.25 for collected invertebrates and were similar for all gear parts. Common starfish (Asterias rubens), however, showed highest damage in the extension part of the net....

  18. Locomotion during digestion changes current estimates of seed dispersal kernels by fish

    NARCIS (Netherlands)

    van Leeuwen, Casper H.A.; Beukeboom, Rosanne; Nolet, Bart A.; Bakker, Elisabeth S.; Pollux, Bart J.A.

    2016-01-01

    Dispersal of seeds by animals is an important mechanism regulating plant diversity, range expansions and invasions. Many birds, mammals, fish, and reptiles regularly ingest, transport and excrete viable seeds (known as endozoochory). The effectiveness of endozoochory is modelled in dispersal

  19. Estimation of the carbon footprint of the Galician fishing activity (NW Spain)

    International Nuclear Information System (INIS)

    Iribarren, Diego; Vazquez-Rowe, Ian; Hospido, Almudena; Moreira, Maria Teresa; Feijoo, Gumersindo

    2010-01-01

    The food production system as a whole is recognized as one of the major contributors to environmental impacts. Accordingly, food production, processing, transport and consumption account for a relevant portion of the greenhouse gas (GHG) emissions associated with any country. In this context, there is an increasing market demand for climate-relevant information regarding the global warming impact of consumer food products throughout the supply chains. This article deals with the assessment of the carbon footprint of seafood products as a key subgroup in the food sector. Galicia (NW Spain) was selected as a case study. The analysis is based on a representative set of species within the Galician fishing sector, including species obtained from coastal fishing (e.g. horse mackerel, Atlantic mackerel, European pilchard and blue whiting), offshore fishing (e.g. European hake, megrim and anglerfish), deep-sea fishing (skipjack and yellowfin tuna), extensive aquaculture (mussels) and intensive aquaculture (turbot). The carbon footprints associated with the production-related activities of each selected species were quantified following a business-to-business approach on the basis of 1 year of fishing activity. These individual carbon footprints were used to calculate the carbon footprint for each of the different Galician fisheries and culture activities. Finally, the lump sum of the carbon footprints for coastal, offshore and deep-sea fishing and extensive and intensive aquaculture brought about the carbon footprint of the Galician fishing activity (i.e., capture and culture). A benchmark for quantifying and communicating emission reductions was then provided, and opportunities to reduce the GHG emissions associated with the Galician fishing activity could be prioritized.

  20. ?How? and ?what? matters: Sampling method affects biodiversity estimates of reef fishes

    OpenAIRE

    Bosch, N?stor E.; Gon?alves, Jorge M. S.; Erzini, Karim; Tuya, Fernando

    2017-01-01

    Abstract Understanding changes in biodiversity requires the implementation of monitoring programs encompassing different dimensions of biodiversity through varying sampling techniques. In this work, fish assemblages associated with the ?outer? and ?inner? sides of four marinas, two at the Canary Islands and two at southern Portugal, were investigated using three complementary sampling techniques: underwater visual censuses (UVCs), baited cameras (BCs), and fish traps (FTs). We firstly investi...

  1. Estimation of the carbon footprint of the Galician fishing activity (NW Spain).

    Science.gov (United States)

    Iribarren, Diego; Vázquez-Rowe, Ian; Hospido, Almudena; Moreira, María Teresa; Feijoo, Gumersindo

    2010-10-15

    The food production system as a whole is recognized as one of the major contributors to environmental impacts. Accordingly, food production, processing, transport and consumption account for a relevant portion of the greenhouse gas (GHG) emissions associated with any country. In this context, there is an increasing market demand for climate-relevant information regarding the global warming impact of consumer food products throughout the supply chains. This article deals with the assessment of the carbon footprint of seafood products as a key subgroup in the food sector. Galicia (NW Spain) was selected as a case study. The analysis is based on a representative set of species within the Galician fishing sector, including species obtained from coastal fishing (e.g. horse mackerel, Atlantic mackerel, European pilchard and blue whiting), offshore fishing (e.g. European hake, megrim and anglerfish), deep-sea fishing (skipjack and yellowfin tuna), extensive aquaculture (mussels) and intensive aquaculture (turbot). The carbon footprints associated with the production-related activities of each selected species were quantified following a business-to-business approach on the basis of 1year of fishing activity. These individual carbon footprints were used to calculate the carbon footprint for each of the different Galician fisheries and culture activities. Finally, the lump sum of the carbon footprints for coastal, offshore and deep-sea fishing and extensive and intensive aquaculture brought about the carbon footprint of the Galician fishing activity (i.e., capture and culture). A benchmark for quantifying and communicating emission reductions was then provided, and opportunities to reduce the GHG emissions associated with the Galician fishing activity could be prioritized. Copyright © 2010 Elsevier B.V. All rights reserved.

  2. SIS - Fish Assessment

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Fish Assessment data set within the Species Information System (SIS) constraints information related to fishery stock assessments, including assessment meta-data...

  3. The stock selection problem: Is the stock selection approach more important than the optimization method? Evidence from the Danish stock market

    OpenAIRE

    Grobys, Klaus

    2011-01-01

    Passive investment strategies basically aim to replicate an underlying benchmark. Thereby, the management usually selects a subset of stocks being employed in the optimization procedure. Apart from the optimization procedure, the stock selection approach determines the stock portfolios' out-of-sample performance. The empirical study here takes into account the Danish stock market from 2000-2010 and gives evidence that stock portfolios including small companies' stocks being estimated via coin...

  4. Equivalence of live tree carbon stocks produced by three estimation approaches for forests of the western United States

    Science.gov (United States)

    Coeli M. Hoover; James E. Smith

    2017-01-01

    The focus on forest carbon estimation accompanying the implementation of increased regulatory and reporting requirements is fostering the development of numerous tools and methods to facilitate carbon estimation. One such well-established mechanism is via the Forest Vegetation Simulator (FVS), a growth and yield modeling system used by public and private land managers...

  5. A simple method to estimate radiation interception by nursery stock conifers: a case study of eastern white cedar

    NARCIS (Netherlands)

    Pronk, A.A.; Goudriaan, J.; Stilma, E.S.C.; Challa, H.

    2003-01-01

    A simple method was developed to estimate the fraction radiation intercepted by small eastern white cedar plants (Thuja occidentalis 'Brabant'). The method, which describes the crop canopy as rows of cuboids, was compared with methods used for estimating radiation interception by crops with

  6. Contribution to the risk characterization of ciguatoxins: LOAEL estimated from eight ciguatera fish poisoning events in Guadeloupe (French West Indies)

    International Nuclear Information System (INIS)

    Hossen, Virginie; Soliño, Lucia; Leroy, Patricia; David, Eric; Velge, Pierre; Dragacci, Sylviane; Krys, Sophie; Flores Quintana, Harold; Diogène, Jorge

    2015-01-01

    From 2010 to 2012, 35 ciguatera fish poisoning (CFP) events involving 87 individuals who consumed locally-caught fish were reported in Guadeloupe (French West Indies). For 12 of these events, the presence of ciguatoxins (CTXs) was indicated in meal remnants and in uncooked fish by the mouse bioassay (MBA). Caribbean ciguatoxins (C-CTXs) were confirmed by liquid chromatography–tandem mass spectrometry (LC–MS/MS) analysis. Using a cell-based assay (CBA), and the only available standard Pacific ciguatoxin-1 (P-CTX-1), the lowest toxins level detected in fish samples causing CFP was 0.022 µg P-CTX-1 equivalent (eq.)·kg −1 fish. Epidemiological and consumption data were compiled for most of the individuals afflicted, and complete data for establishing the lowest observable adverse effects level (LOAEL) were obtained from 8 CFP events involving 21 individuals. Based on toxin intakes, the LOAEL was estimated at 4.2 ng P-CTX-1 eq./individual corresponding to 48.4 pg P-CTX-1 eq. kg −1 body weight (bw). Although based on limited data, these results are consistent with the conclusions of the European Food Safety Authority (EFSA) opinion which indicates that a level of 0.01 µg P-CTX-1 eq. kg −1 fish, regardless of source, should not exert effects in sensitive individuals when consuming a single meal. The calculated LOAEL is also consistent with the U.S. Food and Drug Administration guidance levels for CTXs (0.1 µg C-CTX-1 eq. kg −1 and 0.01 µg P-CTX-1 eq. kg −1 fish). - Highlights: • We report on an epidemiological study on Ciguatera events in the French West Indies. • The collection of consumption data allows for the first time the LOAEL determination. • The LOAEL for ciguatoxins was established at 48.4 pg P-CTX-1 eq. kg −1 bw. • LC–MS/MS provided structural confirmation of C-CTX1 in two suspected samples • Neuro-2A CBA is suitable for assessing composite toxicity levels in fish samples.

  7. Contribution to the risk characterization of ciguatoxins: LOAEL estimated from eight ciguatera fish poisoning events in Guadeloupe (French West Indies)

    Energy Technology Data Exchange (ETDEWEB)

    Hossen, Virginie [Université Paris-Est, ANSES-Laboratory for Food Safety, National Reference Laboratory for the Control of Marine biotoxins, 14 rue Pierre et Marie Curie, 94701 Maisons-Alfort (France); Soliño, Lucia [Institut de Recerca i Tecnologia Agroalimentàries (IRTA), Ctra. Poble Nou km 5.5, Sant Carles de la Rapita (Spain); Leroy, Patricia [Université Paris-Est, ANSES-Laboratory for Food Safety, National Reference Laboratory for the Control of Marine biotoxins, 14 rue Pierre et Marie Curie, 94701 Maisons-Alfort (France); David, Eric [Ministry of Agriculture, Direction de l’Alimentation de l’Agriculture et de la Forêt de Guadeloupe, Abymes (France); Velge, Pierre [Ministry of Agriculture, General Directorate for Food, Paris (France); Dragacci, Sylviane, E-mail: Sylviane.dragacci@anses.fr [Université Paris-Est, ANSES-Laboratory for Food Safety, National Reference Laboratory for the Control of Marine biotoxins, 14 rue Pierre et Marie Curie, 94701 Maisons-Alfort (France); Krys, Sophie [Université Paris-Est, ANSES-Laboratory for Food Safety, National Reference Laboratory for the Control of Marine biotoxins, 14 rue Pierre et Marie Curie, 94701 Maisons-Alfort (France); Flores Quintana, Harold [U.S. Food and Drug Administration (FDA), Division of Seafood Science and Technology, Gulf Coast Seafood Laboratory, 1 Iberville Drive, Dauphin Island, AL 36528 (United States); Diogène, Jorge [Institut de Recerca i Tecnologia Agroalimentàries (IRTA), Ctra. Poble Nou km 5.5, Sant Carles de la Rapita (Spain)

    2015-11-15

    From 2010 to 2012, 35 ciguatera fish poisoning (CFP) events involving 87 individuals who consumed locally-caught fish were reported in Guadeloupe (French West Indies). For 12 of these events, the presence of ciguatoxins (CTXs) was indicated in meal remnants and in uncooked fish by the mouse bioassay (MBA). Caribbean ciguatoxins (C-CTXs) were confirmed by liquid chromatography–tandem mass spectrometry (LC–MS/MS) analysis. Using a cell-based assay (CBA), and the only available standard Pacific ciguatoxin-1 (P-CTX-1), the lowest toxins level detected in fish samples causing CFP was 0.022 µg P-CTX-1 equivalent (eq.)·kg{sup −1} fish. Epidemiological and consumption data were compiled for most of the individuals afflicted, and complete data for establishing the lowest observable adverse effects level (LOAEL) were obtained from 8 CFP events involving 21 individuals. Based on toxin intakes, the LOAEL was estimated at 4.2 ng P-CTX-1 eq./individual corresponding to 48.4 pg P-CTX-1 eq. kg{sup −1} body weight (bw). Although based on limited data, these results are consistent with the conclusions of the European Food Safety Authority (EFSA) opinion which indicates that a level of 0.01 µg P-CTX-1 eq. kg{sup −1} fish, regardless of source, should not exert effects in sensitive individuals when consuming a single meal. The calculated LOAEL is also consistent with the U.S. Food and Drug Administration guidance levels for CTXs (0.1 µg C-CTX-1 eq. kg{sup −1} and 0.01 µg P-CTX-1 eq. kg{sup −1} fish). - Highlights: • We report on an epidemiological study on Ciguatera events in the French West Indies. • The collection of consumption data allows for the first time the LOAEL determination. • The LOAEL for ciguatoxins was established at 48.4 pg P-CTX-1 eq. kg{sup −1} bw. • LC–MS/MS provided structural confirmation of C-CTX1 in two suspected samples • Neuro-2A CBA is suitable for assessing composite toxicity levels in fish samples.

  8. Accounting for correlated observations in an age-based state-space stock assessment model

    DEFF Research Database (Denmark)

    Berg, Casper Willestofte; Nielsen, Anders

    2016-01-01

    Fish stock assessment models often relyon size- or age-specific observations that are assumed to be statistically independent of each other. In reality, these observations are not raw observations, but rather they are estimates from a catch-standardization model or similar summary statistics base...... the independence assumption is rejected. Less fluctuating estimates of the fishing mortality is obtained due to a reduced process error. The improved model does not suffer from correlated residuals unlike the independent model, and the variance of forecasts is decreased....

  9. Impact of entrainment and impingement on fish populations in the Hudson River estuary. Volume I. Entrainment-impact estimates for six fish populations inhabiting the Hudson River estuary

    International Nuclear Information System (INIS)

    Boreman, J.; Barnthouse, L.W.; Vaughn, D.S.; Goodyear, C.P.; Christensen, S.W.; Kumar, K.D.; Kirk, B.L.; Van Winkle, W.

    1982-01-01

    This volume is concerned with the estimation of the direct (or annual) entrainment impact of power plants on populations of striped bass, white perch, Alosa spp. (blueback herring and alewife), American shad, Atlantic tomcod, and bay anchovy in the Hudson River estuary. Entrainment impact results from the killing of fish eggs, larvae, and young juveniles that are contained in the cooling water cycled through a power plant. An Empirical Transport Model (ETM) is presented as the means of estimating a conditional entrainment mortality rate (defined as the fraction of a year class which would be killed due to entrainment in the absence of any other source of mortality). Most of this volume is concerned with the estimation of several parameters required by the ETM: physical input parameters (e.g., power-plant withdrawal flow rates); the longitudinal distribution of ichthyoplankton in time and space; the duration of susceptibility of the vulnerable organisms; the W-factors, which express the ratios of densities of organisms in power plant intakes to densities of organisms in the river; and the entrainment mortality factors (f-factors), which express the probability that an organism will be killed if it is entrained. Once these values are obtained, the ETM is used to estimate entrainment impact for both historical and projected conditions

  10. Stock-catch analysis of carp recreational fisheries in Czech reservoirs: Insights into fish survival, water body productivity and impact of extreme events

    Czech Academy of Sciences Publication Activity Database

    Boukal S., David; Jankovský, Martin; Kubečka, Jan; Heino, M.

    119-120, 20 MAY (2012), s. 23-32 ISSN 0165-7836 R&D Projects: GA MŠk 7F10070 Grant - others:Financial Mechanism of EEA and Norwegian Financial Mechanism(NO) A/CZ0046/2/0029 Institutional support: RVO:60077344 Keywords : management * time series * stock ing Subject RIV: EH - Ecology, Behaviour Impact factor: 1.695, year: 2012 http://www.sciencedirect.com/science/article/pii/S0165783611003687

  11. Stock price prediction using geometric Brownian motion

    Science.gov (United States)

    Farida Agustini, W.; Restu Affianti, Ika; Putri, Endah RM

    2018-03-01

    Geometric Brownian motion is a mathematical model for predicting the future price of stock. The phase that done before stock price prediction is determine stock expected price formulation and determine the confidence level of 95%. On stock price prediction using geometric Brownian Motion model, the algorithm starts from calculating the value of return, followed by estimating value of volatility and drift, obtain the stock price forecast, calculating the forecast MAPE, calculating the stock expected price and calculating the confidence level of 95%. Based on the research, the output analysis shows that geometric Brownian motion model is the prediction technique with high rate of accuracy. It is proven with forecast MAPE value ≤ 20%.

  12. Growth and smolting in lower-mode Atlantic Salmon stocked into the Penobscot River, Maine

    Science.gov (United States)

    Zydlewski, Joseph D.; O'Malley, Andrew; Cox, Oliver; Ruksznis, Peter; Trial, Joan G.

    2014-01-01

    Restoration of Atlantic Salmon Salmo salar in Maine has relied on hatchery-produced fry and smolts for critical stocking strategies. Stocking fry minimizes domestication selection, but these fish have poor survival. Conversely, stocked smolts have little freshwater experience but provide higher adult returns. Lower-mode (LM) fish, those not growing fast enough to ensure smolting by the time of stocking, are a by-product of the smolt program and are an intermediate hatchery product. From 2002 to 2009, between 70,000 and 170,000 marked LM Atlantic Salmon were stocked into the Pleasant River (a tributary in the Penobscot River drainage, Maine) in late September to early October. These fish were recaptured as actively migrating smolts (screw trapping), as nonmigrants (electrofishing), and as returning adults to the Penobscot River (Veazie Dam trap). Fork length (FL) was measured and a scale sample was taken to retrospectively estimate FL at winter annulus one (FW1) using the intercept-corrected direct proportion model. The LM fish were observed to migrate as age-1, age-2, and infrequently as age-3 smolts. Those migrating as age-1 smolts had a distinctly larger estimated FL at FW1 (>112 mm) than those that remained in the river for at least one additional year. At the time of migration, age-2 and age-3 smolts were substantially larger than age-1 smolts. Returning adult Atlantic Salmon of LM origin had estimated FLs at FW1 that corresponded to smolt age (greater FL for age 1 than age 2). The LM product produces both age-1 and age-2 smolts that have greater freshwater experience than hatchery smolts and may have growth and fitness advantages. The data from this study will allow managers to better assess the probability of smolting age and manipulate hatchery growth rates to produce a targeted-size LM product.

  13. A simple method to estimate radiation interception by nursery stock conifers: a case study of eastern white cedar

    International Nuclear Information System (INIS)

    Pronk, A.A.; Goudriaan, J.; Stilma, E.; Challa, H.

    2003-01-01

    A simple method was developed to estimate the fraction radiation intercepted by small eastern white cedar plants (Thuja occidentalis ‘Brabant’). The method, which describes the crop canopy as rows of cuboids, was compared with methods used for estimating radiation interception by crops with homogeneous canopies and crops grown in rows. The extinction coefficient k was determined at different plant arrangements and an average k-value of 0.48 ± 0.03 (R 2 = 0.89) was used in the calculations. Effects of changing plant characteristics and inter- and intra-row plant distances were explored. The fraction radiation intercepted that was estimated with the method for rows of cuboids was up to 20% and for row crops up to 8% lower than estimated with the method for homogeneous canopies at low plant densities and a LAI of 1. The fraction radiation intercepted by small plants of Thuja occidentalis ‘Brabant’ was best estimated by the simple method described in this paper

  14. Derelict fishing line provides a useful proxy for estimating levels of non-compliance with no-take marine reserves.

    Directory of Open Access Journals (Sweden)

    David H Williamson

    Full Text Available No-take marine reserves (NTMRs are increasingly being established to conserve or restore biodiversity and to enhance the sustainability of fisheries. Although effectively designed and protected NTMR networks can yield conservation and fishery benefits, reserve effects often fail to manifest in systems where there are high levels of non-compliance by fishers (poaching. Obtaining reliable estimates of NTMR non-compliance can be expensive and logistically challenging, particularly in areas with limited or non-existent resources for conducting surveillance and enforcement. Here we assess the utility of density estimates and re-accumulation rates of derelict (lost and abandoned fishing line as a proxy for fishing effort and NTMR non-compliance on fringing coral reefs in three island groups of the Great Barrier Reef Marine Park (GBRMP, Australia. Densities of derelict fishing line were consistently lower on reefs within old (>20 year NTMRs than on non-NTMR reefs (significantly in the Palm and Whitsunday Islands, whereas line densities did not differ significantly between reefs in new NTMRs (5 years of protection and non-NTMR reefs. A manipulative experiment in which derelict fishing lines were removed from a subset of the monitoring sites demonstrated that lines re-accumulated on NTMR reefs at approximately one third (32.4% of the rate observed on non-NTMR reefs over a thirty-two month period. Although these inshore NTMRs have long been considered some of the best protected within the GBRMP, evidence presented here suggests that the level of non-compliance with NTMR regulations is higher than previously assumed.

  15. Use of side-scan sonar for estimations of Crassostrea brasiliana (Lamarck, 1819 stocks in subtidal banks on the south coast of Brazil

    Directory of Open Access Journals (Sweden)

    Gisela Geraldine Castilho Westphal

    2016-03-01

    Full Text Available Abstract Uncontrolled extractivism has led to a worldwide reduction in oyster stocks. The use of new and more efficient management tools for impacted environments must increase. The application of such tools requires previous biological and environmental knowledge of the resident populations of these bivalve mollusks. Technical difficulties are usually associated with studies of submerged oyster banks, and these difficulties result in a considerable lack of biological data on the oysters that inhabit subtidal zones. This study aimed to survey Crassostrea brasiliana (also known as C. gasar stocks in submerged banks and to evaluate a method with which to measure the extent of the banks and identify and quantify the oysters in the banks with the use of side-scan sonar. This study was conducted on 10 oysters banks located in the subtidal zone of Guaratuba Bay, on the south coast of Brazil. The prospection of all these banks was later validated by diving, and oyster samples (n = 20/bank were collected for species identification with a molecular method. Only one bank contained oysters that were generically classified as Crassostrea sp.; those in the remaining banks being identified as C. brasiliana. The prospected banks contained oysters of various sizes (average 1.5 m, n = 1,107 that were heterogeneously scattered in the riverbeds. The total number of oysters in the 10 sampled banks was estimated to be 21,159.13 oysters or 1 oyster/4.5 m², which represents a low oyster density in the study site. The results validate the use of side-scan sonar as an efficient means with which to prospect for oysters in banks located within subtidal zones.

  16. Comparison of calculation methods for estimating annual carbon stock change in German forests under forest management in the German greenhouse gas inventory.

    Science.gov (United States)

    Röhling, Steffi; Dunger, Karsten; Kändler, Gerald; Klatt, Susann; Riedel, Thomas; Stümer, Wolfgang; Brötz, Johannes

    2016-12-01

    The German greenhouse gas inventory in the land use change sector strongly depends on national forest inventory data. As these data were collected periodically 1987, 2002, 2008 and 2012, the time series on emissions show several "jumps" due to biomass stock change, especially between 2001 and 2002 and between 2007 and 2008 while within the periods the emissions seem to be constant due to the application of periodical average emission factors. This does not reflect inter-annual variability in the time series, which would be assumed as the drivers for the carbon stock changes fluctuate between the years. Therefore additional data, which is available on annual basis, should be introduced into the calculations of the emissions inventories in order to get more plausible time series. This article explores the possibility of introducing an annual rather than periodical approach to calculating emission factors with the given data and thus smoothing the trajectory of time series for emissions from forest biomass. Two approaches are introduced to estimate annual changes derived from periodic data: the so-called logging factor method and the growth factor method. The logging factor method incorporates annual logging data to project annual values from periodic values. This is less complex to implement than the growth factor method, which additionally adds growth data into the calculations. Calculation of the input variables is based on sound statistical methodologies and periodically collected data that cannot be altered. Thus a discontinuous trajectory of the emissions over time remains, even after the adjustments. It is intended to adopt this approach in the German greenhouse gas reporting in order to meet the request for annually adjusted values.

  17. Estimating parameters of a forest ecosystem C model with measurements of stocks and fluxes as joint constraints

    Science.gov (United States)

    Andrew D. Richardson; Mathew Williams; David Y. Hollinger; David J.P. Moore; D. Bryan Dail; Eric A. Davidson; Neal A. Scott; Robert S. Evans; Holly. Hughes

    2010-01-01

    We conducted an inverse modeling analysis, using a variety of data streams (tower-based eddy covariance measurements of net ecosystem exchange, NEE, of CO2, chamber-based measurements of soil respiration, and ancillary ecological measurements of leaf area index, litterfall, and woody biomass increment) to estimate parameters and initial carbon (C...

  18. Reducing uncertainty for estimating forest carbon stocks and dynamics using integrated remote sensing, forest inventory and process-based modeling

    Science.gov (United States)

    Poulter, B.; Ciais, P.; Joetzjer, E.; Maignan, F.; Luyssaert, S.; Barichivich, J.

    2015-12-01

    Accurately estimating forest biomass and forest carbon dynamics requires new integrated remote sensing, forest inventory, and carbon cycle modeling approaches. Presently, there is an increasing and urgent need to reduce forest biomass uncertainty in order to meet the requirements of carbon mitigation treaties, such as Reducing Emissions from Deforestation and forest Degradation (REDD+). Here we describe a new parameterization and assimilation methodology used to estimate tropical forest biomass using the ORCHIDEE-CAN dynamic global vegetation model. ORCHIDEE-CAN simulates carbon uptake and allocation to individual trees using a mechanistic representation of photosynthesis, respiration and other first-order processes. The model is first parameterized using forest inventory data to constrain background mortality rates, i.e., self-thinning, and productivity. Satellite remote sensing data for forest structure, i.e., canopy height, is used to constrain simulated forest stand conditions using a look-up table approach to match canopy height distributions. The resulting forest biomass estimates are provided for spatial grids that match REDD+ project boundaries and aim to provide carbon estimates for the criteria described in the IPCC Good Practice Guidelines Tier 3 category. With the increasing availability of forest structure variables derived from high-resolution LIDAR, RADAR, and optical imagery, new methodologies and applications with process-based carbon cycle models are becoming more readily available to inform land management.

  19. Locomotion during digestion changes current estimates of seed dispersal kernels by fish

    NARCIS (Netherlands)

    Leeuwen, van C.H.A.; Beukeboom, R.; Nolet, B.A.; Bakker, E.S.; Pollux, B.J.A.

    2016-01-01

    1.Dispersal of seeds by animals is an important mechanism regulating plant diversity, range expansions and invasions. Many birds, mammals, fish and reptiles regularly ingest, transport and excrete viable seeds (known as endozoochory). 2.The effectiveness of endozoochory is modelled in dispersal

  20. Estimating agro-ecosystem carbon balance of northern Japan, and comparing the change in carbon stock by soil inventory and net biome productivity

    International Nuclear Information System (INIS)

    Li, Xi; Toma, Yo; Yeluripati, Jagadeesh; Iwasaki, Shinya; Bellingrath-Kimura, Sonoko D.; Jones, Edward O.; Hatano, Ryusuke

    2016-01-01

    Soil C sequestration in croplands is deemed to be one of the most promising greenhouse gas mitigation options for agriculture. We have used crop-level yields, modeled heterotrophic respiration (Rh) and land use data to estimate spatio-temporal changes in regional scale net primary productivity (NPP), plant C inputs, and net biome productivity (NBP) in northern Japan's arable croplands and grasslands for the period of 1959–2011. We compared the changes in C stocks derived from estimated NBP and using repeated inventory datasets for each individual land use type from 2005 to 2011. For the entire study region of 2193 ha, overall annual plant C inputs to the soil constituted 37% of total region NPP. Plant C inputs in upland areas (excluding bush/fallow) could be predicted by climate variables. Overall NBP for all land use types increased from − 1.26 Mg C ha"−"1 yr"−"1 in 1959–0.26 Mg C ha"−"1 yr"−"1 in 2011. However, upland and paddy fields showed a decreased in NBP over the period of 1959–2011, under the current C input scenario. From 1988, an increase in agricultural abandonment (bush/fallow) and grassland cover caused a slow increase in the regional C pools. The comparison of carbon budgets using the NBP estimation method and the soil inventory method indicated no significant difference between the two methods. Our results showed C loss in upland crops, paddy fields and sites that underwent land use change from paddy field to upland sites. We also show C gain in grassland from 2005 to 2011. An underestimation of NBP or an overestimation of repeated C inventories cannot be excluded, but either method may be suitable for tracking absolute changes in soil C, considering the uncertainty associated with these methods. - Highlights: • We compared C stocks change by two methods: (i) net biome productivity (NBP) and (ii) soil inventory. • Variation in net primary productivity (NPP), plant C input, NBP can be predicted by climate conditions. • NBP

  1. Estimating agro-ecosystem carbon balance of northern Japan, and comparing the change in carbon stock by soil inventory and net biome productivity

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xi, E-mail: icy124@hotmail.com [School of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu 610500 (China); Graduate school of Agriculture, Hokkaido University, Kita 9 Nishi 9, Kita-ku, Sapporo 060-8589 (Japan); Toma, Yo [Faculty of Agriculture, Ehime University, 3-5-7, Tarumi, Matsuyama 790-8566, Ehime (Japan); Yeluripati, Jagadeesh [The James Hutton Institute, Craigiebuckler, Aberdeen AB15 8QH, Scotland (United Kingdom); Iwasaki, Shinya [Graduate school of Agriculture, Hokkaido University, Kita 9 Nishi 9, Kita-ku, Sapporo 060-8589 (Japan); Bellingrath-Kimura, Sonoko D. [Leibniz Centre for Agricultural Landscape Research, Institute of Land Use Systems (Germany); Jones, Edward O. [Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, London (United Kingdom); Hatano, Ryusuke [Graduate school of Agriculture, Hokkaido University, Kita 9 Nishi 9, Kita-ku, Sapporo 060-8589 (Japan)

    2016-06-01

    Soil C sequestration in croplands is deemed to be one of the most promising greenhouse gas mitigation options for agriculture. We have used crop-level yields, modeled heterotrophic respiration (Rh) and land use data to estimate spatio-temporal changes in regional scale net primary productivity (NPP), plant C inputs, and net biome productivity (NBP) in northern Japan's arable croplands and grasslands for the period of 1959–2011. We compared the changes in C stocks derived from estimated NBP and using repeated inventory datasets for each individual land use type from 2005 to 2011. For the entire study region of 2193 ha, overall annual plant C inputs to the soil constituted 37% of total region NPP. Plant C inputs in upland areas (excluding bush/fallow) could be predicted by climate variables. Overall NBP for all land use types increased from − 1.26 Mg C ha{sup −1} yr{sup −1} in 1959–0.26 Mg C ha{sup −1} yr{sup −1} in 2011. However, upland and paddy fields showed a decreased in NBP over the period of 1959–2011, under the current C input scenario. From 1988, an increase in agricultural abandonment (bush/fallow) and grassland cover caused a slow increase in the regional C pools. The comparison of carbon budgets using the NBP estimation method and the soil inventory method indicated no significant difference between the two methods. Our results showed C loss in upland crops, paddy fields and sites that underwent land use change from paddy field to upland sites. We also show C gain in grassland from 2005 to 2011. An underestimation of NBP or an overestimation of repeated C inventories cannot be excluded, but either method may be suitable for tracking absolute changes in soil C, considering the uncertainty associated with these methods. - Highlights: • We compared C stocks change by two methods: (i) net biome productivity (NBP) and (ii) soil inventory. • Variation in net primary productivity (NPP), plant C input, NBP can be predicted by climate

  2. Dredging of blue mussels ( Mytilus edulis L.) in a Danish sound: stock sizes and fishery-effects on mussel population dynamic

    DEFF Research Database (Denmark)

    Dolmer, Per; Kristensen, Per Sand; Hoffmann, Erik

    1999-01-01

    In April 1993, 1994 and 1995 the abundance of blue mussels, Mytilus edulis L., was estimated in Limfjorden, Denmark. The stocks were assessed by using a down-scaled model of a commercial mussel dredge which efficiency was analysed by comparing its samples with others collected by diver. The mean...... dredge efficiency was 17%. The fishing area in Limfjorden (700 km(2)) is divided into 22 fishery zones and mussel stock size was calculated for each zone. From April 1993 to April 1994 the total stock size declined from 771 000 to 616 000 t. In the same period, the exploitation rate in the fishery was 14...

  3. Effects of fish removal in the Furnas Lake, Azores

    Directory of Open Access Journals (Sweden)

    Bio, A.

    2008-01-01

    Full Text Available The Furnas Lake is a small volcanic, monomitic and increasingly eutrophised water body. Next to agricultural nutrient inputs, high densities of herbivorous fish are thought to contribute to high levels of turbidity in the lake, through zooplankton consumption and re suspension of the nutrients accumulated in the sediment. According to the alternative state hypothesis a shift from turbid to clear water conditions is favoured by reduction of nutrient concentrations, increased light availability and reduction of planktivorous and benthos-feeding fish stock. To improve water quality in the Furnas Lake, a substantial part of the bottom-feeding fish population (62% of the estimated common carp population, Cyprinus carpio, and 5% of the estimated roach population, Rutilus rutilus was removed. Effects of fish removal on turbidity and associated trophic state were analysed next to post-manipulation chlorophyll a concentration, zooplankton and macrophytes densities. Results suggest that fish removal was not enough to change lake conditions towards a lasting clear state dominated by macrophytes. Excessive nutrient load, in water and sediments, nutrient input from the lake basin and fish recruitment causing enhanced zooplankton grazing are appointed causes. Any further biomanipulation efforts should be associated to nutrient reduction; and continued monitoring of water quality, fish stock, macrophytes and zooplankton is needed.

  4. Concentration dependence of biotransformation in fish liver S9: Optimizing substrate concentrations to estimate hepatic clearance for bioaccumulation assessment.

    Science.gov (United States)

    Lo, Justin C; Allard, Gayatri N; Otton, S Victoria; Campbell, David A; Gobas, Frank A P C

    2015-12-01

    In vitro bioassays to estimate biotransformation rate constants of contaminants in fish are currently being investigated to improve bioaccumulation assessments of hydrophobic contaminants. The present study investigates the relationship between chemical substrate concentration and in vitro biotransformation rate of 4 environmental contaminants (9-methylanthracene, pyrene, chrysene, and benzo[a]pyrene) in rainbow trout (Oncorhynchus mykiss) liver S9 fractions and methods to determine maximum first-order biotransformation rate constants. Substrate depletion experiments using a series of initial substrate concentrations showed that in vitro biotransformation rates exhibit strong concentration dependence, consistent with a Michaelis-Menten kinetic model. The results indicate that depletion rate constants measured at initial substrate concentrations of 1 μM (a current convention) could underestimate the in vitro biotransformation potential and may cause bioconcentration factors to be overestimated if in vitro biotransformation rates are used to assess bioconcentration factors in fish. Depletion rate constants measured using thin-film sorbent dosing experiments were not statistically different from the maximum depletion rate constants derived using a series of solvent delivery-based depletion experiments for 3 of the 4 test chemicals. Multiple solvent delivery-based depletion experiments at a range of initial concentrations are recommended for determining the concentration dependence of in vitro biotransformation rates in fish liver fractions, whereas a single sorbent phase dosing experiment may be able to provide reasonable approximations of maximum depletion rates of very hydrophobic substances. © 2015 SETAC.

  5. State of the Irish housing stock—Modelling the heat losses of Ireland's existing detached rural housing stock and estimating the benefit of thermal retrofit measures on this stock

    International Nuclear Information System (INIS)

    Ahern, Ciara; Griffiths, Philip; O'Flaherty, Micheál

    2013-01-01

    Ireland's housing stock has been identified as being amongst the least energy efficient in Northern Europe. Consequently, atmospheric emissions are greater than necessary. Government funded schemes have been introduced to incentivise the uptake of thermal retrofit measures in the domestic Irish market. A study of Ireland's housing highlights the dominance of detached houses (43%), 72% of which are rurally located and are predominantly heated with fuel oil. This paper investigates the economic and carbon case for thermal retrofit measures to the existing detached, oil centrally heated, rural housing stock. The study found the case for energy efficiency measures to be categorical and supports the Irish Government's focus on energy efficiency policy measures. Thermal retrofit measures in the detached housing stock have the potential to realise an averaged 65% theoretical reduction in heating costs and CO 2 emissions for houses constructed prior to 1979 (coinciding with the introduction of building regulations) and around 26% for newer homes, thus offering a significant contribution (44%) to Ireland's residential carbon abatement projections and hence in meeting the EU's directives on energy and carbon. The greatest savings (36%) of Ireland's carbon abatement projections result from improving the energy efficiency of the pre 1979 stock. - Highlights: ► Model constructs base geometry of detached rural Irish dwellings by age band. ► Model quantifies savings to this stock via The National Insulation Scheme. ► Results offer significant contribution to Ireland's carbon abatement projections. ► Greatest savings result from retrofitting the pre 1979 stock. ► Government needs to introduce PAYS scheme or similar to engage public at large

  6. Soil organic carbon stocks under native vegetation - revised estimates for use with the simple assessment option of the Carbon Benefits Project system

    NARCIS (Netherlands)

    Batjes, N.H.

    2011-01-01

    The Carbon Benefits Project (CBP) is developing a standardized system for sustainable land management projects to measure, model and report changes in carbon stocks and greenhouse gas (GHG) emissions for use at varying scales. A global framework of soil organic carbon (SOC) stocks under native

  7. Estimation of carbon stock in the natural regeneration of Pinus durangensis Martínez in El Salto, Durango

    Directory of Open Access Journals (Sweden)

    Eduardo Montes de Oca-Cano

    2012-12-01

    Full Text Available The aim of the present study was to adjust linear and non-linear equations in order to estimate the carbon component of leaves, branches and entire trees. The results indicate that at the individual level, the total component shows the best adjustment statistics, while major variation is detected in the branches and in the trunk. In addition an analysis of the percentages of biomass in each component indicates that the trunk accounts for 46.9 % of the biomass, leaves 35.6 % and the branches only 17.3 %. Trunk biomass increases annually by 2.96 %, leaf biomass decreases by 3.13 % and branch biomass increases by 0.17 %.

  8. Estimating agro-ecosystem carbon balance of northern Japan, and comparing the change in carbon stock by soil inventory and net biome productivity.

    Science.gov (United States)

    Li, Xi; Toma, Yo; Yeluripati, Jagadeesh; Iwasaki, Shinya; Bellingrath-Kimura, Sonoko D; Jones, Edward O; Hatano, Ryusuke

    2016-06-01

    Soil C sequestration in croplands is deemed to be one of the most promising greenhouse gas mitigation options for agriculture. We have used crop-level yields, modeled heterotrophic respiration (Rh) and land use data to estimate spatio-temporal changes in regional scale net primary productivity (NPP), plant C inputs, and net biome productivity (NBP) in northern Japan's arable croplands and grasslands for the period of 1959-2011. We compared the changes in C stocks derived from estimated NBP and using repeated inventory datasets for each individual land use type from 2005 to 2011. For the entire study region of 2193 ha, overall annual plant C inputs to the soil constituted 37% of total region NPP. Plant C inputs in upland areas (excluding bush/fallow) could be predicted by climate variables. Overall NBP for all land use types increased from -1.26MgCha(-1)yr(-1) in 1959-0.26 Mg Cha(-1)yr(-1) in 2011. However, upland and paddy fields showed a decreased in NBP over the period of 1959-2011, under the current C input scenario. From 1988, an increase in agricultural abandonment (bush/fallow) and grassland cover caused a slow increase in the regional C pools. The comparison of carbon budgets using the NBP estimation method and the soil inventory method indicated no significant difference between the two methods. Our results showed C loss in upland crops, paddy fields and sites that underwent land use change from paddy field to upland sites. We also show C gain in grassland from 2005 to 2011. An underestimation of NBP or an overestimation of repeated C inventories cannot be excluded, but either method may be suitable for tracking absolute changes in soil C, considering the uncertainty associated with these methods. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Price Earnings Ratio and Stock Return Analysis (Evidence from Liquidity 45 Stocks Listed in Indonesia Stock Exchange

    Directory of Open Access Journals (Sweden)

    Liem Pei Fun

    2012-01-01

    Full Text Available Price to Earnings Ratio (PE Ratio has been broadly used by analysts and investors for stock selection. Stocks with low PE ratio are perceived as having cheaper current price hence expected to generate higher return in subsequent period. This paper aims to examine predictability of stock return using PE Ratio based on historical relationship between PE Ratio and subsequent stock return. Particularly, it seeks to find whether stocks with high PE Ratio followed by low stocks return and on the contrary, stocks with low PE Ratio followed by high stocks return. Using stocks which are included as member of Liquidity 45 and observation period 2005-2010 as samples, results show that there is significance difference between low PE and high PE portfolio stock return in short term (holding period of 6 months but there is no significance difference between both portfolio stock return if they are hold for one, two, three, and four years. This research also finds that there is no significant relationship between stock return and (trailing PE Ratio which suggests that (trailing PE Ratio is not useful in estimating both short term and long term stock returns

  10. Kokanee Stocking and Monitoring, Flathead Lake, 1993-1994 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Deleray, Mark (Montana Department of Fish, Wildlife and Parks, Kalispell, MT); Fredenberg, Wade (US Fish and Wildlife Service, Bozeman, MT); Hansen, Barry (Confederated Salish and Kootenai Tribes of the Flathead Nation, Pablo, MT)

    1995-07-01

    temperatures, an upsurge in the abundance of Duphniu rhorum, and saturation planting in an area believed to have lower lake trout densities was expected to maximize short-term survival of stocked kokanee. A net-pen experiment demonstrated that yearling hatchery kokanee, in the absence of predation, adjusted to conditions in Flathead Lake and utilized available zooplankton during June and July without substantial poststocking mortality. Kokanee captured after several months in the lake exhibited good growth and condition. We concluded that the food supply in Big Arm Bay was not limiting survival of stocked kokanee. The 1994 monitoring objective was to quantify lake trout predation of kokanee in Big Arm Bay in the first eight weeks following stocking. There were three components needed to quantify predation; estimated number of lake trout in Big Arm Bay, average number of kokanee consumed by lake trout, and estimated time required for lake trout to digest kokanee. As in the previous year, the monitoring results from the 1994 kokanee plant demonstrated that lake trout predation is the primary factor reducing survival of stocked kokanee. We estimated that lake trout consumed a minimum of 232,000 kokanee in Big Arm Bay during the first eight weeks following stocking. This represents 29 percent of kokanee planted. The consumption estimate was based on a hydroacoustic estimate for lake trout abundance (7,850 fish over 300 mm in total length), an incidence of kokanee per lake trout stomach sample which ranged from 2.99 to 0.22 fish, and a gastric evacuation rate of 47 hours for lake trout to digest consumed kokanee. Due to hydroacoustic limitations in identifying bottom-oriented lake trout, we underestimated the true abundance of lake trout, which led to an underestimate of kokanee mortality. By fall of 1994, we estimated that an additional 12.7 percent of surviving kokanee matured, based on observations of similar-sized fish in the hatchery. Thus, up to 72,000 additional fish were

  11. An Estimation of the Potential Utilization in Iranian Pharmaceutical Industry Involved in the Stock Exchange, 2008-2012

    Science.gov (United States)

    Annabi, Majid; Kebriaeezadeh, Abbas; Mohammadi, Timor; Marashi Shoshtari, Seyed Nasrolah; Abedin Dorkoosh, Farid; Pourreza, Abolghasem; Heydari, Hassan

    2017-01-01

    The aim of this study was to measure the potential of production and the capacity used in the pharmaceutical industry. Capacity use is the actual production rate to the potential output, which reflects the gap between actual production and production capacity. Through econometric methods, translog cost function in the short run along with functions of share cost of production factors is estimated through seemingly unrelated repeated regression (SURE) as a multivariate regression analysis provided by zeller. During the study the capacity used is decreasing. The capacity used, which calculated by weighted average, also decreased and the amount during the study period is much less than the simple average of the industry. Average capacity utilization in the industry over five years of study is equal to 57% while the average capacity used calculated by the weighted of industry average is 37%. To enhance the economic potential requires a proper use of resources, creation of favorable economic structure and productivity of the industry. Due to the large amount of unused capacity in the pharmaceutical industry there is no need to invest anymore unless in new grounds and it is obvious that more investment will change using capacity. PMID:29552074

  12. An Estimation of the Potential Utilization in Iranian Pharmaceutical Industry Involved in the Stock Exchange, 2008-2012.

    Science.gov (United States)

    Annabi, Majid; Kebriaeezadeh, Abbas; Mohammadi, Timor; Marashi Shoshtari, Seyed Nasrolah; Abedin Dorkoosh, Farid; Pourreza, Abolghasem; Heydari, Hassan

    2017-01-01

    The aim of this study was to measure the potential of production and the capacity used in the pharmaceutical industry. Capacity use is the actual production rate to the potential output, which reflects the gap between actual production and production capacity . Through econometric methods, translog cost function in the short run along with functions of share cost of production factors is estimated through seemingly unrelated repeated regression (SURE) as a multivariate regression analysis provided by zeller. During the study the capacity used is decreasing. The capacity used, which calculated by weighted average, also decreased and the amount during the study period is much less than the simple average of the industry. Average capacity utilization in the industry over five years of study is equal to 57% while the average capacity used calculated by the weighted of industry average is 37%. To enhance the economic potential requires a proper use of resources, creation of favorable economic structure and productivity of the industry. Due to the large amount of unused capacity in the pharmaceutical industry there is no need to invest anymore unless in new grounds and it is obvious that more investment will change using capacity.

  13. Large Differences in Global and Regional Total Soil Carbon Stock Estimates Based on SoilGrids, HWSD, and NCSCD: Intercomparison and Evaluation Based on Field Data From USA, England, Wales, and France

    Science.gov (United States)

    Tifafi, Marwa; Guenet, Bertrand; Hatté, Christine

    2018-01-01

    Soils are the major component of the terrestrial ecosystem and the largest organic carbon reservoir on Earth. However, they are a nonrenewable natural resource and especially reactive to human disturbance and climate change. Despite its importance, soil carbon dynamics is an important source of uncertainty for future climate predictions and there is a growing need for more precise information to better understand the mechanisms controlling soil carbon dynamics and better constrain Earth system models. The aim of our work is to compare soil organic carbon stocks given by different global and regional databases that already exist. We calculated global and regional soil carbon stocks at 1 m depth given by three existing databases (SoilGrids, the Harmonized World Soil Database, and the Northern Circumpolar Soil Carbon Database). We observed that total stocks predicted by each product differ greatly: it is estimated to be around 3,400 Pg by SoilGrids and is about 2,500 Pg according to Harmonized World Soil Database. This difference is marked in particular for boreal regions where differences can be related to high disparities in soil organic carbon concentration. Differences in other regions are more limited and may be related to differences in bulk density estimates. Finally, evaluation of the three data sets versus ground truth data shows that (i) there is a significant difference in spatial patterns between ground truth data and compared data sets and that (ii) data sets underestimate by more than 40% the soil organic carbon stock compared to field data.

  14. Long Memory in the Greek Stock Market

    OpenAIRE

    John T. Barkoulas; Christopher F. Baum; Nickolaos Travlos

    1996-01-01

    We test for stochastic long memory in the Greek stock market, an emerging capital market. The fractional differencing parameter is estimated using the spectral regression method. Contrary to findings for major capital markets, significant and robust evidence of positive long-term persistence is found in the Greek stock market. As compared to benchmark linear models, the estimated fractional models provide improved out-of-sample forecasting accuracy for the Greek stock returns series over long...

  15. Beyond biodiversity: fish metagenomes.

    Directory of Open Access Journals (Sweden)

    Alba Ardura

    Full Text Available Biodiversity and intra-specific genetic diversity are interrelated and determine the potential of a community to survive and evolve. Both are considered together in Prokaryote communities treated as metagenomes or ensembles of functional variants beyond species limits.Many factors alter biodiversity in higher Eukaryote communities, and human exploitation can be one of the most important for some groups of plants and animals. For example, fisheries can modify both biodiversity and genetic diversity (intra specific. Intra-specific diversity can be drastically altered by overfishing. Intense fishing pressure on one stock may imply extinction of some genetic variants and subsequent loss of intra-specific diversity. The objective of this study was to apply a metagenome approach to fish communities and explore its value for rapid evaluation of biodiversity and genetic diversity at community level. Here we have applied the metagenome approach employing the barcoding target gene coi as a model sequence in catch from four very different fish assemblages exploited by fisheries: freshwater communities from the Amazon River and northern Spanish rivers, and marine communities from the Cantabric and Mediterranean seas.Treating all sequences obtained from each regional catch as a biological unit (exploited community we found that metagenomic diversity indices of the Amazonian catch sample here examined were lower than expected. Reduced diversity could be explained, at least partially, by overexploitation of the fish community that had been independently estimated by other methods.We propose using a metagenome approach for estimating diversity in Eukaryote communities and early evaluating genetic variation losses at multi-species level.

  16. Beyond biodiversity: fish metagenomes.

    Science.gov (United States)

    Ardura, Alba; Planes, Serge; Garcia-Vazquez, Eva

    2011-01-01

    Biodiversity and intra-specific genetic diversity are interrelated and determine the potential of a community to survive and evolve. Both are considered together in Prokaryote communities treated as metagenomes or ensembles of functional variants beyond species limits.Many factors alter biodiversity in higher Eukaryote communities, and human exploitation can be one of the most important for some groups of plants and animals. For example, fisheries can modify both biodiversity and genetic diversity (intra specific). Intra-specific diversity can be drastically altered by overfishing. Intense fishing pressure on one stock may imply extinction of some genetic variants and subsequent loss of intra-specific diversity. The objective of this study was to apply a metagenome approach to fish communities and explore its value for rapid evaluation of biodiversity and genetic diversity at community level. Here we have applied the metagenome approach employing the barcoding target gene coi as a model sequence in catch from four very different fish assemblages exploited by fisheries: freshwater communities from the Amazon River and northern Spanish rivers, and marine communities from the Cantabric and Mediterranean seas.Treating all sequences obtained from each regional catch as a biological unit (exploited community) we found that metagenomic diversity indices of the Amazonian catch sample here examined were lower than expected. Reduced diversity could be explained, at least partially, by overexploitation of the fish community that had been independently estimated by other methods.We propose using a metagenome approach for estimating diversity in Eukaryote communities and early evaluating genetic variation losses at multi-species level.

  17. Otter ( Lutra lutra ) predation on stocked brown trout ( Salmo trutta ) in two Danish lowland rivers

    DEFF Research Database (Denmark)

    Jacobsen, Lene

    2005-01-01

    This study aimed to evaluate otter predation on stocked trout. Large hatchery-reared trout (16-30 cm) were stocked into two Danish rivers with different fish populations. Otter diet before and after trout stocking was determined by analysing 685 spraints, collected regularly during the 35-day study...... period. Fish composition in the rivers before stocking was assessed by electrofishing. In River Trend, a typical trout river, the proportion of trout in the otter diet increased from 8% before stocking to 33% a few days after stocking. Moreover, trout lengths in the diet changed significantly towards...... the lengths of stocked trout, indicating that newly stocked trout were preferred to wild trout. In River Skals, dominated by cyprinids, there was no change in otter diet after stocking of hatchery trout, i.e., these were ignored by otter. Otter predation should be taken into account together with fish...

  18. Parental genetic diversity of brown trout (Salmo trutta m. fario) brood stock affects offspring susceptibility to whirling disease.

    Science.gov (United States)

    Eszterbauer, Edit; Forró, Barbara; Tolnai, Zoltán; Guti, Csaba Ferenc; Zsigmond, Gergely; Hoitsy, György; Kallert, Dennis Marc

    2015-03-03

    Whirling disease, caused by the myxozoan parasite Myxobolus cerebralis, has high economical and ecological importance worldwide. Susceptibility to the disease varies considerably among salmonid species. In brown trout (Salmo trutta) the infection is usually subclinical with low mortality, which increases the risk of parasite dissemination, especially when farm fish are used for stocking natural habitats. The influence of intraspecific genetic differences (especially the level of homozygosity) on susceptibility is unknown. Therefore, we examined the possible correlations between parental genetic diversity and offspring susceptibility of brown trout stocks to whirling disease. Two brown trout brood stocks from a German and a Hungarian fish farm were genetically characterized using microsatellite and lineage-specific genetic markers. The individual inbreeding coefficient f and pairwise relatedness factor r were estimated based on eight microsatellite markers. Brood stock populations were divided into groups according to low and high f and r value estimates and subjected to selective fertilization. The offspring from these separate groups were exposed to M. cerebralis actinospores, and the infection prevalence and intensity was measured and statistically analysed. The analysis of phylogeographic lineage heritage revealed high heterogeneity in the Hungarian brood stock since > 50% of individuals were Atlantic-Danubian hybrids, while only pure Atlantic-descending specimens were detected in the German population. Based on f msat and r msat estimations, classified non-inbred (NIB), inbred (IB) and a group of closely related fish (REL) were created. The susceptibility of their offspring varied considerably. Although there was no significant difference in the prevalence of M. cerebralis infection, the mean intensity of infection differed significantly between NIB and IB groups. In REL and IB groups, a high variability was observed in infection intensity. No external

  19. The dependence of Islamic and conventional stocks: A copula approach

    Science.gov (United States)

    Razak, Ruzanna Ab; Ismail, Noriszura

    2015-09-01

    Recent studies have found that Islamic stocks are dependent on conventional stocks and they appear to be more risky. In Asia, particularly in Islamic countries, research on dependence involving Islamic and non-Islamic stock markets is limited. The objective of this study is to investigate the dependence between financial times stock exchange Hijrah Shariah index and conventional stocks (EMAS and KLCI indices). Using the copula approach and a time series model for each marginal distribution function, the copula parameters were estimated. The Elliptical copula was selected to present the dependence structure of each pairing of the Islamic stock and conventional stock. Specifically, the Islamic versus conventional stocks (Shariah-EMAS and Shariah-KLCI) had lower dependence compared to conventional versus conventional stocks (EMAS-KLCI). These findings suggest that the occurrence of shocks in a conventional stock will not have strong impact on the Islamic stock.

  20. Growth and contribution of stocked channel catfish, Ictalurus punctatus (Rafinesque, 1818): the importance of measuring post-stocking performance

    Science.gov (United States)

    Stewart, David R.; Long, James M.

    2015-01-01

    In this study it was sought to quantify post-stocking growth, survival, and contribution of advanced size (178 mm total length [TL]) channel catfish Ictalurus punctatus fingerlings, something rarely done. Channel catfish populations were evaluated before (May 2010) and after (May to August 2011 and 2012) stocking. Relative abundance, stocking contribution, and growth were different (P stocked in Lake Lone Chimney, stocking contribution was lower (3–35%), and average length and weight of stocked fish by age-2 reached 230 mm TL and 85 g, whereas the stocking contribution (84–98%) and growth in length (340 mm TL) and weight (280 g) were higher by age-2 in Lake Greenleaf. Given these unambiguous differences of post-stocking performance, benchmark metrics that represent population-level information such as relative abundance and average length and weight of the sample masked these significant differences, highlighting the importance of marking hatchery-fish and then following them through time to determine the effectiveness of stocking. These results suggest that stock enhancement programmes would benefit from studies that quantify post-stocking performance of hatchery fish.

  1. Brown trout ( Salmo trutta ) stocking impact assessment using microsatellite DNA markers

    DEFF Research Database (Denmark)

    Hansen, Michael Møller; Ruzzante, D.E.; Eg Nielsen, Einar

    2001-01-01

    , and for monitoring the genetic impact of stocking activity on wild populations of salmonid fishes. Brown trout from ten hatchery strains, one supportive breeding "strain," and five wild populations were screened for variation at eight loci. In most hatchery strains, genetic variation was comparable to that of wild...... between the wild and hatchery populations. We assessed whether wild populations were introgressed by stocked hatchery trout by performing assignment tests to determine population of origin and estimating maximum potential introgression rates. The results suggested that genetic introgression by hatchery...... trout had occurred for only two of the five populations potentially influenced by stocking. In one of these two rivers, microsatellite data obtained from a limited number of old scale samples indicated that individuals from the original population were genetically divergent from these of the present...

  2. Optimum sample length for estimating anchovy size distribution and the proportion of juveniles per fishing set for the Peruvian purse-seine fleet

    Directory of Open Access Journals (Sweden)

    Rocío Joo

    2017-04-01

    Full Text Available The length distribution of catches represents a fundamental source of information for estimating growth and spatio-temporal dynamics of cohorts. The length distribution of caught is estimated based on samples of catched individuals. This work studies the optimum sample size of individuals at each fishing set in order to obtain a representative sample of the length and the proportion of juveniles in the fishing set. For that matter, we use anchovy (Engraulis ringens length data from different fishing sets recorded by observers at-sea from the On-board Observers Program from the Peruvian Marine Research Institute. Finally, we propose an optimum sample size for obtaining robust size and juvenile estimations. Though the application of this work corresponds to the anchovy fishery, the procedure can be applied to any fishery, either for on board or inland biometric measurements.

  3. Variation in angler distribution and catch rates of stocked rainbow trout in a small reservoir

    Science.gov (United States)

    Harmon, Brian S.; Martin, Dustin R.; Chizinski, Christopher J.; Pope, Kevin L.

    2018-01-01

    We investigated the spatial and temporal relationship of catch rates and angler party location for two days following a publicly announced put-and-take stocking of rainbow trout (Oncorhynchus mykiss). Catch rates declined with time since stocking and distance from stocking. We hypothesized that opportunity for high catch rates would cause anglers to fish near the stocking location and disperse with time, however distance between angler parties and stocking was highly variable at any given time. Spatially explicit differences in catch rates can affect fishing quality. Further research could investigate the variation between angler distribution and fish distribution within a waterbody.

  4. North Sea Scyphomedusae; summer distribution, estimated biomass and significance particularly for 0-group Gadoid fish

    Science.gov (United States)

    Hay, S. J.; Hislop, J. R. G.; Shanks, A. M.

    Data on the by-catch of Scyphomedusae from pelagic trawls was collected during the routine ICES International 0-group Gadoid Surveys of the North Sea, in June and July of the years 1971-1986 (except 1984). These data are used to describe the distributions, abundances and biomasses of three common North Sea Scyphomedusae: Aurelia aurita (L.), Cyanea capillata (L.) and C. lamarckii (Péron & Lesuer). Information is also presented on inter-annual variability, size (umbrella diameter) frequencies and, for the Cyanea species, umbrella diameter: wet weight relationships. The general role and ecological significance of Scyphomedusae is discussed and, given the well known 'shelter' relationships between Scyphomedusae and certain 0-group fish, whiting ( Merlangius merlangus) and haddock ( Melanogrammus aeglefinus), in particular. The data were examined for evidence of such relationships. Aurelia aurita, although fairly widespread in the northern North Sea was virtually absent from the central North Sea but very abundant in coastal waters. This species was particularly abundant off the Scottish east coast and especially in the Moray Firth. Cyanea lamerckii was most abundant in the southern and eastern North Sea. More widespread than Aurelia, this species was also most abundant in coastal regions, particularly off the Danish west coast. Cyanea capillata, with a more northern distribution was also more widely distributed and abundant offshore. This species was most abundant in the area between the Orkney/Shetland Isles and the Norwegian Deep and in shelf waters of the north west approaches to the North Sea. As with C. lamarckii it was also, in some years, abundant off the Scottish east coast and west of Denmark. The abundance and the size frequency of the jellyfish show considerable inter-annual variability, and variability between regions of the North Sea. It is considered that hydrographic variability and differences in food supply to both medusae and to their sessile

  5. Mapping Congo Basin vegetation types from 300 m and 1 km multi-sensor time series for carbon stocks and forest areas estimation

    Directory of Open Access Journals (Sweden)

    A. Verhegghen

    2012-12-01

    Full Text Available This study aims to contribute to the understanding of the Congo Basin forests by delivering a detailed map of vegetation types with an improved spatial discrimination and coherence for the whole Congo Basin region. A total of 20 land cover classes were described with the standardized Land Cover Classification System (LCCS developed by the FAO. Based on a semi-automatic processing chain, the Congo Basin vegetation types map was produced by combining 19 months of observations from the Envisat MERIS full resolution products (300 m and 8 yr of daily SPOT VEGETATION (VGT reflectances (1 km. Four zones (north, south and two central were delineated and processed separately according to their seasonal and cloud cover specificities. The discrimination between different vegetation types (e.g. forest and savannas was significantly improved thanks to the MERIS sharp spatial resolution. A better discrimination was achieved in cloudy areas by taking advantage of the temporal consistency of the SPOT VGT observations. This resulted in a precise delineation of the spatial extent of the rural complex in the countries situated along the Atlantic coast. Based on this new map, more accurate estimates of the surface areas of forest types were produced for each country of the Congo Basin. Carbon stocks of the Basin were evaluated to a total of 49 360 million metric tons. The regional scale of the map was an opportunity to investigate what could be an appropriate tree cover threshold for a forest class definition in the Congo Basin countries. A 30% tree cover threshold was suggested. Furthermore, the phenology of the different vegetation types was illustrated systematically with EVI temporal profiles. This Congo Basin forest types map reached a satisfactory overall accuracy of 71.5% and even 78.9% when some classes are aggregated. The values of the Cohen's kappa coefficient, respectively 0.64 and 0.76 indicates a result significantly better than random.

  6. Optimum sample size to estimate mean parasite abundance in fish parasite surveys

    Directory of Open Access Journals (Sweden)

    Shvydka S.

    2018-03-01

    Full Text Available To reach ethically and scientifically valid mean abundance values in parasitological and epidemiological studies this paper considers analytic and simulation approaches for sample size determination. The sample size estimation was carried out by applying mathematical formula with predetermined precision level and parameter of the negative binomial distribution estimated from the empirical data. A simulation approach to optimum sample size determination aimed at the estimation of true value of the mean abundance and its confidence interval (CI was based on the Bag of Little Bootstraps (BLB. The abundance of two species of monogenean parasites Ligophorus cephali and L. mediterraneus from Mugil cephalus across the Azov-Black Seas localities were subjected to the analysis. The dispersion pattern of both helminth species could be characterized as a highly aggregated distribution with the variance being substantially larger than the mean abundance. The holistic approach applied here offers a wide range of appropriate methods in searching for the optimum sample size and the understanding about the expected precision level of the mean. Given the superior performance of the BLB relative to formulae with its few assumptions, the bootstrap procedure is the preferred method. Two important assessments were performed in the present study: i based on CIs width a reasonable precision level for the mean abundance in parasitological surveys of Ligophorus spp. could be chosen between 0.8 and 0.5 with 1.6 and 1x mean of the CIs width, and ii the sample size equal 80 or more host individuals allows accurate and precise estimation of mean abundance. Meanwhile for the host sample size in range between 25 and 40 individuals, the median estimates showed minimal bias but the sampling distribution skewed to the low values; a sample size of 10 host individuals yielded to unreliable estimates.

  7. Fish assemblages

    Science.gov (United States)

    McGarvey, Daniel J.; Falke, Jeffrey A.; Li, Hiram W.; Li, Judith; Hauer, F. Richard; Lamberti, G.A.

    2017-01-01

    Methods to sample fishes in stream ecosystems and to analyze the raw data, focusing primarily on assemblage-level (all fish species combined) analyses, are presented in this chapter. We begin with guidance on sample site selection, permitting for fish collection, and information-gathering steps to be completed prior to conducting fieldwork. Basic sampling methods (visual surveying, electrofishing, and seining) are presented with specific instructions for estimating population sizes via visual, capture-recapture, and depletion surveys, in addition to new guidance on environmental DNA (eDNA) methods. Steps to process fish specimens in the field including the use of anesthesia and preservation of whole specimens or tissue samples (for genetic or stable isotope analysis) are also presented. Data analysis methods include characterization of size-structure within populations, estimation of species richness and diversity, and application of fish functional traits. We conclude with three advanced topics in assemblage-level analysis: multidimensional scaling (MDS), ecological networks, and loop analysis.

  8. COST-EFFECTIVE APPROACH TO ESTIMATE UNREPORTED DATA: REBUILDING HISTORY OF LIFT-NET FISHING IN KWANDANG WATERS

    Directory of Open Access Journals (Sweden)

    Andhika Prima Prasetyo

    2014-12-01

    Full Text Available This paper aims to develop cost-effective approach regarding the estimation unreported annual catch data of lift-net fishery using Google Earth imagery. Lift net fishery is one of the main fishing activities of coastal community in Kwandang Bay, it has been faced problem of uncertain fisheries status due to limited recorded data. Combination of a Monte Carlo procedure was applied by involving couple of assumptions on parameters such as estimate growth rate of the total number of lift-net per years (10%, day at sea per unit per month (21 days and operated lift-net per month (50% and 80%. The results showed that 101 units of lift-nets were found around Kwandang waters based on Google Earth imagery recorded in October, 7th 2010, and this were used as a benchmark of calculation. This prediction was 28 units higher than official data from North Gorontalo District of Marine Affairs and Fisheries Services (DKP Gorontalo Utara. Compared with capture fisheries statistics issued by Kwandang CFP, the estimated lift-net catches based on two-scenarios represent additional catches of 46 % and 86 %. These results suggested and could be used as a correction index to improve the reliability of Kwandang District officially reported fisheries statistics as a baseline to develop a local common fisheries policy.

  9. Kokanee Stock Status and Contribution of Cabinet Gorge Hatchery, Lake Pend Oreille, Idaho, 1990 Annual Progress Report.

    Energy Technology Data Exchange (ETDEWEB)

    Paragamian, Vaughn L.

    1991-03-01

    Rehabilitation of kokanee Oncorhynchus nerka in Lake Pend Oreille met with some success in 1990, but unexpected results have raised new questions. Estimated kokanee abundance during late August of 1990 was about 6.9 million fish. This is a decline of 19% from 1989, a continued decrease since 1988. The decreased population was attributed to low stocking of hatchery fry (7.3 million), lower wild fry survival in 1990 (1.5%), and exceptionally poor survival of fish ages 3+ and 4+. Average survival of the older fish was only 11% in 1990 compared to 72% in prior years. Compensatory survival was noted for kokanee ages 1+ and 2+, with an average of 81% in 1990 compared to 44% in 1989. Hatchery fry comprised 47% of the total kokanee fry recruitment in 1990 (80% of fry biomass). This contribution ranked third behind 1988 and 1989 since hatchery supplementation began in the 1970s. Survival of hatchery fry was 20%, the second highest since this investigation began. Findings of 1990 indicate a more comprehensive approach to managing kokanee must take into account predator stockings and predator/prey interaction. An unexpected low adult escapement was responsible for an egg-take of only 5.6 million eggs in 1990, 58% of the previous year, which will limit experimental stocking in 1991. Modification of the fish ladder at the Cabinet Gorge Fish Hatchery to improve adult escapement is strongly recommended to increase egg-take. 27 refs., 28 figs., 6 tabs.

  10. Mark Stock | NREL

    Science.gov (United States)

    Stock Mark Stock Scientific Visualization Specialist Mark.Stock@nrel.gov | 303-275-4174 Dr. Stock , virtual reality, parallel computing, and manipulation of large spatial data sets. As an artist, he creates . Stock built the SUNLIGHT artwork that is installed on the Webb Building in downtown Denver. In addition

  11. Valuation of common and preferred stocks

    Directory of Open Access Journals (Sweden)

    Nikolić Ljubica

    2014-01-01

    Full Text Available Buying stocks is a modern way of investing. The investors may place the available capital on the domestic and foreign stock market, they may buy more stocks of a single issuer or distribute money to purchase stocks of various public (stock-exchange companies, and they may form a portfolio of various securities. The investors' decisions on these options are based on their estimate on returns and risks underlying individual security instruments (securities. The two basic approaches to valuation of common stocks are: the Present Value Approach (method of valuating the capitalization of income and the P/E Ratio Approach (the method of valuating the multiple of per-share earnings. Instead of viewing these methods as competing alternatives, they should better be viewed as mutually complementary methods. Both methods are equally useful and their concurrent use may provide better grounds for the analysts' valuation of stocks.

  12. Estimation of feeding patterns for piscivorous fish using individual prey data from stomach contents

    DEFF Research Database (Denmark)

    Berg, Casper Willestofte; Temming, Axel

    2011-01-01

    The problem of estimating temporal feeding patterns using stomach data is considered, where the time of ingestion for each prey item can be predicted through a gastric evacuation model. The arrival of prey is modelled as a nonhomogeneous Poisson process with known periodic intensity. A maximum...

  13. Fish sampling with active methods

    Czech Academy of Sciences Publication Activity Database

    Kubečka, Jan; Godo, O. R.; Hickley, P.; Prchalová, Marie; Říha, Milan; Rudstam, L.; Welcomme, R.

    2012-01-01

    Roč. 123, July (2012), s. 1-3 ISSN 0165-7836 Institutional support: RVO:60077344 Keywords : fish stock assessment * active and passive gear * intercalibration Subject RIV: EH - Ecology, Behaviour Impact factor: 1.695, year: 2012

  14. Ocean Acidification Effects on Atlantic Cod Larval Survival and Recruitment to the Fished Population.

    Science.gov (United States)

    Stiasny, Martina H; Mittermayer, Felix H; Sswat, Michael; Voss, Rüdiger; Jutfelt, Fredrik; Chierici, Melissa; Puvanendran, Velmurugu; Mortensen, Atle; Reusch, Thorsten B H; Clemmesen, Catriona

    2016-01-01

    How fisheries will be impacted by climate change is far from understood. While some fish populations may be able to escape global warming via range shifts, they cannot escape ocean acidification (OA), an inevitable consequence of the dissolution of anthropogenic carbon dioxide (CO2) emissions in marine waters. How ocean acidification affects population dynamics of commercially important fish species is critical for adapting management practices of exploited fish populations. Ocean acidification has been shown to impair fish larvae's sensory abilities, affect the morphology of otoliths, cause tissue damage and cause behavioural changes. Here, we obtain first experimental mortality estimates for Atlantic cod larvae under OA and incorporate these effects into recruitment models. End-of-century levels of ocean acidification (~1100 μatm according to the IPCC RCP 8.5) resulted in a doubling of daily mortality rates compared to present-day CO2 concentrations during the first 25 days post hatching (dph), a critical phase for population recruitment. These results were consistent under different feeding regimes, stocking densities and in two cod populations (Western Baltic and Barents Sea stock). When mortality data were included into Ricker-type stock-recruitment models, recruitment was reduced to an average of 8 and 24% of current recruitment for the two populations, respectively. Our results highlight the importance of including vulnerable early life stages when addressing effects of climate change on fish stocks.

  15. Estimating Aboveground Forest Carbon Stock of Major Tropical Forest Land Uses Using Airborne Lidar and Field Measurement Data in Central Sumatra

    Science.gov (United States)

    Thapa, R. B.; Watanabe, M.; Motohka, T.; Shiraishi, T.; shimada, M.

    2013-12-01

    Tropical forests are providing environmental goods and services including carbon sequestration, energy regulation, water fluxes, wildlife habitats, fuel, and building materials. Despite the policy attention, the tropical forest reserve in Southeast Asian region is releasing vast amount of carbon to the atmosphere due to deforestation. Establishing quality forest statistics and documenting aboveground forest carbon stocks (AFCS) are emerging in the region. Airborne and satellite based large area monitoring methods are developed to compliment conventional plot based field measurement methods as they are costly, time consuming, and difficult to implement for large regions. But these methods still require adequate ground measurements for calibrating accurate AFCS model. Furthermore, tropical region comprised of varieties of natural and plantation forests capping higher variability of forest structures and biomass volumes. To address this issue and the needs for ground data, we propose the systematic collection of ground data integrated with airborne light detection and ranging (LiDAR) data. Airborne LiDAR enables accurate measures of vertical forest structure, including canopy height and volume demanding less ground measurement plots. Using an appropriate forest type based LiDAR sampling framework, structural properties of forest can be quantified and treated similar to ground measurement plots, producing locally relevant information to use independently with satellite data sources including synthetic aperture radar (SAR). In this study, we examined LiDAR derived forest parameters with field measured data and developed general and specific AFCS models for tropical forests in central Sumatra. The general model is fitted for all types of natural and plantation forests while the specific model is fitted to the specific forest type. The study region consists of natural forests including peat swamp and dry moist forests, regrowth, and mangrove and plantation forests

  16. Predicting the natural mortality of marine fish from life history characteristics

    DEFF Research Database (Denmark)

    Gislason, Henrik

    For fish much of the life history is determined by body size. Body size and asymptotic size significantly influences important life history processes such as growth, maturity, egg production, and natural mortality. Futhermore, for a population to persist, offspring must be able to replace...... their parents on a one-for-one basis in the long run. Otherwise the population would either increase exponentially or become extinct. Combining data on growth and specific fecundity in a size-based fish community model of the North Sea and using the requirement of a one-for-one replacement provides...... the information necessary to estimate the scaling of natural mortality with size and asymptotic size. The estimated scaling is compared with output from multispecies fish stock models, with the empirical scaling of the maximum number of recruits per unit of spawning stock biomass with body size...

  17. The zero inflation of standing dead tree carbon stocks

    Science.gov (United States)

    Christopher W. Woodall; David W. MacFarlane

    2012-01-01

    Given the importance of standing dead trees in numerous forest ecosystem attributes/processes such as carbon (C) stocks, the USDA Forest Service’s Forest Inventory and Analysis (FIA) program began consistent nationwide sampling of standing dead trees in 1999. Modeled estimates of standing dead tree C stocks are currently used as the official C stock estimates for the...

  18. Consumption of freshwater fish by recreational and native freshwater anglers in the upper St-Maurice (Quebec, Canada) and estimation of the intake of methylmercury in humans

    International Nuclear Information System (INIS)

    Loranger, S.; Houde, L.; Schetagne, R.

    1995-01-01

    Hydro-Quebec is planning to build two hydroelectric reservoirs in the upper Saint-Maurice River, which would flood about 80% of the surrounding area. The methylmercury (MeHg) content in freshwater fish will therefore tend to increase during the first few years. This development will have a direct impact on the amount of MeHg that the actual users of this river section are exposed to. The objective of this study is to assess the consumption of local fish of these target groups using a Monte-Carlo approach. This study is part of a larger research project aimed at assessing human exposure and the health risks related to MeHg contamination in local fish. The fish consumption rate for recreational freshwater anglers was calculated using the duration of the average annual fishing trip, the average number of catches per species, the average fish weight per species exceeding a specific length of fish usually caught, and the edible portion of fish consumed. This rate was calculated for the native communities based on the total number of meals per year per species, the average fish weight per species, and the edible portion. Based on these calculations, average intake for sport fishermen is estimated at 6.9 g/day (sd = 6.4). This value is 5 to 25 times lower on average than for other North American native communities. However, it must be pointed out that the food habits of the native population were very similar to those of non-native populations; less than 30% of the food comes from traditional sources

  19. Zooplankton mortality in 3D ecosystem modelling considering variable spatial–temporal fish consumptions in the North Sea

    DEFF Research Database (Denmark)

    Maar, Marie; Rindorf, Anna; Møller, Eva Friis

    2014-01-01

    We tested the feasibility of imposing mesozooplankton mortality into a 3D model based on estimated consumption rates of the dominant planktivorous fish in the North Sea-Kattegat area. The spatial biomass distribution of Atlantic herring (Clupea harengus), horse mackerel (Trachurus trachurus....... The fish larvae grazing pressure was obtained from a spatial, size-based larval community model. In this model, larvae, herring and sandeel were the most important fish predators on mesozooplankton, but these groups had different spatial and temporal (seasonal) distributions. Fish larvae were particularly......, production and mortality. In the present study, the index was kept relatively simple and can be further developed with respect to the description of fish as well carnivorous zooplankton ingestion rates. The data input required to create the fish index is i) planktivorous fish stock biomasses and ii) relative...

  20. Simulation testing the robustness of stock assessment models to error: some results from the ICES strategic initiative on stock assessment methods

    DEFF Research Database (Denmark)

    Deroba, J. J.; Butterworth, D. S.; Methot, R. D.

    2015-01-01

    The World Conference on Stock Assessment Methods (July 2013) included a workshop on testing assessment methods through simulations. The exercise was made up of two steps applied to datasets from 14 representative fish stocks from around the world. Step 1 involved applying stock assessments to dat...

  1. Effect of stocking density on growth, maturity, fecundity, reproductive ...

    African Journals Online (AJOL)

    Jane

    2011-08-29

    Aug 29, 2011 ... niloticus into freshwater habitats of India took place in. 1952 and 1970 ..... Turbot (Psetta maxima) in the net cages on the southeastern Coast ... Asian Fish. ... ideal stocking density for cage culture of Monosex Nile Tilapia.

  2. Changes in abundance of the northern Benguela sardine stock ...

    African Journals Online (AJOL)

    Changes in abundance of the northern Benguela sardine stock during the decade ... with comments on the relative importance of fishing and the environment. ... Survey-based recruitment indices suggest that the changes in the 1990s were ...

  3. Dispersal, growth and diet of stocked and wild northern pike fry in a shallow natural lake, with implications for management of stocking programs

    DEFF Research Database (Denmark)

    Skov, Christian; Koed, Anders; Baastrup-Spohr, Lars

    2011-01-01

    season. Stomach analyses revealed that the stocked pike ingested less diverse prey items and had higher fractions of empty stomachs throughout the study period. Overall, the fraction of stocked pike in samples rapidly declined over the season, which may have been caused by differential survival...... low fitness of stocked individuals in competition with wild conspecifics: (1) genetic-based local maladaptation among the stocked fish and (2) carryover effects from the hatchery. The latter may be less likely because the fry stocked were the offspring of wild fish and only spent a few weeks...

  4. Estimating exposure of piscivorous birds and sport fish to mercury in California lakes using prey fish monitoring: a predictive tool for managers

    Science.gov (United States)

    Ackerman, Joshua T.; Hartman, C. Alex; Eagles-Smith, Collin A.; Herzog, Mark P.; Davison, Jay; Ichikawa, Gary; Bonnema, Autumn

    2015-01-01

    Numerous water bodies in California are listed under the Clean Water Act as being impaired due to mercury (Hg) contamination. The Surface Water Ambient Monitoring Program (SWAMP), via the Bioaccumulation Oversight Group (BOG), has recently completed statewide surveys of contaminants in sport fish tissue from more than 250 lakes and rivers in California and throughout coastal waters. This effort focused on human health issues but did not include beneficial uses by wildlife. Many piscivorous birds such as grebes, terns, cormorants, and mergansers eat fish smaller than those that were sampled by BOG, and sport fish Hg concentrations are not always indicative of wildlife exposure to Hg; therefore, the BOG surveys could not address whether wildlife were at risk due to Hg-induced reproductive impairment in these lakes.

  5. Use of black carp (Mylopharyngodon piceus) in biological control of intermediate host snails of fish-borne zoonotic trematodes in nursery ponds in the Red River Delta, Vietnam

    DEFF Research Database (Denmark)

    Hung, Nguyen M.; Duc, Nguyen V.; Stauffer, Jay R.

    2013-01-01

    is often thought to be linked to fish culture in areas where the habit of eating raw fish is common. Juvenile fish produced in nurseries are often heavily infected with FZT and since fishes are sold to aquaculture facilities for growth, control of FZT in these fishes should be given priority. Controlling....... Here we report the first trials using it for biological control of intermediate host snails in nursery ponds stocked with 1-week old fry (10-12 mm in length) of Indian carp, Labeo rohita. Methods. Semi-field and field experiments were set up to test the effect of black carp on snail populations....... In the semi-field experiment a known quantity of snails was initially introduced into a pond which was subsequently stocked with black carp. In the field trial in nursery ponds, density of snails was estimated prior to a nursing cycle and at the end of the cycle (after 9 weeks). Results: The results showed...

  6. Quality criteria, expiration period and marketing loss estimations of pre-treated and cold stored mullet fish.

    Directory of Open Access Journals (Sweden)

    Hassan, Ibrahim M.

    1999-06-01

    Full Text Available Monitoring of protein breakdown products and lipid autoxidation in farmed mullet fish as a function of a proposed treatments prior to chilling process at 3 °C ± 1 was carried out. Furthermore, sensory evaluation of three investigated treatments, whole mullet fish (RM-eviscerated and soaked in distilled water (WSRM-eviscerated and soaked in a solution containing 5% K-sorbate + 5% Na4P2O7 + 2% Na-citrate + 0.2% ascorbic acid (SSRM, were followed during chilling storage. Estimation of the predicted length of cold storage period as well as the marketing losses of the marketable mullet fish was also elucidated. The marketing losses of mullet fish at whole or retail market levels were also estimated by using a pre-tested questionnaire. Total volatile basic nitrogen (TVB-N and trimethylamine nitrogen (TMA-N increased concomitantly during cold storage of differently treated mullet fish. Moreover, lipid oxidation and hydrolysis products were followed by determining peroxide value (PV, thiobarbituric acid reactive substances (TBARS and ratio of absorbance (A400/A450 as well as acid value (AV and free volatile fatty acids (FVFA. Mostly, these parameters show upward trend with different rates depending on the applied treatment. Soaking treatment greatly retarded fish spoilage during cold storage. As regards, SSRM samples withstand spoilage up to about 15 days compared to only 8 and 9 days for both RM and WSRM samples, respectively.

    El trabajo presenta los resultados de la evolución de productos de rotura de proteínas y de la autoxidación de lípidos del pescado mujol criado en cautividad en función de los tratamientos propuestos antes de su enfriamiento a 3 °C ± 1. Además se sigue la evolución organoléptica durante el almacenamiento en frío de tres tratamientos: pez entero sin vísceras (RM, sin vísceras sumergido en agua destilada (WSRM y sumergido en una solución conteniendo 5

  7. Grey seal predation on forage fish in the Baltic Sea

    DEFF Research Database (Denmark)

    Eero, Aro; Neuenfeldt, Stefan; Aho, Teija

    The mean annual growth rate of grey seal stock in the Baltic has been on average 7.5% annually during the last decade. In 2010, a total of approximately 23 100 grey seals were counted. The increase in stock size was highest in the northern areas and the predation pressure of grey seals on clupeoids...... has increased accordingly. The diet of grey seal in the Baltic consists of ca. 20 fish species. The most abundant prey items in the Baltic proper are Baltic herring, sprat, and cod, and in the Bothnian Sea and Bothnian Bay Baltic herring, Coregonus sp., Baltic salmon, and sea trout. An adult seal...... consumes on average round 4.5 kg fish per day, of which 55% are clupeoids in the Baltic Main basin and 70% in the Bothnian Sea and Bothnian Bay. According to acoustic estimates, predator– prey distribution patterns, migration patterns, and multispecies analysis (SMS), the predation effect of grey seals...

  8. Effect of fish length and nutritional condition on the fecundity of distressed Atlantic cod Gadus morhua from the Baltic Sea

    DEFF Research Database (Denmark)

    Mion, M.; Thorsen, A.; Vitale, F.

    2018-01-01

    for future fecundity studies on this stock. The results showed that FP was mainly positively related to fish length, but K and IH also contributed significantly to the variation in FP . The model predicted that fish with K = 1·2 have a FP 51% higher than fish of the same LT with K = 0·8. The prevalence...... of fecundity regulation by atresia was 5·8%, but it was found only in fish in the pre-spawning maturity stage and with low K. Temporal changes in biological features such as the length composition and individual body condition of eastern Baltic G. morhua, should be accounted for when estimating stock...

  9. Estimation of the groundwater resources of the bedrock aquifers at the Kettle Moraine Springs State Fish Hatchery, Sheboygan County, Wisconsin

    Science.gov (United States)

    Dunning, Charles; Feinstein, Daniel T.; Buchwald, Cheryl A.; Hunt, Randall J.; Haserodt, Megan J.

    2017-10-12

    Groundwater resources information was needed to understand regional aquifer systems and water available to wells and springs for rearing important Lake Michigan fish species at the Kettle Moraine Springs State Fish Hatchery in Sheboygan County, Wisconsin. As a basis for estimating the groundwater resources available, an existing groundwater-flow model was refined, and new groundwater-flow models were developed for the Kettle Moraine Springs State Fish Hatchery area using the U.S. Geological Survey (USGS) finite-difference code MODFLOW. This report describes the origin and construction of these groundwater-flow models and their use in testing conceptual models and simulating the hydrogeologic system.The study area is in the Eastern Ridges and Lowlands geographical province of Wisconsin, and the hatchery property is situated on the southeastern edge of the Kettle Moraine, a north-south trending topographic high of glacial origin. The bedrock units underlying the study area consist of Cambrian, Ordovician, and Silurian units of carbonate and siliciclastic lithology. In the Sheboygan County area, the sedimentary bedrock sequence reaches a thickness of as much as about 1,600 feet (ft).Two aquifer systems are present at the Kettle Moraine Springs State Fish Hatchery. A shallow system is made up of Silurian bedrock, consisting chiefly of dolomite, overlain by unconsolidated Quaternary-age glacial deposits. The glacial deposits of this aquifer system are the typical source of water to local springs, including the springs that have historically supplied the hatchery. The shallow aquifer system, therefore, consists of the unconsolidated glacial aquifer and the underlying bedrock Silurian aquifer. Most residential wells in the area draw from the Silurian aquifer. A deeper confined aquifer system is made up of Cambrian- and Ordovician-age bedrock units including sandstone formations. Because of its depth, very few wells are completed in the Cambrian-Ordovician aquifer system

  10. Consumption dynamics of the adult piscivorous fish community in Spirit Lake, Iowa

    Science.gov (United States)

    Liao, H.; Pierce, C.L.; Larscheid, J.G.

    2004-01-01

    At Spirit Lake, one of Iowa's most important fisheries, walleye Sander vitreus (formerly Stizostedion vitreum) is one of the most popular species with anglers. Despite a century of walleye stocking and management in Spirit Lake, walleye growth rate, size structure, and angler harvest continue to decline. Our purpose was to determine the magnitude and dynamics of walleye population consumption relative to those of other piscivorous species in Spirit Lake, which would allow managers to judge the feasibility of increasing the abundance, growth rate, and size structure of the walleye population. We quantified food consumption by the adult piscivorous fish community in Spirit Lake over a 3-year period. Data on population dynamics, diet, energy density, and water temperature from 1995 to 1997 were used in bioenergetics models to estimate total consumption by walleye, yellow perch Perca flavescens, smallmouth bass Micropterus dolomieu, largemouth bass Micropterus salmoides, black crappie Pomoxis nigromaculatus, and northern pike Esox lucius. Estimated annual consumption by the piscivorous community varied roughly fourfold, ranging from 154,752 kg in 1995 to 662,776 kg in 1997. Walleyes dominated total consumption, accounting for 68, 73, and 90% (1995-1997, respectively) of total food consumption. Walleyes were also the dominant consumers of fish, accounting for 76, 86, and 97% of piscivorous consumption; yellow perch followed, accounting for 16% of piscivorous consumption in 1995 and 12% in 1996. Yellow perch were the predominant fish prey species in all 3 years, accounting for 68, 52, and 36% of the total prey consumed. Natural reproduction is weak, so high walleye densities are maintained by intensive stocking. Walleye stocking drives piscivorous consumption in Spirit Lake, and yearly variation in the cannibalism of stocked walleye fry may be an important determinant of walleye year-class strength and angler success. Reducing walleye stocking intensity, varying stocking

  11. Long memory in the Croatian and Hungarian stock market returns

    Directory of Open Access Journals (Sweden)

    Silvo Dajčman

    2012-06-01

    Full Text Available The objective of this paper is to analyze and compare the fractal structure of the Croatian and Hungarian stock market returns. The presence of long memory components in asset returns provides evidence against the weak-form of stock market efficiency. The starting working hypothesis that there is no long memory in the Croatian and Hungarian stock market returns is tested by applying the Kwiatkowski-Phillips-Schmidt-Shin (KPSS (1992 test, Lo’s (1991 modified rescaled range (R/S test, and the wavelet ordinary least squares (WOLS estimator of Jensen (1999. The research showed that the WOLS estimator may lead to different conclusions regarding long memory presence in the stock returns from the KPSS and unit root tests or Lo’s R/S test. Furthermore, it proved that the fractal structure of individual stock returns may be masked in aggregated stock market returns (i.e. in returns of stock index. The main finding of the paper is that both the Croatian stock index Crobex and individual stocks in this index exhibit long memory. Long memory is identified for some stocks in the Hungarian stock market as well, but not for the stock market index BUX. Based on the results of the long memory tests, it can be concluded that while the Hungarian stock market is weakform efficient, the Croatian stock market is not.

  12. Using recall surveys to estimate harvest of cod, eel and sea migrating brown trout in Danish angling and recreational passive gear fishing

    DEFF Research Database (Denmark)

    Sparrevohn, Claus Reedtz; Nielsen, Jan; Storr-Paulsen, Marie

    , as all recreational fishermen have to purchase a personal non-transferable and time limited national license before fishing. However, this list will not include those fishing illegally without a license. Therefore, two types of recall surveys with their own questionnaires and group of respondents were...... carried out. The first survey - the license list survey – was carried out once in 2009 and twice in 2010. This survey had a sampling frame corresponding to the list of persons that had purchased a license within the last 12 months. Respondents were asked to provide detailed information on catch and effort...... per ICES area and quarter. In order to also estimate the fraction of fishermen that fished without a valid license, a second survey, called – the Omnibus survey-, was carried out four times. This survey targeted the entire Danish population between 16 and 74 of age...

  13. Direct Survival Analysis: a new stock assessment method

    Directory of Open Access Journals (Sweden)

    Eduardo Ferrandis

    2007-03-01

    Full Text Available In this work, a new stock assessment method, Direct Survival Analysis, is proposed and described. The parameter estimation of the Weibull survival model proposed by Ferrandis (2007 is obtained using trawl survey data. This estimation is used to establish a baseline survival function, which is in turn used to estimate the specific survival functions in the different cohorts considered through an adaptation of the separable model of the fishing mortality rates introduced by Pope and Shepherd (1982. It is thus possible to test hypotheses on the evolution of survival during the period studied and to identify trends in recruitment. A link is established between the preceding analysis of trawl survey data and the commercial catch-at-age data that are generally obtained to evaluate the population using analytical models. The estimated baseline survival, with the proposed versions of the stock and catch equations and the adaptation of the Separable Model, may be applied to commercial catch-at-age data. This makes it possible to estimate the survival corresponding to the landing data, the initial size of the cohort and finally, an effective age of first capture, in order to complete the parameter model estimation and consequently the estimation of the whole survival and mortality, along with the reference parameters that are useful for management purposes. Alternatively, this estimation of an effective age of first capture may be obtained by adapting the demographic structure of trawl survey data to that of the commercial fleet through suitable selectivity models of the commercial gears. The complete model provides the evaluation of the stock at any age. The coherence (and hence the mutual “calibration” between the two kinds of information may be analysed and compared with results obtained by other methods, such as virtual population analysis (VPA, in order to improve the diagnosis of the state of exploitation of the population. The model may be

  14. Behavioral heterogeneity in stock prices

    NARCIS (Netherlands)

    Boswijk, H.P.; Hommes, C.H.; Manzan, S.

    2007-01-01

    We estimate a dynamic asset pricing model characterized by heterogeneous boundedly rational agents. The fundamental value of the risky asset is publicly available to all agents, but they have different beliefs about the persistence of deviations of stock prices from the fundamental benchmark. An

  15. Some Environmental and Economic Aspects of Energy Saving Measures in Houses. An estimation model for total energy consumption and emissions to air from the Norwegian dwelling stock, and a life cycle assessment method for energy saving measures in houses

    Energy Technology Data Exchange (ETDEWEB)

    Myhre, L

    1995-12-01

    Motivated by the need to reduce the total energy consumption and the environmental load from society, this doctoral thesis discusses energy conservation measures on existing houses. Alternative additional thermal insulation measures are assessed using an interdisciplinary life cycle approach. The first task is to develop an interdisciplinary assessment method for building improvement measures, taking account of energy consumption, resource consumption, emissions to air of environmentally harmful gases, and economic costs during the entire life cycle of the building. The second task is to develop an estimation model for the total energy consumption and emissions to air of environmentally harmful gases from the dwelling stock of Norway. Finally, the third task is to assess the total energy saving potential and the total environmental benefits of energy saving measures in houses on a national level, including only life cycle analyses of additional thermal insulation measures on single houses. Chap 2 describes the dwelling stock in Norway. Chaps 3 and 4 present an estimation model for total energy consumption and emissions to air from the dwelling stock, and calculations using the model. Chaps 5 and 6 propose and use a calculation method for the assessment of additional thermal insulation measures, using a ``cradle-to-grave`` approach. Since hydroelectric power is the main energy source in this sector in Norway, estimated payback periods for emissions to air are long. But hydroelectric power saved in this sector may be used to obtain reduction in fossil fuel use in other sectors as discussed in Chap 7. Some of the topics discussed are further elaborated on in appendices. 107 refs., 39 figs, 88 tabs.

  16. PiSCES: Pi(scine) stream community estimation software: A tool for nationwide fish assemblage predictions

    Science.gov (United States)

    Background/Question/Methods What species of fish might someone find in a local stream? How might that community change as a result of changes to characteristics of the stream and its watershed? PiSCES is a browser-based toolkit developed to predict a fish community for any NHD-Pl...

  17. Data evaluation of data limited stocks: Dab, flounder, Witch, Lemon Sole, Brill, Turbot and Horse mackerel

    NARCIS (Netherlands)

    Hammen, van der T.; Poos, J.J.

    2012-01-01

    Several commercially important demersal fish stocks for the North Sea fisheries are classified by ICES (International Council for the Exploration of the Sea) as “data limited” stocks, which are stocks for which the data are insufficient to perform a full analytical assessment and forecast (ICES

  18. Impacts of cooking technique on polychlorinated biphenyl and polychlorinated dioxins/furan concentrations in fish and fish products with intake estimates.

    Science.gov (United States)

    Rawn, Dorothea F K; Breakell, Kenneth; Verigin, Victor; Tittlemier, Sheryl A; Del Gobbo, Liana; Diamond, Miriam; Vanderlinden, Loren; Sit, Daniel

    2013-01-30

    Polychlorinated biphenyl (PCB) and polychlorinated dibenzo-p-dioxin (PCDD) and dibenzofuran (PCDF) concentrations were determined in composites of 18 different fish products and were prepared as raw, baked, boiled, and fried. ∑PCB concentrations were found to range from 0.12 ng·g(-1) whole weight (ww) in raw octopus to 33 ng·g(-1) ww in baked mackerel. Boiled monkfish was found to have the lowest ∑PCDD/F concentrations (0.41 pg·g(-1) ww), while maximum concentrations were observed in fried catfish (59 pg·g(-1) ww). PCB and PCDD/F concentrations in fish were generally reduced during cooking, although differences were small. The average PCB reduction in finfish was 7.9%, while an increase in PCB mass was observed in non-finfish (2.9%). PCDD/F losses, on average, were observed in both the finfish (3.6%) and non-finfish products (25%). Maximum ∑PCB, ∑PCDD/F, and TEQ(PCDD/F+DL-PCB) (toxic equivalency) intakes, based on 150 g serving size, were determined to be 3300 ng (mackerel), 6600 pg (catfish), and 270 pg (catfish), respectively. PCB and PCDD/F changes associated with cooking generally were small (fish products (e.g., catfish).

  19. The Effect of Stocking Density on the Performance of the Seaweed ...

    African Journals Online (AJOL)

    The seaweed biofilter Ulva reticulata was grown at two stocking densities (1 and 3 kg m-2) in a low cost integrated system in Zanzibar, Tanzania. The seaweed was stocked in 2 m2 cages made of 1 inch netting material placed at the outflow of fish ponds. Control seaweed was grown at the fish pond inflow channel.

  20. Why fishing magnifies fluctuations in fish abundance.

    Science.gov (United States)

    Anderson, Christian N K; Hsieh, Chih-hao; Sandin, Stuart A; Hewitt, Roger; Hollowed, Anne; Beddington, John; May, Robert M; Sugihara, George

    2008-04-17

    It is now clear that fished populations can fluctuate more than unharvested stocks. However, it is not clear why. Here we distinguish among three major competing mechanisms for this phenomenon, by using the 50-year California Cooperative Oceanic Fisheries Investigations (CalCOFI) larval fish record. First, variable fishing pressure directly increases variability in exploited populations. Second, commercial fishing can decrease the average body size and age of a stock, causing the truncated population to track environmental fluctuations directly. Third, age-truncated or juvenescent populations have increasingly unstable population dynamics because of changing demographic parameters such as intrinsic growth rates. We find no evidence for the first hypothesis, limited evidence for the second and strong evidence for the third. Therefore, in California Current fisheries, increased temporal variability in the population does not arise from variable exploitation, nor does it reflect direct environmental tracking. More fundamentally, it arises from increased instability in dynamics. This finding has implications for resource management as an empirical example of how selective harvesting can alter the basic dynamics of exploited populations, and lead to unstable booms and busts that can precede systematic declines in stock levels.

  1. IMPACT OF FISHING AND HABITAT DEGRADATION ON THE DENSITY OF BANGGAI CARDINAL FISH (Pterapogon kauderni, Koumans 1933 IN BANGGAI ARCHIPELAGO, INDONESIA

    Directory of Open Access Journals (Sweden)

    Kamaluddin Kasim

    2014-06-01

    Full Text Available Banggai cardinal fish (Pterapogonkauderni, Koumans 1933 is uncommon example of a marine fish with distributed in small range area while being in highly exploited. This fish is in high demand as an ornamental fish. However, the information on the number of density is limited. An underwater visual fish census survey was conducted in June to July 2010 at 18 fishing sites around Banggai archipelago to estimate the density of the stock and assess the impact of fishing and habitat on density. The areas are divided into three main islands, namely Banggai Island, Peleng Island, Toropot-Tumbak-Labobo Island. The lowest density index of the P. kauderni recorded at Kindandal village on Peleng Island, 0.014 fish/m2while the highest abundance index of 3.0 fish/m2 found at Toropot village at Toropot Island. In three survey sites (Bonebaru and Toropot villages where the fishing activities are still ongoing, the density has declined compared to the survey conducted in 2004. Majority of the villages in Peleng Island have lower density compared with the other islands probably due to the degradation of microhabitat of P. kauderni. In many cases, microhabitat degradation might be as a result of collection of sea urchins and sea anemone for consumption by local community.

  2. 12 CFR 575.8 - Contents of Stock Issuance Plans.

    Science.gov (United States)

    2010-01-01

    ... extent applicable, Form OC; (11) Provide that the sales price of the shares of stock to be sold in the... shall be sold at a total price equal to the estimated pro forma market value of such stock, based upon... shares of the savings association's common stock or 4.9 percent of the savings association's stockholders...

  3. A statistical model for estimation of fish density including correlation in size, space, time and between species from research survey data.

    Directory of Open Access Journals (Sweden)

    J Rasmus Nielsen

    Full Text Available Trawl survey data with high spatial and seasonal coverage were analysed using a variant of the Log Gaussian Cox Process (LGCP statistical model to estimate unbiased relative fish densities. The model estimates correlations between observations according to time, space, and fish size and includes zero observations and over-dispersion. The model utilises the fact the correlation between numbers of fish caught increases when the distance in space and time between the fish decreases, and the correlation between size groups in a haul increases when the difference in size decreases. Here the model is extended in two ways. Instead of assuming a natural scale size correlation, the model is further developed to allow for a transformed length scale. Furthermore, in the present application, the spatial- and size-dependent correlation between species was included. For cod (Gadus morhua and whiting (Merlangius merlangus, a common structured size correlation was fitted, and a separable structure between the time and space-size correlation was found for each species, whereas more complex structures were required to describe the correlation between species (and space-size. The within-species time correlation is strong, whereas the correlations between the species are weaker over time but strong within the year.

  4. Which Fish Should I Eat? Perspectives Influencing Fish Consumption Choices

    Science.gov (United States)

    Choi, Anna L.; Karagas, Margaret R.; Mariën, Koenraad; Rheinberger, Christoph M.; Schoeny, Rita; Sunderland, Elsie; Korrick, Susan

    2012-01-01

    Background: Diverse perspectives have influenced fish consumption choices. Objectives: We summarized the issue of fish consumption choice from toxicological, nutritional, ecological, and economic points of view; identified areas of overlap and disagreement among these viewpoints; and reviewed effects of previous fish consumption advisories. Methods: We reviewed published scientific literature, public health guidelines, and advisories related to fish consumption, focusing on advisories targeted at U.S. populations. However, our conclusions apply to groups having similar fish consumption patterns. Discussion: There are many possible combinations of matters related to fish consumption, but few, if any, fish consumption patterns optimize all domains. Fish provides a rich source of protein and other nutrients, but because of contamination by methylmercury and other toxicants, higher fish intake often leads to greater toxicant exposure. Furthermore, stocks of wild fish are not adequate to meet the nutrient demands of the growing world population, and fish consumption choices also have a broad economic impact on the fishing industry. Most guidance does not account for ecological and economic impacts of different fish consumption choices. Conclusion: Despite the relative lack of information integrating the health, ecological, and economic impacts of different fish choices, clear and simple guidance is necessary to effect desired changes. Thus, more comprehensive advice can be developed to describe the multiple impacts of fish consumption. In addition, policy and fishery management inter-ventions will be necessary to ensure long-term availability of fish as an important source of human nutrition. PMID:22534056

  5. The Sole Question. Assessing the sustainability of fishing versus farming

    NARCIS (Netherlands)

    Broenland, Eefje

    2007-01-01

    Fish stocks in the world are declining, but the demand for fish products is increasing. Aquaculture practices are increasing because of this gap between supply and demand. Therefore it is important to determine which production system has the least enviro

  6. Abundance, Distribution and Estimated Consumption (kg fish) of Piscivorous Birds Along the Yakima River, Washington State; Implications for Fisheries Management, 2002 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Major, III, Walter; Grassley, James M.; Ryding, Kristen E. (University of Washington, Quantitive Ecology Program, Seattle, WA)

    2003-05-01

    This report is divided into two chapters. The abstract for chapter one is--Understanding of the abundance and spatial and temporal distributions of piscivorous birds and their potential consumption of fish is an increasingly important aspect of fisheries management. During 1999-2002, we determined the abundance and distribution and estimated the maximum consumption (kg biomass) of fish-eating birds along the length of the Yakima River in Washington State. Sixteen different species were observed during the 4-yr study, but only half of those were observed during all years. Abundance and estimated consumption of fish within the upper and middle sections of the river were dominated by common mergansers (Mergus merganser) which are known to breed in those reaches. Common mergansers accounted for 78 to 94% of the estimated total fish take for the upper river or approximately 28,383 {+-} 1,041 kg over the 4 yrs. A greater diversity of avian piscivores occurred in the lower river and potential impacts to fish populations was more evenly distributed among the species. In 1999-2000, great blue herons potentially accounted for 29 and 36% of the fish consumed, whereas in 2001-2002 American white pelicans accounted for 53 and 55%. We estimated that approximately 75,878 {+-} 6,616 kg of fish were consumed by piscivorous birds in the lower sections of the river during the study. Bird assemblages differed spatially along the river with a greater abundance of colonial nesting species within the lower sections of the river, especially during spring and the nesting season. The abundance of avian piscivores and consumption estimates are discussed within the context of salmonid supplementation efforts on the river and juvenile out-migration. The abstract for chapter two is--Consumption of fish by piscivorous birds may be a significant constraint on efforts to enhance salmonid populations within tributaries to the Columbia River in Washington State. During 1999-2002, we determined the

  7. Movement and mortality of stocked brown trout in a stream

    DEFF Research Database (Denmark)

    Aarestrup, Kim; Jepsen, Niels; Koed, Anders

    2005-01-01

    The movement and mortality of stocked brown trout Salmo trutta were investigated using radio telemetry. Four brown trout left the study area whereas the remaining fish were stationary. After 5 weeks, 13 out of 50 tagged brown trout were still alive in the stream. Surviving fish had a significantly...

  8. Investor behavior heterogeneity in the French stock market

    OpenAIRE

    Rania Guirat

    2011-01-01

    We estimate in this paper a non probabilistic Markovien model of stock prices with an evolutionary selection of heterogeneous strategies. It is a model proposed by Brock and Hommes (1997, 1998) and improved later by Boswijk and al. (2007). Indeed, the latter propose one of the few estimations considering stock markets data, characterized by an evolutionary selection procedure of heterogeneous strategies. They estimate the model to annual US stock price data from 1871 to 2003. In this paper, w...

  9. Assessment of heavy metals and estimation of human health risk in Tilapia fish from Naik lake of Nagpur, India

    Digital Repository Service at National Institute of Oceanography (India)

    Giripunje, M.D.; Fulke, A.B.; Meshram, P.U.

    /g dw respectively. These levels were above the maximum permissible limits of Food and Agriculture Organization (FAO)/World Health Organisation (WHO). The results confirmed that tilapia fish from Naik lake are not safe for human consumption. Further...

  10. Quantifying the trade in marine ornamental fishes into Switzerland and an estimation of imports from the European Union

    Directory of Open Access Journals (Sweden)

    Monica V. Biondo

    2017-07-01

    Full Text Available Millions of marine ornamental fishes are traded every year. Today, over half of the known nearly 4000 coral reef fish species are in trade with poor or no monitoring and demand is increasing. This study investigates their trade into and through Switzerland by analyzing import documents for live animals. In 2009, 151 import declarations with attached species lists for marine ornamental fishes from non-EU countries totaled 28 356 specimens. The 62% of the fishes remaining in Switzerland, comprised 440 marine species from 45 families, the rest transited to EU and non-EU countries. Despite the recognized large trade volume for the European region, due to bilateral agreements, no data is collected for imports from the EU. However, inferred data shows that more than 200 000 marine ornamental fishes could be imported into Switzerland every year and an unknown quantity re-exported. As biggest import region, it is therefore safe to assume, that the European region is importing at least as many marine ornamental fishes as the US. There is no adequate data-collecting system known to be in place in any country for monitoring this trade. The EU Trade Control and Expert System (TRACES to monitor animal diseases could be adjusted to gather compulsory information for the EU and Switzerland. More than half of the species imported into Switzerland are not assessed by the IUCN and therefore marked as ‘not evaluated’ on the Red List. Overall, 70% of all known coral reef fish species have not been evaluated. If coral reef fishes are threatened or endangered due to large, possibly unsustainable numbers traded, it may be rational to monitor the trade in these species through the Convention on International Trade of Endangered Species (CITES.

  11. Northern Marshall Islands radiological survey: radionuclide concentrations in fish and clams and estimated doses via the marine pathway

    International Nuclear Information System (INIS)

    Robison, W.L.; Noshkin, V.E.; Phillips, W.A.; Eagle, R.J.

    1981-01-01

    The survey consisted, in part, of an aerial radiological reconnaissance to map the external gamma-ray exposure rates. As a secondary phase, terrestrial and marine samples were collected to assess the radiological dose from pertinent food chains to atoll inhabitants. The marine sample collection, processing, and dose assessment methodology are presented as well as the concentration data for 90 Sr, 137 Cs, 238 Pu, 239+240 Pu, 241 Am, and any of the other gamma emitters in fish and clam muscle tissue from the different species collected. Doses are calculated from the average radionuclide concentrations in fish and clam muscle tissue assuming an average daily intake of 200 and 10 g, respectivelty. The 90 Sr concentration in muscle tissue is very low and there is little difference in the average concentrations from the different fish from different atolls or islands. The 239+240 Pu concentration in the muscle tissue of all reef species, however, is higher than that in pelagic lagoon fish. In contrast, 137 Cs concentrations are lowest in the muscle tissue of the bottom-feeding reef species and highest in pelagic logoon fish. Recent measurements of radionuclide concentrations in fish muscle tissue and other marine dietary items from international sources show that the average concentrations in species from the Marshall Islands are comparable to those in fish typically consumed as food in the United States and are generally lower than those in most international marine dietary items. The whole-body dose rates based on continuous consumption of 200 g/d of fish range from 0.028 to 0.1 mrem/y; the bone-marrow dose rates range from 0.029 to 0.12 mrem/y. The dose commitment, or 30-y integral doses, range from 0.00063 to 0.0022 rem for the whole body and from 0.00065 to 0.0032 rem for the bone marrow

  12. Stime della biomassa marina attraverso il metodo acustico: discernimento delle specie e gestione delle risorse ittiche - Acoustical estimation of fish biomass: species identification and stocks management

    Directory of Open Access Journals (Sweden)

    Víctor Espinosa

    2015-09-01

    Full Text Available L’acustica è alla base delle più importanti tecnologie nelle telecomunicazioni subacquee, nonché nel rilevamento e nella determinazione dei target acustici nei mezzi acquatici. Le misure a multi-frequenza sono lo strumento principale per l’identificazione selettiva delle specie marine e per la pesca sostenibile. Lo sviluppo di sistemi a larga banda larga e le tecniche basate su sonar multi-beam costituiscono l'attuale sfida per gli scienziati e gli sviluppatori. Al contempo, sistemi più semplici ed economicamente efficienti, come boe satellitari, sono in grado di offrire informazioni per il monitoraggio degli ecosistemi o l’individuazione di specie bersaglio nella pesca marittima. ------ Acoustics is the basics of the most important technologies for underwater telecommunication, as well as for target detection and identification in the aquatic media. Multiple frequency measurements are the key for species discrimination and open the door for sustainable fisheries. The development of wider broadband systems and quantitative multi-beam sonars and processing techniques constitute the present challenge for scientists and developers. In parallel, simpler and cost-efficient systems like satellite buoys can offer clue information for marine ecosystem monitoring or target species fisheries.

  13. Raft and floating radio frequency identification (RFID) antenna systems for detecting and estimating abundance of PIT-tagged fish in rivers

    Science.gov (United States)

    Fetherman, Eric R.; Avila, Brian W.; Winkelman, Dana L.

    2016-01-01

    Portable radio frequency identification (RFID) PIT tag antenna systems are increasingly being used in studies examining aquatic animal movement, survival, and habitat use, and their design flexibility permits application in a wide variety of settings. We describe the construction, use, and performance of two portable floating RFID PIT tag antenna systems designed to detect fish that were unavailable for recapture using stationary antennas or electrofishing. A raft antenna system was designed to detect and locate PIT-tagged fish in relatively long (i.e., ≥10 km) river reaches, and consisted of two antennas: (1) a horizontal antenna (4 × 1.2 m) installed on the bottom of the raft and used to detect fish in shallower river reaches (raft antenna system, which covered 21% of the wetted area, was 0.14 ± 0.14. A shore-deployed floating antenna (14.6 × 0.6 m), which covered 100% of the wetted area, was designed for use by two operators for detecting and locating PIT-tagged fish in shorter (i.e., <2 km) river reaches. Detection distances of the shore-deployed floating antenna were between 0.7 and 0.8 m, and detection probabilities during field deployment in the St. Vrain River exceeded 0.52. The shore-deployed floating antenna was also used to estimate abundance of PIT-tagged fish. Results suggest that the shore-deployed floating antenna could be used as an alternative to estimating abundance using traditional sampling methods such as electrofishing.

  14. Mixed stock analysis of Lake Michigan's Lake Whitefish Coregonus clupeaformis commercial fishery

    Science.gov (United States)

    Andvik, Ryan; Sloss, Brian L.; VanDeHey, Justin A.; Claramunt, Randall M.; Hansen, Scott P.; Isermann, Daniel A.

    2016-01-01

    Lake whitefish (Coregonus clupeaformis) support the primary commercial fishery in Lake Michigan. Discrete genetic stocks of lake whitefish have been identified and tagging data suggest stocks are mixed throughout much of the year. Our objectives were to determine if (1) differential stock harvest occurs in the commercial catch, (2) spatial differences in genetic composition of harvested fish were present, and (3) seasonal differences were present in the harvest by commercial fisheries that operate in management zones WI-2 and WFM-01 (Green Bay, Lake Michigan). Mixed stock analysis was conducted on 17 commercial harvest samples (n = 78–145/sample) collected from various ports lake-wide during 2009–2010. Results showed significant mixing with variability in stock composition across most samples. Samples consisted of two to four genetic stocks each accounting for ≥ 10% the catch. In 10 of 17 samples, the stock contributing the largest proportion made up differences existed in the proportional stock contribution at a single capture location. Samples from Wisconsin's primary commercial fishing management zone (WI-2) were composed predominately of fish from the Big Bay de Noc (Michigan) stock as opposed to the geographically proximate, North–Moonlight Bay (Wisconsin) stock. These findings have implications for management and allocation of fish to various quotas. Specifically, geographic location of harvest, the current means of allocating harvest quotas, is not the best predictor of genetic stock harvest.

  15. WAYS TO IMPROVE THE TRANSPORT OF LIVE FISH

    Directory of Open Access Journals (Sweden)

    V. Chernik

    2014-03-01

    Full Text Available Purpose. To calculate the cost of transportation of live fish by various means of transport and to identify ways to improve the efficiency of their transport. Methodology. The studies were conducted using an economic analysis. Findings. Based on the study we estimated the prime cost of live fish delivery, which ranged from 3.7 to 6.5 UAH for 1 km for the delivery of 1 ton depending on the type of vehicle. The main backup to increase the efficiency of the transport is to increase the density of fish. Total economic effect from introduction of a modernized park of transportation of live fish vehicles in Ukraine can be assessed based on the amount of commodity fish and stocking fish. So, last years, enterprises which report their activity in the bodies of state statistics, rear up to 20 000 t of common carp and silver carp annually. Greater part of fish will be sold to the eventual consumer in alive condition and the mean distance where the fish is transported is about 100 km. The economic effect from the decrease of prime price of transportation will make to 2 000 000 UAH per year. In addition, more than 1000 t of rainbow trout is delivered from Western regions of Ukraine at distances greater than 100 km. cost saving during transport of trout will make up to 500 000 UAH per year. Originality. An analysis of the use of different types of vehicles for the transport of live fish has been performed. Practical Value. To ensure the safe transport of live fish it is necessary to use modernized live fish vehicles.

  16. Towards abundance estimates for jack mackerel in the South Pacific based on acoustic data collected by the commercial vessels

    NARCIS (Netherlands)

    Brunel, T.P.A.; Faessler, S.M.M.; Haan, de D.; Hintzen, N.T.; Kamp, van der P.H.J.; Ybema, M.S.

    2010-01-01

    Pelagic trawlers make intensive use of echosounders and therefore could potentially be used as acoustic data collection platforms. This project investigated the possibility of collecting acoustic data and its potential utility to estimate fish stock biomass. The scope of the project was to develop

  17. Correlations between Fruit, Vegetables, Fish, Vitamins, and Fatty Acids Estimated by Web-Based Nonconsecutive Dietary Records and Respective Biomarkers of Nutritional Status.

    Science.gov (United States)

    Lassale, Camille; Castetbon, Katia; Laporte, François; Deschamps, Valérie; Vernay, Michel; Camilleri, Géraldine M; Faure, Patrice; Hercberg, Serge; Galan, Pilar; Kesse-Guyot, Emmanuelle

    2016-03-01

    It is of major importance to measure the validity of self-reported dietary intake using web-based instruments before applying them in large-scale studies. This study aimed to validate self-reported intake of fish, fruit and vegetables, and selected micronutrient intakes assessed by a web-based self-administered dietary record tool used in the NutriNet-Santé prospective cohort study, against the following concentration biomarkers: plasma beta carotene, vitamin C, and n-3 polyunsaturated fatty acids. One hundred ninety-eight adult volunteers (103 men and 95 women, mean age=50.5 years) were included in the protocol: they completed 3 nonconsecutive-day dietary records and two blood samples were drawn 3 weeks apart. The study was conducted in the area of Paris, France, between October 2012 and May 2013. Reported fish, fruit and vegetables, and selected micronutrient intakes and plasma beta carotene, vitamin C, and n-3 polyunsaturated fatty acid levels were compared. Simple and adjusted Spearman's rank correlation coefficients were estimated after de-attenuation for intra-individual variation. Regarding food groups in men, adjusted correlations ranged from 0.20 for vegetables and plasma vitamin C to 0.49 for fruits and plasma vitamin C, and from 0.40 for fish and plasma c20:5 n-3 (eicosapentaenoic acid [EPA]) to 0.55 for fish and plasma c22:6 n-3 (docosahexaenoic acid). In women, correlations ranged from 0.13 (nonsignificant) for vegetables and plasma vitamin C to 0.41 for fruits and vegetables and plasma beta carotene, and from 0.27 for fatty fish and EPA to 0.54 for fish and EPA+docosahexaenoic acid. Regarding micronutrients, adjusted correlations ranged from 0.36 (EPA) to 0.58 (vitamin C) in men and from 0.32 (vitamin C) to 0.38 (EPA) in women. The findings suggest that three nonconsecutive web-based dietary records provide reasonable estimates of true intake of fruits, vegetables, fish, beta carotene, vitamin C, and n-3 fatty acids. Along with other validation

  18. Raft and floating radio frequency identification (RFID) antenna systems for detecting and estimating abundance of PIT-tagged fish in rivers

    Science.gov (United States)

    Fetherman, Eric R.; Avila, Brian W.; Winkelman, Dana L.

    2016-01-01

    Portable radio frequency identification (RFID) PIT tag antenna systems are increasingly being used in studies examining aquatic animal movement, survival, and habitat use, and their design flexibility permits application in a wide variety of settings. We describe the construction, use, and performance of two portable floating RFID PIT tag antenna systems designed to detect fish that were unavailable for recapture using stationary antennas or electrofishing. A raft antenna system was designed to detect and locate PIT-tagged fish in relatively long (i.e., ≥10 km) river reaches, and consisted of two antennas: (1) a horizontal antenna (4 × 1.2 m) installed on the bottom of the raft and used to detect fish in shallower river reaches (<1 m), and (2) a vertical antenna (2.7 × 1.2 m) for detecting fish in deeper pools (≥1 m). Detection distances of the horizontal antenna were between 0.7 and 1.0 m, and detection probability was 0.32 ± 0.02 (mean ± SE) in a field test using rocks marked with 32-mm PIT tags. Detection probability of PIT-tagged fish in the Cache la Poudre River, Colorado, using the raft antenna system, which covered 21% of the wetted area, was 0.14 ± 0.14. A shore-deployed floating antenna (14.6 × 0.6 m), which covered 100% of the wetted area, was designed for use by two operators for detecting and locating PIT-tagged fish in shorter (i.e., <2 km) river reaches. Detection distances of the shore-deployed floating antenna were between 0.7 and 0.8 m, and detection probabilities during field deployment in the St. Vrain River exceeded 0.52. The shore-deployed floating antenna was also used to estimate abundance of PIT-tagged fish. Results suggest that the shore-deployed floating antenna could be used as an alternative to estimating abundance using traditional sampling methods such as electrofishing.

  19. Stock Market Project.

    Science.gov (United States)

    Distel, Brenda D.

    This project is designed to teach students the process of buying stocks and to tracking their investments over the course of a semester. The goals of the course are to teach students about the relationships between conditions in the economy and the stock market; to predict the effect of an economic event on a specific stock or industry; to relate…

  20. Volatility forecasting and value-at-risk estimation in emerging markets: the case of the stock market index portfolio in South Africa

    Directory of Open Access Journals (Sweden)

    Lumengo Bonga-Bonga

    2011-04-01

    Full Text Available Accurate modelling of volatility is important as it relates to the forecasting of Value-at-Risk (VaR. The RiskMetrics model to forecast volatility is the benchmark in the financial sector. In an important regulatory innovation, the Basel Committee has proposed the use of an internal method for modelling VaR instead of the strict use of the benchmark model. The aim of this paper is to evaluate the performance of RiskMetrics in comparison to other models of volatility forecasting, such as some family classes of the Generalised Auto Regressive Conditional Heteroscedasticity models, in forecasting the VaR in emerging markets. This paper makes use of the stock market index portfolio, the All-Share Index, as a case study to evaluate the market risk in emerging markets. The paper underlines the importance of asymmetric behaviour for VaR forecasting in emerging markets’ economies.

  1. Comparison of Neural Networks and Regression Time Series in Estimating the Development of the Afternoon Price of Palladium on the New York Stock Exchange

    Directory of Open Access Journals (Sweden)

    Marek Vochozka

    2017-12-01

    Full Text Available Purpose of the article: Palladium is presently used for producing electronics, industrial products or jewellery, as well as products in the medical field. Its value is raised especially by its unique physical and chemical characteristics. Predicting the value of such a metal is not an easy matter (with regard to the fact that prices may change significantly in time. Methodology/methods: To carry out the analysis, London Fix Price PM data was used, i.e. amounts reported in the afternoon for a period longer than 10 years. To process the data, Statistica software is used. Linear regression is carried out using a whole range of functions, and subsequently regression via neural structures is performed, where several distributional functions are used again. Subsequently, 1000 neural networks are generated, out of which 5 proving the best characteristics are chosen. Scientific aim: The aim of the paper is to perform a regression analysis of the development of the palladium price on the New York Stock Exchange using neural structures and linear regression, then to compare the two methods and determine the more suitable one for a possible prediction of the future development of the palladium price on the New York Stock Exchange. Findings: Results are compared on the level of an expert perspective and the evaluator’s – economist’s experience. Within regression time lines, the curve obtained by the least squares methods via negative-exponential smoothing gets closest to Palladium price line development. Out of the neural networks, all 5 chosen networks prove to be the most practically useful. Conclusions: Because it is not possible to predict extraordinary situations and their impact on the palladium price (at most in the short term, but certainly not over a long period of time, simplification and the creation of a relatively simple model is appropriate and the result is useful.

  2. Importance of Using Multiple Sampling Methodologies for Estimating of Fish Community Composition in Offshore Wind Power Construction Areas of the Baltic Sea

    Energy Technology Data Exchange (ETDEWEB)

    Andersson, Mathias H.; Gullstroem, Martin; Oehman, Marcus C. (Dept. of Zoology, Stockholm Univ., Stockholm (Sweden)); Asplund, Maria E. (Dept. of Marine Ecology, Goeteborg Univ., Kristineberg Marine Research Station, Fiskebaeckskil (Sweden))

    2007-12-15

    In this study a visual SCUBA investigation was conducted in Utgrunden 2, an area where windmills had not yet been constructed, and where the bottom mainly consisted of mud or sand with no or a sparse number of algae or mussel beds. A wind farm at Utgrunden 2 would alter the local habitat from a predominantly sandy soft-bottom habitat to an area in which artificial reef structures that resemble hard-bottom habitats is introduced, i.e., the steel foundations and possibly boulders for scour protection. The fish community that will develop over time would be expected to change to resemble the assemblages observed at Utgrunden 1 and hence not visible using trawling and echosound sampling technique. As the goal of EIA is to assess changes, following human development visual techniques is recommended as a complement when examining the environmental effects of offshore windpower. Otherwise important ecological changes may go unnoticed. For a comprehensive understanding of the ecological effects of windfarm developments it is recommended that a combination of sampling methods is applied and that this should be defined before an investigation commences. Although it is well established in the scientific literature that different sampling methods will give different estimations of fish community composition, environmental impact assessments of offshore windpower have been incorrectly interpreted. In the interpretation of the results of such assessments it is common that the findings are extrapolated by stakeholders and media to include a larger extent of the fish populations than what was intended. Therefore, to fully understand how windpower influences fish the underwater visual census technique is here put forward as a necessary complement to more widescreening fish sampling methods (e.g., gill nets, echo-sounds, trawling)

  3. Estimating Profit Efficiency of Artisanal Fishing in the Pru District of the Brong-Ahafo Region, Ghana

    Directory of Open Access Journals (Sweden)

    Edinam Dope Setsoafia

    2017-01-01

    Full Text Available This study evaluated the profit efficiency of artisanal fishing in the Pru District of Ghana by explicitly computing profit efficiency level, identifying the sources of profit inefficiency, and examining the constraints of artisanal fisheries. Cross-sectional data was obtained from 120 small-scale fishing households using semistructured questionnaire. The stochastic profit frontier model was used to compute profit efficiency level and identify the determinants of profit inefficiency while Garrett ranking technique was used to rank the constraints. The average profit efficiency level was 81.66% which implies that about 82% of the prospective maximum profit was gained due to production efficiency. That is, only 18% of the potential profit was lost due to the fishers’ inefficiency. Also, the age of the household head and household size increase the inefficiency level while experience in artisanal fishing tends to decrease the inefficiency level. From the Garrett ranking, access to credit facility to fully operate the small-scale fishing business was ranked as the most pressing issue followed by unstable prices while perishability was ranked last among the constraints. The study, therefore, recommends that group formation should be encouraged to enable easy access to loans and contract sales to boost profitability.

  4. Sediment distribution coefficients (KD) and concentration factors (CF) in fish for natural radionuclides in a pond of a tropical region and their contributions to estimations of internal absorbed dose rate in fish

    International Nuclear Information System (INIS)

    Souza Pereira, Wagner de; Kelecom, Alphonse

    2008-01-01

    Attention has been paid only recently to the protection of biota against radiation effects. Protection is being considered through modeling of the calculation of absorbed dose rate. In these models, the inputs are the fluxes of radionuclides of environmental concern and their resulting distribution between environmental compartments. Such distribution is estimated for dispersion models. In freshwater systems and when fish is used as biomaker, relevant environmental transfer parameters are transfer between sediment and water (sediment distribution coefficients KD, in l kg -1 ), and between water and fish (concentration factor CF, in l kg -1 ). These coefficients are under the influence of a number o physical, chemical and biological factors, and display following the literature a great variability. The present work establishes the KD's and CF's for uranium, thorium, radium and lead for two ponds: one that receives treated effluents from an ore treatment unit (UTM) situated at Pocos de Caldas, Minas Gerais, Brazil and the other pond from the uranium concentration unit (URA) situated at Caetite, Bahia, Brazil, and for fish used as biomarker. It intends also to compare these parameters with the values recommended by IAEA. Depending on considered radionuclide and on the site, CF's (l kg -1 ) observed values were of the same magnitude as, or one order of magnitude lower than recommended by IAEA. KD's (l kg -1 ) observed values were found of the same magnitude as those recommended by IAEA, approximately 10 times lower or up to 100 times higher than recommended by IAEA, again depending on the radionuclides and on the site. It can be concluded that local parameters should be established in order to obtain a more accurate estimative of biota exposition from man activities. (author)

  5. Fish Allergy

    Science.gov (United States)

    ... Cause Blog Vision Awards Common Allergens Fish Allergy Fish Allergy Learn about fish allergy, how to read ... that you must avoid both. Allergic Reactions to Fish Finned fish can cause severe and potentially life- ...

  6. The price momentum of stock in distribution

    Science.gov (United States)

    Liu, Haijun; Wang, Longfei

    2018-02-01

    In this paper, a new momentum of stock in distribution is proposed and applied in real investment. Firstly, assuming that a stock behaves as a multi-particle system, its share-exchange distribution and cost distribution are introduced. Secondly, an estimation of the share-exchange distribution is given with daily transaction data by 3 σ rule from the normal distribution. Meanwhile, an iterative method is given to estimate the cost distribution. Based on the cost distribution, a new momentum is proposed for stock system. Thirdly, an empirical test is given to compare the new momentum with others by contrarian strategy. The result shows that the new one outperforms others in many places. Furthermore, entropy of stock is introduced according to its cost distribution.

  7. Dynamic Stock Market Participation of Households

    DEFF Research Database (Denmark)

    Khorunzhina, Natalia

    This paper develops and estimates a dynamic model of stock market participation, where consumers’ decisions regarding stock market participation are influenced by participation costs. The practical significance of the participation costs is considered as being a channel through which financial...... education programs can affect consumers’ investment decisions. Using household data from the Panel Study of Income Dynamics, I estimate the magnitude of the participation cost, allowing for individual heterogeneity in it. The results show the average stock market articipation cost is about 5% of labor...... income; however, it varies substantially over consumers’ life. The model successfully predicts the level of the observed articipation rate and the increasing pattern of stock market participation over the consumers’ life cycle....

  8. What can gene flow and recruitment dynamics tell us about connectivity between European hake stocks in the Eastern North Atlantic?

    Science.gov (United States)

    Pita, Alfonso; Pérez, Montse; Cerviño, Santiago; Presa, Pablo

    2011-04-01

    Systematic genetic analyses of fish populations allow the testing of temporal stability in their genetic structures and better understanding their pattern of connectivity. In this study the pattern of gene flow between the two Atlantic stocks of the European hake has been examined for the period 2000-2002. Present analyses indicate that a large genetic homogeneity existed among all Atlantic populations in that period, and that a systematic grouping occurred between Porcupine Bank samples and Cantabric ones. This scenario is congruent with an inter-annual gene flow from central grounds of the northern stock (Porcupine and Great Sole) to Iberian grounds inhabited by the southern stock. Additionally, estimated migration figures were in agreement with the good recruitments observed in the southern stock after 2003 despite the spawning biomass was at its historical minimum. Altogether these results highlight the central role of Porcupine bank and Great Sole in making sustainable both stocks and advocate the integrative management of this hake fishery by means of a multidisciplinary assessment.

  9. Parasites as Biological Tags for Stock Discrimination of Beaked Redfish (Sebastes mentella: Parasite Infra-Communities vs. Limited Resolution of Cytochrome Markers.

    Directory of Open Access Journals (Sweden)

    Regina Klapper

    Full Text Available The use of parasites as biological tags for discrimination of fish stocks has become a commonly used approach in fisheries management. Metazoan parasite community analysis and anisakid nematode population genetics based on a mitochondrial cytochrome marker were applied in order to assess the usefulness of the two parasitological methods for stock discrimination of beaked redfish Sebastes mentella of three fishing grounds in the North East Atlantic. Multivariate, model-based approaches demonstrated that the metazoan parasite fauna of beaked redfish from East Greenland differed from Tampen, northern North Sea, and Bear Island, Barents Sea. A joint model (latent variable model was used to estimate the effects of covariates on parasite species and identified four parasite species as main source of differences among fishing grounds; namely Chondracanthus nodosus, Anisakis simplex s.s., Hysterothylacium aduncum, and Bothriocephalus scorpii. Due to its high abundance and differences between fishing grounds, Anisakis simplex s.s. was considered as a major biological tag for host stock differentiation. Whilst the sole examination of Anisakis simplex s.s. on a population genetic level is only of limited use, anisakid nematodes (in particular, A. simplex s.s. can serve as biological tags on a parasite community level. This study confirmed the use of multivariate analyses as a tool to evaluate parasite infra-communities and to identify parasite species that might serve as biological tags. The present study suggests that S. mentella in the northern North Sea and Barents Sea is not sub-structured.

  10. Genetic restoration of a stocked brown trout Salmo trutta population using microsatellite DNA analysis of historical and contemporary samples

    DEFF Research Database (Denmark)

    Hansen, Michael Møller; Bekkevold, Dorte; Jensen, L.F.

    2006-01-01

    1. Gene flow from domesticated to wild populations is a major threat to wild salmonid fish. However, few studies have addressed how populations could be restored after admixture has occurred. We analysed the prospects for restoring the previously intensively stocked brown trout population...... of the Skjern River, Denmark, by identifying remaining non-admixed individuals to be used for supportive breeding. 2. We analysed microsatellite DNA markers in historical (1940-50s) and contemporary (1992-2004) samples from the Skjern River system, from the strain of domesticated trout previously used...... for stocking, and from the neighbouring Stora River. We analysed admixture proportions to estimate the genetic contribution by domesticated trout. We identified non-admixed trout using assignment tests, and further analysed the possible sources of indigenous trout by estimating contemporary migration among...

  11. Fish-allergic patients may be able to eat fish.

    Science.gov (United States)

    Mourad, Ahmad A; Bahna, Sami L

    2015-03-01

    Reported fish allergy prevalence varies widely, with an estimated prevalence of 0.2% in the general population. Sensitization to fish can occur by ingestion, skin contact or inhalation. The manifestations can be IgE or non-IgE mediated. Several fish allergens have been identified, with parvalbumins being the major allergen in various species. Allergenicity varies among fish species and is affected by processing or preparation methods. Adverse reactions after eating fish are often claimed to be 'allergy' but could be a reaction to hidden food allergen, fish parasite, fish toxins or histamine in spoiled fish. Identifying such causes would allow free consumption of fish. Correct diagnosis of fish allergy, including the specific species, might provide the patient with safe alternatives. Patients have been generally advised for strict universal avoidance of fish. However, testing with various fish species or preparations might identify one or more forms that can be tolerated.

  12. Market Structure and Stock Splits

    OpenAIRE

    David Michayluk; Paul Kofman

    2001-01-01

    Enhanced liquidity is one possible motivation for stock splits but empirical research frequently documents declines in liquidity following stock splits. Despite almost thirty years of inquiry, little is known about all the changes in a stock's trading activity following a stock split. We examine how liquidity measures change around more than 2,500 stock splits and find a pervasive decline in most measures. Large stock splits exhibit a more severe liquidity decline than small stock splits, esp...

  13. Economic values of growth and feed efficiency for fish farming in recirculating aquaculture system with density and nitrogen output limitations: a case study with African catfish (Clarias gariepinus).

    Science.gov (United States)

    Besson, M; Komen, H; Aubin, J; de Boer, I J M; Poelman, M; Quillet, E; Vancoillie, C; Vandeputte, M; van Arendonk, J A M

    2014-12-01

    In fish farming, economic values (EV) of breeding goal traits are lacking, even though they are key parameters when defining selection objectives. The aim of this study was to develop a bioeconomic model to estimate EV of 2 traits representing production performances in fish farming: the thermal growth coefficient (TGC) and the feed conversion ratio (FCR). This approach was applied to a farm producing African catfish (Clarias gariepinus) in a recirculating aquaculture system (RAS). In the RAS, 2 factors could limit production level: the nitrogen treatment capacity of the biofilter or the fish density in rearing tanks at harvest. Profit calculation includes revenue from fish sales, cost of juveniles, cost of feed, cost of waste water treatment, and fixed costs. In the reference scenario, profit was modeled to zero. EV were calculated as the difference in profit per kilogram of fish between the current population mean for both traits (µt) and the next generation of selective breeding (µt+Δt) for either TGC or FCR. EV of TGC and FCR were calculated for three generations of hypothetical selection on either TGC or FCR (respectively 6.8% and 7.6% improvement per generation). The results show that changes in TGC and FCR can affect both the number of fish that can be stocked (number of batches per year and number of fish per batch) and the factor limiting production. The EV of TGC and FCR vary and depend on the limiting factors. When dissolved NH3-N is the limiting factor for both µt and µt+Δt, increasing TGC decreases the number of fish that can be stocked but increases the number of batches that can be grown. As a result, profit remains constant and EVTGC is zero. Increasing FCR, however, increases the number of fish stocked and the ratio of fish produced per kilogram of feed consumed ("economic efficiency"). The EVFCR is 0.14 €/kg of fish, and profit per kilogram of fish increases by about 10%. When density is the limiting factor for both µt and µt+Δt, the

  14. A real-time PCR assay to estimate invertebrate and fish predation on anchovy eggs in the Bay of Biscay

    KAUST Repository

    Albaina, A.

    2015-02-01

    In order to investigate the role of predation on eggs and larvae in the recruitment of anchovy (Engraulis encrasicolus), sardine (Sardina pilchardus), sprat (Sprattus sprattus) and 52 macrozooplankton taxa were assayed for anchovy remains in the gut during the 2010 spawning season using a molecular method. This real-time PCR based assay was capable of detecting 0.005. ng of anchovy DNA (roughly 1/100 of a single egg assay) in a reliable way and allowed detecting predation events up to 6. h after ingestion by small zooplankton taxa. A total of 1069 macrozooplankton individuals, 237 sardines and 213 sprats were tested. Both fish species and 32 macrozooplankton taxa showed remains of anchovy DNA within their stomach contents. The two main findings are (1) that the previously neglected macrozooplankton impact in anchovy eggs/larvae mortality is in the same order of magnitude of that due to planktivorous fishes and that, (2) the predation pressure was notably different in the two main spawning centers of Bay of Biscay anchovy. While relatively low mortality rates were recorded at the shelf-break spawning center, a higher predation pressure from both fish and macrozooplankton was exerted at the shelf one.

  15. Datos recientes de la distribución de la siembra de especies exóticas como base de la producción pesquera en aguas interiores mexicanas Recent data on the distribution of the exotic species used in Mexican freshwater fisheries based on fish stocking

    Directory of Open Access Journals (Sweden)

    Ana L. Ibáñez

    2011-09-01

    Full Text Available Durante los años 2001-2009, el gobierno federal produjo 780 millones de crías pertenecientes a 22 taxa que se sembraron en cuerpos de agua interiores. El principal propósito de esta siembra fue la repoblación con fines pesqueros. Mediante información del mismo gobierno, se analiza la relación producción-siembra de crías de los Centros Piscícolas federales y su efecto en la producción pesquera estatal en aguas interiores mexicanas. Se plantea que esta producción está relacionada con la siembra de crías que llevó a cabo la Comisión Nacional de Acuacultura y Pesca (CONAPESCA, organismo desconcentrado del gobierno federal. Lo anterior fue revisado al analizar la correspondencia entre la densidad de crías sembradas y los rendimientos pesqueros estatales. De los 22 taxa, 19 son especies de peces (7 nativas y 2 son subespecies, 2 son anfibios nativos y 1 es un crustáceo malayo. En promedio, en el lapso, se sembraron anualmente 86.7 ± 37.9 millones de crías, de las que el 90% son tilapias y carpas, y sólo el 3% son especies nativas. La relación siembra/ha vs producción/ha muestra que a mayor densidad de siembra, se obtiene mayor rendimiento pesquero hasta alcanzar un valor asintótico. Si bien, el gobierno federal tiene actualmente por política no sembrar en cuerpos de agua naturales especies exóticas, éstas permanecen de siembras anteriores, o las siembran los gobiernos estatales o son de cultivos privados.Federal government produced around 780 millions of fry belonging to 22 taxa during 2001-2009 which were stocked in Mexican reservoirs basically to enhance fisheries. With official information from the federal fisheries agency CONAPESCA stocking-production analysis for the fish farms from the federal government was studied at state level. We review stocking-yield relationship at state level. From the 22 taxa: 19 are fish (7 native species and 2 subspecies; 2 native amphibious and 1 Malay crustacean. Production mean for nine

  16. Investment Strategies of Different Holding Periods: Evidence from Stock Markets of Hong Kong, Korea, Shanghai, and Taiwan

    OpenAIRE

    Massoud Moslehpour; Munkh-Ulzii Batmunkh

    2013-01-01

    Although there is abundant research focusing on estimating the level of returns on stock market, there is a lack of studies examining the comparison of stock return movements for short-term and long-term investment in the Asian stock market. The present study examines return on investment of different holding periods among selected stock markets in Asia. Based on the trading performance of key indices and market capitalization value, Korean Stock Exchange (KRE), Shanghai Stock Exchange (SSE),...

  17. Atlantic salmon brood stock management and breeding handbook

    Science.gov (United States)

    Kincaid, Harold L.; Stanley, Jon G.

    1989-01-01

    Anadromus runs of Atlantic salmon have been restored to the Connecticut, Merrimack, Pawcatuck, Penobscot, and St. Croix rivers in New England by the stocking of more than 8 million smolts since 1948. Fish-breeding methods have been developed that minimize inbreeding and domestication and enhance natural selection. Methods are available to advance the maturation of brood stock, control the sex of production lots and store gametes. Current hatchery practices emphasize the use of sea-run brood stock trapped upon return to the rivers and a limited number of captive brood stock and rejuvenated kelts. Fish are allowed to mature naturally, after which they are spawned and incubated artificially. Generally, 1-year smolts are produced, and excess fish are stocked as fry in headwater streams. Smolts are stocked during periods of rising water in spring. Self-release pools are planned that enable smolts to choose the emigration time. Culturists keep good records that permit evaluation of the performance of strains and the effects of breeding practices. As Atlantic salmon populations expand, culturists must use sound breeding methods that enhance biotic potential while maintaining genetic diversity and protecting unique gene pools.

  18. Listening in on the past: what can otolith δ18O values really tell us about the environmental history of fishes?

    Science.gov (United States)

    Darnaude, Audrey M; Sturrock, Anna; Trueman, Clive N; Mouillot, David; Campana, Steven E; Hunter, Ewan

    2014-01-01

    Oxygen isotope ratios from fish otoliths are used to discriminate marine stocks and reconstruct past climate, assuming that variations in otolith δ18O values closely reflect differences in temperature history of fish when accounting for salinity induced variability in water δ18O. To investigate this, we exploited the environmental and migratory data gathered from a decade using archival tags to study the behaviour of adult plaice (Pleuronectes platessa L.) in the North Sea. Based on the tag-derived monthly distributions of the fish and corresponding temperature and salinity estimates modelled across three consecutive years, we first predicted annual otolith δ18O values for three geographically discrete offshore sub-stocks, using three alternative plausible scenarios for otolith growth. Comparison of predicted vs. measured annual δ18O values demonstrated >96% correct prediction of sub-stock membership, irrespective of the otolith growth scenario. Pronounced inter-stock differences in δ18O values, notably in summer, provide a robust marker for reconstructing broad-scale plaice distribution in the North Sea. However, although largely congruent, measured and predicted annual δ18O values did not fully match [ corrected]. Small, but consistent, offsets were also observed between individual high-resolution otolith δ18O values measured during tag recording time and corresponding δ18O predictions using concomitant tag-recorded temperatures and location-specific salinity estimates. The nature of the shifts differed among sub-stocks, suggesting specific vital effects linked to variation in physiological response to temperature. Therefore, although otolith δ18O in free-ranging fish largely reflects environmental temperature and salinity, we counsel prudence when interpreting otolith δ18O data for stock discrimination or temperature reconstruction until the mechanisms underpinning otolith δ18O signature acquisition, and associated variation, are clarified.

  19. Estimating reach-specific fish movement probabilities in rivers with a Bayesian state-space model: application to sea lamprey passage and capture at dams

    Science.gov (United States)

    Holbrook, Christopher M.; Johnson, Nicholas S.; Steibel, Juan P.; Twohey, Michael B.; Binder, Thomas R.; Krueger, Charles C.; Jones, Michael L.

    2014-01-01

    Improved methods are needed to evaluate barriers and traps for control and assessment of invasive sea lamprey (Petromyzon marinus) in the Great Lakes. A Bayesian state-space model provided reach-specific probabilities of movement, including trap capture and dam passage, for 148 acoustic tagged invasive sea lamprey in the lower Cheboygan River, Michigan, a tributary to Lake Huron. Reach-specific movement probabilities were combined to obtain estimates of spatial distribution and abundance needed to evaluate a barrier and trap complex for sea lamprey control and assessment. Of an estimated 21 828 – 29 300 adult sea lampreys in the river, 0%–2%, or 0–514 untagged lampreys, could have passed upstream of the dam, and 46%–61% were caught in the trap. Although no tagged lampreys passed above the dam (0/148), our sample size was not sufficient to consider the lock and dam a complete barrier to sea lamprey. Results also showed that existing traps are in good locations because 83%–96% of the population was vulnerable to existing traps. However, only 52%–69% of lampreys vulnerable to traps were caught, suggesting that traps can be improved. The approach used in this study was a novel use of Bayesian state-space models that may have broader applications, including evaluation of barriers for other invasive species (e.g., Asian carp (Hypophthalmichthys spp.)) and fish passage structures for other diadromous fishes.

  20. Eastern Baltic cod in distress: biological changes and challenges for stock assessment

    DEFF Research Database (Denmark)

    Eero, Margit; Hjelm, Joakim; Behrens, Jane

    2015-01-01

    The eastern Baltic (EB) cod (Gadus morhua) stock was depleted and overexploited for decades until the mid-2000s, when fishing mortality rapidly declined and biomass started to increase, as shown by stock assessments. These positive developments were partly assigned to effective management measures...... that the stock is in distress. In this study, we (i) summarize the knowledge of recent changes in cod biology and ecosystem conditions, (ii) describe the subsequent challenges for stock assessment, and (iii) highlight the key questions where answers are urgently needed to understand the present stock status...

  1. Does Employee Stock Ownership Work?

    DEFF Research Database (Denmark)

    Kato, Takao; Miyajima, Hideaki; Owan, Hideo

    studies, we focus on the effects of changes in varying attributes of existing ESO—the effects on the intensive margin. Our fixed effect estimates show that an increase in the strength of the existing ESO plans measured by stake per employee results in statistically significant productivity gains....... Furthermore, such productivity gains are found to lead to profitability gains since wage gains from ESO plans are statistically significant yet rather modest. Our analysis of Tobin's Q suggests that the market tends to view such gains from ESO plans as permanent. We further find that increasing the stake......This paper provides novel evidence on the effects of employee stock ownership (ESO), using new panel data on Japanese ESO plans for a highly representative sample of publicly-traded firms in Japan (covering more than 75% of all firms listed on Tokyo Stock Exchange) over 1989-2013. Unlike most prior...

  2. US forest carbon calculation tool: forest-land carbon stocks and net annual stock change

    Science.gov (United States)

    James E. Smith; Linda S. Heath; Michael C. Nichols

    2007-01-01

    The Carbon Calculation Tool 4.0, CCTv40.exe, is a computer application that reads publicly available forest inventory data collected by the U.S. Forest Service's Forest Inventory and Analysis Program (FIA) and generates state-level annualized estimates of carbon stocks on forest land based on FORCARB2 estimators. Estimates can be recalculated as...

  3. Spatiotemporal dynamics of the Atlantic salmon (Salmo salar) Greenland fishery inferred from mixed-stock analysis

    Science.gov (United States)

    Gauthier-Ouellet, M.; Dionne, M.; Caron, F.; King, T.L.; Bernatchez, L.

    2009-01-01

    Mixed-stock fisheries refer to the exploitation of admixed fish stocks coming from different origins. We identified the North American origin of 2835 Atlantic salmon (Salmo salar) in the Greenland mixed-stock fishery during 11 years (1995-2006) at three localities using 13 microsatellites. The study included 52 baseline populations representing nine genetically distinct regional groups. The contribution of each group ranged from increasing contribution for Labrador (+14.9%) was observed during the time course of the study. The estimated regional contribution to the Greenland fishery was significantly correlated to the number of multi-sea-winter salmon regionally produced in 2002 (r = 0.79) and 2004 (r = 0.92). No difference in contribution was found between the three Greenland sampling localities. Ungava and Southern Qu??bec regions showed the highest mortality estimates caused by the fishery, ranging from 12.10% to 18.08%, for both years tested. No regional group was overrepresented in landings compared with their respective productivity. Yet, management precautions should still be taken as the fishery strongly selects large females, which could have evolutionary impacts on populations over the long term.

  4. Bayesian stock assessment of Pacific herring in Prince William Sound, Alaska.

    Science.gov (United States)

    Muradian, Melissa L; Branch, Trevor A; Moffitt, Steven D; Hulson, Peter-John F

    2017-01-01

    The Pacific herring (Clupea pallasii) population in Prince William Sound, Alaska crashed in 1993 and has yet to recover, affecting food web dynamics in the Sound and impacting Alaskan communities. To help researchers design and implement the most effective monitoring, management, and recovery programs, a Bayesian assessment of Prince William Sound herring was developed by reformulating the current model used by the Alaska Department of Fish and Game. The Bayesian model estimated pre-fishery spawning biomass of herring age-3 and older in 2013 to be a median of 19,410 mt (95% credibility interval 12,150-31,740 mt), with a 54% probability that biomass in 2013 was below the management limit used to regulate fisheries in Prince William Sound. The main advantages of the Bayesian model are that it can more objectively weight different datasets and provide estimates of uncertainty for model parameters and outputs, unlike the weighted sum-of-squares used in the original model. In addition, the revised model could be used to manage herring stocks with a decision rule that considers both stock status and the uncertainty in stock status.

  5. Bayesian stock assessment of Pacific herring in Prince William Sound, Alaska.

    Directory of Open Access Journals (Sweden)

    Melissa L Muradian

    Full Text Available The Pacific herring (Clupea pallasii population in Prince William Sound, Alaska crashed in 1993 and has yet to recover, affecting food web dynamics in the Sound and impacting Alaskan communities. To help researchers design and implement the most effective monitoring, management, and recovery programs, a Bayesian assessment of Prince William Sound herring was developed by reformulating the current model used by the Alaska Department of Fish and Game. The Bayesian model estimated pre-fishery spawning biomass of herring age-3 and older in 2013 to be a median of 19,410 mt (95% credibility interval 12,150-31,740 mt, with a 54% probability that biomass in 2013 was below the management limit used to regulate fisheries in Prince William Sound. The main advantages of the Bayesian model are that it can more objectively weight different datasets and provide estimates of uncertainty for model parameters and outputs, unlike the weighted sum-of-squares used in the original model. In addition, the revised model could be used to manage herring stocks with a decision rule that considers both stock status and the uncertainty in stock status.

  6. [PDF] from biogeosciences.net Global estimates of carbon stock changes in living forest biomass: EDGARv4. 3–time series from 1990 to 2010

    NARCIS (Netherlands)

    Petrescu, A.M.R.; Abad-Vinas, Raul; Janssens-Maenhout, Greet; Blujdea, Viorel; Grassi, Giacomo

    2012-01-01

    While the Emissions Database for Global Atmospheric Research (EDGAR) focuses on global estimates for the full set of anthropogenic activities, the Land Use, Land-Use Change and Forestry (LULUCF) sector might be the most diverse and most challenging to cover consistently for all countries of the

  7. Multifractal structures for the Russian stock market

    Science.gov (United States)

    Ikeda, Taro

    2018-02-01

    In this paper, we apply the multifractal detrended fluctuation analysis (MFDFA) to the Russian stock price returns. To the best of our knowledge, this paper is the first to reveal the multifractal structures for the Russian stock market by financial crises. The contributions of the paper are twofold. (i) Finding the multifractal structures for the Russian stock market. The generalized Hurst exponents estimated become highly-nonlinear to the order of the fluctuation functions. (ii) Computing the multifractality degree according to Zunino et al. (2008). We find that the multifractality degree of the Russian stock market can be categorized within emerging markets, however, the Russian 1998 crisis and the global financial crisis dampen the degree when we consider the order of the polynomial trends in the MFDFA.

  8. On the dynamics of exploited fish populations

    National Research Council Canada - National Science Library

    Beverton, R. J. H; Holt, Sidney J

    1993-01-01

    ...-brooding cichlids, and viviparity in many sharks and toothcarps. Moreover, fish are of considerable importance to the survival of the human species in the form of nutritious, delicious and diverse food. Rational exploitation and management of our global stocks of fishes must rely upon a detailed and precise insight of their biology. The...

  9. An Adjustment Restriction on Fish Quota

    NARCIS (Netherlands)

    Dijk, van Diana; Hendrix, E.M.T.; Haijema, Rene; Groeneveld, R.A.; Ierland, van E.C.

    2017-01-01

    Management objectives of the European Union for North Sea fish stocks are shifting towards considering both biological sustainability and economic benefits. As part of multiannual management plans, an adjustment restriction on fish quota has been introduced. Its objective is to obtain an

  10. Extension of biomass estimates to pre-assessment periods using density dependent surplus production approach.

    Directory of Open Access Journals (Sweden)

    Jan Horbowy

    Full Text Available Biomass reconstructions to pre-assessment periods for commercially important and exploitable fish species are important tools for understanding long-term processes and fluctuation on stock and ecosystem level. For some stocks only fisheries statistics and fishery dependent data are available, for periods before surveys were conducted. The methods for the backward extension of the analytical assessment of biomass for years for which only total catch volumes are available were developed and tested in this paper. Two of the approaches developed apply the concept of the surplus production rate (SPR, which is shown to be stock density dependent if stock dynamics is governed by classical stock-production models. The other approach used a modified form of the Schaefer production model that allows for backward biomass estimation. The performance of the methods was tested on the Arctic cod and North Sea herring stocks, for which analytical biomass estimates extend back to the late 1940s. Next, the methods were applied to extend biomass estimates of the North-east Atlantic mackerel from the 1970s (analytical biomass estimates available to the 1950s, for which only total catch volumes were available. For comparison with other methods which employs a constant SPR estimated as an average of the observed values, was also applied. The analyses showed that the performance of the methods is stock and data specific; the methods that work well for one stock may fail for the others. The constant SPR method is not recommended in those cases when the SPR is relatively high and the catch volumes in the reconstructed period are low.

  11. Radionuclides in resident and migratory fishes of a wedge bank region: Estimation of dose to human beings, South India

    International Nuclear Information System (INIS)

    Feroz Khan, M.; Godwin Wesley, S.

    2012-01-01

    Highlights: ► 137 Cs, 210 Po and 210 Pb accumulation in 47 species of marine fishes. ► Baseline data for Kudankulam Nuclear Power Project. ► Assessment of daily intake and committed effective dose. - Abstract: Baseline activity concentration of 137 Cs, 210 Po and 210 Pb was determined for 25 resident and 22 migratory fish species collected in a so-called wedge bank region in the extreme south of India. A nuclear power station is now under construction at Kudankulam near the target region and the data provide background information on the radionuclide activity concentration in the region. Three-way ANOVA revealed no significant variation in the concentrations of 137 Cs, 210 Po and 210 Pb between species based on feeding habit, habitat and migratory pattern except the effect of feeding habit on 210 Po concentration (p 137 Cs was negligibly small while those due to 210 Po and 210 Pb varied from 1.2 to 36.9 and 0.2 to 2.9 μSv yr −1 , respectively.

  12. Estimation of interfacial heat transfer coefficient in inverse heat conduction problems based on artificial fish swarm algorithm

    Science.gov (United States)

    Wang, Xiaowei; Li, Huiping; Li, Zhichao

    2018-04-01

    The interfacial heat transfer coefficient (IHTC) is one of the most important thermal physical parameters which have significant effects on the calculation accuracy of physical fields in the numerical simulation. In this study, the artificial fish swarm algorithm (AFSA) was used to evaluate the IHTC between the heated sample and the quenchant in a one-dimensional heat conduction problem. AFSA is a global optimization method. In order to speed up the convergence speed, a hybrid method which is the combination of AFSA and normal distribution method (ZAFSA) was presented. The IHTC evaluated by ZAFSA were compared with those attained by AFSA and the advanced-retreat method and golden section method. The results show that the reasonable IHTC is obtained by using ZAFSA, the convergence of hybrid method is well. The algorithm based on ZAFSA can not only accelerate the convergence speed, but also reduce the numerical oscillation in the evaluation of IHTC.

  13. SKEWNESS IN STOCK RETURNS: EVIDENCE FROM THE BUCHAREST STOCK EXCHANGE DURING 2000 – 2011

    Directory of Open Access Journals (Sweden)

    IULIAN PANAIT

    2012-05-01

    Full Text Available Our paper investigates the symmetry in stock returns of the 30 most liquid companies traded on Bucharest Stock Exchange during 2000 – 2011 and also the most representative 5 market indices. Our daily data shows that skewness estimates are slightly negative for most indices and individual stocks, but only a few present values significantly different from the characteristics of a normal distribution. We compare our results with skewness estimates for 21 major and emerging stock market indices around the world and find that such results are similar to other low capitalization and trading volume markets. For all the Romanian and international assets studied, the Studentized-Range (St-R and Jarque-Bera (J-B tests reject the hypothesis of normal distribution of daily returns.

  14. Biodiversity in floodplains with special reference to artificial stocking

    OpenAIRE

    Hossain, M.S.; Ehshan, M.A.; Mazid, M.A.; Rahman, S.; Razzaque, A.

    2000-01-01

    A five years investigation on fish biodiversity in connection with artificial stocking was conducted in three south-western floodplains of Bangladesh from 1992 to 1996. The ten top most available and ten rarest fish species were identified. Puntius sp., Channa punctatus, Mystus sp., Anabus testudinius, Ambasis sp., Colisha sp. and Macrobrachium sp. etc. were the most common available species. On the other hand, Mystus aor, Notopterus chitala, Clupisoma garua, Aplocheilus panchax, Ctenophmyngo...

  15. Fundamental volatility and stock returns : does fundamental volatility explain stock returns?

    OpenAIRE

    Selboe, Guner K.; Virdee, Jaspal Singh

    2017-01-01

    In this thesis, we investigate whether the fundamental uncertainty can explain the crosssection of stock returns. To measure the fundamental uncertainty, we estimate rolling standard deviations and accounting betas of four different fundamentals: revenues, gross profit, earnings and cash flows. The standard deviation and the beta of revenues significantly explain returns in the Fama-Macbeth procedure, but only appears significant among smaller stocks in the portfolio formation ...

  16. Alternatives in international diversification for investment portfolios focused in stocks of Lima Stock Exchange

    Directory of Open Access Journals (Sweden)

    Juan Carlos Ames Santillán

    2012-06-01

    Full Text Available This paper gives an estimation of efficient frontiers for investment portfolios, they include stocks from Lima Stock Exchange General Index, Dow Jones Industrial Average, Gold, Cooper, Fixed Income Instruments of Peruvian government and savings in Peruvian financial institutions. The paper concludes that risk of investment in local portfolio reduces as a consequence of diversification, gold is an important asset and contributes to reduce portfolio risk.

  17. Alternatives in international diversification for investment portfolios focused in stocks of Lima Stock Exchange

    OpenAIRE

    Ames Santillán, Juan Carlos

    2012-01-01

    This paper gives an estimation of efficient frontiers for investment portfolios, they include stocks from Lima Stock Exchange General Index, Dow Jones Industrial Average, Gold, Cooper, Fixed Income Instruments of Peruvian government and savings in Peruvian financial institutions. The paper concludes that risk of investment in local portfolio reduces as a consequence of diversification, gold is an important asset and contributes to reduce portfolio risk. El presente trabajo estima la fronte...

  18. Alternatives in international diversification for investment portfolios focused in stocks of Lima Stock Exchange

    OpenAIRE

    Juan Carlos Ames Santillán

    2012-01-01

    This paper gives an estimation of efficient frontiers for investment portfolios, they include stocks from Lima Stock Exchange General Index, Dow Jones Industrial Average, Gold, Cooper, Fixed Income Instruments of Peruvian government and savings in Peruvian financial institutions. The paper concludes that risk of investment in local portfolio reduces as a consequence of diversification, gold is an important asset and contributes to reduce portfolio risk.

  19. Invasion of parasitic isopods in marine fishes

    Directory of Open Access Journals (Sweden)

    Ganapathy Rameshkumar

    2013-02-01

    Full Text Available Objective: To carry out a detailed three-year observation study on isopod parasites infestation in fish. Methods: Fish samples were collected from different localities in various landing centers along the Tamil Nadu coastal area. The prevalence and mean intensity were calculated. The proximate composition of infestation and uninfestation were studied in different marine fishes. A comparative analysis of bacteria and fungi in the infected and uninfected regions of fishes were analysed. Results: Tweenty six species including 12 genera of isopods (Cymothoidae distributed in 39 species of marine fishes along the Tamil Nadu coast. The isopod parasites were attached in three different microhabitats in host fishes viz. , buccal, branchial and body surfaces. They exhibited host and site specific occurrence. Maximum prevalence 17.11% was recorded in March 2010 and minimum 0.27% in Febuary 2010. The intensity ranged from 1 to 1.7 parasites per fish during the different months from Decmber 2008 to November 2011. There was a decrease in the protein, carbohydrate and lipid content in the infested fishes compared to uninfected fishes. A comparative analysis of bacteria and fungi in the infected and uninfected region of fishes were analysed. It revealed that infected portions had dense bacterial load as observed in the lesions of infected fishes than uninfected fishes. Conclusion: Factors which are able to induce parasitic manifestation are stock quality, stocking density, environmental conditions, biological and physiological characteristics of parasite, zoo technical measures, food quantity, feeding strategies, etc.

  20. Increased stocking density influences the acute physiological stress response of common carp (Cyprinus carpio (L.))

    NARCIS (Netherlands)

    Ruane, N.M.; Carballo, E.C.; Komen, J.

    2002-01-01

    The physiological response of common carp, Cyprinus carpio (L.) to increased stocking density and an additional acute net confinement stressor was investigated. Stocking densities were increased from 28.4 to 56.8 or 113.6 kg m¿3 by the use of crowding screens and fish were sampled from the crowded

  1. Eastern Baltic cod in distress: biological changes and challenges for stock assessment

    DEFF Research Database (Denmark)

    Eero, Margit; Hjelm, Joakim; Behrens, Jane

    2015-01-01

    The eastern Baltic (EB) cod (Gadus morhua) stock was depleted and overexploited for decades until the mid-2000s, when fishing mortality rapidly declined and biomass started to increase, as shown by stock assessments. These positive developments were partly assigned to effective management measure...

  2. Methow River Studies, Washington: abundance estimates from Beaver Creek and the Chewuch River screw trap, methodology testing in the Whitefish Island side channel, and survival and detection estimates from hatchery fish releases, 2013

    Science.gov (United States)

    Martens, Kyle D.; Fish, Teresa M.; Watson, Grace A.; Connolly, Patrick J.

    2014-01-01

    , leaving one large pool near the bottom of the side channel and several shallow isolated pools that may or may not go dry. In seasonally connected side channels, juvenile salmonid survival in pools less than 100 cm average depth was lower than in pools greater than 100 cm average depth (Martens and Connolly, 2014). In this report, we document our field work and analysis completed in 2013. During 2013, USGS sampling efforts were focused on resampling of three reaches in Beaver Creek, testing methodology in the Whitefish Island side channel, conducting hatchery survival estimates, and operating a screw trap on the Chewuch River (funded by Yakama Nation; fig. 1). The Beaver Creek sampling effort was a revisit of three index sites sampled continuously from 2004 to 2007 to look at the fish response to barrier removal. Methodology testing in Whitefish Island side channel was done to determine the best method for evaluating fish populations after restoration efforts in side channels (previous sampling methods were determined to be ineffective after pools were deepened). Hatchery survival estimates were completed to monitor fish survival in the Methow and Columbia Rivers, while the screw trap was operated to estimate migrating fish populations in the Chewuch River and track passive integrated transponder (PIT)-tagged fish. In addition, we maintained a network of PIT-tag interrogation systems (PTIS), assisted Reclamation with fish removal events associated with stream restoration (two people for 9 days; 14 percent of summer field season), and conducted a stream metabolism study designed to help parameterize and calibrate the stream productivity model (Bellmore and others, 2014) with model validation.

  3. Size, growth, temperature and the natural mortality of marine fish

    DEFF Research Database (Denmark)

    Gislason, Henrik; Daan, Niels; Rice, Jake C.

    2010-01-01

    The natural mortality of exploited fish populations is often assumed to be a species-specific constant independent of body size. This assumption has important implications for size-based fish population models and for predicting the outcome of size-dependent fisheries management measures such as ......The natural mortality of exploited fish populations is often assumed to be a species-specific constant independent of body size. This assumption has important implications for size-based fish population models and for predicting the outcome of size-dependent fisheries management measures...... such as mesh-size regulations. To test the assumption, we critically review the empirical estimates of the natural mortality, M (year(-1)), of marine and brackish water fish stocks and model them as a function of von Bertalanffy growth parameters, L-infinity (cm) and K (year(-1)), temperature (Kelvin......) and length, L (cm). Using the Arrhenius equation to describe the relationship between M and temperature, we find M to be significantly related to length, L-infinity and K, but not to temperature (R-2 = 0.62, P Temperature and K are significantly correlated and when K is removed from...

  4. Partitioning of oxygen uptake between the gills and skin in fish larvae: a novel method for estimating cutaneous oxygen uptake.

    Science.gov (United States)

    Rombough, P J

    1998-06-01

    The goal of this study was to develop an alternative to the traditional rubber dam method for measuring cutaneous oxygen uptake in bimodally respiring (skin + gills) fish larvae. The method tested involved using microelectrodes to measure the PO2 gradient in the diffusive boundary layer adjacent to seven positions on the skin surface (one on the head, two on the yolk sac, two on the trunk, one at the base of the dorsal fin-fold and one on the proximal portion of the caudal fin-fold) of rainbow trout (Oncorhynchus mykiss) larvae in still water. The PO2 gradient (deltaPO2/delta x, where x is the distance from the skin surface) was then used to calculate area-specific rate of O2 uptake (.MO2/A) according to the Fick equation, .MO2/A=Dbeta(deltaPO2/deltax), where A is the cross-sectional area of the boundary layer, D is the diffusion coefficient and beta is the capacitance coefficient for O2 in water. The accuracy of the method was assessed by comparing it with the rubber dam method. After correcting for differences in body mass, the two methods gave essentially identical results. According to the boundary layer method, the mean (+/-95 % CI) rate of O2 uptake across the skin of newly hatched rainbow trout at 10 degrees C is 3.13+/-0.18 microg O2 cm-2h-1 (N=265). The corresponding value obtained using the rubber dam method was 3. 36+/-0.35 microg O2 cm-2 h-1 (N=27). The advantages of the boundary layer method are that it can be used with smaller, more delicate larvae and that variables, such as flow rate, that can affect the efficiency of gas exchange can be regulated more precisely. The boundary layer method also permits examination of regional differences in exchange efficiency, although in still water such differences do not appear to be significant in trout larvae. The mean steepness of the PO2 gradient in the boundary layer and, hence, the mean rate of area-specific O2 uptake were essentially the same (P>0.05) at all seven locations tested in this study. The

  5. The Differences Between Stock Splits and Stock Dividends

    DEFF Research Database (Denmark)

    Bechmann, Ken L.; Raaballe, Johannes

    It is often asserted that stock splits and stock dividends are purely cosmetic events. However, many studies have documented several stock market effects associated with stock splits and stock dividends. This paper examines the effects of these two types of events for the Danish stock market...... different. Second, the positive stock market reaction is closely related to associated changes in a firm's payout policy, but the relationship varies for the two types of events. Finally, there is only very weak evidence for a change in the liquidity of the stock. On the whole, after controlling...... for the firm's payout policy, the results suggest that a stock split is a cosmetic event and that a stock dividend on its own is considered negative news....

  6. Breathing life into fisheries stock assessments with citizen science.

    Science.gov (United States)

    Fairclough, D V; Brown, J I; Carlish, B J; Crisafulli, B M; Keay, I S

    2014-11-28

    Citizen science offers a potentially cost-effective way for researchers to obtain large data sets over large spatial scales. However, it is not used widely to support biological data collection for fisheries stock assessments. Overfishing of demersal fishes along 1,000 km of the west Australian coast led to restrictive management to recover stocks. This diminished opportunities for scientists to cost-effectively monitor stock recovery via fishery-dependent sampling, particularly of the recreational fishing sector. As fishery-independent methods would be too expensive and logistically-challenging to implement, a citizen science program, Send us your skeletons (SUYS), was developed. SUYS asks recreational fishers to voluntarily donate fish skeletons of important species from their catch to allow biological data extraction by scientists to produce age structures and conduct stock assessment analyses. During SUYS, recreational fisher involvement, sample sizes and spatial and temporal coverage of samples have dramatically increased, while the collection cost per skeleton has declined substantially. SUYS is ensuring sampling objectives for stock assessments are achieved via fishery-dependent collection and reliable and timely scientific advice can be provided to managers. The program is also encouraging public ownership through involvement in the monitoring process, which can lead to greater acceptance of management decisions.

  7. Stock Market Reactions to Fiscal Policy Shocks: Empirical Evidence ...

    African Journals Online (AJOL)

    This study sets out to investigate the effect of fiscal policy on stock market performance in Nigeria. Specifically, the study examines if shocks in government expenditure and government debt affects stock market performance. The period of the study is from 1981-2012. Following the VAR estimates, the variance ...

  8. Booms, busts and behavioural heterogeneity in stock prices

    NARCIS (Netherlands)

    Hommes, C.; in 't Veld, D.

    2015-01-01

    We estimate a behavioural heterogeneous agents model with boundedly rational traders who know the fundamental stock price, but disagree about the persistence of deviations from the fundamental. Some agents (fundamentalists) believe in mean-reversion of stock prices, while others (chartists) expect a

  9. Booms, busts and behavioural heterogeneity in stock prices

    NARCIS (Netherlands)

    Hommes, C.; in ‘t Veld, D.

    2017-01-01

    We estimate a behavioural heterogeneous agents model with boundedly rational traders who know the fundamental stock price, but disagree about the persistence of deviations from the fundamental. Some agents (fundamentalists) believe in mean-reversion of stock prices, while others (chartists) expect a

  10. Stock Market Reactions To Fiscal Policy Shocks: Empirical Evidence ...

    African Journals Online (AJOL)

    This study sets out to investigate the effect of fiscal policy on stock market performance in Nigeria. Specifically, the study examines if shocks in government expenditure and government debt affects stock market performance. The period of the study is from 1981-2012. Following the VAR estimates, the variance ...

  11. Market skewness risk and the cross section of stock returns

    NARCIS (Netherlands)

    Chang, B.; Christoffersen, P.; Jacobs, K.

    2013-01-01

    The cross section of stock returns has substantial exposure to risk captured by higher moments of market returns. We estimate these moments from daily Standard & Poor's 500 index option data. The resulting time series of factors are genuinely conditional and forward-looking. Stocks with high

  12. 75 FR 46912 - Draft 2010 Marine Mammal Stock Assessment Reports

    Science.gov (United States)

    2010-08-04

    ..., Niihau stock, Kure-Midway stock, and the Pearl and Hermes stock. The SAR for the Hawaii stock of... new bottlenose dolphin stocks are the Kauai-Niihau stock, Oahu stock, Four Islands stock, and the...

  13. Utilizing individual fish biomass and relative abundance models to map environmental niche associations of adult and juvenile targeted fishes.

    Science.gov (United States)

    Galaiduk, Ronen; Radford, Ben T; Harvey, Euan S

    2018-06-21

    Many fishes undergo ontogenetic habitat shifts to meet their energy and resource needs as they grow. Habitat resource partitioning and patterns of habitat connectivity between conspecific fishes at different life-history stages is a significant knowledge gap. Species distribution models were used to examine patterns in the relative abundance, individual biomass estimates and environmental niche associations of different life stages of three iconic West Australian fishes. Continuous predictive maps describing the spatial distribution of abundance and individual biomass of the study species were created as well predictive hotspot maps that identify possible areas for aggregation of individuals of similar life stages of multiple species (i.e. spawning grounds, fisheries refugia or nursery areas). The models and maps indicate that processes driving the abundance patterns could be different from the body size associated demographic processes throughout an individual's life cycle. Incorporating life-history in the spatially explicit management plans can ensure that critical habitat of the vulnerable stages (e.g. juvenile fish, spawning stock) is included within proposed protected areas and can enhance connectivity between various functional areas (e.g. nursery areas and adult populations) which, in turn, can improve the abundance of targeted species as well as other fish species relying on healthy ecosystem functioning.

  14. Politics and the Stock Market ; Evidence from Germany

    OpenAIRE

    Jörg Döpke; Christian Pierdzioch

    2004-01-01

    We analyze the interaction of stock market movements and politics in Germany. In contrast to the empirical evidence available for the U.S., we do not find that German stock market returns tend to be higher during liberal than during conservative governments. Also in contrast to results for the U.S., we find no evidence for an election cycle in German stock market returns. However, estimated popularity functions and VARs suggest that stock market returns have had an impact on the popularity of...

  15. DLA Forward Stocking

    National Research Council Canada - National Science Library

    Flory, John

    2007-01-01

    .... This study evaluates the feasibility of forward stocking in terms of DoD savings. The performance of DLA's criteria is evaluated and a new criteria using a cost and demand threshold is proposed...

  16. Natural mortality estimation and rational exploitation of purpleback flying squid Sthenoteuthis oualaniensis in the southern South China Sea

    Science.gov (United States)

    Wang, Xuehui; Qiu, Yongsong; Zhang, Peng; Du, Feiyan

    2017-07-01

    Based on the biological data of purpleback flying squid ( Sthenoteuthis oualaniensis) collected by light falling-net in the southern South China Sea (SCS) during September to October 2012 and March to April 2013, growth and mortality of `Medium' and `Dwarf' forms of squid are derived using the Powell-Wetherall, ELEFAN methods and length-converted catch curves (FiSAT package). Given a lack of commercial exploitation, we assume total mortality to be due entirely to natural mortality. We estimate these squid have fast growth, with growth coefficients ( k) ranging from 1.42 to 2.39, and high natural mortality ( M), with estimates ranging from 1.61 to 2.92. To sustainably exploit these squid stocks, yield per recruitment based on growth and natural mortality was determined using the Beverton-Holt dynamic pool model. We demonstrate squid stocks could sustain high fishing mortality and low ages at first capture, with an optimal fishing mortality >3.0, with the optimal age at first capture increased to 0.4-0.6 years when fishing mortality approached optimal levels. On the basis of our analyses and estimates of stock biomass, we believe considerable potential exists to expand the squid fishery into the open SCS, relieving fishing pressure on coastal waters.

  17. Oil prices and the stock prices of alternative energy companies

    International Nuclear Information System (INIS)

    Henriques, Irene; Sadorsky, Perry

    2008-01-01

    Energy security issues coupled with increased concern over the natural environment are driving factors behind oil price movements. While it is widely accepted that rising oil prices are good for the financial performance of alternative energy companies, there has been relatively little statistical work done to measure just how sensitive the financial performance of alternative energy companies are to changes in oil prices. In this paper, a four variable vector autoregression model is developed and estimated in order to investigate the empirical relationship between alternative energy stock prices, technology stock prices, oil prices, and interest rates. Our results show technology stock prices and oil prices each individually Granger cause the stock prices of alternative energy companies. Simulation results show that a shock to technology stock prices has a larger impact on alternative energy stock prices than does a shock to oil prices. These results should be of use to investors, managers and policy makers. (author)

  18. effect of stocking density on production of clarias gariepinus

    African Journals Online (AJOL)

    DR. AMINU

    Three hundred (300) fish with a total weight of 1.8Kg were stocked at 25, ... Northern part of Nigeria as compared to the Southern ..... North. American Journal of. Aquaculture 63: 201-207. Eroudo, E. S., Nnubai, C. ... functioning of freshwater.

  19. Effect of Stocking Density on Growth Performance of Hybrids of ...

    African Journals Online (AJOL)

    Fingerlings of Oreochromis niloticus♀ and Oreochromis urolepis urolepis♂ hybrids were reared at stocking densities of control, 5, 10, 15 and 20 fish/m3 at 15 Practical Salinity Units (PSU) in 1m3 plastic tanks for 63 days. They were kept at low, intermediate and high densities respectively. All hybrids were fed on a ...

  20. STOCK ENHANCEMENT IN INDONESIAN LAKE AND RESERVOIRS FISHERIES

    Directory of Open Access Journals (Sweden)

    Endi Setiadi Kartamihardja

    2012-12-01

    enhancement including providing quality and quantity of seeds, regulating of fish catch, developin g of market system, institution and fisheries co-management have supported a steady yearly increase in yield. The governments should take the initiative in protection of genetic diversity, especially in stock enhancement of lakes inhabited by endemic and or threatened species, such as lakes in Sulawesi and Papua Island.

  1. Trading network predicts stock price.

    Science.gov (United States)

    Sun, Xiao-Qian; Shen, Hua-Wei; Cheng, Xue-Qi

    2014-01-16

    Stock price prediction is an important and challenging problem for studying financial markets. Existing studies are mainly based on the time series of stock price or the operation performance of listed company. In this paper, we propose to predict stock price based on investors' trading behavior. For each stock, we characterize the daily trading relationship among its investors using a trading network. We then classify the nodes of trading network into three roles according to their connectivity pattern. Strong Granger causality is found between stock price and trading relationship indices, i.e., the fraction of trading relationship among nodes with different roles. We further predict stock price by incorporating these trading relationship indices into a neural network based on time series of stock price. Experimental results on 51 stocks in two Chinese Stock Exchanges demonstrate the accuracy of stock price prediction is significantly improved by the inclusion of trading relationship indices.

  2. Evidence of market-driven size-selective fishing and the mediating effects of biological and institutional factors

    Science.gov (United States)

    Reddy, Sheila M. W.; Wentz, Allison; Aburto-Oropeza, Octavio; Maxey, Martin; Nagavarapu, Sriniketh; Leslie, Heather M.

    2014-01-01

    Market demand is often ignored or assumed to lead uniformly to the decline of resources. Yet little is known about how market demand influences natural resources in particular contexts, or the mediating effects of biological or institutional factors. Here, we investigate this problem by examining the Pacific red snapper (Lutjanus peru) fishery around La Paz, Mexico, where medium or “plate-sized” fish are sold to restaurants at a premium price. If higher demand for plate-sized fish increases the relative abundance of the smallest (recruit size class) and largest (most fecund) fish, this may be a market mechanism to increase stocks and fishermen’s revenues. We tested this hypothesis by estimating the effect of prices on the distribution of catch across size classes using daily records of prices and catch. We linked predictions from this economic choice model to a staged-based model of the fishery to estimate the effects on the stock and revenues from harvest. We found that the supply of plate-sized fish increased by 6%, while the supply of large fish decreased by 4% as a result of a 13% price premium for plate-sized fish. This market-driven size selection increased revenues (14%) but decreased total fish biomass (−3%). However, when market-driven size selection was combined with limited institutional constraints, both fish biomass (28%) and fishermen’s revenue (22%) increased. These results show that the direction and magnitude of the effects of market demand on biological populations and human behavior can depend on both biological attributes and institutional constraints. Fisheries management may capitalize on these conditional effects by implementing size-based regulations when economic and institutional incentives will enhance compliance, as in the case we describe here, or by creating compliance enhancing conditions for existing regulations. PMID:23865225

  3. Evidence of market-driven size-selective fishing and the mediating effects of biological and institutional factors.

    Science.gov (United States)

    Reddy, Sheila M W; Wentz, Allison; Aburto-Oropeza, Octavio; Maxey, Martin; Nagavarapu, Sriniketh; Leslie, Heather M

    2013-06-01

    Market demand is often ignored or assumed to lead uniformly to the decline of resources. Yet little is known about how market demand influences natural resources in particular contexts, or the mediating effects of biological or institutional factors. Here, we investigate this problem by examining the Pacific red snapper (Lutjanus peru) fishery around La Paz, Mexico, where medium or "plate-sized" fish are sold to restaurants at a premium price. If higher demand for plate-sized fish increases the relative abundance of the smallest (recruit size class) and largest (most fecund) fish, this may be a market mechanism to increase stocks and fishermen's revenues. We tested this hypothesis by estimating the effect of prices on the distribution of catch across size classes using daily records of prices and catch. We linked predictions from this economic choice model to a staged-based model of the fishery to estimate the effects on the stock and revenues from harvest. We found that the supply of plate-sized fish increased by 6%, while the supply of large fish decreased by 4% as a result of a 13% price premium for plate-sized fish. This market-driven size selection increased revenues (14%) but decreased total fish biomass (-3%). However, when market-driven size selection was combined with limited institutional constraints, both fish biomass (28%) and fishermen's revenue (22%) increased. These results show that the direction and magnitude of the effects of market demand on biological populations and human behavior can depend on both biological attributes and institutional constraints. Fisheries management may capitalize on these conditional effects by implementing size-based regulations when economic and institutional incentives will enhance compliance, as in the case we describe here, or by creating compliance enhancing conditions for existing regulations.

  4. Genetic stock identification of Atlantic salmon (Salmo salar populations in the southern part of the European range

    Directory of Open Access Journals (Sweden)

    McGinnity Philip

    2010-04-01

    Full Text Available Abstract Background Anadromous migratory fish species such as Atlantic salmon (Salmo salar have significant economic, cultural and ecological importance, but present a complex case for management and conservation due to the range of their migration. Atlantic salmon exist in rivers across the North Atlantic, returning to their river of birth with a high degree of accuracy; however, despite continuing efforts and improvements in in-river conservation, they are in steep decline across their range. Salmon from rivers across Europe migrate along similar routes, where they have, historically, been subject to commercial netting. This mixed stock exploitation has the potential to devastate weak and declining populations where they are exploited indiscriminately. Despite various tagging and marking studies, the effect of marine exploitation and the marine element of the salmon lifecycle in general, remain the "black-box" of salmon management. In a number of Pacific salmonid species and in several regions within the range of the Atlantic salmon, genetic stock identification and mixed stock analysis have been used successfully to quantify exploitation rates and identify the natal origins of fish outside their home waters - to date this has not been attempted for Atlantic salmon in the south of their European range. Results To facilitate mixed stock analysis (MSA of Atlantic salmon, we have produced a baseline of genetic data for salmon populations originating from the largest rivers from Spain to northern Scotland, a region in which declines have been particularly marked. Using 12 microsatellites, 3,730 individual fish from 57 river catchments have been genotyped. Detailed patterns of population genetic diversity of Atlantic salmon at a sub-continent-wide level have been evaluated, demonstrating the existence of regional genetic signatures. Critically, these appear to be independent of more commonly recognised terrestrial biogeographical and political

  5. Biological and communication skills needed for introduced fish biologists

    Science.gov (United States)

    Bonar, Scott A.

    2016-01-01

    What skills and knowledge will a new graduate seeking employment need to work with introduced fishes? Clearly, success in introduced species management—similar to other disciplines in fisheries—requires a mixture of scientific and communication skills. However, specific abilities especially important to a biologist who manages introduced fishes should be highlighted. Unlike most other management strategies, stocking an introduced species can result in unintended and irreversible impacts, so particular care must be employed when stocking is considered. Furthermore, fish populations in areas outside of the introduced species management area might also be affected, usually negatively, if the introduced fish escapes. Therefore, rock-solid knowledge of basic aquatic ecology, including risk management; fish taxonomy (so the wrong fish species is not mistakenly stocked!); familiarity with human values of both the time and the place (which requires communication skills); and a strong understanding of human history are all important.

  6. Can reduced stocking rates and natural forage utilization produce market sized catfish from fingerlings in one growing season

    Science.gov (United States)

    The purpose of this study was to determine the feasibility of growing marketable channel catfish Ictalurus punctatus from pond-run fingerlings (15.9 g/fish) using low stocking densities (7,413 or 14,826 fish/ha) and electrified bug lights to enhance natural forage available to fish. Even at low sto...

  7. Spatial distribution of soil organic carbon stocks in France

    Directory of Open Access Journals (Sweden)

    M. P. Martin

    2011-05-01

    Full Text Available Soil organic carbon plays a major role in the global carbon budget, and can act as a source or a sink of atmospheric carbon, thereby possibly influencing the course of climate change. Changes in soil organic carbon (SOC stocks are now taken into account in international negotiations regarding climate change. Consequently, developing sampling schemes and models for estimating the spatial distribution of SOC stocks is a priority. The French soil monitoring network has been established on a 16 km × 16 km grid and the first sampling campaign has recently been completed, providing around 2200 measurements of stocks of soil organic carbon, obtained through an in situ composite sampling, uniformly distributed over the French territory.

    We calibrated a boosted regression tree model on the observed stocks, modelling SOC stocks as a function of other variables such as climatic parameters, vegetation net primary productivity, soil properties and land use. The calibrated model was evaluated through cross-validation and eventually used for estimating SOC stocks for mainland France. Two other models were calibrated on forest and agricultural soils separately, in order to assess more precisely the influence of pedo-climatic variables on SOC for such soils.

    The boosted regression tree model showed good predictive ability, and enabled quantification of relationships between SOC stocks and pedo-climatic variables (plus their interactions over the French territory. These relationships strongly depended on the land use, and more specifically, differed between forest soils and cultivated soil. The total estimate of SOC stocks in France was 3.260 ± 0.872 PgC for the first 30 cm. It was compared to another estimate, based on the previously published European soil organic carbon and bulk density maps, of 5.303 PgC. We demonstrate that the present estimate might better represent the actual SOC stock distributions of France, and consequently that the

  8. Using alternative biological information in stock assessment: condition-corrected natural mortality of Eastern Baltic cod

    DEFF Research Database (Denmark)

    Casini, Michele; Eero, Margit; Carlshamre, Sofia

    2016-01-01

    ) assumed in the analytical stock assessment model. The results in terms of Spawning Stock Biomass (SSB), Fishing mortality (F) and Recruitment (R) in the final year from the stock assessment using M values adjusted for low condition were up to 40% different compared with the assessment assuming a constant......The inclusion of biological and ecological aspects in the assessment of fish population status is one of the bases for an ecosystem-based fisheries management. During the past two decades the Eastern Baltic cod has experienced a drastic reduction in growth and body condition that may have affected...

  9. Modeling the stock price returns volatility using GARCH(1,1) in some Indonesia stock prices

    Science.gov (United States)

    Awalludin, S. A.; Ulfah, S.; Soro, S.

    2018-01-01

    In the financial field, volatility is one of the key variables to make an appropriate decision. Moreover, modeling volatility is needed in derivative pricing, risk management, and portfolio management. For this reason, this study presented a widely used volatility model so-called GARCH(1,1) for estimating the volatility of daily returns of stock prices of Indonesia from July 2007 to September 2015. The returns can be obtained from stock price by differencing log of the price from one day to the next. Parameters of the model were estimated by Maximum Likelihood Estimation. After obtaining the volatility, natural cubic spline was employed to study the behaviour of the volatility over the period. The result shows that GARCH(1,1) indicate evidence of volatility clustering in the returns of some Indonesia stock prices.

  10. Benchmark values for forest soil carbon stocks in Europe

    DEFF Research Database (Denmark)

    De Vos, Bruno; Cools, Nathalie; Ilvesniemi, Hannu

    2015-01-01

    Soil organic carbon (SOC) stocks in forest floors and in mineral and peat forest soils were estimated at the European scale. The assessment was based on measured C concentration, bulk density, coarse fragments and effective soil depth data originating from 4914 plots in 22 EU countries belonging...... to the UN/ECE ICP Forests 16 × 16 km Level I network. Plots were sampled and analysed according to harmonized methods during the 2nd European Forest Soil Condition Survey. Using continuous carbon density depth functions, we estimated SOC stocks to 30-cm and 1-m depth, and stratified these stocks according...... to 22 WRB Reference Soil Groups (RSGs) and 8 humus forms to provide European scale benchmark values. Average SOC stocks amounted to 22.1 t C ha− 1 in forest floors, 108 t C ha− 1 in mineral soils and 578 t C ha− 1 in peat soils, to 1 m depth. Relative to 1-m stocks, the vertical SOC distribution...

  11. Combining split-beam and dual-frequency identification sonars to estimate abundance of anadromous fishes in the Roanoke River, North Carolina

    Science.gov (United States)

    Hughes, Jacob B.; Hightower, Joseph E.

    2015-01-01

    Riverine hydroacoustic techniques are an effective method for evaluating abundance of upstream migrating anadromous fishes. To use these methods in the Roanoke River, North Carolina, at a wide site with uneven bottom topography, we used a combination of split-beam sonar and dual-frequency identification sonar (DIDSON) deployments. We aimed a split-beam sonar horizontally to monitor midchannel and near-bottom zones continuously over the 3-month spring monitoring periods in 2010 and 2011. The DIDSON was rotated between seven cross-channel locations (using a vertical aim) and nearshore regions (using horizontal aims). Vertical deployment addressed blind spots in split-beam coverage along the bottom and provided reliable information about the cross-channel and vertical distributions of upstream migrants. Using a Bayesian framework, we modeled sonar counts within four cross-channel strata and apportioned counts by species using species proportions from boat electrofishing and gill netting. Modeled estimates (95% credible intervals [CIs]) of total upstream migrants in 2010 and 2011 were 2.5 million (95% CI, 2.4–2.6 million) and 3.6 million (95% CI, 3.4–3.9 million), respectively. Results indicated that upstream migrants are extremely shore- and bottom-oriented, suggesting nearshore DIDSON monitoring improved the accuracy and precision of our estimates. This monitoring protocol and model may be widely applicable to river systems regardless of their cross-sectional width or profile.

  12. Fish community status in Norwegian lakes in relation to acidification: a comparison between interviews and actual catches by test fishing

    Energy Technology Data Exchange (ETDEWEB)

    Hesthagen, T.; Berger, H.M.; Larsen, B.M. (Norwegian Inst. for Nature Research, Trondheim (Norway)); Rosseland, B.O. (Norwegian Inst. for Water Research, Oslo (Norway))

    1993-01-01

    Inquiries are used to obtain information on fish community status in terms of unchanged, reduced and lost communities, to assess the effects of acidification in lakes. The aim of this paper was to investigate the validity of this method by comparing fish status with actual catches on standard gill net series (CPUE). Data from 230 test fishing incidents comprising 357 stocks of 7 different fish species are presented. We found significant differences in CPUE between perceived fish status categories for brown trout (Salmo trutta), arctic char (Salvelinus alpinus) and perch (Perca fluviatilis), for which sufficient data were available. A discriminant analysis revealed that for stocks reported as unchanged and lost, the predicted membership ranged between 60.0-72.1 % respectively. However, a dominant fraction (50.0-66.7 %) of stocks reported as reduced were assigned as lost. Stocks which have been declining for less than 10 years, had a significantly higher CPUE than stocks which have declined for a longer period of time. Another apparent change in population characteristics was an acidification induced increase in mean weight for fish affected stocks. It is suggested that interviews tend to overestimate the current fish status. This is discussed in relation to a time lag between the damage and the time when it became apparent to fishermen, and rapid decline in population numbers. 26 refs, 2 figs, 4 tabs

  13. Potential gains in storage on productive forestlands in the northeastern United Sates through stocking management

    Science.gov (United States)

    Coeli Hoover; Linda S. Heath

    2011-01-01

    One method of increasing forest carbon stocks that is often discussed is increasing stocking levels on existing forested lands. However, estimates of the potential increases in forest carbon sequestration as a result of increased stocking levels are not readily available. Using the USDA Forest Service's Forest Inventory and Analysis data coupled with the Forest...

  14. Stock assessment of the lizardfish Saurida tumbil (Bloch, 1795 in Jizan fisheries, Saudi Arabia

    Directory of Open Access Journals (Sweden)

    Mohamed Hosny Gabr

    2017-06-01

    Full Text Available To evaluate the current stock status of the lizardfish Saurida tumbil in Jizan fisheries, growth parameters, mortality coefficients and size at first capture were determined. Otoliths collected from 623 specimens were used for age determination and back calculations of lengths at ages. The growth parameters of von Bertalanffy were estimated and found to be L∞ = 52.98 cm, K = 0.27 yr−1, and to = -0.84 yr. The mortality coefficients were estimated to be 1.365, 0.403 and 0.962 yr−1 for the total 'Z', natural 'M', and fishing 'F' mortality coefficient, respectively. The current exploitation rate 'Ecur' was 0.705 yr−1. The length at first capture 'Lc' was determined to be 25.1 cm. The relative yield and biomass per recruit were estimated, and the results showed that the exploitation rate is currently higher than Emax = 0.685 yr−1 and E0.1 = 0.551 yr−1 as biological reference points, which indicates that the stock of Saurida tumbil in Jizan fisheries is currently overexploited.

  15. ACCOUNTING TREATMENTS USED IN STOCKS VALUATION

    Directory of Open Access Journals (Sweden)

    Suciu Gheorghe

    2012-12-01

    Full Text Available Accounting treatments represent the methods used by a company to apply its own accounting policies. Accounting treatments can be divided into two categories: basic accounting treatments and alternative treatments. Stocks represent the quantities of material resources, half-finished goods, finished goods which stockpile in supply repositories of the economic entities, with a certain structure and volume, for a certain period of time, in order to ensure continuity and regularity of the manufacturing process and of consumption. Stocks will be acknowledges only when the company is likely to make an economic benefit and when the costs and values can be estimated in a credible way.

  16. Commodities and Stock Investment

    Directory of Open Access Journals (Sweden)

    Syed Jawad Hussain Shahzad

    2014-09-01

    Full Text Available This study is a multivariate analysis of commodities and stock investment in a newly established market scenario. Return distribution asymmetry is examined with higher order movements. Skewness in commodity future’s return is largely insignificant, whereas kurtosis is highly significant for both stock and commodity future contracts. Correlation analysis is done with Pearson’s and Kendall’s tau measures. Commodities provide significant diversification benefits when added in a portfolio of stocks. Compared with stocks, commodity future’s returns show stronger correlation with unexpected inflation. The volatility is measured through Glosten-Jagannathan-Runkle - Generalized Autoregressive Conditional Heteroskedasticity (GJR-GARCH model and reflects that commodities have inverted asymmetric behavior, that is, more impact from the upward shocks compared with downward. Stocks have asymmetric volatility, that is, more impact from negative shocks compared with positive. Gold has highest inverted asymmetric volatility. Tail dependence, measured through Student’s t copula, shows no combined downside movement. In conclusion, commodity investments provide diversification and inflation protection.

  17. Endogenous fishing mortalities: a state-space bioeconomic model

    OpenAIRE

    DA-ROCHA JOSÉ MARIA; GARCÍA-CUTRÍN JAVIER; GUTIÉRREZ MARÍA-JOSÉ; GAMITO JARDIM JOSÉ ERNESTO

    2017-01-01

    A methodology that endogenously determines catchability functions that link fishing mortality with contemporaneous stock abundance is presented. We consider a stochastic age-structured model for a fishery composed by a number of fishing units (fleets, vessels or métiers) that optimally select the level of fishing effort to be applied considering total mortalities as given. The introduction of a balance constrain which guarantees that total mortality is equal to the sum of individual fishing m...

  18. the mauritius stock exchange: sectoral analysis, risk and return

    African Journals Online (AJOL)

    cistvr

    In Section III beta estimates are calculated for each share using the Capital. Asset Pricing ... In a stock market therefore, investors would need information such as the ..... In Mauritius however, capital account restrictions were lifted only in 1995 ...

  19. Stock discrimination in Great Lakes Walleye using mitochondrial DNA restriction analysis

    International Nuclear Information System (INIS)

    Billington, N.; Hebert, P.D.N.

    1986-01-01

    Over the past two years it has become evident that because of its strict maternal inheritance and rapid rate of evolutionary differentiation, mitochondrial (mt) DNA diversity offers exceptional promise in the discrimination of fish stocks. The current project aims to determine the extent of mt DNA variation among stocks of walleye (Stizostedion vitreum) from the Great Lakes. At this point, mt DNA has been isolated from 68 walleye representing the Thames River stock and a reef breeding stock from western Lake Erie, as well as from individuals of S. canadense, a species which hybridizes with S. vitreum. Mitochondrial DNA was extracted from livers of these fish, purified by CsCl density gradient centrifugation and digested using 20 endonucleases. Polymorphisms were detected with 8 of the enzymes. There was a great deal of variation among fish from both spawning populations, so much so that individual fish could be identified by this technique. No single enzyme allowed discrimination of the two stocks, but restriction pattern variation following Dde I digestion permitted separation of 50% of Lake Erie fish from Thames River stock. Comparison of mt DNA restriction patterns of walleye and sauger showed that two species are easily separable, setting the stage for a more detailed study of hybridization between the taxa

  20. Framework of stock-recovery strategies: analyses of factors affecting success and failure

    DEFF Research Database (Denmark)

    Hammer, Cornelius; Dorrien, Christian von; Hopkins, Christopher C. E.

    2010-01-01

    The EU FP6 UNCOVER project was aimed at producing a rational scientific basis for developing recovery strategies for some ecologically and socio-economically important fish stocks/fisheries in European seas. The immediate objectives were to identify changes experienced during stock depletion...... to the recovery of more than 30 fish stocks/fisheries worldwide by multivariate exploratory analysis (canonical correspondence analysis), followed by model building [discriminant analysis (DA)] to quantify the relative importance of key performance criteria, singly or combined. Using the existing database, DA...... indicated that the four best additive predictors of successful recovery were “rapid reduction in fishing mortality”, “environmental conditions during the recovery period”, “life-history characteristics” of the target stock, and “management performance criteria”. The model classified the status “recovered...

  1. Energy savings in Danish residential building stock

    DEFF Research Database (Denmark)

    Tommerup, Henrik M.; Svendsen, Svend

    2006-01-01

    a short account of the technical energy-saving possibilities that are present in existing dwellings and presents a financial methodology used for assessing energy-saving measures. In order to estimate the total savings potential detailed calculations have been performed in a case with two typical...... buildings representing the residential building stock and based on these calculations an assessment of the energy-saving potential is performed. A profitable savings potential of energy used for space heating of about 80% is identified over 45 years (until 2050) within the residential building stock......A large potential for energy savings exists in the Danish residential building stock due to the fact that 75% of the buildings were constructed before 1979 when the first important demands for energy performance of building were introduced. It is also a fact that many buildings in Denmark face...

  2. Modelling the impact of oil prices on Vietnam's stock prices

    International Nuclear Information System (INIS)

    Narayan, Paresh Kumar; Narayan, Seema

    2010-01-01

    The goal of this paper is to model the impact of oil prices on Vietnam's stock prices. We use daily data for the period 2000-2008 and include the nominal exchange rate as an additional determinant of stock prices. We find that stock prices, oil prices and nominal exchange rates are cointegrated, and oil prices have a positive and statistically significant impact on stock prices. This result is inconsistent with theoretical expectations. The growth of the Vietnamese stock market was accompanied by rising oil prices. However, the boom of the stock market was marked by increasing foreign portfolio investment inflows which are estimated to have doubled from US$0.9 billion in 2005 to US$1.9 billion in 2006. There was also a change in preferences from holding foreign currencies and domestic bank deposits to stocks local market participants, and there was a rise in leveraged investment in stock as well as investments on behalf of relatives living abroad. It seems that the impact of these internal and domestic factors were more dominant than the oil price rise on the Vietnamese stock market. (author)

  3. Analyses of Trawling Track and Fishing Activity Based on the Data of Vessel Monitoring System (VMS):A Case Study of the Single Otter Trawl Vessels in the Zhoushan Fishing Ground

    Institute of Scientific and Technical Information of China (English)

    WANG Yang; WANG Yingbin; ZHENG Ji

    2015-01-01

    The original purpose of Vessel Monitoring System (VMS) is for enforcement and control of vessel sailing. With the ap-plication of VMS in fishing vessels, more and more population dynamic studies have used VMS data to improve the accuracy of fisheries stock assessment. In this paper, we simulated the trawl trajectory under different time intervals using the cubic Hermite spline (cHs) interpolation method based on the VMS data of 8 single otter trawl vessels (totally 36000 data items) fishing in Zhou-shan fishing ground from September 2012 to December 2012, and selected the appropriate time interval. We then determined vessels’ activities (fishing or non-fishing) by comparing VMS speed data with the corresponding speeds from logbooks. The results showed that the error of simulated trajectory greatly increased with the increase of time intervals of VMS data when they were longer than 30 minutes. Comparing the speeds from VMS with those from the corresponding logbooks, we found that the vessels’ speeds were be-tween 2.5kn and 5.0kn in fishing. The cHs interpolation method is a new choice for improving the accuracy of estimation of sailing trajectory, and the VMS can be used to determine the vessels’ activities with the analysis of their trajectories and speeds. Therefore, when the fishery information is limited, VMS can be one of the important data sources for fisheries stock assessment, and more at-tention should be paid to its construction and application to fisheries stock assessment and management.

  4. A test for the relative strength of maternal and stock effects in spring Chinook salmon (Oncorhynchus tshawytscha) from two different hatcheries (Study site: Warm Springs Hatchery; Stocks: Warm Springs Hatchery and Carson Hatchery; Year class: 1993): Chapter 10

    Science.gov (United States)

    Wetzel, Lisa A.; Rubin, Stephen P.; Reisenbichler, Reginald R.; Stenberg, Karl D.; Rubin, Stephen P.; Reisenbichler, Reginald R.; Wetzel, Lisa A.; Hayes, Michael C.

    2012-01-01

    An experiment was undertaken to determine the relative strength of maternal and stock effects in Chinook salmon (Oncorhynchus tshawytscha) reared in a common environment, as a companion study to our investigation of hatchery and wild Chinook salmon. Pure-strain and reciprocal crosses were made between two hatchery stocks (Carson and Warm Springs National Fish Hatcheries). The offspring were reared together in one of the hatcheries to the smolt stage, and then were transferred to a seawater rearing facility (USGS-Marrowstone Field Station). Differences in survival, growth and disease prevalence were assessed. Fish with Carson parentage grew to greater size at the hatchery and in seawater than the pure-strain Warm Springs fish, but showed higher mortality at introduction to seawater. The analyses of maternal and stock effects were inconclusive, but the theoretical responses to different combinations of maternal and stock effects may be useful in interpreting stock comparison studies.

  5. Effects of human population density and proximity to markets on coral reef fishes vulnerable to extinction by fishing.

    Science.gov (United States)

    Brewer, T D; Cinner, J E; Green, A; Pressey, R L

    2013-06-01

    Coral reef fisheries are crucial to the livelihoods of tens of millions of people; yet, widespread habitat degradation and unsustainable fishing are causing severe depletion of stocks of reef fish. Understanding how social and economic factors, such as human population density, access to external markets, and modernization interact with fishing and habitat degradation to affect fish stocks is vital to sustainable management of coral reef fisheries. We used fish survey data, national social and economic data, and path analyses to assess whether these factors explain variation in biomass of coral reef fishes among 25 sites in Solomon Islands. We categorized fishes into 3 groups on the basis of life-history characteristics associated with vulnerability to extinction by fishing (high, medium, and low vulnerability). The biomass of fish with low vulnerability was positively related to habitat condition. The biomass of fishes with high vulnerability was negatively related to fishing conducted with efficient gear. Use of efficient gear, in turn, was strongly and positively related to both population density and market proximity. This result suggests local population pressure and external markets have additive negative effects on vulnerable reef fish. Biomass of the fish of medium vulnerability was not explained by fishing intensity or habitat condition, which suggests these species may be relatively resilient to both habitat degradation and fishing. © 2012 Society for Conservation Biology.

  6. Fish Allergy

    Science.gov (United States)

    ... Safe Videos for Educators Search English Español Fish Allergy KidsHealth / For Parents / Fish Allergy What's in this ... Print en español Alergia al pescado About Fish Allergy A fish allergy is not exactly the same ...

  7. Structured Monte Carlo. Estimated value at risk in a stock portfolio in Colombia Montecarlo estructurado. Estimación del valor en riesgo en un portafolio accionario en Colombia

    Directory of Open Access Journals (Sweden)

    María Auxiliadora Vergara Cogollo

    2009-12-01

    Full Text Available De acuerdo con el estudio que se presenta, por las características de los activos que lo conforman, el método de Montecarlo Estructurado es el más completo y robusto para la medición del valor en riesgo (VaR de un portafolio hipotético de acciones colombianas de alta y mediana bursatilidad, en comparación con métodos paramétricos o de simulación histórica. Sin embargo, para su aplicación, es necesaria una cuidadosa modelación del comportamiento de las distintas variables de riesgo. La presencia de colas pesadas en las series de retornos de estos activos obliga al uso de modelos de volatilidad del tipo GARCH, EGARCH, PARCH y APARCH. Se evalúa su capacidad de pronóstico del VaR del periodo siguiente en paralelo con el obtenido por el método Normal. Los modelos tipo Garch pronostican mejor el VaR, puesto que logran capturar el efecto de colas pesadas en las series. Definido el proceso estocástico que siguen los activos, se procede a su cálculo con Montecarlo Estructurado. This research explores various methods to estimate Value at Risk for a portfolio of high and medium liquidity Colombian stocks. It concludes that, according to the characteristics of these assets, Full Montecarlo is more robust than other parametric methods –particularly the Normal method-, and the historical simulation. However, to avoid model risk, it requires a correct specification of the stochastic process followed by each of the risk factors. Given the evidence of fat tails on the return series, volatility models such as GARCH, EGARCH, PARCH and APARCH are used for this purpose. After that, we compare the one-step ahead VaR forecast given by these models with the one obtained by parametric methods. It is found that Garch models predict VaR better since they capture the fat tails characteristic of these series. Once the stochastic process for each asset is properly identified, the Full Montecarlo is applied to estimate VaR.

  8. Intelligent Fish Freshness Assessment

    Directory of Open Access Journals (Sweden)

    Hamid Gholam Hosseini

    2008-01-01

    Full Text Available Fish species identification and automated fish freshness assessment play important roles in fishery industry applications. This paper describes a method based on support vector machines (SVMs to improve the performance of fish identification systems. The result is used for the assessment of fish freshness using artificial neural network (ANN. Identification of the fish species involves processing of the images of fish. The most efficient features were extracted and combined with the down-sampled version of the images to create a 1D input vector. Max-Win algorithm applied to the SVM-based classifiers has enhanced the reliability of sorting to 96.46%. The realisation of Cyranose 320 Electronic nose (E-nose, in order to evaluate the fish freshness in real-time, is experimented. Intelligent processing of the sensor patterns involves the use of a dedicated ANN for each species under study. The best estimation of freshness was provided by the most sensitive sensors. Data was collected from four selected species of fishes over a period of ten days. It was concluded that the performance can be increased using individual trained ANN for each specie. The proposed system has been successful in identifying the number of days after catching the fish with an accuracy of up to 91%.

  9. Cascading effect of contagion in Indian stock market: Evidence from reachable stocks

    Directory of Open Access Journals (Sweden)

    Rajan Sruthi

    2017-12-01

    Full Text Available The financial turbulence in a country percolates to another along the trajectories of reachable stocks owned by foreign investors. To indemnify the losses originating from the crisis country, foreign investors dispose of shares in other markets triggering a contagion in an unrelated market. This paper provides empirical evidence for the stock market crisis that spreads globally through investors owning international portfolios, with special reference to the global financial crisis of 2008–09. Using two-step Limited Information Maximum Likelihood estimation and Murphy-Topel variance estimate, the results show that reachability plays a crucial role in the transposal of distress from one country to another, explaining investor-induced contagion in the Indian stock market.

  10. Stock Assessment Supplementary Information (SASINF)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In the interest of efficiency, clarity and standardization of stock assessment materials, the stock assessment reports for the 2015 Groundfish update have been...

  11. Stock Issues in Aristotle's Rhetoric

    Science.gov (United States)

    Harpine, Bill

    1977-01-01

    Defines "stock issue" by the manner in which they function in Aristotle's theory, reviews examples of modern theories of stock issues, examines previous investigations of the "Rhetoric," and analyzes Aristotle's approach to this aspect of argumentation. (MH)

  12. Use of recent and historical records to estimate status and trends of a rare and imperiled stream fish, Percina jenkinsi (Percidae)

    Science.gov (United States)

    Hagler, Megan M.; Freeman, Mary C.; Wenger, Seth J.; Freeman, Byron J.; Rakes, Patrick L.; Shute, J.R.

    2011-01-01

    Rarely encountered animals may be present but undetected, potentially leading to incorrect assumptions about the persistence of a local population or the conservation priority of a particular area. The federally endangered and narrowly endemic Conasauga logperch (Percina jenkinsi) is a good example of a rarely encountered fish species of conservation concern, for which basic population statistics are lacking. We evaluated the occurrence frequency for this species using surveys conducted with a repeat-observation sampling approach during the summer of 2008. We also analyzed museum records since the late 1980s to evaluate the trends in detected status through time. The results of these analyses provided support for a declining trend in this species over a portion of its historical range, despite low estimated detection probability. We used the results to identify the expected information return for a given level of monitoring where the sampling approach incorporates incomplete detection. The method applied here may be of value where historic occurrence records are available, provided that the assumption of constant capture efficiency is reasonable.

  13. Absorbed Dose Rate Due to Intake of Natural Radionuclides by Tilapia Fish (Tilapia nilotica,Linnaeus, 1758) Estimated Near Uranium Mining at Caetité, Bahia, Brazil

    Science.gov (United States)

    Pereira, Wagner de S.; Kelecom, Alphonse; Py Júnior, Delcy de Azevedo

    2008-08-01

    The uranium mining at Caetité (Uranium Concentrate Unit—URA) is in its operational phase. Aiming to estimate the radiological environmental impact of the URA, a monitoring program is underway. In order to preserve the biota of the deleterious effects from radiation and to act in a pro-active way as expected from a licensing body, the present work aims to use an environmental protection methodology based on the calculation of absorbed dose rate in biota. Thus, selected target organism was the Tilapia fish (Tilapia nilotica, Linnaeus, 1758) and the radionuclides were: uranium (U-238), thorium (Th-232), radium (Ra-226 and Ra-228) and lead (Pb-210). As, in Brazil there are no radiation exposure limits adopted for biota the value proposed by the Department of Energy (DOE) of the United States of 3.5×103 μGy y-1 has been used. The derived absorbed dose rate calculated for Tilapia was 2.51×100 μGy y-1, that is less than 0.1% of the dose limit established by DOE. The critical radionuclide was Ra-226, with 56% of the absorbed dose rate, followed by U-238 with 34% and Th-232 with 9%. This value of 0.1% of the limit allows to state that, in the operational conditions analyzed, natural radionuclides do not represent a radiological problem to biota.

  14. Absorbed dose rate due to intake of natural radionuclides by Tilapia fish (Tilapia nilotica, Linnaeus, 1758) estimated near uranium anomaly at Santa Quiteria, Ceara, Brazil

    International Nuclear Information System (INIS)

    Pereira, Wagner de; Kelecom, Alphonse; Py Junior, Delcy de Azevedo

    2007-01-01

    The uranium mining at Santa Quiteria (Santa Quiteria Unit - USQ) is in its environmental licensing phase. Aiming to estimate the radiological environmental impact of the USQ, a monitoring program is underway. However, radioprotection of biota is not explicitly mentioned in Brazilian norms. In order to preserve the biota of the deleterious effects from radiation and to behave in a pro-active way as expected by licensing organs, the present work aims to use an environmental protection methodology, based on the calculation of absorbed dose rate in biota. Thus, selected biomarker was the fish tilapia (Tilapia nilotica, Linnaeus, 1758) and the radionuclides were: uranium (U-238), thorium (Th-232), radium (Ra-226 and Ra-228) and lead (Pb-210). Since there are no exposition limits for biota, in Brazil, the value proposed by the Department of Energy (DOE) of the United States of 3.5 x 10 3 μGy/y has been used. The derived absorbed dose rate calculated for tilapia was 2.76 x 10 0 μGy/y, that is less than 0.1 % of the limit established by DOE. The critical radionuclide was U-238, with 99% of the absorbed dose rate. This value of 0.1% of the limit allows to state that in pre-operational conditions analyzed natural radionuclides do not represent a radiological problem to the biota. (author)

  15. Absorbed dose rate due to intake of natural radionuclides by Tilapia fish (Tilapia nilotica, Linnaeus, 1758) estimated near uranium anomaly at Santa Quiteria, Ceara, Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, Wagner de [Industrias Nucleares do Brasil S.A. (INB), Pocos de Caldas, MG (Brazil). Coordenacao de Protecao Radiologica. Unidade de Tratamento de Minerios], E-mail: wspereira@inb.gov.br; Kelecom, Alphonse [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Programa de Pos-graduacao em Ciencia Ambiental; Py Junior, Delcy de Azevedo [Industrias Nucleares do Brasil S.A. (INB), Caetite, BA (Brazil). Coordenacao de Protecao Radiologica. Unidade de Concentrado de Uranio], E-mail: Delcy@inb.gov.br

    2007-07-01

    The uranium mining at Santa Quiteria (Santa Quiteria Unit - USQ) is in its environmental licensing phase. Aiming to estimate the radiological environmental impact of the USQ, a monitoring program is underway. However, radioprotection of biota is not explicitly mentioned in Brazilian norms. In order to preserve the biota of the deleterious effects from radiation and to behave in a pro-active way as expected by licensing organs, the present work aims to use an environmental protection methodology, based on the calculation of absorbed dose rate in biota. Thus, selected biomarker was the fish tilapia (Tilapia nilotica, Linnaeus, 1758) and the radionuclides were: uranium (U-238), thorium (Th-232), radium (Ra-226 and Ra-228) and lead (Pb-210). Since there are no exposition limits for biota, in Brazil, the value proposed by the Department of Energy (DOE) of the United States of 3.5 x 10{sup 3} {mu}Gy/y has been used. The derived absorbed dose rate calculated for tilapia was 2.76 x 10{sup 0} {mu}Gy/y, that is less than 0.1 % of the limit established by DOE. The critical radionuclide was U-238, with 99% of the absorbed dose rate. This value of 0.1% of the limit allows to state that in pre-operational conditions analyzed natural radionuclides do not represent a radiological problem to the biota. (author)

  16. Absorbed Dose Rate Due to Intake of Natural Radionuclides by Tilapia Fish (Tilapia nilotica,Linnaeus, 1758) Estimated Near Uranium Mining at Caetite, Bahia, Brazil

    International Nuclear Information System (INIS)

    Pereira, Wagner de S; Kelecom, Alphonse; Azevedo Py Junior, Delcy de

    2008-01-01

    The uranium mining at Caetite (Uranium Concentrate Unit--URA) is in its operational phase. Aiming to estimate the radiological environmental impact of the URA, a monitoring program is underway. In order to preserve the biota of the deleterious effects from radiation and to act in a pro-active way as expected from a licensing body, the present work aims to use an environmental protection methodology based on the calculation of absorbed dose rate in biota. Thus, selected target organism was the Tilapia fish (Tilapia nilotica, Linnaeus, 1758) and the radionuclides were: uranium (U-238), thorium (Th-232), radium (Ra-226 and Ra-228) and lead (Pb-210). As, in Brazil there are no radiation exposure limits adopted for biota the value proposed by the Department of Energy (DOE) of the United States of 3.5x10 3 μGy y -1 has been used. The derived absorbed dose rate calculated for Tilapia was 2.51x10 0 μGy y -1 , that is less than 0.1% of the dose limit established by DOE. The critical radionuclide was Ra-226, with 56% of the absorbed dose rate, followed by U-238 with 34% and Th-232 with 9%. This value of 0.1% of the limit allows to state that, in the operational conditions analyzed, natural radionuclides do not represent a radiological problem to biota

  17. Rainy Day Stocks

    DEFF Research Database (Denmark)

    Gormsen, Niels Joachim; Greenwood, Robin

    We study the good- and bad-times performance of equity portfolios formed on characteristics. Many characteristics associated with good performance during bad times—value, profitability, small size, safety, and total volatility—also perform well during good times. Stocks with characteristics signi...

  18. Optimizing Plutonium stock management

    International Nuclear Information System (INIS)

    Niquil, Y.; Guillot, J.

    1997-01-01

    Plutonium from spent fuel reprocessing is reused in new MOX assemblies. Since plutonium isotopic composition deteriorates with time, it is necessary to optimize plutonium stock management over a long period, to guarantee safe procurement, and contribute to a nuclear fuel cycle policy at the lowest cost. This optimization is provided by the prototype software POMAR

  19. Stock Market Savvy.

    Science.gov (United States)

    Okula, Susan

    2003-01-01

    This issue of Keying In, the newsletter of the National Business Education Association, focuses upon teaching young adults how to develop both investment strategies and an understanding of the stock market. The first article, "Sound Investing Know-How: A Must for Today's Young Adults," describes how young adults can plan for their own…

  20. Stock Selection, Style Rotation

    NARCIS (Netherlands)

    Lucas, A.; van Dijk, R.; Prof. Kloek, T.

    2002-01-01

    Using US data from June 1984 to July 1999, we show that the impact of firm-specific characteristics like size and book-to-price on future excess stock returns varies considerably over time. The impact can be either positive or negative at different times. This time variation is partially