Multi-Year Impacts of Ecotourism on Whale Shark (Rhincodon typus) Visitation at Ningaloo Reef, Western Australia.

Science.gov (United States)

Sanzogni, R L; Meekan, M G; Meeuwig, J J

2015-01-01

In-water viewing of sharks by tourists has become a popular and lucrative industry. There is some concern that interactions with tourists with ecotourism operations might harm sharks through disruption of behaviours. Here, we analysed five years of whale shark (Rhincodon typus) encounter data by an ecotourism industry at Ningaloo Reef, Western Australia, to assess the impact of ecotourism interactions on shark visitation, within the context of the biological and physical oceanography of the region. Our data base consisted of 2823 encounter records for 951 individual whale sharks collected by ecotourism operators between 2007 and 2011. We found that total encounters per whale shark and encounters per boat trip increased through time. On average, whale sharks re-encountered in subsequent years were encountered earlier, stayed longer and tended to be encountered more often within a season than sharks that were only encountered in a single year. Sequential comparisons between years did not show any patterns consistent with disturbance and the rate of departure of whale sharks from the aggregation was negatively correlated to the number of operator trips. Overall, our analysis of this multi-year data base found no evidence that interactions with tourists affected the likelihood of whale shark re-encounters and that instead, physical and biological environmental factors had a far greater influence on whale shark visitation rates. Our approach provides a template for assessing the effects of ecotourism interactions and environmental factors on the visitation patterns of marine megafauna over multiple years.

Acoustic Monitoring of a Previously Unstudied Whale Shark Aggregation in the Red Sea

KAUST Repository

Cochran, Jesse

2012-01-01

in the area and to inform local management. Continued study will add to the collective knowledge on Red Sea whale sharks, including the population dynamics within the region and how they interact with the global whale shark community.

Feeding the world's largest fish: highly variable whale shark residency patterns at a provisioning site in the Philippines.

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Thomson, Jordan A; Araujo, Gonzalo; Labaja, Jessica; McCoy, Emer; Murray, Ryan; Ponzo, Alessandro

2017-09-01

Provisioning wildlife for tourism is a controversial yet widespread practice. We analysed the residency patterns of juvenile whale sharks ( Rhincodon typus ) in Oslob, Philippines, where provisioning has facilitated a large shark-watching operation since 2011. We identified 208 individual sharks over three years, with an average of 18.6 (s.d. = 7.8, range = 6-43) individuals sighted per week. Weekly shark abundance varied seasonally and peak-season abundance (approx. May-November) increased across years. Whale sharks displayed diverse individual site visitation patterns ranging from a single visit to sporadic visits, seasonal residency and year-round residency. Nine individuals became year-round residents, which represents a clear response to provisioning. The timing of the seasonal peak at Oslob did not align with known non-provisioned seasonal aggregations elsewhere in the Philippines, which could suggest that seasonal residents at Oslob exploit this food source when prey availability at alternative sites is low. Since prolonged residency equates to less time foraging naturally, provisioning could influence foraging success, alter distributions and lead to dependency in later life stages. Such impacts must be carefully weighed against the benefits of provisioning (i.e. tourism revenue in a remote community) to facilitate informed management decisions.

Juvenile morphology in baleen whale phylogeny.

Science.gov (United States)

Tsai, Cheng-Hsiu; Fordyce, R Ewan

2014-09-01

Phylogenetic reconstructions are sensitive to the influence of ontogeny on morphology. Here, we use foetal/neonatal specimens of known species of living baleen whales (Cetacea: Mysticeti) to show how juvenile morphology of extant species affects phylogenetic placement of the species. In one clade (sei whale, Balaenopteridae), the juvenile is distant from the usual phylogenetic position of adults, but in the other clade (pygmy right whale, Cetotheriidae), the juvenile is close to the adult. Different heterochronic processes at work in the studied species have different influences on juvenile morphology and on phylogenetic placement. This study helps to understand the relationship between evolutionary processes and phylogenetic patterns in baleen whale evolution and, more in general, between phylogeny and ontogeny; likewise, this study provides a proxy how to interpret the phylogeny when fossils that are immature individuals are included. Juvenile individuals in the peramorphic acceleration clades would produce misleading phylogenies, whereas juvenile individuals in the paedomorphic neoteny clades should still provide reliable phylogenetic signals.

The complete mitochondrial genome sequence of the world's largest fish, the whale shark (Rhincodon typus), and its comparison with those of related shark species.

Science.gov (United States)

Alam, Md Tauqeer; Petit, Robert A; Read, Timothy D; Dove, Alistair D M

2014-04-10

The whale shark (Rhincodon typus) is the largest extant species of fish, belonging to the order Orectolobiformes. It is listed as a "vulnerable" species on the International Union for Conservation of Nature (IUCN)'s Red List of Threatened Species, which makes it an important species for conservation efforts. We report here the first complete sequence of the mitochondrial genome (mitogenome) of the whale shark obtained by next-generation sequencing methods. The assembled mitogenome is a 16,875 bp circle, comprising of 13 protein-coding genes, two rRNA genes, 22 tRNA genes and a control region. We also performed comparative analysis of the whale shark mitogenome to the available mitogenome sequences of 17 other shark species, four from the order Orectolobiformes, five from Lamniformes and eight from Carcharhiniformes. The nucleotide composition, number and arrangement of the genes in whale shark mitogenome are the same as found in the mitogenomes of the other members of the order Orectolobiformes and its closest orders Lamniformes and Carcharhiniformes, although the whale shark mitogenome had a slightly longer control region. The availability of mitogenome sequence of whale shark will aid studies of molecular systematics, biogeography, genetic differentiation, and conservation genetics in this species. Copyright © 2014 Elsevier B.V. All rights reserved.

Characterization of Novel Whale Shark Aggregations at Shib Habil, Saudi Arabia and Mafia Island, Tanzania

KAUST Repository

Cochran, Jesse

2014-12-01

Passive acoustic monitoring has been successfully used on many elasmobranch species, but no such study has yet been published for the whale shark (Rhincodon typus). In some ways this is surprising as the known whale shark aggregation sites would seem to be ideal targets for this method. For this dissertation, two acoustic studies were carried out in Saudi Arabia and Tanzania. Each was performed in parallel with visual surveys and the Saudi population was also studied using satellite telemetry. Sighting and acoustic data were compared at both sites, and the results were mixed. The acoustic monitoring largely confirmed the results of visual surveys for the Saudi Arabian sharks, including seasonality, residency and a degree of parity and integration between the sexes that is unique to this site. Satellite tracks of tagged Saudi sharks were used to confirm that some animals migrated away from the aggregation site before returning in subsequent seasons, confirming philopatric behavior in this species. In contrast, the acoustic results in Tanzania demonstrated year-round residency of whale sharks in the area, despite seasonal declines in visually estimated abundance. Seasonal changes in habitat selection render the sharks at this site temporarily cryptic to visual sampling. The differing results are compelling because both the philopatric behavior demonstrated in Saudi Arabia and the cryptic residency of the Tanzanian sharks could explain the seasonal patterns in whale shark abundances reported at other aggregation sites. Despite their differences, both sites in this study can be classified as secondary whale shark nurseries and each may be a vital feeding ground for its respective population.

Horizontal movements, migration patterns, and population structure of whale sharks in the Gulf of Mexico and northwestern Caribbean sea.

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Hueter, Robert E; Tyminski, John P; de la Parra, Rafael

2013-01-01

Whale sharks, Rhincodon typus, aggregate by the hundreds in a summer feeding area off the northeastern Yucatan Peninsula, Mexico, where the Gulf of Mexico meets the Caribbean Sea. The aggregation remains in the nutrient-rich waters off Isla Holbox, Isla Contoy and Isla Mujeres, Quintana Roo for several months in the summer and then dissipates between August and October. Little has been known about where these sharks come from or migrate to after they disperse. From 2003-2012, we used conventional visual tags, photo-identification, and satellite tags to characterize the basic population structure and large-scale horizontal movements of whale sharks that come to this feeding area off Mexico. The aggregation comprised sharks ranging 2.5-10.0 m in total length and included juveniles, subadults, and adults of both sexes, with a male-biased sex ratio (72%). Individual sharks remained in the area for an estimated mean duration of 24-33 days with maximum residency up to about 6 months as determined by photo-identification. After leaving the feeding area the sharks showed horizontal movements in multiple directions throughout the Gulf of Mexico basin, the northwestern Caribbean Sea, and the Straits of Florida. Returns of individual sharks to the Quintana Roo feeding area in subsequent years were common, with some animals returning for six consecutive years. One female shark with an estimated total length of 7.5 m moved at least 7,213 km in 150 days, traveling through the northern Caribbean Sea and across the equator to the South Atlantic Ocean where her satellite tag popped up near the Mid-Atlantic Ridge. We hypothesize this journey to the open waters of the Mid-Atlantic was for reproductive purposes but alternative explanations are considered. The broad movements of whale sharks across multiple political boundaries corroborates genetics data supporting gene flow between geographically distinct areas and underscores the need for management and conservation strategies for

Effects of oceanographic factors on spatial distribution of Whale Shark in Cendrawasih Bay National Park, West Papua

Science.gov (United States)

Ranintyari, Maulida; Sunarto; Syamsuddin, Mega L.; Astuty, Sri

2018-05-01

Whale sharks are a leading species in Cendrawasih Bay due to its benign nature and its regular appearance. Recently, whale sharks are vulnerable to scarcity and even extinction. One of the efforts to maintain the existence of the whale shark population is by knowing its spatial distribution. This study aims to analyze how the oceanographic factors affect the spatial distribution of whale sharks in Cendrawasih Bay National Park. The method used in this research is descriptive with the quantitative approach using the Generalized Additive Model (GAM) analysis. The data consisted of the whale shark monitoring data in TNTC taken by WWF-Indonesia, and image data of sea surface temperature (SST) and chlorophyll-a concentration of Aqua-MODIS, and also sea surface current from Aviso. Analyses were conducted for the period of January 2012 until March 2015. The GAM result indicated that sea surface current was better than the other environment (SST and chlorophyll-a concentration) as an oceanographic predictor of whale shark appearance. High probabilities of the whale shark’s to appear on the surface were observed in sea surface current velocities between 0.30-0.60 m/s, for SST ranged from 30.50-31.80 °C, and for chlorophyll-a concentration ranged from 0.20-0.40 mg/m3.

Environmental Factors Affecting the Whale Shark Aggregation site in the South Central Red Sea

KAUST Repository

Hozumi, Aya

2015-12-01

Motivation behind the spring whale shark (Rhincodon typus) aggregation in Al-Lith, on the Saudi Arabian coast of the South Central Red Sea, is uncertain. A plausible hypothesis is that whale sharks gather to feed on high prey density, leading to questions about the cause of the prey density. A bottom-up process fueled by nutrient input or accumulation from physical advection could create a peak in prey biomass. Wastewater discharged from an aquaculture facility could affect productivity or provide a chemosensory cue for whale sharks. Yet, basic physico-biological oceanography of this region is unresolved. Monthly profiles, long-term moorings, and spatial surveys were used to describe the temporal variability of potential prey biomass and water masses in this region for the first time. Plankton abundance of individuals larger than ~0.7 cm did not peak during whale shark season. Rather, a decrease coinciding the trailing end of whale shark detections was observed. Sites 180 m apart had differences in acoustic backscatter, suggesting small-scale biomass patchiness, supporting the small-scale variability in whale shark habitat selectivity. Red Sea Deep Water, a nutrient-rich water mass formed in the northern Red Sea, appeared in July at the same time the Tokar wind jet from the Sudanese mountain gap is the highest. Gulf of Aden Water, a nutrient-rich water mass from the Indian Ocean, arrived as episodes from May to September, contrary to previous expectations that the water arrives continuously. It is unlikely that these natural nutrient sources are directly responsible for the high prey density attracting the whale sharks. The aquaculture plume, observed at the aggregation site, had a distinct seasonality from the ambient waters. The plume’s highest salinity (>48) approached the extreme limits of coral tolerances. Nutrient concentrations (nitrate, nitrite, phosphate, silica), suspended particulate matter, phytoplankton biomass, bacteria and cyanobacteria cell counts

Learning from a provisioning site: code of conduct compliance and behaviour of whale sharks in Oslob, Cebu, Philippines.

Science.gov (United States)

Schleimer, Anna; Araujo, Gonzalo; Penketh, Luke; Heath, Anna; McCoy, Emer; Labaja, Jessica; Lucey, Anna; Ponzo, Alessandro

2015-01-01

While shark-based tourism is a rapidly growing global industry, there is ongoing controversy about the effects of provisioning on the target species. This study investigated the effect of feeding on whale sharks (Rhincodon typus) at a provisioning site in Oslob, Cebu, in terms of arrival time, avoidance and feeding behaviour using photo-identification and focal follows. Additionally, compliance to the code of conduct in place was monitored to assess tourism pressure on the whale sharks. Newly identified sharks gradually arrived earlier to the provisioning site after their initial sighting, indicating that the animals learn to associate the site with food rewards. Whale sharks with a long resighting history showed anticipatory behaviour and were recorded at the site on average 5 min after the arrival of feeder boats. Results from a generalised linear mixed model indicated that animals with a longer resighting history were less likely to show avoidance behaviour to touches or boat contact. Similarly, sequential data on feeding behaviour was modelled using a generalised estimating equations approach, which suggested that experienced whale sharks were more likely to display vertical feeding behaviour. It was proposed that the continuous source of food provides a strong incentive for the modification of behaviours, i.e., learning, through conditioning. Whale sharks are large opportunistic filter feeders in a mainly oligotrophic environment, where the ability to use novel food sources by modifying their behaviour could be of great advantage. Non-compliance to the code of conduct in terms of minimum distance to the shark (2 m) increased from 79% in 2012 to 97% in 2014, suggesting a high tourism pressure on the whale sharks in Oslob. The long-term effects of the observed behavioural modifications along with the high tourism pressure remain unknown. However, management plans are traditionally based on the precautionary principle, which aims to take preventive actions even

An unprecedented aggregation of whale sharks, Rhincodon typus, in Mexican coastal waters of the Caribbean Sea.

Directory of Open Access Journals (Sweden)

Rafael de la Parra Venegas

Full Text Available Whale sharks, Rhincodon typus, are often perceived as solitary behemoths that live and feed in the open ocean. To the contrary, evidence is accumulating that they are gregarious and form seasonal aggregations in some coastal waters. One such aggregation occurs annually north of Cabo Catoche, off Isla Holbox on the Yucatán Peninsula of Mexico. Here we report a second, much denser aggregation of whale sharks (dubbed "the Afuera" that occurs east of the tip of the Yucatán Peninsula in the Caribbean Sea. The 2009 Afuera event comprised the largest aggregation of whale sharks ever reported, with up to 420 whale sharks observed in a single aerial survey, all gathered in an elliptical patch of ocean approximately 18 km(2. Plankton studies indicated that the sharks were feeding on dense homogenous patches of fish eggs, which DNA barcoding analysis identified as belonging to little tunny, Euthynnus alletteratus. This contrasts with the annual Cabo Catoche aggregation nearby, where prey consists mostly of copepods and sergestid shrimp. Increased sightings at the Afuera coincide with decreased sightings at Cabo Catoche, and both groups have the same sex ratio, implying that the same animals are likely involved in both aggregations; tagging data support this idea. With two whale shark aggregation areas, high coastal productivity and a previously-unknown scombrid spawning ground, the northeastern Yucatán marine region is a critical habitat that deserves more concerted conservation efforts.

An Unprecedented Aggregation of Whale Sharks, Rhincodon typus, in Mexican Coastal Waters of the Caribbean Sea

Science.gov (United States)

de la Parra Venegas, Rafael; Hueter, Robert; González Cano, Jaime; Tyminski, John; Gregorio Remolina, José; Maslanka, Mike; Ormos, Andrea; Weigt, Lee; Carlson, Bruce; Dove, Alistair

2011-01-01

Whale sharks, Rhincodon typus, are often perceived as solitary behemoths that live and feed in the open ocean. To the contrary, evidence is accumulating that they are gregarious and form seasonal aggregations in some coastal waters. One such aggregation occurs annually north of Cabo Catoche, off Isla Holbox on the Yucatán Peninsula of Mexico. Here we report a second, much denser aggregation of whale sharks (dubbed “the Afuera”) that occurs east of the tip of the Yucatán Peninsula in the Caribbean Sea. The 2009 Afuera event comprised the largest aggregation of whale sharks ever reported, with up to 420 whale sharks observed in a single aerial survey, all gathered in an elliptical patch of ocean approximately 18 km2. Plankton studies indicated that the sharks were feeding on dense homogenous patches of fish eggs, which DNA barcoding analysis identified as belonging to little tunny, Euthynnus alletteratus. This contrasts with the annual Cabo Catoche aggregation nearby, where prey consists mostly of copepods and sergestid shrimp. Increased sightings at the Afuera coincide with decreased sightings at Cabo Catoche, and both groups have the same sex ratio, implying that the same animals are likely involved in both aggregations; tagging data support this idea. With two whale shark aggregation areas, high coastal productivity and a previously-unknown scombrid spawning ground, the northeastern Yucatán marine region is a critical habitat that deserves more concerted conservation efforts. PMID:21559508

Foraging and ingestive behaviors of whale sharks, Rhincodon typus, in response to chemical stimulus cues.

Science.gov (United States)

Dove, Alistair D M

2015-02-01

Whale sharks, Rhincodon typus, display a number of behaviors that suggest these animals can locate food from afar, as well as identify and discriminate between food items. However, their intractably large size and relative rarity in the field has so far prevented direct studies of their behavior and sensory capability. A small population of aquarium-held whale sharks facilitated direct studies of behavior in response to chemical stimulus plumes. Whale sharks were exposed to plumes composed of either homogenized krill or simple aqueous solutions of dimethyl sulfide (DMS), which is associated with krill aggregations and is used by several pelagic species as a food-finding stimulus. Whale sharks exhibited pronounced ingestive and search behaviors when exposed to both types of stimuli, compared to control trials. Ingestive behaviors included open mouth swimming and active surface feeding (gulping). These behaviors were stronger and more prevalent in response to krill homogenate plumes than to DMS plumes. Both chemical stimuli also increased visitation rate, and krill homogenate plumes additionally affected swimming speed. Whale sharks use chemosensory cues of multiple types to locate and identify palatable food, suggesting that chemical stimuli can help direct long-range movements and allow discrimination of different food items. There appears to be a hierarchy of responses: krill metabolites directly associated with food produced more frequent and intense feeding responses relative to DMS, which is indirectly associated with krill. DMS is used to find food by a number of pelagic species and may be an important signaling molecule in pelagic food webs. © 2015 Marine Biological Laboratory.

Whale sharks, Rhincodon typus, aggregate around offshore platforms in Qatari waters of the Arabian Gulf to feed on fish spawn.

Directory of Open Access Journals (Sweden)

David P Robinson

Full Text Available Whale sharks, Rhincodon typus, are known to aggregate to feed in a small number of locations in tropical and subtropical waters. Here we document a newly discovered major aggregation site for whale sharks within the Al Shaheen oil field, 90 km off the coast of Qatar in the Arabian Gulf. Whale sharks were observed between April and September, with peak numbers observed between May and August. Density estimates of up to 100 sharks within an area of 1 km(2 were recorded. Sharks ranged between four and eight metres' estimated total length (mean 6.92 ± 1.53 m. Most animals observed were actively feeding on surface zooplankton, consisting primarily of mackerel tuna, Euthynnus affinis, eggs.

Whale Sharks, Rhincodon typus, Aggregate around Offshore Platforms in Qatari Waters of the Arabian Gulf to Feed on Fish Spawn

Science.gov (United States)

Robinson, David P.; Jaidah, Mohammed Y.; Jabado, Rima W.; Lee-Brooks, Katie; Nour El-Din, Nehad M.; Malki, Ameena A. Al.; Elmeer, Khaled; McCormick, Paul A.; Henderson, Aaron C.; Pierce, Simon J.; Ormond, Rupert F. G.

2013-01-01

Whale sharks, Rhincodon typus, are known to aggregate to feed in a small number of locations in tropical and subtropical waters. Here we document a newly discovered major aggregation site for whale sharks within the Al Shaheen oil field, 90 km off the coast of Qatar in the Arabian Gulf. Whale sharks were observed between April and September, with peak numbers observed between May and August. Density estimates of up to 100 sharks within an area of 1 km2 were recorded. Sharks ranged between four and eight metres’ estimated total length (mean 6.92±1.53 m). Most animals observed were actively feeding on surface zooplankton, consisting primarily of mackerel tuna, Euthynnus affinis, eggs. PMID:23516456

Acoustic telemetry reveals cryptic residency of whale sharks.

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Cagua, E Fernando; Cochran, Jesse E M; Rohner, Christoph A; Prebble, Clare E M; Sinclair-Taylor, Tane H; Pierce, Simon J; Berumen, Michael L

2015-04-01

Although whale sharks (Rhincodon typus) have been documented to move thousands of kilometres, they are most frequently observed at a few predictable seasonal aggregation sites. The absence of sharks at the surface during visual surveys has led to the assumption that sharks disperse to places unknown during the long 'off-seasons' at most of these locations. Here we compare 2 years of R. typus visual sighting records from Mafia Island in Tanzania to concurrent acoustic telemetry of tagged individuals. Sightings revealed a clear seasonal pattern with a peak between October and February and no sharks observed at other times. By contrast, acoustic telemetry demonstrated year-round residency of R. typus. The sharks use a different habitat in the off-season, swimming deeper and further away from shore, presumably in response to prey distributions. This behavioural change reduces the sharks' visibility, giving the false impression that they have left the area. We demonstrate, for the first time to our knowledge, year-round residency of unprovisioned, individual R. typus at an aggregation site, and highlight the importance of using multiple techniques to study the movement ecology of marine megafauna. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Demographics and feeding ecology of whale sharks at Mafia Island, Tanzania

KAUST Repository

Cagua, Edgar F.; Cochran, Jesse; Rohner, Chris; Igulu, Mathias M; Rubens, Jason; Pierce, Simon J; Berumen, Michael L.

2013-01-01

. The size range and gender distribution of whale sharks at Mafia Island is similar to other coastal aggregations in the Indian Ocean, but the relatively high site fidelity and residency time stands in contrast.

Zooplankton communities in Cenderawasih Bay National Park, West Papua: can their composition be used to predict whale shark Rhincodon typus Smith, 1828 appearance frequencies?

Science.gov (United States)

Marliana, S. N.; Bataona, M.; Ihsan, E. N.

2018-03-01

The use of lift net fishing vessels in Cenderawasih Bay National Park (CBNP) along with the increased popularity of CBNP as an ecotourism area is suspected to have an impact on the behavior and population of its whale sharks Rhincodon typus Smith, 1828. The differing frequency of whale shark appearances along the waters of CBNP has been alleged to be related to the distribution of the whale sharks’ food sources, one of which is zooplankton. This preliminary research aimed to investigate the composition of the zooplankton community in CBNP based on distance from the coast and difference in locations, and to use the pattern of zooplankton compositional variation as a basis for indication of the frequency of whale shark appearances. There were clear differences in the composition and diversity of zooplankton communities among sampling stations, but these differences were not strong enough to infer the cause of the different whale shark appearance frequencies in different locations. Nevertheless, the waters of CBNP had an equal availability of zooplankton for whale sharks. With the increasing popularity of whale shark tourism, understanding the species’ feeding habits is critical to the sustainability of both the industry and the enigmatic species on which it depends.

Social learning in juvenile lemon sharks, Negaprion brevirostris.

Science.gov (United States)

Guttridge, Tristan L; van Dijk, Sander; Stamhuis, Eize J; Krause, Jens; Gruber, Samuel H; Brown, Culum

2013-01-01

Social learning is taxonomically widespread and can provide distinct behavioural advantages, such as in finding food or avoiding predators more efficiently. Although extensively studied in bony fishes, no such empirical evidence exists for cartilaginous fishes. Our aim in this study was to experimentally investigate the social learning capabilities of juvenile lemon sharks, Negaprion brevirostris. We designed a novel food task, where sharks were required to enter a start zone and subsequently make physical contact with a target in order to receive a food reward. Naive sharks were then able to interact with and observe (a) pre-trained sharks, that is, 'demonstrators', or (b) sharks with no previous experience, that is, 'sham demonstrators'. On completion, observer sharks were then isolated and tested individually in a similar task. During the exposure phase observers paired with 'demonstrator' sharks performed a greater number of task-related behaviours and made significantly more transitions from the start zone to the target, than observers paired with 'sham demonstrators'. When tested in isolation, observers previously paired with 'demonstrator' sharks completed a greater number of trials and made contact with the target significantly more often than observers previously paired with 'sham demonstrators'. Such experience also tended to result in faster overall task performance. These results indicate that juvenile lemon sharks, like numerous other animals, are capable of using socially derived information to learn about novel features in their environment. The results likely have important implications for behavioural processes, ecotourism and fisheries.

Genetic structure of populations of whale sharks among ocean basins and evidence for their historic rise and recent decline

KAUST Repository

Vignaud, Thomas M.

2014-05-01

This study presents genetic evidence that whale sharks, Rhincodon typus, are comprised of at least two populations that rarely mix and is the first to document a population expansion. Relatively high genetic structure is found when comparing sharks from the Gulf of Mexico with sharks from the Indo-Pacific. If mixing occurs between the Indian and Atlantic Oceans, it is not sufficient to counter genetic drift. This suggests whale sharks are not all part of a single global metapopulation. The significant population expansion we found was indicated by both microsatellite and mitochondrial DNA. The expansion may have happened during the Holocene, when tropical species could expand their range due to sea-level rise, eliminating dispersal barriers and increasing plankton productivity. However, the historic trend of population increase may have reversed recently. Declines in genetic diversity are found for 6 consecutive years at Ningaloo Reef in Australia. The declines in genetic diversity being seen now in Australia may be due to commercial-scale harvesting of whale sharks and collision with boats in past decades in other countries in the Indo-Pacific. The study findings have implications for models of population connectivity for whale sharks and advocate for continued focus on effective protection of the world\\'s largest fish at multiple spatial scales. © 2014 John Wiley & Sons Ltd.

Genetic structure of populations of whale sharks among ocean basins and evidence for their historic rise and recent decline.

Science.gov (United States)

Vignaud, Thomas M; Maynard, Jeffrey A; Leblois, Raphael; Meekan, Mark G; Vázquez-Juárez, Ricardo; Ramírez-Macías, Dení; Pierce, Simon J; Rowat, David; Berumen, Michael L; Beeravolu, Champak; Baksay, Sandra; Planes, Serge

2014-05-01

This study presents genetic evidence that whale sharks, Rhincodon typus, are comprised of at least two populations that rarely mix and is the first to document a population expansion. Relatively high genetic structure is found when comparing sharks from the Gulf of Mexico with sharks from the Indo-Pacific. If mixing occurs between the Indian and Atlantic Oceans, it is not sufficient to counter genetic drift. This suggests whale sharks are not all part of a single global metapopulation. The significant population expansion we found was indicated by both microsatellite and mitochondrial DNA. The expansion may have happened during the Holocene, when tropical species could expand their range due to sea-level rise, eliminating dispersal barriers and increasing plankton productivity. However, the historic trend of population increase may have reversed recently. Declines in genetic diversity are found for 6 consecutive years at Ningaloo Reef in Australia. The declines in genetic diversity being seen now in Australia may be due to commercial-scale harvesting of whale sharks and collision with boats in past decades in other countries in the Indo-Pacific. The study findings have implications for models of population connectivity for whale sharks and advocate for continued focus on effective protection of the world's largest fish at multiple spatial scales. © 2014 John Wiley & Sons Ltd.

Predicting occurrence of juvenile shark habitat to improve conservation planning.

Science.gov (United States)

Oh, Beverly Z L; Sequeira, Ana M M; Meekan, Mark G; Ruppert, Jonathan L W; Meeuwig, Jessica J

2017-06-01

Fishing and habitat degradation have increased the extinction risk of sharks, and conservation strategies recognize that survival of juveniles is critical for the effective management of shark populations. Despite the rapid expansion of marine protected areas (MPAs) globally, the paucity of shark-monitoring data on large scales (100s-1000s km) means that the effectiveness of MPAs in halting shark declines remains unclear. Using data collected by baited remote underwater video systems (BRUVS) in northwestern Australia, we developed generalized linear models to elucidate the ecological drivers of habitat suitability for juvenile sharks. We assessed occurrence patterns at the order and species levels. We included all juvenile sharks sampled and the 3 most abundant species sampled separately (grey reef [Carcharhinus amblyrhynchos], sandbar [Carcharhinus plumbeus], and whitetip reef sharks [Triaenodon obesus]). We predicted the occurrence of juvenile sharks across 490,515 km 2 of coastal waters and quantified the representation of highly suitable habitats within MPAs. Our species-level models had higher accuracy (ĸ ≥ 0.69) and deviance explained (≥48%) than our order-level model (ĸ = 0.36 and deviance explained of 10%). Maps of predicted occurrence revealed different species-specific patterns of highly suitable habitat. These differences likely reflect different physiological or resource requirements between individual species and validate concerns over the utility of conservation targets based on aggregate species groups as opposed to a species-focused approach. Highly suitable habitats were poorly represented in MPAs with the most restrictions on extractive activities. This spatial mismatch possibly indicates a lack of explicit conservation targets and information on species distribution during the planning process. Non-extractive BRUVS provided a useful platform for building the suitability models across large scales to assist conservation planning across

Are whale sharks exposed to persistent organic pollutants and plastic pollution in the Gulf of California (Mexico)? First ecotoxicological investigation using skin biopsies.

Science.gov (United States)

Fossi, Maria Cristina; Baini, Matteo; Panti, Cristina; Galli, Matteo; Jiménez, Begoña; Muñoz-Arnanz, Juan; Marsili, Letizia; Finoia, Maria Grazia; Ramírez-Macías, Dení

2017-09-01

The whale shark (Rhincodon typus) is an endangered species that may be exposed to micro- and macro-plastic ingestion as a result of their filter-feeding activity, particularly on the sea surface. In this pilot project we perform the first ecotoxicological investigation on whale sharks sampled in the Gulf of California exploring the potential interaction of this species with plastic debris (macro-, micro-plastics and related sorbed contaminants). Due to the difficulty in obtaining stranded specimens of this endangered species, an indirect approach, by skin biopsies was used for the evaluation of the whale shark ecotoxicological status. The levels of organochlorine compounds (PCBs, DDTs), polybrominated diphenyl ethers (PBDEs) plastic additives, and related biomarkers responses (CYP1A) were investigated for the first time in the whale shark. Twelve whale shark skin biopsy samples were collected in January 2014 in La Paz Bay (BCS, Mexico) and a preliminary investigation on microplastic concentration and polymer composition was also carried out in seawater samples from the same area. The average abundance pattern for the target contaminants was PCBs>DDTs>PBDEs>HCB. Mean concentration values of 8.42ng/g w.w. were found for PCBs, 1.31ng/g w.w. for DDTs, 0.29ng/g w.w. for PBDEs and 0.19ng/g w.w. for HCB. CYP1A-like protein was detected, for the first time, in whale shark skin samples. First data on the average density of microplastics in the superficial zooplankton/microplastic samples showed values ranging from 0.00items/m 3 to 0.14items/m 3 . A focused PCA analysis was performed to evaluate a possible correlation among the size of the whale sharks, contaminants and CYP1A reponses. Further ecotoxicological investigation on whale shark skin biopsies will be carried out for a worldwide ecotoxicological risk assessment of this endangerd species. Copyright © 2017 Elsevier Inc. All rights reserved.

Draft sequencing and assembly of the genome of the world's largest fish, the whale shark: Rhincodon typus Smith 1828.

Science.gov (United States)

Read, Timothy D; Petit, Robert A; Joseph, Sandeep J; Alam, Md Tauqeer; Weil, M Ryan; Ahmad, Maida; Bhimani, Ravila; Vuong, Jocelyn S; Haase, Chad P; Webb, D Harry; Tan, Milton; Dove, Alistair D M

2017-07-14

The whale shark (Rhincodon typus) has by far the largest body size of any elasmobranch (shark or ray) species. Therefore, it is also the largest extant species of the paraphyletic assemblage commonly referred to as fishes. As both a phenotypic extreme and a member of the group Chondrichthyes - the sister group to the remaining gnathostomes, which includes all tetrapods and therefore also humans - its genome is of substantial comparative interest. Whale sharks are also listed as an endangered species on the International Union for Conservation of Nature's Red List of threatened species and are of growing popularity as both a target of ecotourism and as a charismatic conservation ambassador for the pelagic ecosystem. A genome map for this species would aid in defining effective conservation units and understanding global population structure. We characterised the nuclear genome of the whale shark using next generation sequencing (454, Illumina) and de novo assembly and annotation methods, based on material collected from the Georgia Aquarium. The data set consisted of 878,654,233 reads, which yielded a draft assembly of 1,213,200 contigs and 997,976 scaffolds. The estimated genome size was 3.44Gb. As expected, the proteome of the whale shark was most closely related to the only other complete genome of a cartilaginous fish, the holocephalan elephant shark. The whale shark contained a novel Toll-like-receptor (TLR) protein with sequence similarity to both the TLR4 and TLR13 proteins of mammals and TLR21 of teleosts. The data are publicly available on GenBank, FigShare, and from the NCBI Short Read Archive under accession number SRP044374. This represents the first shotgun elasmobranch genome and will aid studies of molecular systematics, biogeography, genetic differentiation, and conservation genetics in this and other shark species, as well as providing comparative data for studies of evolutionary biology and immunology across the jawed vertebrate lineages.

Monogenoid infection of neonatal and older juvenile lemon sharks, Negaprion brevirostris (Carcharhinidae), in a shark nursery.

Science.gov (United States)

Young, Joy M; Frasca, Salvatore; Gruber, Samuel H; Benz, George W

2013-12-01

Fifty lemon sharks, Negaprion brevirostris , were captured in a shallow, mangrove-fringed shark nursery at Bimini, Bahamas and examined for the presence of skin-dwelling ectoparasitic monogenoids (Monogenoidea). Sixteen sharks were infected by Dermophthirius nigrellii (Microbothriidae); the youngest host was estimated to be 3- to 4-wk-old. Infection prevalence, mean intensity, and median intensity (0.32, 2.63, and 2.0, respectively, for all sharks) were not significantly different between neonates (estimated ages 3- to 10-wk-old) and non-neonatal juveniles (estimated ages 1- to 4-yr-old), suggesting that soon after parturition lemon sharks acquire infection levels of D. nigrellii matching those of juvenile conspecifics. Monogenoids were only found on the trailing portion of the first and second dorsal fins and upper lobe of the caudal fin. The prevalence of D. nigrellii was highest on the first dorsal fin; however, the mean and median intensities of D. nigrellii were similar between fins in all but 1 case. These results raise important husbandry implications regarding the practice of preferentially seeking neonatal and other small lemon sharks for captivity.

How large is the world's largest fish? Measuring whale sharks Rhincodon typus with laser photogrammetry.

Science.gov (United States)

Rohner, C A; Richardson, A J; Marshall, A D; Weeks, S J; Pierce, S J

2011-01-01

Laser photogrammetry was found to be a promising new cost-effective technique for measuring free-swimming whale sharks Rhincodon typus. Photogrammetric measurements were more precise than visual size estimates by experienced researchers, with results from the two methods differing by 9· 8 ± 1· 1% (mean ±s.e.). A new metric of total length and the length between the fifth gill and first dorsal fin (r² = 0· 93) is proposed to facilitate easy, accurate length measurements of whale sharks in the field. © 2011 The Authors. Journal of Fish Biology © 2011 The Fisheries Society of the British Isles.

Whale shark economics: a valuation of wildlife tourism in South Ari Atoll, Maldives

KAUST Repository

Cagua, Edgar F.; Collins, Neal; Hancock, James; Rees, Richard

2014-01-01

Whale sharks attract large numbers of tourists, divers and snorkelers each year to South Ari Atoll in the Republic of Maldives. Yet without information regarding the use and economic extent of the attraction, it is difficult to prioritize

Population structure of a whale shark Rhincodon typus aggregation in the Red Sea

KAUST Repository

Cochran, Jesse; Hardenstine, Royale; Braun, C. D.; Skomal, G. B.; Thorrold, S. R.; Xu, K.; Genton, Marc G.; Berumen, Michael L.

2016-01-01

The presence of whale sharks Rhincodon typus were recorded around Shib Habil, a small, coastal reef off the Red Sea coast of Saudi Arabia, from 2010 to 2015. A total of 267 suitable photographs resulting in the identification of 136 individuals, were documented from 305 encounters. Sharks were divided evenly between the sexes with no evidence of temporal or spatial segregation. All individuals were immature based on size estimates and, for males, juvenile clasper morphology. Scars were reported for 57% of R. typus with 15% showing evidence of propeller trauma. Estimates of population size and patterns of residency were calculated by modelling the lagged identification rate. Multiple models were run simultaneously and compared using the Akaike information criterion. An open population model was found to best represent the data and estimates a daily abundance between 15 and 34 R. typus during the aggregation season, with local residence times ranging from 4 to 44 days. Residence times away from Shib Habil range from 15 to 156 days with a permanent emigration–death rate between 0·07 and 0·58 individuals year−1. These results are broadly similar to those from other aggregations of R. typus, although the observed sexual parity and integration found at this site is unique for the species and needs further study. © 2016 The Fisheries Society of the British Isles

Population structure of a whale shark Rhincodon typus aggregation in the Red Sea

KAUST Repository

Cochran, Jesse

2016-07-12

The presence of whale sharks Rhincodon typus were recorded around Shib Habil, a small, coastal reef off the Red Sea coast of Saudi Arabia, from 2010 to 2015. A total of 267 suitable photographs resulting in the identification of 136 individuals, were documented from 305 encounters. Sharks were divided evenly between the sexes with no evidence of temporal or spatial segregation. All individuals were immature based on size estimates and, for males, juvenile clasper morphology. Scars were reported for 57% of R. typus with 15% showing evidence of propeller trauma. Estimates of population size and patterns of residency were calculated by modelling the lagged identification rate. Multiple models were run simultaneously and compared using the Akaike information criterion. An open population model was found to best represent the data and estimates a daily abundance between 15 and 34 R. typus during the aggregation season, with local residence times ranging from 4 to 44 days. Residence times away from Shib Habil range from 15 to 156 days with a permanent emigration–death rate between 0·07 and 0·58 individuals year−1. These results are broadly similar to those from other aggregations of R. typus, although the observed sexual parity and integration found at this site is unique for the species and needs further study. © 2016 The Fisheries Society of the British Isles

Genetic structure of populations of whale sharks among ocean basins and evidence for their historic rise and recent decline

KAUST Repository

Vignaud, Thomas M.; Maynard, Jeffrey Allen; Leblois, Raphaë l; Meekan, Mark G.; Vá zquez-Juá rez, Ricardo; Ramí rez-Mací as, Dení ; Pierce, Simon J.; Rowat, David; Berumen, Michael L.; Beeravolu, Champak R.; Baksay, Sandra; Planes, Serge

2014-01-01

This study presents genetic evidence that whale sharks, Rhincodon typus, are comprised of at least two populations that rarely mix and is the first to document a population expansion. Relatively high genetic structure is found when comparing sharks

Fine-Scale Movements and Behaviors of Whale Sharks, Rhincodon typus, in a Seasonal Aggregation near Al Lith, Saudi Arabia

KAUST Repository

Sun, Lu

2016-01-01

. In another dimension, depth use of whale sharks derived from biologgers showed distinct diel patterns. The sharks heavily utilized shallow waters with mixed depth usage consisting of surface swimming and varied types of dives, which explained the data

Population Structure, Abundance and Movement of Whale Sharks in the Arabian Gulf and the Gulf of Oman.

Science.gov (United States)

Robinson, David P; Jaidah, Mohammed Y; Bach, Steffen; Lee, Katie; Jabado, Rima W; Rohner, Christoph A; March, Abi; Caprodossi, Simone; Henderson, Aaron C; Mair, James M; Ormond, Rupert; Pierce, Simon J

2016-01-01

Data on the occurrence of whale sharks, Rhincodon typus, in the Arabian Gulf and Gulf of Oman were collected by dedicated boat surveys and via a public-sightings scheme during the period from 2011 to 2014. A total of 422 individual whale sharks were photo-identified from the Arabian Gulf and the northern Gulf of Oman during that period. The majority of sharks (81%, n = 341) were encountered at the Al Shaheen area of Qatar, 90 km off the coast, with the Musandam region of Oman a secondary area of interest. At Al Shaheen, there were significantly more male sharks (n = 171) than females (n = 78; X2 = 17.52, P 9 m individuals were visually assessed as pregnant. Connectivity among sharks sighted in Qatari, Omani and UAE waters was confirmed by individual spot pattern matches. A total of 13 identified sharks were re-sighted at locations other than that at which they were first sighted, including movements into and out of the Arabian Gulf through the Strait of Hormuz. Maximum likelihood techniques were used to model an estimated combined population for the Arabian Gulf and Gulf of Oman of 2837 sharks ± 1243.91 S.E. (95% C.I. 1720-6295). The Al Shaheen aggregation is thus the first site described as being dominated by mature males while the free-swimming pregnant females are the first reported from the Indian Ocean.

Fine-Scale Movements and Behaviors of Whale Sharks, Rhincodon typus, in a Seasonal Aggregation near Al Lith, Saudi Arabia

KAUST Repository

Sun, Lu

2016-12-01

Movement and behavior studies are traditional yet effective ways to understand the biology and ecology of a species. For an endangered species like the whale shark (Rhincodon typus), a comprehensive knowledge of its movement and behavior is particularly critical for successful management and conservation. For this dissertation, acoustic telemetry and biologging tagging studies were carried out at a seasonal whale shark aggregation site near Al Lith in the Saudi Arabian Red Sea. Acoustic telemetry data revealed consistent path usage in a narrow longshore area with patterns in seasonality and diel horizontal movements within a smaller scale. Some individuals specifically concentrated on this path and made non-stop back and forth movements along it. In another dimension, depth use of whale sharks derived from biologgers showed distinct diel patterns. The sharks heavily utilized shallow waters with mixed depth usage consisting of surface swimming and varied types of dives, which explained the data of previous visual surveys. Vertical velocities indicated potential energy expenditure strategies that were further investigated based on acceleration data. Energy expenditure data suggested strategies that fine-tuned foraging efforts to optimize the balance between feeding and foraging. However, while these strategies fit well in the natural habitat, local human impacts could be of great disturbance if not well managed.

Association of whale sharks (Rhincodon typus) with thermo-biological frontal systems of the eastern tropical Pacific.

Science.gov (United States)

Ryan, John P; Green, Jonathan R; Espinoza, Eduardo; Hearn, Alex R

2017-01-01

Satellite tracking of 27 whale sharks in the eastern tropical Pacific, examined in relation to environmental data, indicates preferential occupancy of thermo-biological frontal systems. In these systems, thermal gradients are caused by wind-forced circulation and mixing, and biological gradients are caused by associated nutrient enrichment and enhanced primary productivity. Two of the frontal systems result from upwelling, driven by divergence in the current systems along the equator and the west coast of South America; the third results from wind jet dynamics off Central America. All whale sharks were tagged near Darwin Island, Galápagos, within the equatorial Pacific upwelling system. Occupancy of frontal habitat is pronounced in synoptic patterns of shark locations in relation to serpentine, temporally varying thermal fronts across a zonal expanse > 4000 km. 80% of shark positions in northern equatorial upwelling habitat and 100% of positions in eastern boundary upwelling habitat were located within the upwelling front. Analysis of equatorial shark locations relative to thermal gradients reveals occupancy of a transition point in environmental stability. Equatorial subsurface tag data show residence in shallow, warm (>22°C) water 94% of the time. Surface zonal current speeds for all equatorial tracking explain only 16% of the variance in shark zonal movement speeds, indicating that passive drifting is not a primary determinant of movement patterns. Movement from equatorial to eastern boundary frontal zones occurred during boreal winter, when equatorial upwelling weakens seasonally. Off Peru sharks tracked upwelling frontal positions within ~100-350 km from the coast. Off Central America, the largest tagged shark (12.8 m TL) occupied an oceanic front along the periphery of the Panama wind jet. Seasonal movement from waning equatorial upwelling to productive eastern boundary habitat is consistent with underlying trophic dynamics. Persistent shallow residence in

Vertical Movements and Patterns in Diving Behavior of Whale Sharks as Revealed by Pop-Up Satellite Tags in the Eastern Gulf of Mexico.

Directory of Open Access Journals (Sweden)

John P Tyminski

Full Text Available The whale shark (Rhincodon typus is a wide-ranging, filter-feeding species typically observed at or near the surface. This shark's sub-surface habits and behaviors have only begun to be revealed in recent years through the use of archival and satellite tagging technology. We attached pop-up satellite archival transmitting tags to 35 whale sharks in the southeastern Gulf of Mexico off the Yucatan Peninsula from 2003-2012 and three tags to whale sharks in the northeastern Gulf off Florida in 2010, to examine these sharks' long-term movement patterns and gain insight into the underlying factors influencing their vertical habitat selection. Archived data were received from 31 tags deployed on sharks of both sexes with total lengths of 5.5-9 m. Nine of these tags were physically recovered facilitating a detailed long-term view into the sharks' vertical movements. Whale sharks feeding inshore on fish eggs off the northeast Yucatan Peninsula demonstrated reverse diel vertical migration, with extended periods of surface swimming beginning at sunrise followed by an abrupt change in the mid-afternoon to regular vertical oscillations, a pattern that continued overnight. When in oceanic waters, sharks spent about 95% of their time within epipelagic depths (500 m that largely occurred during daytime or twilight hours (max. depth recorded 1,928 m, had V-shaped depth-time profiles, and comprised more rapid descents (0.68 m sec-1 than ascents (0.50 m sec-1. Nearly half of these extreme dives had descent profiles with brief but conspicuous changes in vertical direction at a mean depth of 475 m. We hypothesize these stutter steps represent foraging events within the deep scattering layer, however, the extreme dives may have additional functions. Overall, our results demonstrate complex and dynamic patterns of habitat utilization for R. typus that appear to be in response to changing biotic and abiotic conditions influencing the distribution and abundance of their

Oceanographic Factors in Fishing Ground Location of Anchovy at Teluk Cenderawasih National Park, West Papua : Are These Factors Have an Effect of Whale Sharks Appearance Frequencies?

Science.gov (United States)

Nurul Ihsan, Evi; Yasmina Enita, Siti; Kunarso; Wirasatriya, Anindya

2018-02-01

The appearance frequencies of whale sharks in Teluk Cenderawasih National Park (TCNP) is unique because they appear throughout the year and are not related to any seasons. WWF Indonesia's monitoring results from 2011 untill now showed the appearance of whale sharks is closely related to the presence of fisherman liftnet and anchovies. This study focuses on oceanographic factors in fishing ground areas such as chlorophyll-a and satellite imagery data including chlorophyll-a, Sea surface Temperature (SST) over the last four years resulting in AQUA MODIS level 2 recording with 1km resolution in 2013-2016. The catch of anchovies and chlorophyll-a values showed a fairly good correlation during the west monsoon, 0.305, in addition the relationship between the anchovies with SST has a good correlation value starting in the transition period 1 towards the east monsoon. Based on these data, oceanographic factor conditions in TCNP provide a good opportunity for anchovies that live in warm waters to grow and reproduce. This also influences the appearance of whale sharks closely related to the presence of the anchovies where a positive correlation value is found between the catch of anchovies and whale sharks during the west monsoon and east monsoon in sequence 0,912 and 0.819. Chlorophyll-a and SST have a significant effect on fish catch of anchovies and the appearance frequencies of whale sharks even it were not in all seasons.

Population structure and residency patterns of whale sharks, Rhincodon typus, at a provisioning site in Cebu, Philippines.

Science.gov (United States)

Araujo, Gonzalo; Lucey, Anna; Labaja, Jessica; So, Catherine Lee; Snow, Sally; Ponzo, Alessandro

2014-01-01

This study represents the first description of whale sharks, Rhincodon typus, occurring at a provisioning site in Oslob, Cebu, Philippines. Frequent observations of sharks are often difficult, even at tourism sites, giving rise to provisioning activities to attract them. The present study provides repeated longitudinal data at a site where daily provisioning activities took place, and whale sharks were present every day. A total of 158 individual whale sharks were photographically identified between Mar 2012 and Dec 2013, with 129 males (82%), 19 females (12%) and 10 (6%) of undetermined sex. Mean estimated total length was 5.5 m (±1.3 m S.D.). Twenty individuals were measured with laser photogrammetry to validate researchers' estimated sizes, yielding a good correlation (r (2) = 0.83). Fifty-four (34%) individuals were observed being hand-fed by local fishermen (provisioned), through in-water behavioural observations. Maximum likelihood methods were used to model mean residency time of 44.9 days (±20.6 days S.E.) for provisioned R. typus contrasting with 22.4 days (±8.9 days S.E.) for non-provisioned individuals. Propeller scars were observed in 47% of the animals. A mean of 12.7 (±4.3 S.D.) R. typus were present in the survey area daily, with a maximum of 26 individuals (Aug 10 2013) and a minimum of 2 (Dec 6 2012). Twelve (8%) individuals were seen on at least 50% of survey days (n = 621), with a maximum residency of 572 days for one individual (P-396). Twenty four individuals were photographically identified across regional hotsposts, highlighting the species' migratory nature and distribution. Extended residency and differences in lagged identification rates suggest behavioural modification on provisioned individuals, underlying the necessity for proper management of this tourism activity.

Population structure and residency patterns of whale sharks, Rhincodon typus, at a provisioning site in Cebu, Philippines

Directory of Open Access Journals (Sweden)

Gonzalo Araujo

2014-09-01

Full Text Available This study represents the first description of whale sharks, Rhincodon typus, occurring at a provisioning site in Oslob, Cebu, Philippines. Frequent observations of sharks are often difficult, even at tourism sites, giving rise to provisioning activities to attract them. The present study provides repeated longitudinal data at a site where daily provisioning activities took place, and whale sharks were present every day. A total of 158 individual whale sharks were photographically identified between Mar 2012 and Dec 2013, with 129 males (82%, 19 females (12% and 10 (6% of undetermined sex. Mean estimated total length was 5.5 m (±1.3 m S.D.. Twenty individuals were measured with laser photogrammetry to validate researchers’ estimated sizes, yielding a good correlation (r2 = 0.83. Fifty-four (34% individuals were observed being hand-fed by local fishermen (provisioned, through in-water behavioural observations. Maximum likelihood methods were used to model mean residency time of 44.9 days (±20.6 days S.E. for provisioned R. typus contrasting with 22.4 days (±8.9 days S.E. for non-provisioned individuals. Propeller scars were observed in 47% of the animals. A mean of 12.7 (±4.3 S.D. R. typus were present in the survey area daily, with a maximum of 26 individuals (Aug 10 2013 and a minimum of 2 (Dec 6 2012. Twelve (8% individuals were seen on at least 50% of survey days (n = 621, with a maximum residency of 572 days for one individual (P-396. Twenty four individuals were photographically identified across regional hotsposts, highlighting the species’ migratory nature and distribution. Extended residency and differences in lagged identification rates suggest behavioural modification on provisioned individuals, underlying the necessity for proper management of this tourism activity.

Identifying the "demon whale-biter": Patterns of scarring on large whales attributed to a cookie-cutter shark Isistius sp.

Science.gov (United States)

Best, Peter B; Photopoulou, Theoni

2016-01-01

The presence of crater-like wounds on cetaceans and other large marine vertebrates and invertebrates has been attributed to various organisms. We review the evidence for the identity of the biting agent responsible for crater wounds on large whales, using data collected from sei (Balaenoptera borealis), fin (B. physalus), inshore and offshore Bryde's (B. brydeii sp) and sperm whales (Physeter macrocephalus) examined at the Donkergat whaling station, Saldanha Bay, South Africa between March and October 1963. We then analyse the intensity and trends in its predation on large whales. Despite the scarcity of local records, we conclude that a cookie-cutter shark Isistius sp is the most likely candidate. We make inferences about the trends in (1) total counts of unhealed bitemarks, and (2) the proportion of unhealed bitemarks that were recent. We use day of the year; reproductive class, social grouping or sex; depth interval and body length as candidate covariates. The models with highest support for total counts of unhealed bitemarks involve the day of the year in all species. Depth was an important predictor in all species except offshore Bryde's whales. Models for the proportion of recent bites were only informative for sei and fin whales. We conclude that temporal scarring patterns support what is currently hypothesized about the distribution and movements of these whale species, given that Isistius does not occur in the Antarctic and has an oceanic habitat. The incidence of fresh bites confirms the presence of Isistius in the region. The lower numbers of unhealed bites on medium-sized sperm whales suggests that this group spends more time outside the area in which bites are incurred, providing a clue to one of the biggest gaps in our understanding of the movements of mature and maturing sperm males.

Vertical Movements and Patterns in Diving Behavior of Whale Sharks as Revealed by Pop-Up Satellite Tags in the Eastern Gulf of Mexico

Science.gov (United States)

Tyminski, John P.; de la Parra-Venegas, Rafael; González Cano, Jaime; Hueter, Robert E.

2015-01-01

The whale shark (Rhincodon typus) is a wide-ranging, filter-feeding species typically observed at or near the surface. This shark’s sub-surface habits and behaviors have only begun to be revealed in recent years through the use of archival and satellite tagging technology. We attached pop-up satellite archival transmitting tags to 35 whale sharks in the southeastern Gulf of Mexico off the Yucatan Peninsula from 2003–2012 and three tags to whale sharks in the northeastern Gulf off Florida in 2010, to examine these sharks’ long-term movement patterns and gain insight into the underlying factors influencing their vertical habitat selection. Archived data were received from 31 tags deployed on sharks of both sexes with total lengths of 5.5–9 m. Nine of these tags were physically recovered facilitating a detailed long-term view into the sharks’ vertical movements. Whale sharks feeding inshore on fish eggs off the northeast Yucatan Peninsula demonstrated reverse diel vertical migration, with extended periods of surface swimming beginning at sunrise followed by an abrupt change in the mid-afternoon to regular vertical oscillations, a pattern that continued overnight. When in oceanic waters, sharks spent about 95% of their time within epipelagic depths (500 m) that largely occurred during daytime or twilight hours (max. depth recorded 1,928 m), had V-shaped depth-time profiles, and comprised more rapid descents (0.68 m sec-1) than ascents (0.50 m sec-1). Nearly half of these extreme dives had descent profiles with brief but conspicuous changes in vertical direction at a mean depth of 475 m. We hypothesize these stutter steps represent foraging events within the deep scattering layer, however, the extreme dives may have additional functions. Overall, our results demonstrate complex and dynamic patterns of habitat utilization for R. typus that appear to be in response to changing biotic and abiotic conditions influencing the distribution and abundance of their prey

Do they stay or do they go? Acoustic monitoring of whale sharks at Ningaloo Marine Park, Western Australia.

Science.gov (United States)

Norman, B M; Whitty, J M; Beatty, S J; Reynolds, S D; Morgan, D L

2017-12-01

Whale sharks Rhincodon typus were monitored via acoustic transmitters at the northern end of Western Australia's Ningaloo Marine Park to establish the extent to which the species inhabits the region beyond the whale-shark ecotourism industry season, which usually extends from March to August in each year. Despite the vast majority (c. 98%) of photographic submissions of R. typus from Ningaloo Reef being between March and August, acoustic detections from the tagged R. typus at Ningaloo were recorded in all months of the year, but do not preclude the occurrence of extended absences. It is concluded that as a species, R. typus occurs year round at Ningaloo, where it generally remains in close proximity to the reef edge, but that some individuals move outside of the detection range of the array for extended periods. © 2017 The Fisheries Society of the British Isles.

Identifying the “demon whale-biter”: Patterns of scarring on large whales attributed to a cookie-cutter shark Isistius sp

Science.gov (United States)

Photopoulou, Theoni

2016-01-01

The presence of crater-like wounds on cetaceans and other large marine vertebrates and invertebrates has been attributed to various organisms. We review the evidence for the identity of the biting agent responsible for crater wounds on large whales, using data collected from sei (Balaenoptera borealis), fin (B. physalus), inshore and offshore Bryde’s (B. brydeii sp) and sperm whales (Physeter macrocephalus) examined at the Donkergat whaling station, Saldanha Bay, South Africa between March and October 1963. We then analyse the intensity and trends in its predation on large whales. Despite the scarcity of local records, we conclude that a cookie-cutter shark Isistius sp is the most likely candidate. We make inferences about the trends in (1) total counts of unhealed bitemarks, and (2) the proportion of unhealed bitemarks that were recent. We use day of the year; reproductive class, social grouping or sex; depth interval and body length as candidate covariates. The models with highest support for total counts of unhealed bitemarks involve the day of the year in all species. Depth was an important predictor in all species except offshore Bryde’s whales. Models for the proportion of recent bites were only informative for sei and fin whales. We conclude that temporal scarring patterns support what is currently hypothesized about the distribution and movements of these whale species, given that Isistius does not occur in the Antarctic and has an oceanic habitat. The incidence of fresh bites confirms the presence of Isistius in the region. The lower numbers of unhealed bites on medium-sized sperm whales suggests that this group spends more time outside the area in which bites are incurred, providing a clue to one of the biggest gaps in our understanding of the movements of mature and maturing sperm males. PMID:27055057

Shark Detectives

Science.gov (United States)

Hitt, Dia

2005-01-01

Oceans are often considered mysterious, fascinating places filled with unique and scary animals. One of the most misunderstood and therefore scariest animals is the shark, yet the whale shark, the world's largest fish, is considered harmless to humans. This student-directed activity involves research, deductive reasoning, and students' own…

Diet Composition and Trophic Ecology of Northeast Pacific Ocean Sharks.

Science.gov (United States)

Bizzarro, Joseph J; Carlisle, Aaron B; Smith, Wade D; Cortés, Enric

Although there is a general perception of sharks as large pelagic, apex predators, most sharks are smaller, meso- and upper-trophic level predators that are associated with the seafloor. Among 73 shark species documented in the eastern North Pacific (ENP), less than half reach maximum lengths >200cm, and 78% occur in demersal or benthic regions of the continental shelf or slope. Most small (≤200cm) species (e.g., houndsharks) and demersal, nearshore juveniles of larger species (e.g., requiem sharks) consume small teleosts and decapod crustaceans, whereas large species in pelagic coastal and oceanic environments feed on large teleosts and squids. Several large, pelagic apex predator species occur in the ENP, but the largest species (i.e., Basking Shark, Whale Shark) consume zooplankton or small nekton. Size-based dietary variability is substantial for many species, and segregation of juvenile and adult foraging habitats also is common (e.g., Horn Shark, Shortfin Mako). Temporal dietary differences are most pronounced for temperate, nearshore species with wide size ranges, and least pronounced for smaller species in extreme latitudes and deep-water regions. Sympatric sharks often occupy various trophic positions, with resource overlap differing by space and time and some sharks serving as prey to other species. Most coastal species remain in the same general region over time and feed opportunistically on variable prey inputs (e.g., season migrations, spawning, or recruitment events), whereas pelagic, oceanic species actively seek hot spots of prey abundance that are spatiotemporally variable. The influence of sharks on ecosystem structure and regulation has been downplayed compared to that of large teleosts species with higher per capita consumption rates (e.g., tunas, billfishes). However, sharks also exert indirect influences on prey populations by causing behavioural changes that may result in restricted ranges and reduced fitness. Except for food web modelling

Isolation and characterization of microsatellite loci in the whale shark (Rhincodon typus)

Science.gov (United States)

Ramirez-Macias, D.; Shaw, K.; Ward, R.; Galvan-Magana, F.; Vazquez-Juarez, R.

2009-01-01

In preparation for a study on population structure of the whale shark (Rhincodon typus), nine species-specific polymorphic microsatellite DNA markers were developed. An initial screening of 50 individuals from Holbox Island, Mexico found all nine loci to be polymorphic, with two to 17 alleles observed per locus. Observed and expected heterozygosity per locus ranged from 0.200 to 0.826 and from 0.213 to 0.857, respectively. Neither statistically significant deviations from Hardy–Weinberg expectations nor statistically significant linkage disequilibrium between loci were observed. These microsatellite loci appear suitable for examining population structure, kinship assessment and other applications.

78 FR 50032 - Endangered and Threatened Wildlife; 90-Day Finding on a Petition To List the Whale Shark as...

Science.gov (United States)

2013-08-16

... ovoviviparous--meaning the egg cases hatch in utero, and females give birth to live young. Whale sharks are also... available data suggest that size at birth may vary considerably (Rowat and Brooks, 2012). Small, free-living... Food and Agriculture Organization's International Plan of Action for the Conservation and Management of...

New records of whale shark (Rhincodon typus), giant manta ray (Manta birostris) and Chilean devil ray (Mobula tarapacana) for Suriname

NARCIS (Netherlands)

Boer, De M.N.; Saulino, J.T.; Lewis, T.P.; Notarbartolo-Di-Sciara, G.

2015-01-01

Little is known about elasmobranchs along the northern coast of South America. During five boat surveys in Suriname offshore waters we visually documented the presence and behaviour of the free-ranging whale shark Rhincodon typus and two mobulid rays: the giant manta ray Manta birostris and the

Species co-occurrence affects the trophic interactions of two juvenile reef shark species in tropical lagoon nurseries in Moorea (French Polynesia).

Science.gov (United States)

Matich, Philip; Kiszka, Jeremy J; Mourier, Johann; Planes, Serge; Heithaus, Michael R

2017-06-01

Food web structure is shaped by interactions within and across trophic levels. As such, understanding how the presence and absence of predators, prey, and competitors affect species foraging patterns is important for predicting the consequences of changes in species abundances, distributions, and behaviors. Here, we used plasma δ 13 C and δ 15 N values from juvenile blacktip reef sharks (Carcharhinus melanopterus) and juvenile sicklefin lemon sharks (Negaprion acutidens) to investigate how species co-occurrence affects their trophic interactions in littoral waters of Moorea, French Polynesia. Co-occurrence led to isotopic niche partitioning among sharks within nurseries, with significant increases in δ 15 N values among sicklefin lemon sharks, and significant decreases in δ 15 N among blacktip reef sharks. Niche segregation likely promotes coexistence of these two predators during early years of growth and development, but data do not suggest coexistence affects life history traits, such as body size, body condition, and ontogenetic niche shifts. Plasticity in trophic niches among juvenile blacktip reef sharks and sicklefin lemon sharks also suggests these predators are able to account for changes in community structure, resource availability, and intra-guild competition, and may fill similar functional roles in the absence of the other species, which is important as environmental change and human impacts persist in coral reef ecosystems. Copyright © 2017 Elsevier Ltd. All rights reserved.

Regional-scale migrations and habitat use of juvenile lemon sharks (Negaprion brevirostris) in the US South Atlantic.

Science.gov (United States)

Reyier, Eric A; Franks, Bryan R; Chapman, Demian D; Scheidt, Douglas M; Stolen, Eric D; Gruber, Samuel H

2014-01-01

Resolving the geographic extent and timing of coastal shark migrations, as well as their environmental cues, is essential for refining shark management strategies in anticipation of increasing anthropogenic stressors to coastal ecosystems. We employed a regional-scale passive acoustic telemetry array encompassing 300 km of the east Florida coast to assess what factors influence site fidelity of juvenile lemon sharks (Negaprion brevirostris) to an exposed coastal nursery at Cape Canaveral, and to document the timing and rate of their seasonal migrations. Movements of 54 juvenile lemon sharks were monitored for three years with individuals tracked for up to 751 days. While most sharks demonstrated site fidelity to the Cape Canaveral region December through February under typical winter water temperatures, historically extreme declines in ocean temperature were accompanied by rapid and often temporary, southward displacements of up to 190 km along the Florida east coast. From late February through April each year, most sharks initiated a northward migration at speeds of up to 64 km day(-1) with several individuals then detected in compatible estuarine telemetry arrays in Georgia and South Carolina up to 472 km from release locations. Nineteen sharks returned for a second or even third consecutive winter, thus demonstrating strong seasonal philopatry to the Cape Canaveral region. The long distance movements and habitat associations of immature lemon sharks along the US southeast coast contrast sharply with the natal site fidelity observed in this species at other sites in the western Atlantic Ocean. These findings validate the existing multi-state management strategies now in place. Results also affirm the value of collaborative passive arrays for resolving seasonal movements and habitat preferences of migratory coastal shark species not easily studied with other tagging techniques.

A preliminary survey of whale shark Rhincodon typus catch and trade in China: an emerging crisis.

Science.gov (United States)

Li, W; Wang, Y; Norman, B

2012-04-01

This study gives an account of spatial and temporal distribution of whale shark Rhincodon typus catch events in China on the basis of historical records and information obtained from interviews with fishing industry stakeholders. A total of 186 R. typus were recorded with key harvest areas identified as in Hainan and Zhejiang, and the peak catching seasons were May to June and September to October. Aspects of the R. typus trade are discussed, including products, markets and the process. The results suggest that R. typus is increasingly becoming a targeted resource in China as a consequence of fierce competition for large shark fins and an emerging local market for consumption of all body parts. Current obstacles and potential measures for sustainable exploitation and trade of R. typus are discussed. © 2012 The Authors. Journal of Fish Biology © 2012 The Fisheries Society of the British Isles.

A Tale of Two Aggregations: Kinship and Population Genetics of Whale Sharks (Rhincodon typus) at Shib Habil, Saudi Arabia, and Mafia Island, Tanzania.

KAUST Repository

Hardenstine, Royale

2015-12-01

In a recent global study of whale shark population genetics, aggregations were found to belong to either the Indo-Pacific or Atlantic population. This overview included an aggregation found within the Red Sea near Al Lith, Saudi Arabia, however the Mafia Island, Tanzania, aggregation was not part of the study. Both aggregations have unique aspects with the Saudi Arabian individuals showing sexual parity with no segregation, while recent acoustic results have revealed cryptic residency at Mafia Island. Genetic analysis using 11 microsatellite markers was performed on whale sharks from both locations. A combination of primers sourced from previous studies and newly designed primers were used to compare both aggregations and the individuals within. Samples were collected in the Red Sea for 5 seasons spanning 6 years, and for 2 seasons in Tanzania. Analysis with STRUCTURE showed a lack of significant genetic differences between the two aggregations, confirming that whale sharks in Tanzania are part of the Indo-Pacific population. Kinship analysis using COLONY found two potential pairs of full siblings in Tanzania. One pair had a high probability (.993) of being a full sibling dyad while the other had a lower probability (.357). There were no sibling pairs identified from the Red Sea aggregation. Genetic diversity was investigated using allelic richness over the 6 seasons at Al Lith, with values showing no significant change. This is in contrast to results that showed a decline in genetic diversity at Western Australia’s Ningaloo reef. These differences, however, only highlight the need for genetic diversity studies over longer time periods and at other aggregations within the Indo-Pacific.

Physiological Optics of the Eye of the Juvenile Lemon Shark (Negaprion brevirostris).

Science.gov (United States)

1980-05-01

fUr Lher affects of ametropia ) is the distance between the second nodal point vI lhe -’otoreceptor layer. This dimension is known as the posterior...gauge on the negative effect of ametropia on visual acuity, t the size of these retinal blur circles can be calculated using the schematic eye, 96...the working distance between retinoscopist and subject eye. My retinoscopic measurements of the underwater ametropia in juvenile lemon sharks have been

Acoustic telemetry reveals cryptic residency of whale sharks

KAUST Repository

Cagua, Edgar F.

2015-04-01

Althoughwhale sharks (Rhincodon typus) have beendocumentedtomove thousands of kilometres, they are most frequently observed at a few predictable seasonal aggregation sites. The absence of sharks at the surface during visual surveys has led to the assumption that sharks disperse to places unknown during the long \\'off-seasons\\' at most of these locations. Here we compare 2 years of R. typus visual sighting records from Mafia Island in Tanzania to concurrent acoustic telemetry of tagged individuals. Sightings revealed a clear seasonal pattern with a peak between October and February and no sharks observed at other times. By contrast, acoustic telemetry demonstrated yearround residency of R. typus. The sharks use a different habitat in the offseason, swimming deeper and further away from shore, presumably in response to prey distributions. This behavioural change reduces the sharks\\' visibility, giving the false impression that they have left the area.We demonstrate, for the first timeto our knowledge, year-roundresidencyofunprovisioned, individual R. typus at an aggregation site, and highlight the importance of using multiple techniques to study the movement ecology of marine megafauna. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

When bigger is not better: selection against large size, high condition and fast growth in juvenile lemon sharks.

Science.gov (United States)

Dibattista, J D; Feldheim, K A; Gruber, S H; Hendry, A P

2007-01-01

Selection acting on large marine vertebrates may be qualitatively different from that acting on terrestrial or freshwater organisms, but logistical constraints have thus far precluded selection estimates for the former. We overcame these constraints by exhaustively sampling and repeatedly recapturing individuals in six cohorts of juvenile lemon sharks (450 age-0 and 255 age-1 fish) at an enclosed nursery site (Bimini, Bahamas). Data on individual size, condition factor, growth rate and inter-annual survival were used to test the 'bigger is better', 'fatter is better' and 'faster is better' hypotheses of life-history theory. For age-0 sharks, selection on all measured traits was weak, and generally acted against large size and high condition. For age-1 sharks, selection was much stronger, and consistently acted against large size and fast growth. These results suggest that selective pressures at Bimini may be constraining the evolution of large size and fast growth, an observation that fits well with the observed small size and low growth rate of juveniles at this site. Our results support those of some other recent studies in suggesting that bigger/fatter/faster is not always better, and may often be worse.

Evidence for vocal learning in juvenile male killer whales, Orcinus orca, from an adventitious cross-socializing experiment.

Science.gov (United States)

Crance, Jessica L; Bowles, Ann E; Garver, Alan

2014-04-15

Killer whales (Orcinus orca) are thought to learn their vocal dialect. Dispersal in the species is rare, but effects of shifts in social association on the dialect can be studied under controlled conditions. Individual call repertoires and social association were measured in three adult female killer whales and three males (two juveniles and an adult) during two periods, 2001-2003 and 2005-2006. Three distinct dialect repertoires were represented among the subjects. An adventitious experiment in social change resulted from the birth of a calf and the transfer of two non-focal subjects in 2004. Across the two periods, 1691 calls were collected, categorized and attributed to individuals. Repertoire overlap for each subject dyad was compared with an index of association. During 2005-2006, the two juvenile males increased association with the unrelated adult male. By the end of the period, both had begun producing novel calls and call features characteristic of his repertoire. However, there was little or no reciprocal change and the adult females did not acquire his calls. Repertoire overlap and association were significantly correlated in the first period. In the second, median association time and repertoire similarity increased, but the relationship was only marginally significant. The results provided evidence that juvenile male killer whales are capable of learning new call types, possibly stimulated by a change in social association. The pattern of learning was consistent with a selective convergence of male repertoires.

Trends and interventions in large whale entanglement along the ...

African Journals Online (AJOL)

Generalised linear models with a Poisson or quasi-Poisson distribution were used to describe the relationship between the number of incidents and time. Taking into account the combined length of shark-net installations per year as an offset variable, entanglement of humpback whales in shark nets increased at 15.1% per ...

First Direct Evidence for Natal Wintering Ground Fidelity and Estimate of Juvenile Survival in the New Zealand Southern Right Whale Eubalaena australis.

Science.gov (United States)

Carroll, E L; Fewster, R M; Childerhouse, S J; Patenaude, N J; Boren, L; Baker, C S

2016-01-01

Juvenile survival and recruitment can be more sensitive to environmental, ecological and anthropogenic factors than adult survival, influencing population-level processes like recruitment and growth rate in long-lived, iteroparous species such as southern right whales. Conventionally, Southern right whales are individually identified using callosity patterns, which do not stabilise until 6-12 months, by which time the whale has left its natal wintering grounds. Here we use DNA profiling of skin biopsy samples to identify individual Southern right whales from year of birth and document their return to the species' primary wintering ground in New Zealand waters, the Subantarctic Auckland Islands. We find evidence of natal fidelity to the New Zealand wintering ground by the recapture of 15 of 57 whales, first sampled in year of birth and available for subsequent recapture, during winter surveys to the Auckland Islands in 1995-1998 and 2006-2009. Four individuals were recaptured at the ages of 9 to 11, including two females first sampled as calves in 1998 and subsequently resampled as cows with calves in 2007. Using these capture-recapture records of known-age individuals, we estimate changes in survival with age using Cormack-Jolly-Seber models. Survival is modelled using discrete age classes and as a continuous function of age. Using a bootstrap method to account for uncertainty in model selection and fitting, we provide the first direct estimate of juvenile survival for this population. Our analyses indicate a high annual apparent survival for juveniles at between 0.87 (standard error (SE) 0.17, to age 1) and 0.95 (SE 0.05: ages 2-8). Individual identification by DNA profiling is an effective method for long-term demographic and genetic monitoring, particularly in animals that change identifiable features as they develop or experience tag loss over time.

The Greenland shark (Somniosus microcephalus)

DEFF Research Database (Denmark)

Nielsen, Julius

radiocarbon dating and a Bayesian calibration model to estimate longevity of the Greenland shark. The analyzed tissue stems from the eye lens nucleus – unique material which presumably reflects age 0 of the shark, as it has not undergone metabolic changes during the animal’s life. By studying 28 Greenland...... shark females between 81 cm and 502 cm, I estimate the oldest shark to be between 272 years and 512 years. With an estimated lifespan of at least 272 years, the Greenland shark is the longest living vertebrate animal in the world. In order to produce these age estimates, it has been necessary to study...... continental shelf waters in southern Greenland at depths between 200 and 550 m and fed primarily on cod, redfish and seals. From previous investigations of predatory sharks and whales in the north Atlantic, bomb radiocarbon has been widely applied, and I argue that a similar calibration approach is valid...

Size of the great white shark (carcharodon).

Science.gov (United States)

Randall, J E

1973-07-13

The maximum length of 36.5 feet (11.1 meters) attributed to the white shark (Carcharodon carcharias) by Günther and others is a mistake. Examination of the jaws and teeth of the specimen referred to by Günther and comparison with the jaws of white sharks of known length revealed a length of about 17 feet ( approximately 5 meters). The largest white shark reliably measured was a 21-foot (6.4-meter) individual from Cuba. Bites on whale carcasses found off southern Australia suggest that white sharks as long as 25 or 26 feet (7 (1/2) or 8 meters) exist today. The size of extinct Carcharodon has also been grossly exaggerated. Based on a projection of a curve of tooth size of Recent Carcharodon carcharias, the largest fossil Carcharodon were about 43 feet ( approximately 13 meters) long.

Early-life exposure to climate change impairs tropical shark survival.

Science.gov (United States)

Rosa, Rui; Baptista, Miguel; Lopes, Vanessa M; Pegado, Maria Rita; Paula, José Ricardo; Trübenbach, Katja; Leal, Miguel Costa; Calado, Ricardo; Repolho, Tiago

2014-10-22

Sharks are one of the most threatened groups of marine animals worldwide, mostly owing to overfishing and habitat degradation/loss. Although these cartilaginous fish have evolved to fill many ecological niches across a wide range of habitats, they have limited capability to rapidly adapt to human-induced changes in their environments. Contrary to global warming, ocean acidification was not considered as a direct climate-related threat to sharks. Here we show, for the first time, that an early ontogenetic acclimation process of a tropical shark (Chiloscyllium punctatum) to the projected scenarios of ocean acidification (ΔpH = 0.5) and warming (+4°C; 30°C) for 2100 elicited significant impairments on juvenile shark condition and survival. The mortality of shark embryos at the present-day thermal scenarios was 0% both at normocapnic and hypercapnic conditions. Yet routine metabolic rates (RMRs) were significantly affected by temperature, pH and embryonic stage. Immediately after hatching, the Fulton condition of juvenile bamboo sharks was significantly different in individuals that experienced future warming and hypercapnia; 30 days after hatching, survival rapidly declined in individuals experiencing both ocean warming and acidification (up to 44%). The RMR of juvenile sharks was also significantly affected by temperature and pH. The impact of low pH on ventilation rates was significant only under the higher thermal scenario. This study highlights the need of experimental-based risk assessments of sharks to climate change. In other words, it is critical to directly assess risk and vulnerability of sharks to ocean acidification and warming, and such effort can ultimately help managers and policy-makers to take proactive measures targeting most endangered species. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

Endohelminth parasites of the leafscale gulper shark, Centrophorus squamosus (Bonnaterre, 1788) (Squaliformes:Centrophoridae) off Madeira Archipelago.

Science.gov (United States)

Costa, Graça; Chada, Tomás; Melo-Moreira, Egberto; Cavallero, Serena; D'Amelio, Stefano

2014-06-01

The endohelminth parasite fauna of a deep water shark, the leafscale gulper shark, Centrophorus squamosus, examined from Madeiran waters, from September 2009 to January 2010, consisted of larval and juvenile cestodes of two orders, namely Trypanorhyncha and Tetraphyllidea, and L3 stages of Anisakis spp. Infection with Anisakis spp. could be due to the shark's opportunistic feeding on squids and black-scabbard fish, Aphanopus carbo, which is heavily parasitized by Anisakis spp. in Madeira waters. The occurrence of larval and juvenile cestodes only, in this shark, suggests that the leafscale gulper shark features as a paratenic or a dead-end host for the parasites.

Nursery area and size structure of the lemon shark population, Negaprion brevirostris (Poey, 1868, in Los Roques Archipelago National Park, Venezuela

Directory of Open Access Journals (Sweden)

Rafael Tavares

2016-01-01

Full Text Available The protection of the habitats used by juvenile sharks is a management strategy that has recently caught the attention of fishery biologists. In the present study, we evaluated the population of the lemon shark (Negaprion brevirostris from Los Roques Archipelago in order to identify the nursery area, describe the size composition, and examine the variation in nocturnal activity of the juvenile individuals. The data analysed came from three different sources: commercial shark fishery, tag-recapture sampling, and visual records. A total of 375 lemon sharks with total lengths between 55 and 281 cm were recorded during the study period. Overall data showed that the area occupied by juvenile lemon sharks was clearly partitioned into primary and secondary nurseries. Additionally, nighttime activity seemed to change according to the size of sharks in the primary nursery, suggesting a reduction of time activity overlapping among juveniles of distinct size/age. Results suggest that the strategy of utilization of the primary nurseries by the lemon shark may lead to important ecological benefits by reducing the competition, predation and natural mortality.

Novel acoustic technology for studying free-ranging shark social behaviour by recording individuals' interactions.

Directory of Open Access Journals (Sweden)

Tristan L Guttridge

Full Text Available Group behaviours are widespread among fish but comparatively little is known about the interactions between free-ranging individuals and how these might change across different spatio-temporal scales. This is largely due to the difficulty of observing wild fish groups directly underwater over long enough time periods to quantify group structure and individual associations. Here we describe the use of a novel technology, an animal-borne acoustic proximity receiver that records close-spatial associations between free-ranging fish by detection of acoustic signals emitted from transmitters on other individuals. Validation trials, held within enclosures in the natural environment, on juvenile lemon sharks Negaprion brevirostris fitted with external receivers and transmitters, showed receivers logged interactions between individuals regularly when sharks were within 4 m ( approximately 4 body lengths of each other, but rarely when at 10 m distance. A field trial lasting 17 days with 5 juvenile lemon sharks implanted with proximity receivers showed one receiver successfully recorded association data, demonstrating this shark associated with 9 other juvenile lemon sharks on 128 occasions. This study describes the use of acoustic underwater proximity receivers to quantify interactions among wild sharks, setting the scene for new advances in understanding the social behaviours of marine animals.

A secondary nursery area for the copper shark Carcharhinus brachyurus from the late Miocene of Peru

Science.gov (United States)

Landini, Walter; Collareta, Alberto; Pesci, Fabio; Di Celma, Claudio; Urbina, Mario; Bianucci, Giovanni

2017-10-01

The life history strategies of sharks often include the use of protected nursery areas by young-of-the-year and juveniles. Nursery areas can be primary (i.e., grounds where the sharks are born and spend the very first part of their lives) or secondary (i.e., grounds inhabited by slightly older but not yet mature individuals). Criteria utilized to recognize these strategic habitats include: high concentration of young sharks, high food availability, and low predation risk. Since the fossil record of sharks consists mainly of isolated teeth, identification of paleonurseries involves a series of problems due to difficult application of actualistic criteria. A rich shark tooth-bearing level (ST-low1) has recently been discovered in the upper Miocene deposits of the Pisco Formation exposed at Cerro Colorado (southern coast of Peru). Most of the teeth collected from this level belong to the extant copper shark Carcharhinus brachyurus. These teeth are small and compatible with those of extant juveniles. This observation, coupled with other paleoenvironmental considerations, indicates that the ST-low1 horizon could have represented a nursery ground for juvenile individuals of C. brachyurus. The absence of very small-sized teeth (i.e., referable to young-of-the-year) suggests a secondary nursery ground inhabited by immature copper sharks. Observations on the tooth size of other Lamniformes, Carcharhiniformes, and Myliobatiformes occurring along with C. brachyurus point to a significantly juvenile structure of this elasmobranch assemblage, thus supporting the hypothesis of a communal use of the Cerro Colorado paleonursery.

A new gnathiid (Crustacea: Isopoda) parasitizing two species of requiem sharks from Lizard Island, Great Barrier Reef, Australia.

Science.gov (United States)

Coetzee, Maryke L; Smit, Nico J; Grutter, Alexandra S; Davies, Angela J

2008-06-01

Third-stage juveniles (praniza 3) of Gnathia grandilaris n. sp. were collected from the gill filaments and septa of 5 requiem sharks, including a white tip reef shark, Triaenodon obesus, and 4 grey reef sharks, Carcharhinus amblyrhynchos, at Lizard Island, Great Barrier Reef, Australia, in March 2002. Some juvenile gnathiids were then maintained in fresh sea water until they molted to adults. Adult males appeared 19 days following detachment of juveniles from host fishes, but no juveniles molted successfully into females. The current description is based, therefore, on bright field and scanning electron microscopy observations of adult males and third-stage juveniles. Unique features of the male include the triangular-shaped inferior medio-frontal process, 2 areolae on the dorsal surface of the pylopod, and a slender pleotelson (twice as long as wide) with lateral concavities. The third-stage juvenile has distinctive white pigmentation on the black pereon when alive, while the mandible has 9 triangular backwardly directed teeth. This species has the largest male and third-stage juvenile of any Gnathia spp. from Australia and of any gnathiid isopods associated with elasmobranchs.

Coupled solar-magnetic orientation during leatherback turtle (Dermochelys coriacea), great white shark (Carcharodon carcharias), arctic tern (Sterna paradisaea), and humpback whale (Megaptera novaeangliae) long-distance migration

Science.gov (United States)

Horton, T. W.; Holdaway, R. N.; Zerbini, A.; Andriolo, A.; Clapham, P. J.

2010-12-01

Determining how animals perform long-distance animal migration remains one of the most enduring and fundamental mysteries of behavioural ecology. It is widely accepted that navigation relative to a reference datum is a fundamental requirement of long-distance return migration between seasonal habitats, and significant experimental research has documented a variety of viable orientation and navigation cues. However, relatively few investigations have attempted to reconcile experimentally determined orientation and navigation capacities of animals with empirical remotely sensed animal track data, leaving most theories of navigation and orientation untested. Here we show, using basic hypothesis testing, that leatherback turtle (Dermochelys coriacea), great white shark (Carcharodon carcharias), arctic tern (Sterna paradisaea), and humpback whale (Megaptera novaeangliae) migration paths are non-randomly distributed in magnetic coordinate space, with local peaks in magnetic coordinate distributions equal to fractional multiples of the angular obliquity of Earth’s axis of rotation. Time series analysis of humpback whale migratory behaviours, including migration initiation, changes in course, and migratory stop-overs, further demonstrate coupling of magnetic and celestial orientation cues during long-distance migration. These unexpected and highly novel results indicate that diverse taxa integrate magnetic and celestial orientation cues during long-distance migration. These results are compatible with a 'map and compass' orientation and navigation system. Humpback whale migration track geometries further indicate a map and compass orientation system is used. Several humpback whale tracks include highly directional segments (Mercator latitude vs. longitude r2>0.99) exceeding 2000 km in length, despite exposure to variable strength (c. 0-1 km/hr) surface cross-currents. Humpback whales appear to be able to compensate for surface current drift. The remarkable directional

Gill lesions associated with Erpocotyle tiburonis (Monogenea: Hexabothriidae) on wild and aquarium-held bonnethead sharks (Sphyrna tiburo).

Science.gov (United States)

Bullard, S A; Frasca, S; Benz, G W

2001-10-01

Gill lesions associated with infections of Erpocotyle tiburonis (Brooks, 1934) (Monogenea: Hexabothriidae) on wild bonnethead sharks (Sphyrna tiburo (L., 1758) (Carcharhiniformes: Sphyrinidae)) were compared with those on aquarium-held ones using light and scanning electron microscopy. Uninfected gill filaments had slender, triangular, smooth-surfaced lamellae and interlamellar water channels that were approximately equal in size. Four wild sharks were each infected by 3-11 widely separated adult E. tiburonis, and 1 of these sharks hosted a juvenile specimen. Lamellae flanking or touching adult E. tiburonis were pushed aside or bent, but were otherwise identical to those of uninfected filaments. Two aquarium-held sharks were each infected by hundreds of juvenile and adult E. tiburonis. In these sharks, lamellae near juveniles were pushed apart or bent, but were otherwise normal, whereas a thick, ragged-surfaced layer of hyperplastic epithelium both filled interlamellar water channels and partially or completely covered lamellae near adults. Results of this study suggest that the intense infections of E. tiburonis were facilitated by captivity and caused severe hyperplastic lesions that ultimately led to the death of the sharks by reducing or blocking the respiratory water flow over lamellae and thus reducing the exchange of gases and ions across the lamellar epithelium. In contrast, the wild sharks were infected by fewer worms and exhibited relatively minor lesions.

No rainbow for grey bamboo sharks: evidence for the absence of colour vision in sharks from behavioural discrimination experiments.

Science.gov (United States)

Schluessel, V; Rick, I P; Plischke, K

2014-11-01

Despite convincing data collected by microspectrophotometry and molecular biology, rendering sharks colourblind cone monochromats, the question of whether sharks can perceive colour had not been finally resolved in the absence of any behavioural experiments compensating for the confounding factor of brightness. The present study tested the ability of juvenile grey bamboo sharks to perceive colour in an experimental design based on a paradigm established by Karl von Frisch using colours in combination with grey distractor stimuli of equal brightness. Results showed that contrasts but no colours could be discriminated. Blue and yellow stimuli were not distinguished from a grey distractor stimulus of equal brightness but could be distinguished from distractor stimuli of varying brightness. In addition, different grey stimuli were distinguished significantly above chance level from one another. In conclusion, the behavioural results support the previously collected physiological data on bamboo sharks, which mutually show that the grey bamboo shark, like several marine mammals, is a cone monochromate and colourblind.

Movements of Blue Sharks (Prionace glauca) across Their Life History

Science.gov (United States)

Vandeperre, Frederic; Aires-da-Silva, Alexandre; Fontes, Jorge; Santos, Marco; Serrão Santos, Ricardo; Afonso, Pedro

2014-01-01

Spatial structuring and segregation by sex and size is considered to be an intrinsic attribute of shark populations. These spatial patterns remain poorly understood, particularly for oceanic species such as blue shark (Prionace glauca), despite its importance for the management and conservation of this highly migratory species. This study presents the results of a long-term electronic tagging experiment to investigate the migratory patterns of blue shark, to elucidate how these patterns change across its life history and to assess the existence of a nursery area in the central North Atlantic. Blue sharks belonging to different life stages (n = 34) were tracked for periods up to 952 days during which they moved extensively (up to an estimated 28.139 km), occupying large parts of the oceanic basin. Notwithstanding a large individual variability, there were pronounced differences in movements and space use across the species' life history. The study provides strong evidence for the existence of a discrete central North Atlantic nursery, where juveniles can reside for up to at least 2 years. In contrast with previously described nurseries of coastal and semi-pelagic sharks, this oceanic nursery is comparatively vast and open suggesting that shelter from predators is not its main function. Subsequently, male and female blue sharks spatially segregate. Females engage in seasonal latitudinal migrations until approaching maturity, when they undergo an ontogenic habitat shift towards tropical latitudes. In contrast, juvenile males generally expanded their range southward and apparently displayed a higher degree of behavioural polymorphism. These results provide important insights into the spatial ecology of pelagic sharks, with implications for the sustainable management of this heavily exploited shark, especially in the central North Atlantic where the presence of a nursery and the seasonal overlap and alternation of different life stages coincides with a high fishing

Ancestor–descendant relationships in evolution: origin of the extant pygmy right whale, Caperea marginata

Science.gov (United States)

Tsai, Cheng-Hsiu; Fordyce, R. Ewan

2015-01-01

Ancestor–descendant relationships (ADRs), involving descent with modification, are the fundamental concept in evolution, but are usually difficult to recognize. We examined the cladistic relationship between the only reported fossil pygmy right whale, †Miocaperea pulchra, and its sole living relative, the enigmatic pygmy right whale Caperea marginata, the latter represented by both adult and juvenile specimens. †Miocaperea is phylogenetically bracketed between juvenile and adult Caperea marginata in morphologically based analyses, thus suggesting a possible ADR—the first so far identified within baleen whales (Cetacea: Mysticeti). The †Miocaperea–Caperea lineage may show long-term morphological stasis and, in turn, punctuated equilibrium. PMID:25589485

Biological aspects of sharks caught off the Coast of Pernambuco, Northeast Brazil

Directory of Open Access Journals (Sweden)

AF. Fischer

Full Text Available One hundred seventeen specimens of sharks were caught along the coast of Pernambuco State, Northern Brazil, between May 2004 and May 2007, among which 86 were blacknose sharks, Carcharhinus acronotus, enabling a more detailed study of the species. Blacknose sharks were caught in the 2 study areas along the Boa Viagem/Piedade and Paiva beaches, accounting for the highest relative abundance among the species caught (73.5% of total. Potentially dangerous sharks, tiger and bull sharks, were also caught in the same areas, whereas hammerhead and blacktip sharks were only captured off Boa Viagem/Piedade. Concerning the blacknose shark, the total length (TL ranged from 39.0 to 180.0 cm. Among the 38 females analysed, 32 were juveniles, 11 were maturing, 2 were pre-ovulatory and 21 were pregnant. Sexing was possible for 75 of the 83 embryos, 38 of which were males and 37 were females, with a sex proportion of 1:0.9 and total length ranging between 6.4 and 63.5 cm. Ovarian fecundity ranged from 5 to 10 and uterine fecundity from 1 to 3, with an estimated gestational period of 9 months. Among the 48 males, 6 were juveniles and 42 were adults. Both males and females seem to reach sexual maturity at about 105.0 cm TL. Among the 86 stomachs analysed, only 22.1% had contents, with teleosts as the most frequent item.

Ecological impact of the end-Cretaceous extinction on lamniform sharks.

Directory of Open Access Journals (Sweden)

Rachel A Belben

Full Text Available Lamniform sharks are apex marine predators undergoing dramatic local and regional decline worldwide, with consequences for marine ecosystems that are difficult to predict. Through their long history, lamniform sharks have faced widespread extinction, and understanding those 'natural experiments' may help constrain predictions, placing the current crisis in evolutionary context. Here we show, using novel morphometric analyses of fossil shark teeth, that the end-Cretaceous extinction of many sharks had major ecological consequences. Post-extinction ecosystems supported lower diversity and disparity of lamniforms, and were dominated by significantly smaller sharks with slimmer, smoother and less robust teeth. Tooth shape is intimately associated with ecology, feeding and prey type, and by integrating data from extant sharks we show that latest Cretaceous sharks occupied similar niches to modern lamniforms, implying similar ecosystem structure and function. By comparison, species in the depauperate post-extinction community occupied niches most similar to those of juvenile sand tigers (Carcharias taurus. Our data show that quantitative tooth morphometrics can distinguish lamniform sharks due to dietary differences, providing critical insights into ecological consequences of past extinction episodes.

Ecological impact of the end-Cretaceous extinction on lamniform sharks.

Science.gov (United States)

Belben, Rachel A; Underwood, Charlie J; Johanson, Zerina; Twitchett, Richard J

2017-01-01

Lamniform sharks are apex marine predators undergoing dramatic local and regional decline worldwide, with consequences for marine ecosystems that are difficult to predict. Through their long history, lamniform sharks have faced widespread extinction, and understanding those 'natural experiments' may help constrain predictions, placing the current crisis in evolutionary context. Here we show, using novel morphometric analyses of fossil shark teeth, that the end-Cretaceous extinction of many sharks had major ecological consequences. Post-extinction ecosystems supported lower diversity and disparity of lamniforms, and were dominated by significantly smaller sharks with slimmer, smoother and less robust teeth. Tooth shape is intimately associated with ecology, feeding and prey type, and by integrating data from extant sharks we show that latest Cretaceous sharks occupied similar niches to modern lamniforms, implying similar ecosystem structure and function. By comparison, species in the depauperate post-extinction community occupied niches most similar to those of juvenile sand tigers (Carcharias taurus). Our data show that quantitative tooth morphometrics can distinguish lamniform sharks due to dietary differences, providing critical insights into ecological consequences of past extinction episodes.

Ontogeny of head and caudal fin shape of an apex marine predator: The tiger shark (Galeocerdo cuvier).

Science.gov (United States)

Fu, Amy L; Hammerschlag, Neil; Lauder, George V; Wilga, Cheryl D; Kuo, Chi-Yun; Irschick, Duncan J

2016-05-01

How morphology changes with size can have profound effects on the life history and ecology of an animal. For apex predators that can impact higher level ecosystem processes, such changes may have consequences for other species. Tiger sharks (Galeocerdo cuvier) are an apex predator in tropical seas, and, as adults, are highly migratory. However, little is known about ontogenetic changes in their body form, especially in relation to two aspects of shape that influence locomotion (caudal fin) and feeding (head shape). We captured digital images of the heads and caudal fins of live tiger sharks from Southern Florida and the Bahamas ranging in body size (hence age), and quantified shape of each using elliptical Fourier analysis. This revealed changes in the shape of the head and caudal fin of tiger sharks across ontogeny. Smaller juvenile tiger sharks show an asymmetrical tail with the dorsal (upper) lobe being substantially larger than the ventral (lower) lobe, and transition to more symmetrical tail in larger adults, although the upper lobe remains relatively larger in adults. The heads of juvenile tiger sharks are more conical, which transition to relatively broader heads over ontogeny. We interpret these changes as a result of two ecological transitions. First, adult tiger sharks can undertake extensive migrations and a more symmetrical tail could be more efficient for swimming longer distances, although we did not test this possibility. Second, adult tiger sharks expand their diet to consume larger and more diverse prey with age (turtles, mammals, and elasmobranchs), which requires substantially greater bite area and force to process. In contrast, juvenile tiger sharks consume smaller prey, such as fishes, crustaceans, and invertebrates. Our data reveal significant morphological shifts in an apex predator, which could have effects for other species that tiger sharks consume and interact with. © 2016 Wiley Periodicals, Inc.

Freshwater to seawater acclimation of juvenile bull sharks (Carcharhinus leucas): plasma osmolytes and Na+/K+-ATPase activity in gill, rectal gland, kidney and intestine.

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Pillans, Richard D; Good, Jonathan P; Anderson, W Gary; Hazon, Neil; Franklin, Craig E

2005-01-01

This study examined the osmoregulatory status of the euryhaline elasmobranch Carcharhinus leucas acclimated to freshwater (FW) and seawater (SW). Juvenile C. leucas captured in FW (3 mOsm l(-1) kg(-1)) were acclimated to SW (980-1,000 mOsm l(-1) kg(-1)) over 16 days. A FW group was maintained in captivity over a similar time period. In FW, bull sharks were hyper-osmotic regulators, having a plasma osmolarity of 595 mOsm l(-1) kg(-1). In SW, bull sharks had significantly higher plasma osmolarities (940 mOsm l(-1) kg(-1)) than FW-acclimated animals and were slightly hypo-osmotic to the environment. Plasma Na(+), Cl(-), K(+), Mg(2+), Ca(2+), urea and trimethylamine oxide (TMAO) concentrations were all significantly higher in bull sharks acclimated to SW, with urea and TMAO showing the greatest increase. Gill, rectal gland, kidney and intestinal tissue were taken from animals acclimated to FW and SW and analysed for maximal Na(+)/K(+)-ATPase activity. Na(+)/K(+)-ATPase activity in the gills and intestine was less than 1 mmol Pi mg(-1) protein h(-1) and there was no difference in activity between FW- and SW-acclimated animals. In contrast Na(+)/K(+)-ATPase activity in the rectal gland and kidney were significantly higher than gill and intestine and showed significant differences between the FW- and SW-acclimated groups. In FW and SW, rectal gland Na(+)/K(+)-ATPase activity was 5.6+/-0.8 and 9.2+/-0.6 mmol Pi mg(-1) protein h(-1), respectively. Na(+)/K(+)-ATPase activity in the kidney of FW and SW acclimated animals was 8.4+/-1.1 and 3.3+/-1.1 Pi mg(-1) protein h(-1), respectively. Thus juvenile bull sharks have the osmoregulatory plasticity to acclimate to SW; their preference for the upper reaches of rivers where salinity is low is therefore likely to be for predator avoidance and/or increased food abundance rather than because of a physiological constraint.

Ancestor-descendant relationships in evolution: origin of the extant pygmy right whale, Caperea marginata.

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Tsai, Cheng-Hsiu; Fordyce, R Ewan

2015-01-01

Ancestor-descendant relationships (ADRs), involving descent with modification, are the fundamental concept in evolution, but are usually difficult to recognize. We examined the cladistic relationship between the only reported fossil pygmy right whale, †Miocaperea pulchra, and its sole living relative, the enigmatic pygmy right whale Caperea marginata, the latter represented by both adult and juvenile specimens. †Miocaperea is phylogenetically bracketed between juvenile and adult Caperea marginata in morphologically based analyses, thus suggesting a possible ADR-the first so far identified within baleen whales (Cetacea: Mysticeti). The †Miocaperea-Caperea lineage may show long-term morphological stasis and, in turn, punctuated equilibrium. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

An empirical test of the 'shark nursery area concept' in Texas bays using a long-term fisheries-independent data set

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Froeschke, John T.; Stunz, Gregory W.; Sterba-Boatwright, Blair; Wildhaber, Mark L.

2010-01-01

Using a long-term fisheries-independent data set, we tested the 'shark nursery area concept' proposed by Heupel et al. (2007) with the suggested working assumptions that a shark nursery habitat would: (1) have an abundance of immature sharks greater than the mean abundance across all habitats where they occur; (2) be used by sharks repeatedly through time (years); and (3) see immature sharks remaining within the habitat for extended periods of time. We tested this concept using young-of-the-year (age 0) and juvenile (age 1+ yr) bull sharks Carcharhinus leucas from gill-net surveys conducted in Texas bays from 1976 to 2006 to estimate the potential nursery function of 9 coastal bays. Of the 9 bay systems considered as potential nursery habitat, only Matagorda Bay satisfied all 3 criteria for young-of-the-year bull sharks. Both Matagorda and San Antonio Bays met the criteria for juvenile bull sharks. Through these analyses we examined the utility of this approach for characterizing nursery areas and we also describe some practical considerations, such as the influence of the temporal or spatial scales considered when applying the nursery role concept to shark populations.

Ancient Nursery Area for the Extinct Giant Shark Megalodon from the Miocene of Panama

OpenAIRE

Pimiento, Catalina; Ehret, Dana J.; MacFadden, Bruce J.; Hubbell, Gordon

2010-01-01

BACKGROUND: As we know from modern species, nursery areas are essential shark habitats for vulnerable young. Nurseries are typically highly productive, shallow-water habitats that are characterized by the presence of juveniles and neonates. It has been suggested that in these areas, sharks can find ample food resources and protection from predators. Based on the fossil record, we know that the extinct Carcharocles megalodon was the biggest shark that ever lived. Previous proposed paleo-nurser...

Conservation markets for wildlife management with case studies from whaling.

Science.gov (United States)

Gerber, Leah R; Costello, Christopher; Gaines, Steven D

2014-01-01

Although market-based incentives have helped resolve many environmental challenges, conservation markets still play a relatively minor role in wildlife management. Establishing property rights for environmental goods and allowing trade between resource extractors and resource conservationists may offer a path forward in conserving charismatic species like whales, wolves, turtles, and sharks. In this paper, we provide a conceptual model for implementing a conservation market for wildlife and evaluate how such a market could be applied to three case studies for whales (minke [Balaenoptera acutorostrata], bowhead [Balaena mysticetus], and gray [Eschrictius robustus]). We show that, if designed and operated properly, such a market could ensure persistence of imperiled populations, while simultaneously improving the welfare of resource harvesters.

Diet of scalloped hammerhead shark in eastern Gulf of Mexico

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National Oceanic and Atmospheric Administration, Department of Commerce — Juvenile scalloped hammerhead sharks, Sphyrna lewini, were collected in northwest Florida to examine foraging ecology, bioenergetics, and trophic level (30-60 cm FL...

Something worth remembering: visual discrimination in sharks.

Science.gov (United States)

Fuss, Theodora; Schluessel, Vera

2015-03-01

This study investigated memory retention capabilities of juvenile gray bamboo sharks (Chiloscyllium griseum) using two-alternative forced-choice experiments. The sharks had previously been trained in a range of visual discrimination tasks, such as distinguishing between squares, triangles and lines, and their corresponding optical illusions (i.e., the Kanizsa figures or Müller-Lyer illusions), and in the present study, we tested them for memory retention. Despite the absence of reinforcement, sharks remembered the learned information for a period of up to 50 weeks, after which testing was terminated. In fish, as in other vertebrates, memory windows vary in duration depending on species and task; while it may seem beneficial to retain some information for a long time or even indefinitely, other information may be forgotten more easily to retain flexibility and save energy. The results of this study indicate that sharks are capable of long-term memory within the framework of selected cognitive skills. These could aid sharks in activities such as food retrieval, predator avoidance, mate choice or habitat selection and therefore be worth being remembered for extended periods of time. As in other cognitive tasks, intraspecific differences reflected the behavioral breadth of the species.

The impact of whaling on the ocean carbon cycle: why bigger was better.

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Andrew J Pershing

Full Text Available BACKGROUND: Humans have reduced the abundance of many large marine vertebrates, including whales, large fish, and sharks, to only a small percentage of their pre-exploitation levels. Industrial fishing and whaling also tended to preferentially harvest the largest species and largest individuals within a population. We consider the consequences of removing these animals on the ocean's ability to store carbon. METHODOLOGY/PRINCIPAL FINDINGS: Because body size is critical to our arguments, our analysis focuses on populations of baleen whales. Using reconstructions of pre-whaling and modern abundances, we consider the impact of whaling on the amount of carbon stored in living whales and on the amount of carbon exported to the deep sea by sinking whale carcasses. Populations of large baleen whales now store 9.1×10(6 tons less carbon than before whaling. Some of the lost storage has been offset by increases in smaller competitors; however, due to the relative metabolic efficiency of larger organisms, a shift toward smaller animals could decrease the total community biomass by 30% or more. Because of their large size and few predators, whales and other large marine vertebrates can efficiently export carbon from the surface waters to the deep sea. We estimate that rebuilding whale populations would remove 1.6×10(5 tons of carbon each year through sinking whale carcasses. CONCLUSIONS/SIGNIFICANCE: Even though fish and whales are only a small portion of the ocean's overall biomass, fishing and whaling have altered the ocean's ability to store and sequester carbon. Although these changes are small relative to the total ocean carbon sink, rebuilding populations of fish and whales would be comparable to other carbon management schemes, including ocean iron fertilization.

Mortality estimates for juvenile dusky sharks carcharhinus Obscurus ...

African Journals Online (AJOL)

A maximum likelihood model is developed, using mark-recapture data, to estimate total and fishing mortality rates for the dusky shark Carcharhinus obscurus in South Africa. The model accounts for tag-shedding, nonreporting of recaptured tags, the multiple release and single recapture nature of the study and the usage of ...

Bycatch and catch-release mortality of small sharks in the Gulf coast nursery grounds of Tampa Bay and Charlotte Harbor

OpenAIRE

Hueter, Robert E.; Manire, Charles A.

1994-01-01

The bays and estuaries of the southeast United States coast generally are thought to serve as nursery areas for various species of coastal sharks, where juvenile sharks find abundant food and are less exposed to predation by larger sharks. Because these areas typically support substantial commercial and recreational fisheries, fishing mortality of sharks in the nurseries particularly by bycatch, may be significant. This two-year project assessed the relative importance of two estuaries of the...

Feeding of the megamouth shark (Pisces: Lamniformes: Megachasmidae) predicted by its hyoid arch: a biomechanical approach.

Science.gov (United States)

Tomita, Taketeru; Sato, Keiichi; Suda, Kenta; Kawauchi, Junro; Nakaya, Kazuhiro

2011-05-01

Studies of the megamouth shark, one of three planktivorous sharks, can provide information about their evolutionary history. Megamouth shark feeding has never been observed in life animals, but two alternative hypotheses on biomechanics suggest either feeding, i.e., ram feeding or suction feeding. In this study, the second moment of area of the ceratohyal cartilages, which is an indicator of the flexural stiffness of the cartilages, is calculated for 21 species of ram- and suction-feeding sharks using computed tomography. The results indicate that suction-feeding sharks have ceratohyal cartilages with a larger second moment of area than ram-feeding sharks. The result also indicates that the ram-suction index, which is an indicator of relative contribution of ram and suction behavior, is also correlated with the second moment of area of the ceratohyal. Considering that large bending stresses are expected to be applied to the ceratohyal cartilage during suction, the larger second moment of area of the ceratohyal of suction-feeding sharks can be interpreted as an adaptation for suction feeding. Based on the small second moment of area of the ceratohyal cartilage of the megamouth shark, the feeding mode of the megamouth shark is considered to be ram feeding, similar to the planktivorous basking shark. From these results, an evolutionary scenario of feeding mechanics of three species of planktivorous sharks can be suggested. In this scenario, the planktivorous whale shark evolved ram feeding from a benthic suction-feeding ancestor. Ram feeding in the planktivorous megamouth shark and the basking shark evolved from ram feeding swimming-type ancestors and that both developed their unique filtering system to capture small-sized prey. Copyright © 2011 Wiley-Liss, Inc.

Sharks senses and shark repellents.

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Hart, Nathan S; Collin, Shaun P

2015-01-01

Despite over 70 years of research on shark repellents, few practical and reliable solutions to prevent shark attacks on humans or reduce shark bycatch and depredation in commercial fisheries have been developed. In large part, this deficiency stems from a lack of fundamental knowledge of the sensory cues that drive predatory behavior in sharks. However, the widespread use of shark repellents is also hampered by the physical constraints and technical or logistical difficulties of deploying substances or devices in an open-water marine environment to prevent an unpredictable interaction with a complex animal. Here, we summarize the key attributes of the various sensory systems of sharks and highlight residual knowledge gaps that are relevant to the development of effective shark repellents. We also review the most recent advances in shark repellent technology within the broader historical context of research on shark repellents and shark sensory systems. We conclude with suggestions for future research that may enhance the efficacy of shark repellent devices, in particular, the continued need for basic research on shark sensory biology and the use of a multi-sensory approach when developing or deploying shark repellent technology. © 2014 International Society of Zoological Sciences, Institute of Zoology/Chinese Academy of Sciences and Wiley Publishing Asia Pty Ltd.

Residency, Habitat Use and Sexual Segregation of White Sharks, Carcharodon carcharias in False Bay, South Africa

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Kock, Alison; O’Riain, M. Justin; Mauff, Katya; Meÿer, Michael; Kotze, Deon; Griffiths, Charles

2013-01-01

White sharks (Carcharodon carcharias) are threatened apex predators and identification of their critical habitats and how these are used are essential to ensuring improved local and ultimately global white shark protection. In this study we investigated habitat use by white sharks in False Bay, South Africa, using acoustic telemetry. 56 sharks (39 female, 17 male), ranging in size from 1.7–5 m TL, were tagged with acoustic transmitters and monitored on an array of 30 receivers for 975 days. To investigate the effects of season, sex and size on habitat use we used a generalized linear mixed effects model. Tagged sharks were detected in the Bay in all months and across all years, but their use of the Bay varied significantly with the season and the sex of the shark. In autumn and winter males and females aggregated around the Cape fur seal colony at Seal Island, where they fed predominantly on young of the year seals. In spring and summer there was marked sexual segregation, with females frequenting the Inshore areas and males seldom being detected. The shift from the Island in autumn and winter to the Inshore region in spring and summer by females mirrors the seasonal peak in abundance of juvenile seals and of migratory teleost and elasmobranch species respectively. This study provides the first evidence of sexual segregation at a fine spatial scale and demonstrates that sexual segregation in white sharks is not restricted to adults, but is apparent for juveniles and sub-adults too. Overall, the results confirm False Bay as a critical area for white shark conservation as both sexes, across a range of sizes, frequent the Bay on an annual basis. The finding that female sharks aggregate in the Inshore regions when recreational use peaks highlights the need for ongoing shark-human conflict mitigation strategies. PMID:23383052

Effects of age, sex and reproductive status on persistent organic pollutant concentrations in 'Southern Resident' killer whales

International Nuclear Information System (INIS)

Krahn, Margaret M.; Bradley Hanson, M.; Schorr, Gregory S.; Emmons, Candice K.; Burrows, Douglas G.; Bolton, Jennie L.; Baird, Robin W.; Ylitalo, Gina M.

2009-01-01

'Southern Resident' killer whales (Orcinus orca) that comprise three fish-eating 'pods' (J, K and L) were listed as 'endangered' in the US and Canada following a 20% population decline between 1996 and 2001. Blubber biopsy samples from Southern Resident juveniles had statistically higher concentrations of certain persistent organic pollutants than were found for adults. Most Southern Resident killer whales, including the four juveniles, exceeded the health-effects threshold for total PCBs in marine mammal blubber. Maternal transfer of contaminants to the juveniles during rapid development of their biological systems may put these young whales at greater risk than adults for adverse health effects (e.g., immune and endocrine system dysfunction). Pollutant ratios and field observations established that two of the pods (K- and L-pod) travel to California to forage. Nitrogen stable isotope values, supported by field observations, indicated possible changes in the diet of L-pod over the last decade.

Killer whale (Orcinus orca photo-identification in the eastern Canadian Arctic

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Brent G. Young

2011-05-01

Full Text Available We identified individual killer whales (Orcinus orca using recent (2004–09 photographs to obtain a minimum count of whales that use eastern Canadian Arctic waters. Fifty-three individuals were identified from nine different sightings; 11 individuals from western Hudson Bay sightings and 42 from the areas around northern and eastern Baffin Island. One whale was re-sighted: an adult female or large juvenile photographed 17 days and 375 km apart at Churchill, Manitoba, and off-shore of Rankin Inlet, Nunavut, in August 2007. With only one individual re-sighted, the number of individuals that use this area is likely much larger. No re-sightings occurred between Arctic killer whales and individuals photographed off the coast of Newfoundland. Our results represent the minimum number of killer whales sighted in eastern Canadian Arctic waters and provide the foundation for further killer whale research. Little is known about Arctic killer whales and, as a top predator, it is unclear what effect they have on Arctic marine ecosystems.

First record of the blacktip reef shark Carcharhinus melanopterus (Carcharhiniformes: Carcharhinidae from the Tropical Eastern Pacific

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Andrés López-Garro

2012-11-01

Full Text Available The blacktip reef shark Carcharhinus melanopterus, is one of the most common Indo-Pacific reef sharks. On April 29, 2012, a juvenile male blacktip reef shark measuring 89 cm total length (TL, was incidentally caught during a research expedition in Chatham Bay, Isla del Coco National Park, Costa Rica, located in the Tropical Eastern Pacific. This is the first record of the species from Isla del Coco National Park, Costa Rica, and from the Tropical Eastern Pacific.

Ancient nursery area for the extinct giant shark megalodon from the Miocene of Panama.

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Catalina Pimiento

Full Text Available BACKGROUND: As we know from modern species, nursery areas are essential shark habitats for vulnerable young. Nurseries are typically highly productive, shallow-water habitats that are characterized by the presence of juveniles and neonates. It has been suggested that in these areas, sharks can find ample food resources and protection from predators. Based on the fossil record, we know that the extinct Carcharocles megalodon was the biggest shark that ever lived. Previous proposed paleo-nursery areas for this species were based on the anecdotal presence of juvenile fossil teeth accompanied by fossil marine mammals. We now present the first definitive evidence of ancient nurseries for C. megalodon from the late Miocene of Panama, about 10 million years ago. METHODOLOGY/PRINCIPAL FINDINGS: We collected and measured fossil shark teeth of C. megalodon, within the highly productive, shallow marine Gatun Formation from the Miocene of Panama. Surprisingly, and in contrast to other fossil accumulations, the majority of the teeth from Gatun are very small. Here we compare the tooth sizes from the Gatun with specimens from different, but analogous localities. In addition we calculate the total length of the individuals found in Gatun. These comparisons and estimates suggest that the small size of Gatun's C. megalodon is neither related to a small population of this species nor the tooth position within the jaw. Thus, the individuals from Gatun were mostly juveniles and neonates, with estimated body lengths between 2 and 10.5 meters. CONCLUSIONS/SIGNIFICANCE: We propose that the Miocene Gatun Formation represents the first documented paleo-nursery area for C. megalodon from the Neotropics, and one of the few recorded in the fossil record for an extinct selachian. We therefore show that sharks have used nursery areas at least for 10 millions of years as an adaptive strategy during their life histories.

Vertical movement patterns and ontogenetic niche expansion in the tiger shark, Galeocerdo cuvier.

Science.gov (United States)

Afonso, André S; Hazin, Fábio H V

2015-01-01

Sharks are top predators in many marine ecosystems and can impact community dynamics, yet many shark populations are undergoing severe declines primarily due to overfishing. Obtaining species-specific knowledge on shark spatial ecology is important to implement adequate management strategies for the effective conservation of these taxa. This is particularly relevant concerning highly-mobile species that use wide home ranges comprising coastal and oceanic habitats, such as tiger sharks, Galeocerdo cuvier. We deployed satellite tags in 20 juvenile tiger sharks off northeastern Brazil to assess the effect of intrinsic and extrinsic factors on depth and temperature usage. Sharks were tracked for a total of 1184 d and used waters up to 1112 m in depth. The minimum temperature recorded equaled 4°C. All sharks had a clear preference for surface (sharks used mostly shallow (sharks spending considerably more time in surface (shark habitat was observed, with generalized linear models estimating a ~4-fold increase in maximum diving depth from 150- to 300-cm size-classes. The time spent in the upper 5 m of the water column did not vary ontogenetically but shark size was the most important factor explaining the utilization of deeper water layers. Young-of-the-year tiger sharks seem to associate with shallow, neritic habitats but they progressively move into deeper oceanic habitats as they grow larger. Such an early plasticity in habitat use could endow tiger sharks with access to previously unavailable prey, thus contributing to a wider ecological niche.

Migration Pathways, Behavioural Thermoregulation and Overwintering Grounds of Blue Sharks in the Northwest Atlantic

Science.gov (United States)

Campana, Steven E.; Dorey, Anna; Fowler, Mark; Joyce, Warren; Wang, Zeliang; Yashayaev, Igor

2011-01-01

The blue shark Prionace glauca is the most abundant large pelagic shark in the Atlantic Ocean. Although recaptures of tagged sharks have shown that the species is highly migratory, migration pathways towards the overwintering grounds remain poorly understood. We used archival satellite pop-up tags to track 23 blue sharks over a mean period of 88 days as they departed the coastal waters of North America in the autumn. Within 1–2 days of entering the Gulf Stream (median date of 21 Oct), all sharks initiated a striking diel vertical migration, taking them from a mean nighttime depth of 74 m to a mean depth of 412 m during the day as they appeared to pursue vertically migrating squid and fish prey. Although functionally blind at depth, calculations suggest that there would be a ∼2.5-fold thermoregulatory advantage to swimming and feeding in the markedly cooler deep waters, even if there was any reduced foraging success associated with the extreme depth. Noting that the Gulf Stream current speeds are reduced at depth, we used a detailed circulation model of the North Atlantic to examine the influence of the diving behaviour on the advection experienced by the sharks. However, there was no indication that the shark diving resulted in a significant modification of their net migratory pathway. The relative abundance of deep-diving sharks, swordfish, and sperm whales in the Gulf Stream and adjacent waters suggests that it may serve as a key winter feeding ground for large pelagic predators in the North Atlantic. PMID:21373198

Book review: Unveiling the Whale: Discourses on Whales and Whaling

Science.gov (United States)

John Schelhas

2012-01-01

Whaling represents one of the most internationally controversial and highly polarized environmental issues of recent times. Arne Kalland, in Unveiling the Whale: Discourses on Whales and Whaling, examines the whaling issue from the perspective of a pro-whaling country with an emphasis on analysis of discourse in international arenas, primarily the International Whaling...

Mercury levels in the Smooth Hammerhead Shark Sphyrna zygaena (Carcharhiniformes: Sphyrnidae from Northern Peru

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Adriana Gonzalez-Pestana

2017-12-01

Full Text Available The smooth hammerhead shark Sphyrna zygaena (Linnaeus, 1758 is one of the elasmobranch species most used for human consumption in Peru. However, the level of mercury in hammerhead muscle tissue is unknown. This study assessed the level of mercury found in the muscle of hammerhead sharks and its relation with human health. Moreover, we evaluated the relationship between shark body size and mercury levels. We analyzed 27 muscle samples of neonates and juveniles captured in northern Peru. Mercury concentrations varied between 0.13 and 0.86 mg kg-1 wet weight. Moreover, we found a negative and significant relationship between shark body size and mercury levels. This study represents the first evaluation of mercury levels of sharks in Peru. Although the values found do not exceed levels recommended by the World Health Organization (< 1 mg kg-1, we recommend expanding this study to include other size classes of sharks as well as other marine resources used for human consumption.

Age-related polychlorinated biphenyl dynamics in immature bull sharks (Carcharhinus leucas).

Science.gov (United States)

Olin, Jill A; Beaudry, Marina; Fisk, Aaron T; Paterson, Gordon

2014-01-01

Polychlorinated biphenyls (PCBs) were quantified in liver tissues of bull sharks (Carcharhinus leucas) ranging in age from 3 yr. Summed values of PCBs (ΣPCBs) ranged from 310 ng/g to 22 070 ng/g (lipid wt) across age classes with ΣPCB concentrations for the youngest sharks in the present study (3-yr-old sharks, highlighting the extent of exposure of this young life stage to this class of persistent organic pollutants (POPs). Age normalization of PCB congener concentrations to those measured for the youngest sharks demonstrated a significant hydrophobicity (log octanol/water partition coefficient [KOW ]) effect that was indicative of maternal offloading of highly hydrophobic (log KOW ≥6.5) congeners to the youngest individuals. A distinct shift in the PCB congener profiles was also observed as these young sharks grew in size. This shift was consistent with a transition from the maternally offloaded signal to the initiation of exogenous feeding and the contributions of mechanisms including growth dilution and whole-body elimination. These results add to the growing pool of literature documenting substantially high concentrations of POPs in juvenile sharks that are most likely attributable to maternal offloading. Collectively, such results underscore the potential vulnerability of young sharks to POP exposure and pose additional concerns for shark-conservation efforts. © 2013 SETAC.

Basking Shark (Cetorhinus maximus Movements in the Eastern North Pacific Determined Using Satellite Telemetry

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Heidi Dewar

2018-05-01

Full Text Available To fill data gaps on movements, behaviors and habitat use, both near- and offshore, two programs were initiated to deploy satellite tags on basking sharks off the coast of California. Basking sharks are large filter-feeding sharks that are second in size only to whale sharks. Similar to many megafauna populations, available data suggest that populations are below historic levels. In the eastern North Pacific (ENP Ocean, the limited information on basking sharks comes from nearshore habitats where they forage. From 2010 to 2011, four sharks were tagged with pop-off satellite archival tags with deployments ranging from 9 to 240 days. The tags provided both transmitted and archived data on habitat use and geographic movement patterns. Nearshore, sharks tended to move north in the summer and prefer shelf and slope habitat around San Diego, Point Conception and Monterey Bay. The two sharks with 180 and 240 days deployments left the coast in the summer and fall. Offshore their paths diverged and by January one shark had moved to near the tip of the Baja Peninsula, Mexico and the other to the waters near Hawaii, USA. Vertical habitat use was variable both within and among individuals and changed as sharks moved offshore. Nearshore, most time was spent in the mixed layer but sharks did spend hours in cold waters below the mixed layer. Offshore vertical movements depended on location. The shark that went to Hawaii had a distinct diel pattern, with days spent at ~450–470 m and nights at ~250–300 m and almost no time in surface waters, corresponding with the diel migration of a specific portion of the deep scattering layer. The shark that moved south along the Baja Peninsula spent progressively more time in deep water but came to the surface daily. Movement patterns and shifts in vertical habitat and use are likely linked to shifts in prey availability and oceanography. Data collected indicate the potential for large-scale movements and the need for

Effect of weight and frontal area of external telemetry packages on the kinematics, activity levels and swimming performance of small-bodied sharks.

Science.gov (United States)

Bouyoucos, I A; Suski, C D; Mandelman, J W; Brooks, E J

2017-05-01

This study sought to observe the effects of submerged weight and frontal cross-sectional area of external telemetry packages on the kinematics, activity levels and swimming performance of small-bodied juvenile sharks, using lemon sharks Negaprion brevirostris (60-80 cm total length, L T ) as a model species. Juveniles were observed free-swimming in a mesocosm untagged and with small and large external accelerometer packages that increased frontal cross-sectional area of the animals and their submerged weight. Despite adhering to widely used standards for tag mass, the presence of an external telemetry package altered swimming kinematics, activity levels and swimming performance of juvenile N. brevirostris relative to untagged individuals, suggesting that tag mass is not a suitable standalone metric of device suitability. Changes in swimming performance could not be detected from tail-beat frequency, which suggests that tail-beat frequency is an unsuitable standalone metric of swimming performance for small N. brevirostris. Lastly, sharks experienced treatment-specific changes in activity level and swimming kinematics from morning to afternoon observation. Therefore, the presence of external telemetry packages altered the kinematics, activity levels and swimming performance of small young-of-the-year N. brevirostris and these data may therefore be relevant to other similar-sized juveniles of other shark species. © 2017 The Fisheries Society of the British Isles.

Convergent evolution in mechanical design of lamnid sharks and tunas.

Science.gov (United States)

Donley, Jeanine M; Sepulveda, Chugey A; Konstantinidis, Peter; Gemballa, Sven; Shadwick, Robert E

2004-05-06

The evolution of 'thunniform' body shapes in several different groups of vertebrates, including whales, ichthyosaurs and several species of large pelagic fishes supports the view that physical and hydromechanical demands provided important selection pressures to optimize body design for locomotion during vertebrate evolution. Recognition of morphological similarities between lamnid sharks (the most well known being the great white and the mako) and tunas has led to a general expectation that they also have converged in their functional design; however, no quantitative data exist on the mechanical performance of the locomotor system in lamnid sharks. Here we examine the swimming kinematics, in vivo muscle dynamics and functional morphology of the force-transmission system in a lamnid shark, and show that the evolutionary convergence in body shape and mechanical design between the distantly related lamnids and tunas is much more than skin deep; it extends to the depths of the myotendinous architecture and the mechanical basis for propulsive movements. We demonstrate that not only have lamnids and tunas converged to a much greater extent than previously known, but they have also developed morphological and functional adaptations in their locomotor systems that are unlike virtually all other fishes.

A streamlined DNA tool for global identification of heavily exploited coastal shark species (genus Rhizoprionodon.

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Danillo Pinhal

Full Text Available Obtaining accurate species-specific landings data is an essential step toward achieving sustainable shark fisheries. Globally distributed sharpnose sharks (genus Rhizoprionodon exhibit life-history characteristics (rapid growth, early maturity, annual reproduction that suggests that they could be fished in a sustainable manner assuming an investment in monitoring, assessment and careful management. However, obtaining species-specific landings data for sharpnose sharks is problematic because they are morphologically very similar to one another. Moreover, sharpnose sharks may also be confused with other small sharks (either small species or juveniles of large species once they are processed (i.e., the head and fins are removed. Here we present a highly streamlined molecular genetics approach based on seven species-specific PCR primers in a multiplex format that can simultaneously discriminate body parts from the seven described sharpnose shark species commonly occurring in coastal fisheries worldwide. The species-specific primers are based on nucleotide sequence differences among species in the nuclear ribosomal internal transcribed spacer 2 locus (ITS2. This approach also distinguishes sharpnose sharks from a wide range of other sharks (52 species and can therefore assist in the regulation of coastal shark fisheries around the world.

A novel mini-DNA barcoding assay to identify processed fins from internationally protected shark species.

Science.gov (United States)

Fields, Andrew T; Abercrombie, Debra L; Eng, Rowena; Feldheim, Kevin; Chapman, Demian D

2015-01-01

There is a growing need to identify shark products in trade, in part due to the recent listing of five commercially important species on the Appendices of the Convention on International Trade in Endangered Species (CITES; porbeagle, Lamna nasus, oceanic whitetip, Carcharhinus longimanus scalloped hammerhead, Sphyrna lewini, smooth hammerhead, S. zygaena and great hammerhead S. mokarran) in addition to three species listed in the early part of this century (whale, Rhincodon typus, basking, Cetorhinus maximus, and white, Carcharodon carcharias). Shark fins are traded internationally to supply the Asian dried seafood market, in which they are used to make the luxury dish shark fin soup. Shark fins usually enter international trade with their skin still intact and can be identified using morphological characters or standard DNA-barcoding approaches. Once they reach Asia and are traded in this region the skin is removed and they are treated with chemicals that eliminate many key diagnostic characters and degrade their DNA ("processed fins"). Here, we present a validated mini-barcode assay based on partial sequences of the cytochrome oxidase I gene that can reliably identify the processed fins of seven of the eight CITES listed shark species. We also demonstrate that the assay can even frequently identify the species or genus of origin of shark fin soup (31 out of 50 samples).

A novel mini-DNA barcoding assay to identify processed fins from internationally protected shark species.

Directory of Open Access Journals (Sweden)

Andrew T Fields

Full Text Available There is a growing need to identify shark products in trade, in part due to the recent listing of five commercially important species on the Appendices of the Convention on International Trade in Endangered Species (CITES; porbeagle, Lamna nasus, oceanic whitetip, Carcharhinus longimanus scalloped hammerhead, Sphyrna lewini, smooth hammerhead, S. zygaena and great hammerhead S. mokarran in addition to three species listed in the early part of this century (whale, Rhincodon typus, basking, Cetorhinus maximus, and white, Carcharodon carcharias. Shark fins are traded internationally to supply the Asian dried seafood market, in which they are used to make the luxury dish shark fin soup. Shark fins usually enter international trade with their skin still intact and can be identified using morphological characters or standard DNA-barcoding approaches. Once they reach Asia and are traded in this region the skin is removed and they are treated with chemicals that eliminate many key diagnostic characters and degrade their DNA ("processed fins". Here, we present a validated mini-barcode assay based on partial sequences of the cytochrome oxidase I gene that can reliably identify the processed fins of seven of the eight CITES listed shark species. We also demonstrate that the assay can even frequently identify the species or genus of origin of shark fin soup (31 out of 50 samples.

Structure and dynamics of the shark assemblage off Recife, Northeastern Brazil.

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André S Afonso

Full Text Available Understanding the ecological factors that regulate elasmobranch abundance in nearshore waters is essential to effectively manage coastal ecosystems and promote conservation. However, little is known about elasmobranch populations in the western South Atlantic Ocean. An 8-year, standardized longline and drumline survey conducted in nearshore waters off Recife, northeastern Brazil, allowed us to describe the shark assemblage and to monitor abundance dynamics using zero-inflated generalized additive models. This region is mostly used by several carcharhinids and one ginglymostomid, but sphyrnids are also present. Blacknose sharks, Carcharhinus acronotus, were mostly mature individuals and declined in abundance throughout the survey, contrasting with nurse sharks, Ginglymostoma cirratum, which proliferated possibly due to this species being prohibited from all harvest since 2004 in this region. Tiger sharks, Galeocerdo cuvier, were mostly juveniles smaller than 200 cm and seem to use nearshore waters off Recife between January and September. No long-term trend in tiger shark abundance was discernible. Spatial distribution was similar in true coastal species (i.e. blacknose and nurse sharks whereas tiger sharks were most abundant at the middle continental shelf. The sea surface temperature, tidal amplitude, wind direction, water turbidity, and pluviosity were all selected to predict shark abundance off Recife. Interspecific variability in abundance dynamics across spatiotemporal and environmental gradients suggest that the ecological processes regulating shark abundance are generally independent between species, which could add complexity to multi-species fisheries management frameworks. Yet, further research is warranted to ascertain trends at population levels in the South Atlantic Ocean.

Structure and dynamics of the shark assemblage off Recife, Northeastern Brazil.

Science.gov (United States)

Afonso, André S; Andrade, Humber A; Hazin, Fábio H V

2014-01-01

Understanding the ecological factors that regulate elasmobranch abundance in nearshore waters is essential to effectively manage coastal ecosystems and promote conservation. However, little is known about elasmobranch populations in the western South Atlantic Ocean. An 8-year, standardized longline and drumline survey conducted in nearshore waters off Recife, northeastern Brazil, allowed us to describe the shark assemblage and to monitor abundance dynamics using zero-inflated generalized additive models. This region is mostly used by several carcharhinids and one ginglymostomid, but sphyrnids are also present. Blacknose sharks, Carcharhinus acronotus, were mostly mature individuals and declined in abundance throughout the survey, contrasting with nurse sharks, Ginglymostoma cirratum, which proliferated possibly due to this species being prohibited from all harvest since 2004 in this region. Tiger sharks, Galeocerdo cuvier, were mostly juveniles smaller than 200 cm and seem to use nearshore waters off Recife between January and September. No long-term trend in tiger shark abundance was discernible. Spatial distribution was similar in true coastal species (i.e. blacknose and nurse sharks) whereas tiger sharks were most abundant at the middle continental shelf. The sea surface temperature, tidal amplitude, wind direction, water turbidity, and pluviosity were all selected to predict shark abundance off Recife. Interspecific variability in abundance dynamics across spatiotemporal and environmental gradients suggest that the ecological processes regulating shark abundance are generally independent between species, which could add complexity to multi-species fisheries management frameworks. Yet, further research is warranted to ascertain trends at population levels in the South Atlantic Ocean.

Gulf of Mexico Shark Pupping and Nursery (GULFSPAN) survey from 1994-2016 (NCEI Accession 0162100)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The GULFPSAN survey is a fishery-independent survey that began in 1994 to examine the distribution and abundance of juvenile sharks in coastal areas of the Gulf of...

Nuclear and mitochondrial DNA reveals isolation of imperilled grey nurse shark populations (Carcharias taurus).

Science.gov (United States)

Ahonen, H; Harcourt, R G; Stow, A J

2009-11-01

Loss of sharks and other upper-trophic marine predators has sparked worldwide concern for the stability of ocean ecosystems. The grey nurse (ragged-tooth or sand tiger) shark (Carcharias taurus) is Vulnerable on a global scale, Critically Endangered in Australia and presumed extinct in parts of its historical range. We used 193 muscle and fin samples collected from six extant populations to assess global mtDNA and microsatellite diversity and the degree of global population genetic structure. Control region mtDNA diversity was low in every population, and two populations (eastern Australia and Japan) contained only a single mtDNA haplotype. Genetic signatures of recent losses of genetic variation were not yet apparent at microsatellite loci, indicating that this low mtDNA variation is not a result of anthropogenic population declines. Population differentiation was substantial between each population pair except Brazil and South Africa, F(ST) values ranged from 0.050 to 0.699 and 0.100 to 1.00 for microsatellite and mitochondrial data respectively. Bayesian analysis clearly partitioned individuals into five of the populations from which they were sampled. Our data imply a low frequency of immigrant exchange among each of these regions and we suggest that each be recognized as a distinct evolutionary significant unit. In contrast to pelagic species such as whale shark and white shark that may cross ocean basins and where cooperative international efforts are necessary for conservation, grey nurse shark, like many coastal species, need to be managed regionally.

A WELL PRESERVED SKELETON OF THE FOSSIL SHARK COSMOPOLITODUS HASTALIS FROM THE LATE MIOCENE OF PERU, FEATURING FISH REMAINS AS FOSSILIZED STOMACH CONTENTS

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ALBERTO COLLARETA

2017-01-01

Full Text Available Both the preservation of the poorly mineralized skeleton of sharks and the preservation of stomach contents are rarely observed in the fossil record. Here we report on a partial skeleton of a lamniform shark, including portions of the visceral arches and the anterior segment of the vertebral column, collected from the late Miocene beds of the Pisco Formation exposed at Cerro Yesera (Ica Desert, South Peru. Based on the morphology of the preserved teeth, this specimen was determined as a juvenile of the extinct lamnid species Cosmopolitodus hastalis. The shark skeleton includes remains of fish (featuring a pilchard determined as Sardinops sp. cf. S. sagax in the abdominal region. These fish remains are interpreted herein as the fossilized stomach contents of the shark. For the first time, piscivory is demonstrated in a juvenile individual of Cosmopolitodus hastalis. This result is consistent with the current knowledge about the feeding habits of immature individuals of extant lamniform shark species (including Carcharodon carcharias and Isurus oxyrinchus. Our report further outlines the fundamental role of schooling pilchards in the late Miocene trophic chains of the highly productive coastal waters off present South Peru. Moreover, the find of this well preserved shark skeleton strengthens the qualification of the Pisco Formation as a Fossil-Lagerstätte, and emphasizes the role of early mineralization processes in cases of exceptional preservation.

The energetic, physiological, and behavioral response of lemon sharks (Negaprion brevirostris) to simulated longline capture.

Science.gov (United States)

Bouyoucos, Ian A; Suski, Cory D; Mandelman, John W; Brooks, Edward J

2017-05-01

Commercial fisheries bycatch is a considerable threat to elasmobranch population recovery, and techniques to mitigate sub-lethal consequences can be improved with data on the energetic, physiological, and behavioral response of individuals to capture. This study sought to estimate the effects of simulated longline capture on the behavior, energy use, and physiological stress of juvenile lemon sharks (Negaprion brevirostris). Captive sharks equipped with acceleration biologgers were subjected to 1h of simulated longline capture. Swimming behaviors were identified from acceleration data using a machine-learning algorithm, energetic costs were estimated using accelerometer-calibrated relationships and respirometry, and physiological stress was quantified with point-of-care blood analyzers. During capture, sharks exhibited nine-fold increases in the frequency of burst swimming, 98% reductions in resting, and swam as often as unrestrained sharks. Aerobic metabolic rates during capture were 8% higher than for unrestrained sharks, and accounted for a 57.7% increase in activity costs when excess post-exercise oxygen consumption was included. Lastly, sharks exhibited significant increases in blood lactate and glucose, but no change in blood pH after 1h of capture. Therefore, these results provide preliminary insight into the behavioral and energetic responses of sharks to capture, and have implications for mitigating sub-lethal consequences of capture for sharks as commercial longline bycatch. Copyright © 2017 Elsevier Inc. All rights reserved.

First record of the blacktip reef shark Carcharhinus melanopterus (Carcharhiniformes: Carcharhinidae from the Tropical Eastern Pacific

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Andrés López-Garro

2012-11-01

Full Text Available The blacktip reef shark Carcharhinus melanopterus, is one of the most common Indo-Pacific reef sharks. On April 29, 2012, a juvenile male blacktip reef shark measuring 89 cm total length (TL, was incidentally caught during a research expedition in Chatham Bay, Isla del Coco National Park, Costa Rica, located in the Tropical Eastern Pacific. This is the first record of the species from Isla del Coco National Park, Costa Rica, and from the Tropical Eastern Pacific.El tiburón punta negra de arrecife, Carcharhinus melanopterus, es uno de los tiburones de arrecife más comunes del Indo-Pacífico. Durante una expedición científica al Parque Nacional Isla del Coco, Costa Rica, Pacífico Tropical Oriental, un tiburón punta negra de arrecife fue capturado en Bahía Chatham, Parque Nacional Isla del Coco, el 29 de abril 2012. El espécimen capturado era un macho juvenil de 89 cm. Este es el primer informe de esta especie para el Parque Nacional Isla del Coco, Costa Rica y para el Pacífico Tropical Oriental.

Food approach conditioning and discrimination learning using sound cues in benthic sharks.

Science.gov (United States)

Vila Pouca, Catarina; Brown, Culum

2018-07-01

The marine environment is filled with biotic and abiotic sounds. Some of these sounds predict important events that influence fitness while others are unimportant. Individuals can learn specific sound cues and 'soundscapes' and use them for vital activities such as foraging, predator avoidance, communication and orientation. Most research with sounds in elasmobranchs has focused on hearing thresholds and attractiveness to sound sources, but very little is known about their abilities to learn about sounds, especially in benthic species. Here we investigated if juvenile Port Jackson sharks could learn to associate a musical stimulus with a food reward, discriminate between two distinct musical stimuli, and whether individual personality traits were linked to cognitive performance. Five out of eight sharks were successfully conditioned to associate a jazz song with a food reward delivered in a specific corner of the tank. We observed repeatable individual differences in activity and boldness in all eight sharks, but these personality traits were not linked to the learning performance assays we examined. These sharks were later trained in a discrimination task, where they had to distinguish between the same jazz and a novel classical music song, and swim to opposite corners of the tank according to the stimulus played. The sharks' performance to the jazz stimulus declined to chance levels in the discrimination task. Interestingly, some sharks developed a strong side bias to the right, which in some cases was not the correct side for the jazz stimulus.

Estimating the impact of whaling on global whale watching

NARCIS (Netherlands)

H-I. Kuo (Hsiao-I); C-C. Chen (Chi-Chung); M.J. McAleer (Michael)

2009-01-01

textabstractAfter the commercial whaling moratorium was enacted in 1986, whale watching became one of the fastest growing tourism industries worldwide. As whaling was regarded as an activity incompatible with whale watching, the possible resumption of commercial whaling caused an urgent need to

Global versus local causes and health implications of high mercury concentrations in sharks from the east coast of South Africa.

Science.gov (United States)

McKinney, Melissa A; Dean, Kylie; Hussey, Nigel E; Cliff, Geremy; Wintner, Sabine P; Dudley, Sheldon F J; Zungu, M Philip; Fisk, Aaron T

2016-01-15

Conservation concern regarding the overharvest of global shark populations for meat and fin consumption largely surrounds documented deleterious ecosystem effects, but may be further supported by improved knowledge of possibly high levels in their edible tissues (particularly meat) of the neurotoxin, methylmercury (CH3Hg). For many regions, however, little data exist on shark tissue Hg concentrations, and reasons for Hg variation within and among species or across regions are poorly understood. We quantified total Hg (THg) in 17 shark species (total n=283) from the east coast of South Africa, a top Hg emitter globally. Concentrations varied from means of around 0.1 mg kg(-1) dry weight (dw) THg in hardnose smoothhound (Mustelus mosis) and whale (Rhincodon typus) sharks to means of over 10 mg kg(-1) dw in shortfin mako (Isurus oxyrinchus), scalloped hammerhead (Sphyrna lewini), white (Carcharodon carcharias) and ragged-tooth (Carcharias taurus) sharks. These sharks had higher THg levels than conspecifics sampled from coastal waters of the North Atlantic and North, mid-, and South Pacific, and although sampling year and shark size may play a confounding role, this result suggests the potential importance of elevated local emissions. Values of THg showed strong, species-specific correlations with length, and nearly half the remaining variation was explained by trophic position (using nitrogen stable isotopes, δ(15)N), whereas measures of foraging habitat (using carbon stable isotopes, δ(13)C) were not significant. Mercury concentrations were above the regulatory guidelines for fish health effects and safe human consumption for 88% and 70% of species, respectively, suggesting on-going cause for concern for shark health, and human consumers of shark meat. Copyright © 2015 Elsevier B.V. All rights reserved.

Characterization of Novel Whale Shark Aggregations at Shib Habil, Saudi Arabia and Mafia Island, Tanzania

KAUST Repository

Cochran, Jesse

2014-01-01

between the sexes that is unique to this site. Satellite tracks of tagged Saudi sharks were used to confirm that some animals migrated away from the aggregation site before returning in subsequent seasons, confirming philopatric behavior in this species

Shark Cartilage

Science.gov (United States)

Shark cartilage (tough elastic tissue that provides support, much as bone does) used for medicine comes primarily from sharks ... Several types of extracts are made from shark cartilage including squalamine lactate, AE-941, and U-995. ...

Use of a fishery-independent trawl survey to evaluate distribution patterns of subadult sharks in Georgia

Science.gov (United States)

Belcher, C.N.; Jennings, Cecil A.

2009-01-01

We investigated the utility of a fishery-independent trawl survey for assessing a potential multispecies shark nursery in Georgia's nearshore and inshore waters. A total of 234 subadult sharks from six species were captured during 85 of 216 trawls. Catch rates and size distributions for subadult sharks and the ratio of neonates to juveniles were consistent among areas. The highest concentrations of subadult sharks occurred in creeks and sounds. Species composition varied among areas. The Atlantic sharpnose shark Rhizoprionodon terraenovae was the most abundant species in sound and nearshore stations, whereas the bonnethead Sphyrna tiburo was the most abundant species in creeks. The aggregate of other species occurred with higher frequency in the sounds and nearshore. Sampling characteristics of the trawl survey were compared with those from a fishery-independent longline survey of subadult sharks to assess the similarity of the two gears. A total of 193 subadult sharks from seven species were captured during 57 of 96 longline sets, whereas 52 subadults from four species were captured during 20 of 48 trawls. Selectivity and efficiency differed between the two gears. The trawl had lower catch rates, caught smaller sharks, and encountered a different suite of species than the longline. General seasonal trends in relative abundance also differed between the two gears; the longline showed an increasing trend in abundance, whereas the trawl showed a stable trend. Although trawls were not found to be efficient for sampling subadult sharks from most species, they can be a useful source of supplemental data.

Bioaccumulation of organohalogenated compounds in sharks and rays from the southeastern USA.

Science.gov (United States)

Weijs, Liesbeth; Briels, Nathalie; Adams, Douglas H; Lepoint, Gilles; Das, Krishna; Blust, Ronny; Covaci, Adrian

2015-02-01

Organohalogenated compounds are widespread in the marine environment and can be a serious threat to organisms in all levels of aquatic food webs, including elasmobranch species. Information about the concentrations of POPs (persistent organic pollutants) and of MeO-PBDEs (methoxylated polybrominated diphenyl ethers) in elasmobranchs is scarce and potential toxic effects are poorly understood. The aims of the present study were therefore to investigate the occurrence of multiple POP classes (PCBs, PBDEs, DDXs, HCB, CHLs) and of MeO-PBDEs in various elasmobranch species from different trophic levels in estuarine and marine waters of the southeastern United States. Overall, levels and patterns of PCBs, PBDEs, DDXs, HCB, CHLs and of MeO-PBDEs varied according to the species, maturity stage, gender and habitat type. The lowest levels of POPs were found in Atlantic stingrays and the highest levels were found in bull sharks. As both species are respectively near the bottom and at top of the trophic web, with juvenile bull sharks frequently feeding on Atlantic stingrays, these findings further suggest a bioaccumulation and biomagnification process with trophic position. MeO-PBDEs were not detected in Atlantic stingrays, but were found in all shark species. HCB was not found in Atlantic stingrays, bonnetheads or lemon sharks, but was detected in the majority of bull sharks examined. Comparison with previous studies suggests that Atlantic stingrays may be experiencing toxic effects of PCBs and DDXs on their immune system. However, the effect of these compounds on the health of shark species remains unclear. Copyright © 2014 Elsevier Inc. All rights reserved.

Global versus local causes and health implications of high mercury concentrations in sharks from the east coast of South Africa

International Nuclear Information System (INIS)

McKinney, Melissa A.; Dean, Kylie; Hussey, Nigel E.; Cliff, Geremy; Wintner, Sabine P.; Dudley, Sheldon F.J.; Zungu, M. Philip; Fisk, Aaron T.

2016-01-01

Conservation concern regarding the overharvest of global shark populations for meat and fin consumption largely surrounds documented deleterious ecosystem effects, but may be further supported by improved knowledge of possibly high levels in their edible tissues (particularly meat) of the neurotoxin, methylmercury (CH_3Hg). For many regions, however, little data exist on shark tissue Hg concentrations, and reasons for Hg variation within and among species or across regions are poorly understood. We quantified total Hg (THg) in 17 shark species (total n = 283) from the east coast of South Africa, a top Hg emitter globally. Concentrations varied from means of around 0.1 mg kg"−"1 dry weight (dw) THg in hardnose smoothhound (Mustelus mosis) and whale (Rhincodon typus) sharks to means of over 10 mg kg"−"1 dw in shortfin mako (Isurus oxyrinchus), scalloped hammerhead (Sphyrna lewini), white (Carcharodon carcharias) and ragged-tooth (Carcharias taurus) sharks. These sharks had higher THg levels than conspecifics sampled from coastal waters of the North Atlantic and North, mid-, and South Pacific, and although sampling year and shark size may play a confounding role, this result suggests the potential importance of elevated local emissions. Values of THg showed strong, species-specific correlations with length, and nearly half the remaining variation was explained by trophic position (using nitrogen stable isotopes, δ"1"5N), whereas measures of foraging habitat (using carbon stable isotopes, δ"1"3C) were not significant. Mercury concentrations were above the regulatory guidelines for fish health effects and safe human consumption for 88% and 70% of species, respectively, suggesting on-going cause for concern for shark health, and human consumers of shark meat. - Highlights: • Hg concentrations in 17 shark species from South Africa's east coast were measured. • Higher values relative to other regions suggested the importance of local emissions. • Length and

Predicting synergistic effects of resources and predators on foraging decisions by juvenile Steller sea lions.

Science.gov (United States)

Frid, Alejandro; Burns, Jennifer; Baker, Gregory G; Thorne, Richard E

2009-01-01

Many theoretical and experimental studies suggest that synergistic interactions between resources and predators influence foraging decisions and their fitness consequences. This framework, however, has been ignored almost completely by hypotheses on causes of the population decline of Steller sea lions (SSLs) (Eumetopias jubatus) in western Alaska. By comparing predictions from a dynamic state variable model to empirical data on the behaviour of individuals instrumented with satellite-linked time-at-depth recorders, we develop and find preliminary support for the hypothesis that, during winter in Prince William Sound, juvenile SSLs (a) underutilise walleye pollock, a predictable resource in deep strata, due to predation risk from Pacific sleeper sharks, and (b) underutilise the potential energy bonanza of inshore aggregations of Pacific herring due to risk from either killer whales, larger conspecifics, or both. Further, under conditions of resource scarcity-induced by overfishing, long-term oceanographic cycles, or their combination-trade-offs between mortality risk and energy gain may influence demographic parameters. Accordingly, computer simulations illustrated the theoretical plausibility that a decline of Pacific herring in shallow strata would greatly increase the number of deep foraging dives, thereby increasing exposure to sleeper sharks and mortality rates. These results suggest that hypotheses on the decline of SSLs should consider synergistic effects of predators and resources on behaviour and mortality rates. Empirical support for our model, however, is limited and we outline tasks for empirical research that emerge from these limitations. More generally, in the context of today's conservation crises, our work illustrates that the greater the dearth of system-specific data, the greater the need to apply principles of behavioural ecology toward the understanding and management of large-scale marine systems.

Necrophagy of a nurse shark (Ginglymostoma cirratum) by tiger sharks (Galeocerdo cuvier)

OpenAIRE

Rada, Danilo P; Programa de Pós Graduação em Ciências Biológicas, CCEN, Universidade Federal da Paraíba, João Pessoa, Paraíba, Brazil; Burgess, George H; Florida Museum of Natural History University of Florida, Gainesville, Florida, U.S.A.; Rosa, Ricardo S; Departamento de Sistemática e Ecologia, CCEN, Universidade Federal da Paraíba, João Pessoa, Paraíba, Brazil.; Gadig, Otto F; Laboratório de Pesquisa em Elasmobrânquios e Nécton Marinho, UNESP, São Vicente, São Paulo, Brazil.

2015-01-01

The aim of this study is to report a scavenging event, involving the consumption of a nurse shark, Ginglymostoma cirratum, by tiger sharks, Galeocerdo cuvier, at Fernando de Noronha archipelago, Brazil. Recreational divers found and photographed a bitten nurse shark carcass, just after sighting two tiger sharks near of the site. We estimated the sharks total lengths and discussed aspects of this feeding interaction using of images of forensic analysis. A straight cut on the nurse shark caudal...

Advanced Whale Detection Methods to Improve Whale-Ship Collision Avoidance

Science.gov (United States)

McGillivary, P. A.; Tougher, B.

2010-12-01

Collisions between whales and ships are now estimated to account for fully a third of all whale deaths worldwide. Such collisions can incur costly ship repairs, and may damage or disable ship steering requiring costly response efforts from state and federal agencies. While collisions with rare whale species are problematic in further reducing their low population numbers, collisions with some of the more abundant whale species are also becoming more common as their populations increase. The problem is compounded as ship traffic likewise continues to grow, thus posing a growing risk to both whales and ships. Federal agencies are considering policies to alter shipping lanes to minimize whale-ship collisions off California and elsewhere. Similar efforts have already been undertaken for the Boston Harbor ship approach, where a bend in the shipping lane was introduced to reduce ship traffic through a favorite area of the highly endangered North Atlantic Right Whale. The Boston shipping approach lane was also flanked with a system of moorings with whale detection hydrophones which broadcast the presence of calling whales in or near the ship channel to approaching ships in real time. When so notified, ships can post lookouts to avoid whale collisions, and reduce speed to reduce the likelihood of whale death, which is highly speed dependent. To reduce the likelihood and seriousness of whale-ship collisions off California and Alaska in particular, there is a need to better know areas of particularly high use by whales, and consider implementation of reduced ship speeds in these areas. There is also an ongoing discussion of altering shipping lanes in the Santa Barbara Channel to avoid habitual Blue whales aggregation areas in particular. However, unlike the case for Boston Harbor, notification of ships that whales are nearby to reduce or avoid collisions is complicated because many California and Alaska whale species do not call regularly, and would thus be undetected by

Shark Conservation: An Educational Approach Based on Children's Knowledge and Perceptions toward Sharks.

Science.gov (United States)

Tsoi, Kwok Ho; Chan, Sau Ying; Lee, Yeung Chung; Ip, Brian Ho Yeung; Cheang, Chi Chiu

Shark conservation has become a focus of current international conservation efforts. However, the misunderstanding of sharks and their negative public portrayal may hinder their conservation. More importantly, the consumption of shark fin, which is very common in Chinese cultures, poses a significant threat to sharks. Hong Kong has long been the world's largest shark fin trading center. Shark conservation would become more sustainable if public understanding of this predatory fish and an appreciation of its ecological significance could be promoted. It is possible that the demand for fins could be effectively managed through long-term educational efforts targeted at younger generations. To provide essential baseline data for planning of these educational efforts, this project investigated the perceptions of 11 to 12 year-old primary school students in Hong Kong about sharks, and their understanding of ecological concepts and shark-related knowledge. The findings indicate that these students lack sufficient knowledge and possess misconceptions about sharks and their ecological significance in the marine ecosystem. The students' conceptual understanding level is strongly correlated with their perceptions. Correlational analyses further demonstrated a positive association between formal education and perceptions toward shark conservation. The students who favoured shark fin consumption did so because of its tastiness, whereas concerns about shark population decline and the cruelty of shark hunting were the main reasons for not favoring shark fin consumption. This pilot study provides preliminary but important insights into primary school education regarding the conservation of sharks.

Effects of fishing rope strength on the severity of large whale entanglements.

Science.gov (United States)

Knowlton, Amy R; Robbins, Jooke; Landry, Scott; McKenna, Henry A; Kraus, Scott D; Werner, Timothy B

2016-04-01

Entanglement in fixed fishing gear affects whales worldwide. In the United States, deaths of North Atlantic right (Eubalaena glacialis) and humpback whales (Megaptera novaeangliae) have exceeded management limits for decades. We examined live and dead whales entangled in fishing gear along the U.S. East Coast and the Canadian Maritimes from 1994 to 2010. We recorded whale species, age, and injury severity and determined rope polymer type, breaking strength, and diameter of the fishing gear. For the 132 retrieved ropes from 70 cases, tested breaking strength range was 0.80-39.63 kN (kiloNewtons) and the mean was 11.64 kN (SD 8.29), which is 26% lower than strength at manufacture (range 2.89-53.38 kN, mean = 15.70 kN [9.89]). Median rope diameter was 9.5 mm. Right and humpback whales were found in ropes with significantly stronger breaking strengths at time of manufacture than minke whales (Balaenoptera acuturostrata) (19.30, 17.13, and 10.47 mean kN, respectively). Adult right whales were found in stronger ropes (mean 34.09 kN) than juvenile right whales (mean 15.33 kN) and than all humpback whale age classes (mean 17.37 kN). For right whales, severity of injuries increased since the mid 1980s, possibly due to changes in rope manufacturing in the mid 1990s that resulted in production of stronger ropes at the same diameter. Our results suggest that broad adoption of ropes with breaking strengths of ≤ 7.56 kN (≤ 1700 lbsf) could reduce the number of life-threatening entanglements for large whales by at least 72%, and yet could provide sufficient strength to withstand the routine forces involved in many fishing operations. A reduction of this magnitude would achieve nearly all the mitigation legally required for U.S. stocks of North Atlantic right and humpback whales. Ropes with reduced breaking strength should be developed and tested to determine the feasibility of their use in a variety of fisheries. © 2015 The Authors. Conservation Biology published by Wiley

Risky business for a juvenile marine predator? Testing the influence of foraging strategies on size and growth rate under natural conditions.

Science.gov (United States)

Hussey, Nigel E; DiBattista, Joseph D; Moore, Jonathan W; Ward, Eric J; Fisk, Aaron T; Kessel, Steven; Guttridge, Tristan L; Feldheim, Kevin A; Franks, Bryan R; Gruber, Samuel H; Weideli, Ornella C; Chapman, Demian D

2017-04-12

Mechanisms driving selection of body size and growth rate in wild marine vertebrates are poorly understood, thus limiting knowledge of their fitness costs at ecological, physiological and genetic scales. Here, we indirectly tested whether selection for size-related traits of juvenile sharks that inhabit a nursery hosting two dichotomous habitats, protected mangroves (low predation risk) and exposed seagrass beds (high predation risk), is influenced by their foraging behaviour. Juvenile sharks displayed a continuum of foraging strategies between mangrove and seagrass areas, with some individuals preferentially feeding in one habitat over another. Foraging habitat was correlated with growth rate, whereby slower growing, smaller individuals fed predominantly in sheltered mangroves, whereas larger, faster growing animals fed over exposed seagrass. Concomitantly, tracked juveniles undertook variable movement behaviours across both the low and high predation risk habitat. These data provide supporting evidence for the hypothesis that directional selection favouring smaller size and slower growth rate, both heritable traits in this shark population, may be driven by variability in foraging behaviour and predation risk. Such evolutionary pathways may be critical to adaptation within predator-driven marine ecosystems. © 2017 The Author(s).

Wintering habitat model for the North Atlantic Right Whale (Eubalaena glacialis) in the southeastern United States.

Science.gov (United States)

Gowan, Timothy A; Ortega-Ortiz, Joel G

2014-01-01

The coastal waters off the southeastern United States (SEUS) are a primary wintering ground for the endangered North Atlantic right whale (Eubalaena glacialis), used by calving females along with other adult and juvenile whales. Management actions implemented in this area for the recovery of the right whale population rely on accurate habitat characterization and the ability to predict whale distribution over time. We developed a temporally dynamic habitat model to predict wintering right whale distribution in the SEUS using a generalized additive model framework and aerial survey data from 2003/2004 through 2012/2013. We built upon previous habitat models for right whales in the SEUS and include data from new aerial surveys that extend the spatial coverage of the analysis, particularly in the northern portion of this wintering ground. We summarized whale sightings, survey effort corrected for probability of whale detection, and environmental data at a semimonthly resolution. Consistent with previous studies, sea surface temperature (SST), water depth, and survey year were significant predictors of right whale relative abundance. Additionally, distance to shore, distance to the 22°C SST isotherm, and an interaction between time of year and latitude (to account for the latitudinal migration of whales) were also selected in the analysis presented here. Predictions from the model revealed that the location of preferred habitat differs within and between years in correspondence with variation in environmental conditions. Although cow-calf pairs were rarely sighted in the company of other whales, there was minimal evidence that the preferred habitat of cow-calf pairs was different than that of whale groups without calves at the scale of this study. The results of this updated habitat model can be used to inform management decisions for a migratory species in a dynamic oceanic environment.

Tiger sharks can connect equatorial habitats and fisheries across the Atlantic Ocean basin.

Directory of Open Access Journals (Sweden)

André S Afonso

Full Text Available Increasing our knowledge about the spatial ecology of apex predators and their interactions with diverse habitats and fisheries is necessary for understanding the trophic mechanisms that underlie several aspects of marine ecosystem dynamics and for guiding informed management policies. A preliminary assessment of tiger shark (Galeocerdo cuvier population structure off the oceanic insular system of Fernando de Noronha (FEN and the large-scale movements performed by this species in the equatorial Atlantic Ocean was conducted using longline and handline fishing gear and satellite telemetry. A total of 25 sharks measuring 175-372 cm in total length (TL were sampled. Most sharks were likely immature females ranging between 200 and 260 cm TL, with few individuals < 200 cm TL being caught. This contrasts greatly with the tiger shark size-distribution previously reported for coastal waters off the Brazilian mainland, where most individuals measured < 200 cm TL. Also, the movements of 8 individuals measuring 202-310 cm TL were assessed with satellite transmitters for a combined total of 757 days (mean = 94.6 days∙shark-1; SD = 65.6. These sharks exhibited a considerable variability in their horizontal movements, with three sharks showing a mostly resident behavior around FEN during the extent of the respective tracks, two sharks traveling west to the South American continent, and two sharks moving mostly along the middle of the oceanic basin, one of which ending up in the northern hemisphere. Moreover, one shark traveled east to the African continent, where it was eventually caught by fishers from Ivory Coast in less than 474 days at liberty. The present results suggest that young tiger sharks measuring < 200 cm TL make little use of insular oceanic habitats from the western South Atlantic Ocean, which agrees with a previously-hypothesized ontogenetic habitat shift from coastal to oceanic habitats experienced by juveniles of this species in this region

Instant BrainShark

CERN Document Server

Li, Daniel

2013-01-01

Filled with practical, step-by-step instructions and clear explanations for the most important and useful tasks. ""Instant BrainShark"" is a step-by-step guide to creating online presentations using BrainShark. The book covers digital marketing best practices alongside tips for sales conversions. The book is written in an easy-to-read style for anybody to easily pick up and get started with BrainShark.Instant BrainShark is for anyone who wants to use BrainShark to create presentations online and share them around the community. The book is also useful for developers who are looking to explore

Shark Conservation: An Educational Approach Based on Children’s Knowledge and Perceptions toward Sharks

Science.gov (United States)

Chan, Sau Ying; Lee, Yeung Chung; Ip, Brian Ho Yeung; Cheang, Chi Chiu

2016-01-01

Shark conservation has become a focus of current international conservation efforts. However, the misunderstanding of sharks and their negative public portrayal may hinder their conservation. More importantly, the consumption of shark fin, which is very common in Chinese cultures, poses a significant threat to sharks. Hong Kong has long been the world’s largest shark fin trading center. Shark conservation would become more sustainable if public understanding of this predatory fish and an appreciation of its ecological significance could be promoted. It is possible that the demand for fins could be effectively managed through long-term educational efforts targeted at younger generations. To provide essential baseline data for planning of these educational efforts, this project investigated the perceptions of 11 to 12 year-old primary school students in Hong Kong about sharks, and their understanding of ecological concepts and shark-related knowledge. The findings indicate that these students lack sufficient knowledge and possess misconceptions about sharks and their ecological significance in the marine ecosystem. The students’ conceptual understanding level is strongly correlated with their perceptions. Correlational analyses further demonstrated a positive association between formal education and perceptions toward shark conservation. The students who favoured shark fin consumption did so because of its tastiness, whereas concerns about shark population decline and the cruelty of shark hunting were the main reasons for not favoring shark fin consumption. This pilot study provides preliminary but important insights into primary school education regarding the conservation of sharks. PMID:27684706

Global versus local causes and health implications of high mercury concentrations in sharks from the east coast of South Africa

Energy Technology Data Exchange (ETDEWEB)

McKinney, Melissa A., E-mail: melissa.mckinney@uconn.edu [Great Lakes Institute for Environmental Research, University of Windsor, Windsor, Ontario N9B 3P4 (Canada); Dean, Kylie; Hussey, Nigel E. [Great Lakes Institute for Environmental Research, University of Windsor, Windsor, Ontario N9B 3P4 (Canada); Cliff, Geremy; Wintner, Sabine P. [KwaZulu-Natal Sharks Board, Umhlanga Rocks 4320 (South Africa); Biomedical Resource Unit, University of KwaZulu-Natal, Durban 4000 (South Africa); Dudley, Sheldon F.J. [KwaZulu-Natal Sharks Board, Umhlanga Rocks 4320 (South Africa); Department of Agriculture, Forestry and Fisheries, Cape Town 8012 (South Africa); Zungu, M. Philip [Department of Agriculture, Forestry and Fisheries, Cape Town 8012 (South Africa); Fisk, Aaron T. [Great Lakes Institute for Environmental Research, University of Windsor, Windsor, Ontario N9B 3P4 (Canada)

2016-01-15

Conservation concern regarding the overharvest of global shark populations for meat and fin consumption largely surrounds documented deleterious ecosystem effects, but may be further supported by improved knowledge of possibly high levels in their edible tissues (particularly meat) of the neurotoxin, methylmercury (CH{sub 3}Hg). For many regions, however, little data exist on shark tissue Hg concentrations, and reasons for Hg variation within and among species or across regions are poorly understood. We quantified total Hg (THg) in 17 shark species (total n = 283) from the east coast of South Africa, a top Hg emitter globally. Concentrations varied from means of around 0.1 mg kg{sup −1} dry weight (dw) THg in hardnose smoothhound (Mustelus mosis) and whale (Rhincodon typus) sharks to means of over 10 mg kg{sup −1} dw in shortfin mako (Isurus oxyrinchus), scalloped hammerhead (Sphyrna lewini), white (Carcharodon carcharias) and ragged-tooth (Carcharias taurus) sharks. These sharks had higher THg levels than conspecifics sampled from coastal waters of the North Atlantic and North, mid-, and South Pacific, and although sampling year and shark size may play a confounding role, this result suggests the potential importance of elevated local emissions. Values of THg showed strong, species-specific correlations with length, and nearly half the remaining variation was explained by trophic position (using nitrogen stable isotopes, δ{sup 15}N), whereas measures of foraging habitat (using carbon stable isotopes, δ{sup 13}C) were not significant. Mercury concentrations were above the regulatory guidelines for fish health effects and safe human consumption for 88% and 70% of species, respectively, suggesting on-going cause for concern for shark health, and human consumers of shark meat. - Highlights: • Hg concentrations in 17 shark species from South Africa's east coast were measured. • Higher values relative to other regions suggested the importance of local

Shark tales: a molecular species-level phylogeny of sharks (Selachimorpha, Chondrichthyes).

Science.gov (United States)

Vélez-Zuazo, Ximena; Agnarsson, Ingi

2011-02-01

Sharks are a diverse and ecologically important group, including some of the ocean's largest predatory animals. Sharks are also commercially important, with many species suffering overexploitation and facing extinction. However, despite a long evolutionary history, commercial, and conservation importance, phylogenetic relationships within the sharks are poorly understood. To date, most studies have either focused on smaller clades within sharks, or sampled taxa sparsely across the group. A more detailed species-level phylogeny will offer further insights into shark taxonomy, provide a tool for comparative analyses, as well as facilitating phylogenetic estimates of conservation priorities. We used four mitochondrial and one nuclear gene to investigate the phylogenetic relationships of 229 species (all eight Orders and 31 families) of sharks, more than quadrupling the number of taxon sampled in any prior study. The resulting Bayesian phylogenetic hypothesis agrees with prior studies on the major relationships of the sharks phylogeny; however, on those relationships that have proven more controversial, it differs in several aspects from the most recent molecular studies. The phylogeny supports the division of sharks into two major groups, the Galeomorphii and Squalimorphii, rejecting the hypnosqualean hypothesis that places batoids within sharks. Within the squalimorphs the orders Hexanchiformes, Squatiniformes, Squaliformes, and Pristiophoriformes are broadly monophyletic, with minor exceptions apparently due to missing data. Similarly, within Galeomorphs, the orders Heterodontiformes, Lamniformes, Carcharhiniformes, and Orectolobiformes are broadly monophyletic, with a couple of species 'misplaced'. In contrast, many of the currently recognized shark families are not monophyletic according to our results. Our phylogeny offers some of the first clarification of the relationships among families of the order Squaliformes, a group that has thus far received relatively

Methylmercury in dried shark fins and shark fin soup from American restaurants.

Science.gov (United States)

Nalluri, Deepthi; Baumann, Zofia; Abercrombie, Debra L; Chapman, Demian D; Hammerschmidt, Chad R; Fisher, Nicholas S

2014-10-15

Consumption of meat from large predatory sharks exposes human consumers to high levels of toxic monomethylmercury (MMHg). There also have been claims that shark fins, and hence the Asian delicacy shark fin soup, contain harmful levels of neurotoxic chemicals in combination with MMHg, although concentrations of MMHg in shark fins are unknown. We measured MMHg in dried, unprocessed fins (n=50) of 13 shark species that occur in the international trade of dried shark fins as well as 50 samples of shark fin soup prepared by restaurants from around the United States. Concentrations of MMHg in fins ranged from 9 to 1720 ng/g dry wt. MMHg in shark fin soup ranged from sharks such as hammerheads (Sphyrna spp.). Consumption of a 240 mL bowl of shark fin soup containing the average concentration of MMHg (4.6 ng/mL) would result in a dose of 1.1 μg MMHg, which is 16% of the U.S. EPA's reference dose (0.1 μg MMHg per 1 kg per day in adults) of 7.4 μg per day for a 74 kg person. If consumed, the soup containing the highest measured MMHg concentration would exceed the reference dose by 17%. While shark fin soup represents a potentially important source of MMHg to human consumers, other seafood products, particularly the flesh of apex marine predators, contain much higher MMHg concentrations and can result in substantially greater exposures of this contaminant for people. Copyright © 2014 Elsevier B.V. All rights reserved.

The behaviour and recovery of juvenile lemon sharks Negaprion brevirostris in response to external accelerometer tag attachment.

Science.gov (United States)

Bullock, R W; Guttridge, T L; Cowx, I G; Elliott, M; Gruber, S H

2015-12-01

Behavioural responses of lemon sharks Negaprion brevirostris to a fin-mounted tag package (CEFAS G6A tri-axial accelerometer with epoxied Sonotronics PT4 acoustic transmitter) were measured in a controlled captive environment (n = 10, total length, LT range 80-140 cm) and in free-ranging sharks upon release (n = 7, LT range 100-160 cm). No changes were detected in behaviour (i.e. swimming speed, tailbeat frequency, time spent resting and frequency of chafing) between control and tagged captive shark trials, suggesting that the tag package itself does not alter behaviour. In the free-ranging trials, an initial period of elevated swimming activity was found in all individuals (represented by overall dynamic body acceleration). Negaprion brevirostris, however, appeared to recover quickly, returning to a steady swimming state between 2 and 35 min after release. Post-release tracking found that all sharks swim immediately for the shoreline and remain within 100 m of shore for prolonged periods. Hence, although N. brevirostris are capable of quick adaptation to stressors and demonstrate rapid recovery in terms of activity, tracking data suggest that they may modify their spatial use patterns post release. This research is important in separating deviation in behaviour due to environmental stressors from artefacts caused by experimental techniques. © 2015 The Fisheries Society of the British Isles.

Spatial and seasonal distribution of American whaling and whales in the age of sail.

Science.gov (United States)

Smith, Tim D; Reeves, Randall R; Josephson, Elizabeth A; Lund, Judith N

2012-01-01

American whalemen sailed out of ports on the east coast of the United States and in California from the 18(th) to early 20(th) centuries, searching for whales throughout the world's oceans. From an initial focus on sperm whales (Physeter macrocephalus) and right whales (Eubalaena spp.), the array of targeted whales expanded to include bowhead whales (Balaena mysticetus), humpback whales (Megaptera novaeangliae), and gray whales (Eschrichtius robustus). Extensive records of American whaling in the form of daily entries in whaling voyage logbooks contain a great deal of information about where and when the whalemen found whales. We plotted daily locations where the several species of whales were observed, both those caught and those sighted but not caught, on world maps to illustrate the spatial and temporal distribution of both American whaling activity and the whales. The patterns shown on the maps provide the basis for various inferences concerning the historical distribution of the target whales prior to and during this episode of global whaling.

50 CFR 600.1204 - Shark finning; possession at sea and landing of shark fins.

Science.gov (United States)

2010-10-01

... 50 Wildlife and Fisheries 8 2010-10-01 2010-10-01 false Shark finning; possession at sea and landing of shark fins. 600.1204 Section 600.1204 Wildlife and Fisheries FISHERY CONSERVATION AND... PROVISIONS Shark Finning § 600.1204 Shark finning; possession at sea and landing of shark fins. (a)(1) No...

Highly migratory shark fisheries research by the National Shark Research Consortium (NSRC), 2002-2007

OpenAIRE

Hueter, Robert E.; Cailliet, Gregor M.; Ebert, David A.; Musick, John A.; Burgess, George H.

2007-01-01

The National Shark Research Consortium (NSRC) includes the Center for Shark Research at Mote Marine Laboratory, the Pacific Shark Research Center at Moss Landing Marine Laboratories, the Shark Research Program at the Virginia Institute of Marine Science, and the Florida Program for Shark Research at the University of Florida. The consortium objectives include shark-related research in the Gulf of Mexico and along the Atlantic and Pacific coasts of the U.S., education and scientific cooperation.

Spatial and seasonal distribution of American whaling and whales in the age of sail.

Directory of Open Access Journals (Sweden)

Tim D Smith

Full Text Available American whalemen sailed out of ports on the east coast of the United States and in California from the 18(th to early 20(th centuries, searching for whales throughout the world's oceans. From an initial focus on sperm whales (Physeter macrocephalus and right whales (Eubalaena spp., the array of targeted whales expanded to include bowhead whales (Balaena mysticetus, humpback whales (Megaptera novaeangliae, and gray whales (Eschrichtius robustus. Extensive records of American whaling in the form of daily entries in whaling voyage logbooks contain a great deal of information about where and when the whalemen found whales. We plotted daily locations where the several species of whales were observed, both those caught and those sighted but not caught, on world maps to illustrate the spatial and temporal distribution of both American whaling activity and the whales. The patterns shown on the maps provide the basis for various inferences concerning the historical distribution of the target whales prior to and during this episode of global whaling.

An exceptionally preserved Eocene shark and the rise of modern predator-prey interactions in the coral reef food web.

Science.gov (United States)

Fanti, Federico; Minelli, Daniela; Conte, Gabriele Larocca; Miyashita, Tetsuto

2016-01-01

Following extreme climatic warming events, Eocene Lagerstätten document aquatic and terrestrial vertebrate faunas surprisingly similar to modern counterparts. This transition in marine systems is best documented in the earliest teleost-dominated coral reef assemblage of Pesciara di Bolca, northern Italy, from near the end of the Eocene Climatic Optimum. Its rich fauna shows similarities with that of the modern Great Barrier Reef in niche exploitation by and morphological disparity among teleost primary consumers. However, such paleoecological understanding has not transcended trophic levels above primary consumers, particularly in carcharhiniform sharks. We report an exceptionally preserved fossil school shark (Galeorhinus cuvieri) from Pesciara di Bolca. In addition to the spectacular preservation of soft tissues, including brain, muscles, and claspers, this male juvenile shark has stomach contents clearly identifiable as a sphyraenid acanthomorph (barracuda). This association provides evidence that a predator-prey relationship between Galeorhinus and Sphyraena in the modern coral reefs has roots in the Eocene. A growth curve of the living species of Galeorhinus fitted to G. cuvieri suggests that all specimens of G. cuvieri from the lagoonal deposits of Bolca represent sexually and somatically immature juveniles. The modern trophic association between higher-degree consumers (Galeorhinus and Sphyraena) has a counterpart in the Eocene Bolca, just as Bolca and the Great Barrier Reef show parallels among teleost primary consumers. Given the age of Bolca, trophic networks among consumers observed in modern coral reefs arose by the exit from the Climatic Optimum. The biased representation of juveniles suggests that the Bolca Lagerstätte served as a nursery habitat for G. cuvieri. Ultraviolet photography may be useful in probing for exceptional soft tissue preservation before common acid preparation methods.

The Effect of Background Music in Shark Documentaries on Viewers' Perceptions of Sharks.

Science.gov (United States)

Nosal, Andrew P; Keenan, Elizabeth A; Hastings, Philip A; Gneezy, Ayelet

2016-01-01

Despite the ongoing need for shark conservation and management, prevailing negative sentiments marginalize these animals and legitimize permissive exploitation. These negative attitudes arise from an instinctive, yet exaggerated fear, which is validated and reinforced by disproportionate and sensationalistic news coverage of shark 'attacks' and by highlighting shark-on-human violence in popular movies and documentaries. In this study, we investigate another subtler, yet powerful factor that contributes to this fear: the ominous background music that often accompanies shark footage in documentaries. Using three experiments, we show that participants rated sharks more negatively and less positively after viewing a 60-second video clip of swimming sharks set to ominous background music, compared to participants who watched the same video clip set to uplifting background music, or silence. This finding was not an artifact of soundtrack alone because attitudes toward sharks did not differ among participants assigned to audio-only control treatments. This is the first study to demonstrate empirically that the connotative attributes of background music accompanying shark footage affect viewers' attitudes toward sharks. Given that nature documentaries are often regarded as objective and authoritative sources of information, it is critical that documentary filmmakers and viewers are aware of how the soundtrack can affect the interpretation of the educational content.

The Effect of Background Music in Shark Documentaries on Viewers' Perceptions of Sharks.

Directory of Open Access Journals (Sweden)

Andrew P Nosal

Full Text Available Despite the ongoing need for shark conservation and management, prevailing negative sentiments marginalize these animals and legitimize permissive exploitation. These negative attitudes arise from an instinctive, yet exaggerated fear, which is validated and reinforced by disproportionate and sensationalistic news coverage of shark 'attacks' and by highlighting shark-on-human violence in popular movies and documentaries. In this study, we investigate another subtler, yet powerful factor that contributes to this fear: the ominous background music that often accompanies shark footage in documentaries. Using three experiments, we show that participants rated sharks more negatively and less positively after viewing a 60-second video clip of swimming sharks set to ominous background music, compared to participants who watched the same video clip set to uplifting background music, or silence. This finding was not an artifact of soundtrack alone because attitudes toward sharks did not differ among participants assigned to audio-only control treatments. This is the first study to demonstrate empirically that the connotative attributes of background music accompanying shark footage affect viewers' attitudes toward sharks. Given that nature documentaries are often regarded as objective and authoritative sources of information, it is critical that documentary filmmakers and viewers are aware of how the soundtrack can affect the interpretation of the educational content.

Whales from space: counting southern right whales by satellite.

Science.gov (United States)

Fretwell, Peter T; Staniland, Iain J; Forcada, Jaume

2014-01-01

We describe a method of identifying and counting whales using very high resolution satellite imagery through the example of southern right whales breeding in part of the Golfo Nuevo, Península Valdés in Argentina. Southern right whales have been extensively hunted over the last 300 years and although numbers have recovered from near extinction in the early 20(th) century, current populations are fragmented and are estimated at only a small fraction of pre-hunting total. Recent extreme right whale calf mortality events at Península Valdés, which constitutes the largest single population, have raised fresh concern for the future of the species. The WorldView2 satellite has a maximum 50 cm resolution and a water penetrating coastal band in the far-blue part of the spectrum that allows it to see deeper into the water column. Using an image covering 113 km², we identified 55 probable whales and 23 other features that are possibly whales, with a further 13 objects that are only detected by the coastal band. Comparison of a number of classification techniques, to automatically detect whale-like objects, showed that a simple thresholding technique of the panchromatic and coastal band delivered the best results. This is the first successful study using satellite imagery to count whales; a pragmatic, transferable method using this rapidly advancing technology that has major implications for future surveys of cetacean populations.

Shark fishing effort and catch of the ragged-tooth shark Carcharias ...

African Journals Online (AJOL)

An integrated telephone and on-site questionnaire survey was used to estimate total shark fishing effort and specific catch of the ragged-tooth shark Carcharias taurus by coastal club-affiliated shore-anglers, primarily along the east coast of South Africa. Mean total shark fishing effort was estimated to be 37 820 fisherdays ...

Grey Nurse Shark ( Carcharias taurus) Diving Tourism: Tourist Compliance and Shark Behaviour at Fish Rock, Australia

Science.gov (United States)

Smith, Kirby; Scarr, Mark; Scarpaci, Carol

2010-11-01

Humans can dive with critically endangered grey nurse sharks ( Carcharias taurus) along the east coast of Australia. This study investigated both compliance of tourist divers to a code of conduct and legislation and the behaviour of grey nurse sharks in the presence of divers. A total of 25 data collection dives were conducted from December 2008 to January 2009. Grey nurse shark and diver behaviour were documented using 2-min scan samples and continuous observation. The proportion of time spent observing human-shark interactions was 9.4% of total field time and mean human-shark interaction time was 15.0 min. Results were used to gauge the effectiveness of current management practices for the grey nurse shark dive industry at Fish Rock in New South Wales, Australia. Grey nurse shark dive tourists were compliant to stipulations in the code of conduct and legislation (compliance ranged from 88 to 100%). The research detailed factors that may promote compliance in wildlife tourism operations such as the clarity of the stipulations, locality of the target species and diver perceptions of sharks. Results indicated that grey nurse sharks spent the majority of their time milling (85%) followed by active swimming (15%). Milling behaviour significantly decreased in the presence of more than six divers. Distance between sharks and divers, interaction time and number of sharks were not significantly correlated with grey nurse shark school behaviour. Jaw gaping, rapid withdrawal and stiff or jerky movement were the specific behaviours of grey nurse sharks that occurred most frequently and were associated with distance between divers and sharks and the presence of six or more divers. Revision of the number of divers allowed per interaction with a school of grey nurse sharks and further research on the potential impacts that shark-diving tourism may pose to grey nurse sharks is recommended.

Grey nurse shark (Carcharias taurus) diving tourism: Tourist compliance and shark behaviour at Fish Rock, Australia.

Science.gov (United States)

Smith, Kirby; Scarr, Mark; Scarpaci, Carol

2010-11-01

Humans can dive with critically endangered grey nurse sharks (Carcharias taurus) along the east coast of Australia. This study investigated both compliance of tourist divers to a code of conduct and legislation and the behaviour of grey nurse sharks in the presence of divers. A total of 25 data collection dives were conducted from December 2008 to January 2009. Grey nurse shark and diver behaviour were documented using 2-min scan samples and continuous observation. The proportion of time spent observing human-shark interactions was 9.4% of total field time and mean human-shark interaction time was 15.0 min. Results were used to gauge the effectiveness of current management practices for the grey nurse shark dive industry at Fish Rock in New South Wales, Australia. Grey nurse shark dive tourists were compliant to stipulations in the code of conduct and legislation (compliance ranged from 88 to 100%). The research detailed factors that may promote compliance in wildlife tourism operations such as the clarity of the stipulations, locality of the target species and diver perceptions of sharks. Results indicated that grey nurse sharks spent the majority of their time milling (85%) followed by active swimming (15%). Milling behaviour significantly decreased in the presence of more than six divers. Distance between sharks and divers, interaction time and number of sharks were not significantly correlated with grey nurse shark school behaviour. Jaw gaping, rapid withdrawal and stiff or jerky movement were the specific behaviours of grey nurse sharks that occurred most frequently and were associated with distance between divers and sharks and the presence of six or more divers. Revision of the number of divers allowed per interaction with a school of grey nurse sharks and further research on the potential impacts that shark-diving tourism may pose to grey nurse sharks is recommended.

Population trends in Pacific Oceanic sharks and the utility of regulations on shark finning.

Science.gov (United States)

Clarke, Shelley C; Harley, Shelton J; Hoyle, Simon D; Rice, Joel S

2013-02-01

Accurate assessment of shark population status is essential for conservation but is often constrained by limited and unreliable data. To provide a basis for improved management of shark resources, we analyzed a long-term record of species-specific catches, sizes, and sexes of sharks collected by onboard observers in the western and central Pacific Ocean from 1995 to 2010. Using generalized linear models, we estimated population-status indicators on the basis of catch rate and biological indicators of fishing pressure on the basis of median size to identify trends for blue (Prionace glauca), mako (Isurus spp.), oceanic whitetip (Carcharhinus longimanus), and silky (Carcharhinus falciformis) sharks. Standardized catch rates of longline fleets declined significantly for blue sharks in the North Pacific (by 5% per year [CI 2% to 8%]), for mako sharks in the North Pacific (by 7% per year [CI 3% to 11%]), and for oceanic whitetip sharks in tropical waters (by 17% per year [CI 14% to 20%]). Median lengths of silky and oceanic whitetip sharks decreased significantly in their core habitat, and almost all sampled silky sharks were immature. Our results are consistent with results of analyses of similar data sets. Combined, these results and evidence of targeted fishing for sharks in some regional fisheries heighten concerns for sustainable utilization, particularly for oceanic whitetip and North Pacific blue sharks. Regional regulations that prohibit shark finning (removal of fins and discarding of the carcass) were enacted in 2007 and are in many cases the only form of control on shark catches. However, there is little evidence of a reduction of finning in longline fisheries. In addition, silky and oceanic whitetip sharks are more frequently retained than finned, which suggests that even full implementation of and adherence to a finning prohibition may not substantially reduce mortality rates for these species. We argue that finning prohibitions divert attention from

Distribution and dynamic habitat use of young bull sharks Carcharhinus leucas in a highly stratified northern Gulf of Mexico estuary.

Directory of Open Access Journals (Sweden)

J Marcus Drymon

Full Text Available Understanding how animals alter habitat use in response to changing abiotic conditions is important for effective conservation management. For bull sharks (Carcharhinus leucas, habitat use has been widely examined in the eastern and western Gulf of Mexico; however, knowledge of their movements and the factors influencing them is lacking for populations in the more temperate north-central Gulf of Mexico. To examine how changes in hydrographic conditions affected the presence of young bull sharks in Mobile Bay, Alabama, thirty-five sharks were fitted with internal acoustic transmitters and monitored with an acoustic monitoring array consisting of thirty-three receivers between June 2009 and December 2010. Tagged sharks ranged in size from 60 to 114 cm fork length and were detected between the upper and lower portions of Mobile Bay. Despite a variety of freshwater sources associated with this highly productive estuary, sharks were most consistently detected at the largest input to the system--the Mobile and Tensaw Rivers. Our findings suggest a combination of hydrographic factors interact to influence the distribution of juvenile bull sharks in Mobile Bay. The factors affecting the probability of detecting at least one bull shark varied both temporally (2009 vs 2010 and spatially (upper vs lower bay. Electivity analysis demonstrated that bull sharks showed highest affinity for warm water (29-32 °C, moderate salinities (10-11 psu and normoxic waters (5-7 mg/l, although these patterns were not consistent between regions or across years. We suggest future studies coupling telemetry and hydrographic variables should, when possible, consider the interactions of multiple environmental parameters when defining the dynamic factors explaining the spatial distribution of coastal sharks.

Distribution and dynamic habitat use of young bull sharks Carcharhinus leucas in a highly stratified northern Gulf of Mexico estuary.

Science.gov (United States)

Drymon, J Marcus; Ajemian, Matthew J; Powers, Sean P

2014-01-01

Understanding how animals alter habitat use in response to changing abiotic conditions is important for effective conservation management. For bull sharks (Carcharhinus leucas), habitat use has been widely examined in the eastern and western Gulf of Mexico; however, knowledge of their movements and the factors influencing them is lacking for populations in the more temperate north-central Gulf of Mexico. To examine how changes in hydrographic conditions affected the presence of young bull sharks in Mobile Bay, Alabama, thirty-five sharks were fitted with internal acoustic transmitters and monitored with an acoustic monitoring array consisting of thirty-three receivers between June 2009 and December 2010. Tagged sharks ranged in size from 60 to 114 cm fork length and were detected between the upper and lower portions of Mobile Bay. Despite a variety of freshwater sources associated with this highly productive estuary, sharks were most consistently detected at the largest input to the system--the Mobile and Tensaw Rivers. Our findings suggest a combination of hydrographic factors interact to influence the distribution of juvenile bull sharks in Mobile Bay. The factors affecting the probability of detecting at least one bull shark varied both temporally (2009 vs 2010) and spatially (upper vs lower bay). Electivity analysis demonstrated that bull sharks showed highest affinity for warm water (29-32 °C), moderate salinities (10-11 psu) and normoxic waters (5-7 mg/l), although these patterns were not consistent between regions or across years. We suggest future studies coupling telemetry and hydrographic variables should, when possible, consider the interactions of multiple environmental parameters when defining the dynamic factors explaining the spatial distribution of coastal sharks.

Sharks and people: insight into the global practices of tourism operators and their attitudes to shark behaviour.

Science.gov (United States)

Richards, Kirsty; O'Leary, Bethan C; Roberts, Callum M; Ormond, Rupert; Gore, Mauvis; Hawkins, Julie P

2015-02-15

Shark tourism is a popular but controversial activity. We obtained insights into this industry via a global e-mailed questionnaire completed by 45 diving/snorkelling operators who advertised shark experiences (shark operators) and 49 who did not (non-shark operators). 42% of shark operators used an attractant to lure sharks and 93% stated they had a formal code of conduct which 86% enforced "very strictly". While sharks were reported to normally ignore people, 9 operators had experienced troublesome behaviour from them. Whilst our research corroborates previous studies indicating minimal risk to humans from most shark encounters, a precautionary approach to provisioning is required to avoid potential ecological and societal effects of shark tourism. Codes of conduct should always stipulate acceptable diver behaviour and appropriate diver numbers and shark operators should have a moral responsibility to educate their customers about the need for shark conservation. Copyright © 2014 Elsevier Ltd. All rights reserved.

Severity of Expert-Identified Behavioural Responses of Humpback Whale, Minke Whale, and Northern Bottlenose Whale to Naval Sonar

NARCIS (Netherlands)

Sivle, L.D.; Kvadsheim, P.H.; Cure, C.; Isojunno, S.; Wensveen, P.J.; Lam, F.P.A.; Visser, F.; Kleivane, L.; Tyack, P.L.; Harris, C.M.; Miller, P.J.O.

2015-01-01

Controlled exposure experiments using 1 to2 kHz sonar signals were conducted with 11 humpback whales (Megaptera novaeangliae), one minke whale (Balaenoptera acutorostrata), and one northern bottlenose whale (Hyperoodon ampullatus) during three field trials from 2011 to 2013. Ship approaches without

Changes in dive behavior during naval sonar exposure in killer whales, long-finned pilot whales, and sperm whales

NARCIS (Netherlands)

Sivle, L.D.; Kvadsheim, P.H.; Fahlman, A.; Lam, F.P.A.; Tyack, P.L.; Miller, P.J.O.

2012-01-01

Anthropogenic underwater sound in the environment might potentially affect the behavior of marine mammals enough to have an impact on their reproduction and survival. Diving behavior of four killer whales (Orcinus orca), seven long-finned pilot whales (Globicephala melas), and four sperm whales

Whale, Whale, Everywhere: Increasing Abundance of Western South Atlantic Humpback Whales (Megaptera novaeangliae) in Their Wintering Grounds.

Science.gov (United States)

Bortolotto, Guilherme A; Danilewicz, Daniel; Andriolo, Artur; Secchi, Eduardo R; Zerbini, Alexandre N

2016-01-01

The western South Atlantic (WSA) humpback whale population inhabits the coast of Brazil during the breeding and calving season in winter and spring. This population was depleted to near extinction by whaling in the mid-twentieth century. Despite recent signs of recovery, increasing coastal and offshore development pose potential threats to these animals. Therefore, continuous monitoring is needed to assess population status and support conservation strategies. The aim of this work was to present ship-based line-transect estimates of abundance for humpback whales in their WSA breeding ground and to investigate potential changes in population size. Two cruises surveyed the coast of Brazil during August-September in 2008 and 2012. The area surveyed in 2008 corresponded to the currently recognized population breeding area; effort in 2012 was limited due to unfavorable weather conditions. WSA humpback whale population size in 2008 was estimated at 16,410 (CV = 0.228, 95% CI = 10,563-25,495) animals. In order to compare abundance between 2008 and 2012, estimates for the area between Salvador and Cabo Frio, which were consistently covered in the two years, were computed at 15,332 (CV = 0.243, 95% CI = 9,595-24,500) and 19,429 (CV = 0.101, 95% CI = 15,958-23,654) whales, respectively. The difference in the two estimates represents an increase of 26.7% in whale numbers in a 4-year period. The estimated abundance for 2008 is considered the most robust for the WSA humpback whale population because the ship survey conducted in that year minimized bias from various sources. Results presented here indicate that in 2008, the WSA humpback whale population was at least around 60% of its estimated pre-modern whaling abundance and that it may recover to its pre-exploitation size sooner than previously estimated.

Comparison of echolocation clicks from geographically sympatric killer whales and long-finned pilot whales

DEFF Research Database (Denmark)

Eskesen, Ida; Wahlberg, Magnus; Simon, Malene

2010-01-01

The source characteristics of biosonar signals from sympatric killer whales and long-finned pilot whales in a Norwegian fjord were compared. A total of 137 pilot whale and more than 2000 killer whale echolocation clicks were recorded using a linear four-hydrophone array. Of these, 20 pilot whale...... clicks and 28 killer whale clicks were categorized as being recorded on-axis. The clicks of pilot whales had a mean apparent source level of 196 dB re 1 lPa pp and those of killer whales 203 dB re 1 lPa pp. The duration of pilot whale clicks was significantly shorter (23 ls, S.E.¼1.3) and the centroid...... frequency significantly higher (55 kHz, S.E.¼2.1) than killer whale clicks (duration: 41 ls, S.E.¼2.6; centroid frequency: 32 kHz, S.E.¼1.5). The rate of increase in the accumulated energy as a function of time also differed between clicks from the two species. The differences in duration, frequency...

Is Host Ectoparasite Load Related to Echeneid Fish Presence?

Directory of Open Access Journals (Sweden)

Gonzalo R. Mucientes

2008-01-01

Full Text Available This study used field data of echeneid and ectoparasite associations with free-swimming whale sharks (Rhincodon typus and captured mako sharks (Isurus oxyrinchus to test whether (1 echeneid presence was positively correlated with ectoparasite presence; and (2 the number of ectoparasites was negatively correlated with the number of echeneid fish. Data from whale and mako sharks do not support the first hypothesis whereas data from mako sharks yields support for the second hypothesis. The results indicate that echeneids do regulate the number of ectoparasites on at least some host species, but these benefits may be contingent on the echeneid species.

Is Host Ectoparasite Load Related to Echeneid Fish Presence?

International Nuclear Information System (INIS)

Mucientes, G.R.; Queiroz, N.; Queiroz, N.; Pierce, S.J.; Pierce, S.J.; Sazima, I.; Brunnschweiler, J.M.

2008-01-01

This study used field data of echeneid and ectoparasitic associations with free-swimming whale sharks (Rhincodon typus) and captured mako sharks (Isurus oxyrinchus) to test whether (1) echeneid presence was positively correlated with ectoparasitic presence; and (2) the number of ectoparasitic was negatively correlated with the number of echeneid fish. Data from whale and mako sharks do not support the first hypothesis whereas data from mako sharks yields support for the second hypothesis. The results indicate that echeneids do regulate the number of ectoparasitic on at least some host species, but these benefits may be contingent on the echeneid species.

Implantable Neural Interfaces for Sharks

Science.gov (United States)

2007-05-01

technology for recording and stimulating from the auditory and olfactory sensory nervous systems of the awake, swimming nurse shark , G. cirratum (Figures...overlay of the central nervous system of the nurse shark on a horizontal MR image. Implantable Neural Interfaces for Sharks ...Neural Interfaces for Characterizing Population Responses to Odorants and Electrical Stimuli in the Nurse Shark , Ginglymostoma cirratum.” AChemS Abs

Whales, science, and scientific whaling in the International Court of Justice.

Science.gov (United States)

Mangel, Marc

2016-12-20

I provide a brief review of the origins of the International Convention on the Regulation of Whaling and the failure to successfully regulate whaling that led to the commercial moratorium in 1986. I then describe the Japanese Whale Research Programs Under Special Permit in the Antarctica (JARPA I, JARPA II) and the origins of the case Whaling in the Antarctic (Australia v. Japan: New Zealand Intervening) in the International Court of Justice. I explain that the International Court of Justice chose to conduct an objective review of JARPA II, the standard that it used for the review, and the pathway that it took to adjudicate the case without providing a definition of science to be used in international law. I conclude with a brief discussion of the implications of the Judgment for the International Convention on the Regulation of Whaling, and the International Whaling Commission in particular, for other international treaties, and for the interaction of science and law more generally.

The Greenland shark

DEFF Research Database (Denmark)

Costantini, David; Smith, Shona; Killen, Shaun S.

2017-01-01

the oxidative status of the Greenland shark (Somniosus microcephalus), which has recently been found as the longest living vertebrate animal known to science with a lifespan of at least 272years. As compared to other species, the Greenland shark had body mass-corrected values of muscle glutathione peroxidase...... that the values of metrics of oxidative status we measured might be linked to ecological features (e.g., adaptation to cold waters and deep dives) of this shark species rather to its lifespan....

Oceanic sharks clean at coastal seamount.

Directory of Open Access Journals (Sweden)

Simon P Oliver

2011-03-01

Full Text Available Interactions between pelagic thresher sharks (Alopias pelagicus and cleaner wrasse were investigated at a seamount in the Philippines. Cleaning associations between sharks and teleosts are poorly understood, but the observable interactions seen at this site may explain why these mainly oceanic sharks regularly venture into shallow coastal waters where they are vulnerable to disturbance from human activity. From 1,230 hours of observations recorded by remote video camera between July 2005 and December 2009, 97 cleaner-thresher shark events were analyzed, 19 of which were interrupted. Observations of pelagic thresher sharks interacting with cleaners at the seamount were recorded at all times of day but their frequency declined gradually from morning until evening. Cleaners showed preferences for foraging on specific areas of a thresher shark's body. For all events combined, cleaners were observed to conduct 2,757 inspections, of which 33.9% took place on the shark's pelvis, 23.3% on the pectoral fins, 22.3% on the caudal fin, 8.6% on the body, 8.3% on the head, 2.1% on the dorsal fin, and 1.5% on the gills respectively. Cleaners did not preferentially inspect thresher sharks by time of day or by shark sex, but there was a direct correlation between the amount of time a thresher shark spent at a cleaning station and the number of inspections it received. Thresher shark clients modified their behavior by "circular-stance-swimming," presumably to facilitate cleaner inspections. The cleaner-thresher shark association reflected some of the known behavioral trends in the cleaner-reef teleost system since cleaners appeared to forage selectively on shark clients. Evidence is mounting that in addition to acting as social refuges and foraging grounds for large visiting marine predators, seamounts may also support pelagic ecology by functioning as cleaning stations for oceanic sharks and rays.

"Shark is the man!": ethnoknowledge of Brazil's South Bahia fishermen regarding shark behaviors.

Science.gov (United States)

Barbosa-Filho, Márcio Luiz Vargas; Schiavetti, Alexandre; Alarcon, Daniela Trigueirinho; Costa-Neto, Eraldo Medeiros

2014-07-03

Fishermen's knowledge is a source of indispensable information in decision-making processes related to efforts to stimulate the management and conservation of fishing resources, especially in developing countries. This study analyzed the knowledge of fishermen from three municipal areas of Bahia in northeast Brazil regarding the behavior repertoire of sharks and the possible influence that these perceptions may have on the inclination to preserve these animals. This is a pioneering study on the ethnobiological aspects of elasmobranchs in Brazil. Open, semi-structured interviews with shark fishing specialists were conducted between September 2011 and October 2012. The interviews addressed the fishermen's profile, fishing techniques and knowledge about sharks, focusing on the behaviours exhibited by sharks. The data were analysed with quantitative approach and conducted with the use of descriptive statistical techniques. Sixty-five fishermen were interviewed. They descend from the rafting subculture of Brazil's northeast, which has historically been disregarded by public policies addressing the management and conservation of fishing resources. The fishing fleet involved in shark fishing includes rafts, fishing boats and lobster boats equipped with fishing lines, gillnets, longlines and "esperas". The informers classified sharks' behaviour repertoire into 19 ethological categories, related especially to feeding, reproduction, and social and migratory behaviours. Because they identify sharks as predators, the detailed recognition of the behaviours exhibited is crucial both for an efficient catch and to avoid accidents. Therefore, this knowledge is doubly adaptive as it contributes to safer, more lucrative fishing. A feeling of respect for sharks predominates, since informers recognize the ecological role of these animals in marine ecosystems, attributing them the status of leader (or "the man") in the sea. This work demonstrates the complexity and robustness of

Are Antarctic minke whales unusually abundant because of 20th century whaling?

Science.gov (United States)

Ruegg, Kristen C; Anderson, Eric C; Scott Baker, C; Vant, Murdoch; Jackson, Jennifer A; Palumbi, Stephen R

2010-01-01

Severe declines in megafauna worldwide illuminate the role of top predators in ecosystem structure. In the Antarctic, the Krill Surplus Hypothesis posits that the killing of more than 2 million large whales led to competitive release for smaller krill-eating species like the Antarctic minke whale. If true, the current size of the Antarctic minke whale population may be unusually high as an indirect result of whaling. Here, we estimate the long-term population size of the Antarctic minke whale prior to whaling by sequencing 11 nuclear genetic markers from 52 modern samples purchased in Japanese meat markets. We use coalescent simulations to explore the potential influence of population substructure and find that even though our samples are drawn from a limited geographic area, our estimate reflects ocean-wide genetic diversity. Using Bayesian estimates of the mutation rate and coalescent-based analyses of genetic diversity across loci, we calculate the long-term population size of the Antarctic minke whale to be 670,000 individuals (95% confidence interval: 374,000-1,150,000). Our estimate of long-term abundance is similar to, or greater than, contemporary abundance estimates, suggesting that managing Antarctic ecosystems under the assumption that Antarctic minke whales are unusually abundant is not warranted.

Trophic Ecology and Movement Patters of Tiger Sharks (Galeocerdo Cuvier) off the Western North Atlantic Coastal and Continental Shelf Waters

Science.gov (United States)

Sancho, G.; Edman, R.; Frazier, B.; Bubley, W.

2016-02-01

Understanding the trophic dynamics and habitat utilization of apex predators is central to inferring their influence on different marine landscapes and to help design effective management plans for these animals. Tiger sharks (Galeocerdo cuvier) are abundant in shelf and offshore Gulf Stream waters of the western North Atlantic Ocean, and based on movements from individuals captured in Florida and Bahamas, seem to avoid coastal and shelf waters off South Carolina and Georgia. This contradicts reports of tiger sharks regularly being caught nearshore by anglers in these states, indicating that separate sub-populations may exist in the western North Atlantic. In the present study we captured Tiger Sharks in coastal waters off South Carolina in 2014 and 2015 in order to describe their movement patterns through acoustic and satellite tagging, and trophic dynamics through stable isotope analyses. Movement data show that these tiger sharks repeatedly visit particular inshore areas and mainly travel over the continental shelf, but rarely venture offshore beyond the continental shelf edge. Ongoing C and N stable isotope analyses of muscle, blood and skin tissues from adult and juvenile tiger sharks, as well as from potential prey species and primary producers, will help determine if their diets are based on inshore, shelf or offshore based food webs. Tiger sharks exploiting nearshore environments and shelf waters have much higher probabilities of interacting with humans than individuals occupying far offshore Gulf Stream habitats.

Whale Teaching Unit.

Science.gov (United States)

Peninsula Humane Society, San Mateo, CA.

Materials in this teaching unit are designed to foster an interest in whale preservation among intermediate grade and junior high school students. Several readings provide background information on various types of whales and the economic value of whales. Student activities include a true and false game, a crossword, and a mobile. A resource list…

Multi-tissue stable isotope analysis and acoustic telemetry reveal seasonal variability in the trophic interactions of juvenile bull sharks in a coastal estuary.

Science.gov (United States)

Matich, Philip; Heithaus, Michael R

2014-01-01

Understanding how natural and anthropogenic drivers affect extant food webs is critical to predicting the impacts of climate change and habitat alterations on ecosystem dynamics. In the Florida Everglades, seasonal reductions in freshwater flow and precipitation lead to annual migrations of aquatic taxa from marsh habitats to deep-water refugia in estuaries. The timing and intensity of freshwater reductions, however, will be modified by ongoing ecosystem restoration and predicted climate change. Understanding the importance of seasonally pulsed resources to predators is critical to predicting the impacts of management and climate change on their populations. As with many large predators, however, it is difficult to determine to what extent predators like bull sharks (Carcharhinus leucas) in the coastal Everglades make use of prey pulses currently. We used passive acoustic telemetry to determine whether shark movements responded to the pulse of marsh prey. To investigate the possibility that sharks fed on marsh prey, we modelled the predicted dynamics of stable isotope values in bull shark blood and plasma under different assumptions of temporal variability in shark diets and physiological dynamics of tissue turnover and isotopic discrimination. Bull sharks increased their use of upstream channels during the late dry season, and although our previous work shows long-term specialization in the diets of sharks, stable isotope values suggested that some individuals adjusted their diets to take advantage of prey entering the system from the marsh, and as such this may be an important resource for the nursery. Restoration efforts are predicted to increase hydroperiods and marsh water levels, likely shifting the timing, duration and intensity of prey pulses, which could have negative consequences for the bull shark population and/or induce shifts in behaviour. Understanding the factors influencing the propensity to specialize or adopt more flexible trophic interactions

HMSRP Hawaiian Monk Seal Shark Predation Mitigation Shark Sightings and Incidents

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Data on direct sightings of large sharks around monk seal pupping sites and shark incidents on preweaned and newly weaned pups at French Frigate Shoals are entered...

Shark complement: an assessment.

Science.gov (United States)

Smith, S L

1998-12-01

The classical (CCP) and alternative (ACP) pathways of complement activation have been established for the nurse shark (Ginglymostoma cirratum). The isolation of a cDNA clone encoding a mannan-binding protein-associated serine protease (MASP)-1-like protein from the Japanese dogfish (Triakis scyllia) suggests the presence of a lectin pathway. The CCP consists of six functionally distinct components: C1n, C2n, C3n, C4n, C8n and C9n, and is activated by immune complexes in the presence of Ca++ and Mg++ ions. The ACP is antibody independent, requiring Mg++ ions and a heat-labile 90 kDa factor B-like protein for activity. Proteins considered homologues of C1q, C3 and C4 (C2n) of the mammalian complement system have been isolated from nurse shark serum. Shark C1q is composed of at least two chain types each showing 50% identity to human C1q chains A and B. Partial sequence of the globular domain of one of the chains shows it to be C1q-like rather than like mannan-binding protein. N-terminal amino acid sequences of the alpha and beta chain of shark C3 and C4 molecules show significant identity with corresponding human C3 and C4 chains. A sequence representing shark C4 gamma chain, shows little similarity to human C4 gamma chain. The terminal shark components C8n and C9n are functional analogues of mammalian C8 and C9. Anaphylatoxin activity has been demonstrated in activated shark serum, and porcine C5a desArg induces shark leucocyte chemotaxis. The deduced amino acid sequence of a partial C3 cDNA clone from the nurse shark shows 50%, 30% and 24% homology with the corresponding region of mammalian C3, C4 and alpha 2-macroglobulin. Deduced amino acid sequence data from partial Bf/C2 cDNA clones, two from the nurse shark and one from the Japanese dogfish, suggest that at least one species of elasmobranch has two distinct Bf/C2 genes.

Life history of the silvertip shark Carcharhinus albimarginatus from Papua New Guinea

Science.gov (United States)

Smart, Jonathan J.; Chin, Andrew; Baje, Leontine; Tobin, Andrew J.; Simpfendorfer, Colin A.; White, William T.

2017-06-01

Growth and maturity of the silvertip shark Carcharhinus albimarginatus from Papua New Guinea were estimated to form the basis of future population assessments. Samples were collected from commercial longline vessels targeting sharks in the Bismarck and Solomon Seas. A total of 48 C. albimarginatus—28 males (95-219 cm total length, TL) and 20 females (116-250 cm TL)—provided data for the analyses. Employing back-calculation techniques accounted for missing juvenile length classes and supplemented the sample size. A multi-model framework incorporating the Akaike information criterion was used to estimate growth parameters. The von Bertalanffy growth function (VBGF) provided the best-fit growth estimates. Parameter estimates were L 0 = 72.1 cm TL, k = 0.04 yr-1 and L ∞ = 311.3 cm TL for males; and L 0 = 70.8 cm TL, k = 0.02 yr-1 and L ∞ = 497.9 cm TL for females. The biologically implausible L ∞ occurred for females as their growth did not asymptote; a typical trait of large shark species. The maximum age estimated from vertebral analysis was 18 yr for both sexes, while the calculated longevity from the VBGF parameters was 27.4 yr for males and 32.2 yr for females. Males matured at 174.7 cm TL and 10.5 yr old, while females matured at 208.9 cm TL and 14.8 yr old.

Regional movements of the tiger shark, Galeocerdo cuvier, off Northeastern Brazil: inferences regarding shark attack hazard.

Science.gov (United States)

Hazin, Fábio H V; Afonso, André S; De Castilho, Pedro C; Ferreira, Luciana C; Rocha, Bruno C L M

2013-09-01

An abnormally high shark attack rate verified off Recife could be related to migratory behavior of tiger sharks. This situation started after the construction of the Suape port to the south of Recife. A previous study suggested that attacking sharks could be following northward currents and that they were being attracted shoreward by approaching vessels. In this scenario, such northward movement pattern could imply a higher probability of sharks accessing the littoral area of Recife after leaving Suape. Pop-up satellite archival tags were deployed on five tiger sharks caught off Recife to assess their movement patterns off northeastern Brazil. All tags transmitted from northward latitudes after 7-74 days of freedom. The shorter, soak distance between deployment and pop-up locations ranged between 33-209 km and implied minimum average speeds of 0.02-0.98 km.h-1. Both pop-up locations and depth data suggest that tiger shark movements were conducted mostly over the continental shelf. The smaller sharks moved to deeper waters within 24 hours after releasing, but they assumed a shallower (shark movements in the South Atlantic, this study also adds new information for the reasoning of the high shark attack rate verified in this region.

Relative abundance and size of coastal sharks derived from commercial shark longline catch and effort data.

Science.gov (United States)

Carlson, J K; Hale, L F; Morgan, A; Burgess, G

2012-04-01

In the north-west Atlantic Ocean, stock assessments conducted for some commercially harvested coastal sharks indicate declines from 64 to 80% with respect to virgin population levels. While the status of commercially important species is available, abundance trend information for other coastal shark species in the north-west Atlantic Ocean are unavailable. Using a generalized linear modelling (GLM) approach, a relative abundance index was derived from 1994 to 2009 using observer data collected in a commercial bottom longline fishery. Trends in abundance and average size were estimated for bull shark Carcharhinus leucas, spinner shark Carcharhinus brevipinna, tiger shark Galeocerdo cuvier and lemon shark Negaprion brevirostris. Increases in relative abundance for all shark species ranged from 14% for C. brevipinna, 12% for C. leucas, 6% for N. brevirostris and 3% for G. cuvier. There was no significant change in the size at capture over the time period considered for all species. While the status of shark populations should not be based exclusively on abundance trend information, but ultimately on stock assessment models, results from this study provide some cause for optimism on the status of these coastal shark species. Published 2012. This article is a U.S. Government work and is in the public domain in the USA.

Shark Spotters: Successfully reducing spatial overlap between white sharks (Carcharodon carcharias) and recreational water users in False Bay, South Africa.

Science.gov (United States)

Engelbrecht, Tamlyn; Kock, Alison; Waries, Sarah; O'Riain, M Justin

2017-01-01

White sharks (Carcharodon carcharias) are apex predators that play an important role in the structure and stability of marine ecosystems. Despite their ecological importance and protected status, white sharks are still subject to lethal control to reduce the risk of shark bites for recreational water users. The Shark Spotters program, pioneered in Cape Town, South Africa, provides a non-lethal alternative for reducing the risk of human-shark conflict. In this study we assessed the efficacy of the Shark Spotters program in reducing overlap between water users and white sharks at two popular beaches in False Bay, South Africa. We investigated seasonal and diel patterns in water use and shark presence at each beach, and thereafter quantified the impact of different shark warnings from shark spotters on water user abundance. We also assessed the impact of a fatal shark incident on patterns of water use. Our results revealed striking diel and seasonal overlap between white sharks and water users at both beaches. Despite this, there was a low rate of shark-human incidents (0.5/annum) which we attribute partly to the success of the Shark Spotters program. Shark spotters use visual (coloured flags) and auditory (siren) cues to inform water users of risk associated with white shark presence in the surf zone. Our results showed that the highest risk category (denoted by a white flag and accompanying siren) caused a significant reduction in water user abundance; however the secondary risk category (denoted by a red flag with no siren) had no significant effect on water users. A fatal shark incident was shown to negatively impact the number of water users present for at least three months following the incident. Our results indicate that the Shark Spotters program effectively reduces spatial overlap between white sharks and water users when the risk of conflict is highest.

Characterization of cholinesterases present in brain and muscle tissues of juvenile blue shark (Prionace glauca

Directory of Open Access Journals (Sweden)

Luís Miguel Fonseca Alves

2014-06-01

Regarding the in vitro exposure to chlorpyrifos-oxon, we have observed a dose-response pattern showing higher ChE inhibitions with increasing pesticide concentrations and with more than 90% inhibition in the highest concentrations, which reveals the potential of this biomarker for biomonitoring studies and contaminant effect assessment in the blue shark.

Characteristics of the shark fisheries of Fiji

Science.gov (United States)

Glaus, Kerstin B. J.; Adrian-Kalchhauser, Irene; Burkhardt-Holm, Patricia; White, William T.; Brunnschweiler, Juerg M.

2015-12-01

Limited information is available on artisanal and subsistence shark fisheries across the Pacific. The aim of this study was to investigate Fiji’s inshore fisheries which catch sharks. In January and February 2013, 253 semi-directive interviews were conducted in 117 villages and at local harbours on Viti Levu, Vanua Levu, Taveuni, Ovalau and a number of islands of the Mamanuca and Yasawa archipelagos. Of the 253 interviewees, 81.4% reported to presently catch sharks, and 17.4% declared that they did not presently catch any sharks. Of the 206 fishers that reported to catch sharks, 18.4% targeted sharks and 81.6% caught sharks as bycatch. When targeted, primary use of sharks was for consumption or for sale. Sharks caught as bycatch were frequently released (69.6%), consumed (64.9%) or shared amongst the community (26.8%). Fishers’ identification based on an identification poster and DNA barcoding revealed that at least 12 species of elasmobranchs, 11 shark and one ray species (Rhynchobatus australiae) were caught. This study, which is the first focused exploration of the shark catch in Fiji’s inshore fisheries, suggests that the country’s artisanal shark fisheries are small but have the potential to develop into larger and possibly more targeted fisheries.

Characteristics of the shark fisheries of Fiji.

Science.gov (United States)

Glaus, Kerstin B J; Adrian-Kalchhauser, Irene; Burkhardt-Holm, Patricia; White, William T; Brunnschweiler, Juerg M

2015-12-02

Limited information is available on artisanal and subsistence shark fisheries across the Pacific. The aim of this study was to investigate Fiji's inshore fisheries which catch sharks. In January and February 2013, 253 semi-directive interviews were conducted in 117 villages and at local harbours on Viti Levu, Vanua Levu, Taveuni, Ovalau and a number of islands of the Mamanuca and Yasawa archipelagos. Of the 253 interviewees, 81.4% reported to presently catch sharks, and 17.4% declared that they did not presently catch any sharks. Of the 206 fishers that reported to catch sharks, 18.4% targeted sharks and 81.6% caught sharks as bycatch. When targeted, primary use of sharks was for consumption or for sale. Sharks caught as bycatch were frequently released (69.6%), consumed (64.9%) or shared amongst the community (26.8%). Fishers' identification based on an identification poster and DNA barcoding revealed that at least 12 species of elasmobranchs, 11 shark and one ray species (Rhynchobatus australiae) were caught. This study, which is the first focused exploration of the shark catch in Fiji's inshore fisheries, suggests that the country's artisanal shark fisheries are small but have the potential to develop into larger and possibly more targeted fisheries.

Fatal tiger shark, Galeocerdo cuvier attack in New Caledonia erroneously ascribed to great white shark, Carcharodon carcharias.

Science.gov (United States)

Tirard, Philippe; Maillaud, Claude; Borsa, Philippe

2015-07-01

To understand the causes and patterns of shark attacks on humans, accurate identification of the shark species involved is necessary. Often, the only reliable evidence for this comes from the characteristics of the wounds exhibited by the victim. The present case report is intended as a reappraisal of the Luengoni, 2007 case (International Shark Attack File no. 4299) where a single shark bite provoked the death of a swimmer by haemorrhagic shock. Our examination of the wounds on the body of the victim, here documented by so-far unpublished photographic evidence, determined that the shark possessed large and homodontous jaws. This demonstrates that the attacker was a tiger shark, not a great white shark as previously published. Copyright © 2015 Elsevier Ltd and Faculty of Forensic and Legal Medicine. All rights reserved.

Distribution and relative abundance of large whales in a former whaling ground off eastern South America

Directory of Open Access Journals (Sweden)

Artur Andriolo

2010-10-01

Full Text Available Ship-based sighting surveys for cetaceans were conducted in the former whaling ground off the northeastern coast of Brazil. The cruises took place in winter and spring of 1998-2001 with the objectives of investigating current distribution and abundance of cetaceans, particularly large whale species taken during whaling. In 1998 the survey were conducted between the parallels 5°30'W and 9°S and the 200 m isobath and the meridian 033°W. A total of about 3,100 nm were surveyed between 1998 and 2001 Surveys were conducted using line transect methods from about 5-10°S, and from the coast to 33°W. A total of 151 sightings (203 individuals of large whales were recorded on effort. The Antarctic minke whale - Balaenoptera bonaerensis (Burmeister, 1867 was the most frequently sighted species (97 groups/132 individuals; Sighting Rate [SR] = 0.031 groups/nm, being recorded only in offshore waters. Density gradually increased from August to October. Minke whales were distributed throughout the area, both to the north and the south of former whaling ground. Sighting data indicate this is the most abundant species, particularly in the area beyond the continental shelf break. Breeding behavior was observed for Antarctic minke whales, but few groups containing calves were recorded (4.3% of the groups sighted on effort. Three other large whale species were recorded in low numbers: the Bryde's whale - Balaenoptera edeni (Anderson, 1879¹; the sei whale, B. borealis (Lesson, 1828, and the sperm, Physeter macrocephalus (Linnaeus, 1758. Sei, Bryde and sperm whales were regularly caught during whaling operations, but are rare in the area, suggesting they were depleted by whaling and have yet to recover to their pre-explotation abundance. In contrast, minke whales are abundant in this area, suggesting that either they were not substantially depleted, or that they have recovered rapidly. Blue whale, Balaenoptera musculus (Linnaeus, 1758, and fin whale, B. physalus

The International Whaling Commission – Beyond Whaling

Directory of Open Access Journals (Sweden)

Andrew John Wright

2016-08-01

Full Text Available Since its establishment in 1946 as the international body intended to manage whaling, the International Whaling Commission (IWC has expanded its areas of interest to ensure the wider conservation of whales. Several key conservation topics have been taken forward under its auspices including climate change, chemical and noise pollution, marine debris and whale watching. Work on each of these topics at the IWC has grown substantially since the 1990s and remains ongoing. Important developments were the establishment of the Standing Working Group on Environmental Concerns in 1996 and the IWC’s Conservation Committee in 2003. Trying to address this diverse set of issues is obviously a challenge but will be necessary if the long term conservation of cetaceans is to be achieved. Through research, workshops, resolutions and collaboration with other organisations, the IWC has advanced both the understanding of the various issues and the means to manage them with increasing effectiveness. The IWC is likely to remain on the forefront of continuing efforts to address these, and other, conservation concerns and ensure the continued viability of cetacean populations around the globe.

POPs in free-ranging pilot whales, sperm whales and fin whales from the Mediterranean Sea: Influence of biological and ecological factors

Energy Technology Data Exchange (ETDEWEB)

Pinzone, Marianna [Laboratory of Oceanology, MARE Centre, B6c, University of Liege, B6c, Allée du 6 Août, 4000 Liege (Belgium); Budzinski, Hélène [ISM/LPTC, Laboratory of Physical and Chemical Chemistry, University of Bordeaux I, 351 Cours de la Libération, 33405 Bordeaux (France); CNRS, EPOC, UMR 5805, F-33400 Talence (France); Tasciotti, Aurélie; Ody, Denis [WWF-France, 6 Rue des Fabres, 13001 Marseille France (France); Lepoint, Gilles; Schnitzler, Joseph [Laboratory of Oceanology, MARE Centre, B6c, University of Liege, B6c, Allée du 6 Août, 4000 Liege (Belgium); Scholl, George [CART, Laboratory of Mass Spectrometry LSM, University of Liege, B6C, Allée du 6 Août, 4000, Liege (Belgium); Thomé, Jean-Pierre [CART, Laboratory of Animal Ecology and Ecotoxicology LEAE, University of Liege, B6c, Allée du 6 Août 11, 4000 Liege (Belgium); Tapie, Nathalie [ISM/LPTC, Laboratory of Physical and Chemical Chemistry, University of Bordeaux I, 351 Cours de la Libération, 33405 Bordeaux (France); CNRS, EPOC, UMR 5805, F-33400 Talence (France); Eppe, Gauthier [CART, Laboratory of Mass Spectrometry LSM, University of Liege, B6C, Allée du 6 Août, 4000, Liege (Belgium); Das, Krishna, E-mail: krishna.das@ulg.ac.be [Laboratory of Oceanology, MARE Centre, B6c, University of Liege, B6c, Allée du 6 Août, 4000 Liege (Belgium)

2015-10-15

The pilot whale Globicephala melas, the sperm whale Physeter macrocephalus, and the fin whale Balaenoptera physalus are large cetaceans permanently inhabiting the Mediterranean Sea. These species are subjected to numerous anthropogenic threats such as exposure to high levels of contaminants. Therefore, selected persistent organic pollutants POPs (29 PCBs, 15 organochlorine compounds, 9 PBDEs and 17 PCDD/Fs) were analysed in blubber biopsies of 49 long-finned pilot whales, 61 sperm whales and 70 fin whales sampled in the North Western Mediterranean Sea (NWMS) from 2006 to 2013. Contamination profile and species feeding ecology were then combined through the use of stable isotopes. δ{sup 13}C, δ{sup 15}N values and POPs levels were assessed through IR-MS and GC–MS respectively. To assess the toxic potency of the dioxin-like compounds, the TEQ approach was applied. δ{sup 15}N values were 12.2±1.3‰ for sperm whales, 10.5±0.7‰ for pilot whales and 7.7±0.8‰ in fin whales, positioning sperm whales at higher trophic levels. δ{sup 13}C of the two odontocetes was similar and amounted to −17.3±0.4‰ for sperm whales and −17.8±0.3‰ for pilot whales; whilst fin whales were more depleted (−18.7±0.4‰). This indicates a partial overlap in toothed-whales feeding habitats, while confirms the differences in feeding behaviour of the mysticete. Pilot whales presented higher concentrations than sperm whales for ΣPCBs (38,666±25,731 ng g{sup −1} lw and 22,849±15,566 ng g{sup −1} lw respectively), ΣPBDEs (712±412 ng g{sup −1} lw and 347±173 ng g{sup −1} lw respectively) and ΣDDTs (46,081±37,506 ng g{sup −1} lw and 37,647±38,518 ng g{sup −1} lw respectively). Fin whales presented the lowest values, in accordance with its trophic position (ΣPCBs: 5721±5180 ng g{sup −1} lw, ΣPBDEs: 177±208 ng g{sup −1} lw and ΣDDTs: 6643±5549 ng g{sup −1} lw). Each species was characterized by large inter-individual variations that are more

POPs in free-ranging pilot whales, sperm whales and fin whales from the Mediterranean Sea: Influence of biological and ecological factors

International Nuclear Information System (INIS)

Pinzone, Marianna; Budzinski, Hélène; Tasciotti, Aurélie; Ody, Denis; Lepoint, Gilles; Schnitzler, Joseph; Scholl, George; Thomé, Jean-Pierre; Tapie, Nathalie; Eppe, Gauthier; Das, Krishna

2015-01-01

The pilot whale Globicephala melas, the sperm whale Physeter macrocephalus, and the fin whale Balaenoptera physalus are large cetaceans permanently inhabiting the Mediterranean Sea. These species are subjected to numerous anthropogenic threats such as exposure to high levels of contaminants. Therefore, selected persistent organic pollutants POPs (29 PCBs, 15 organochlorine compounds, 9 PBDEs and 17 PCDD/Fs) were analysed in blubber biopsies of 49 long-finned pilot whales, 61 sperm whales and 70 fin whales sampled in the North Western Mediterranean Sea (NWMS) from 2006 to 2013. Contamination profile and species feeding ecology were then combined through the use of stable isotopes. δ 13 C, δ 15 N values and POPs levels were assessed through IR-MS and GC–MS respectively. To assess the toxic potency of the dioxin-like compounds, the TEQ approach was applied. δ 15 N values were 12.2±1.3‰ for sperm whales, 10.5±0.7‰ for pilot whales and 7.7±0.8‰ in fin whales, positioning sperm whales at higher trophic levels. δ 13 C of the two odontocetes was similar and amounted to −17.3±0.4‰ for sperm whales and −17.8±0.3‰ for pilot whales; whilst fin whales were more depleted (−18.7±0.4‰). This indicates a partial overlap in toothed-whales feeding habitats, while confirms the differences in feeding behaviour of the mysticete. Pilot whales presented higher concentrations than sperm whales for ΣPCBs (38,666±25,731 ng g −1 lw and 22,849±15,566 ng g −1 lw respectively), ΣPBDEs (712±412 ng g −1 lw and 347±173 ng g −1 lw respectively) and ΣDDTs (46,081±37,506 ng g −1 lw and 37,647±38,518 ng g −1 lw respectively). Fin whales presented the lowest values, in accordance with its trophic position (ΣPCBs: 5721±5180 ng g −1 lw, ΣPBDEs: 177±208 ng g −1 lw and ΣDDTs: 6643±5549 ng g −1 lw). Each species was characterized by large inter-individual variations that are more related to sex than trophic level, with males presenting higher

Encountering whales: How encounter rates became the basis for managing whaling

Directory of Open Access Journals (Sweden)

Tim D Smith

2009-09-01

Full Text Available Declining rates of encountering whales, including both sighting and catching, were noted by whalers throughout the 19th century, and these declines became the first indication that whaling was adversely affecting whale abundance. The interpretation of declines in both sighting and catch rates proved to be a difficult scientific task. Satisfactory quantitative methods of interpreting changes in whale encounter rates were not developed until the second half of the 20th century. Rates of encountering whales played a key role in the International Whaling Commission (IWC Scientific Committee from its beginning in the early 1950s, as well as in the US in implementing its Marine Mammal Protection Act beginning in the early 1970s. The development of methods of collecting and interpreting sighting and catch data was intimately interwoven with the development of themanagement of whaling and cetacean by-catches in fisheries throughout the world, but especially within the context of the Scientific Committees of the IWC and the North Atlantic Marine Mammal Commission (NAMMCO. Although overfishing of whales was initially identified through the use of sighting rate data, catch rate data provided the IWC’s Committee its first firm footing for management advice. However, it was sighting rate data that ultimately became the basis for the scientific advice on whaling and for management advice in other settings. This led to the development of large scale cetacean sighting programmes, such as the IWC’s International Decade of Cetacean Researchsurveys in Antarctic aboard Japanese ships, the North Atlantic Sighting Surveys (NASS aboard Norwegian, Icelandic, Spanish, Greenlandic and Faroese vessels and aircraft (coordinated by NAMMCO through its Scientific Committee from 1995, and surveys under the US’s Marine Mammal Protection Act and the European Union’s Small Cetacean Abundance in the North Sea (SCANS programme. Fishery independent cetacean sighting surveys

World without borders-genetic population structure of a highly migratory marine predator, the blue shark (Prionace glauca).

Science.gov (United States)

Veríssimo, Ana; Sampaio, Íris; McDowell, Jan R; Alexandrino, Paulo; Mucientes, Gonzalo; Queiroz, Nuno; da Silva, Charlene; Jones, Catherine S; Noble, Leslie R

2017-07-01

Highly migratory, cosmopolitan oceanic sharks often exhibit complex movement patterns influenced by ontogeny, reproduction, and feeding. These elusive species are particularly challenging to population genetic studies, as representative samples suitable for inferring genetic structure are difficult to obtain. Our study provides insights into the genetic population structure one of the most abundant and wide-ranging oceanic shark species, the blue shark Prionace glauca, by sampling the least mobile component of the populations, i.e., young-of-year and small juveniles (<2 year; N  = 348 individuals), at three reported nursery areas, namely, western Iberia, Azores, and South Africa. Samples were collected in two different time periods (2002-2008 and 2012-2015) and were screened at 12 nuclear microsatellites and at a 899-bp fragment of the mitochondrial control region. Our results show temporally stable genetic homogeneity among the three Atlantic nurseries at both nuclear and mitochondrial markers, suggesting basin-wide panmixia. In addition, comparison of mtDNA CR sequences from Atlantic and Indo-Pacific locations also indicated genetic homogeneity and unrestricted female-mediated gene flow between ocean basins. These results are discussed in light of the species' life history and ecology, but suggest that blue shark populations may be connected by gene flow at the global scale. The implications of the present findings to the management of this important fisheries resource are also discussed.

How Close is too Close? The Effect of a Non-Lethal Electric Shark Deterrent on White Shark Behaviour.

Science.gov (United States)

Kempster, Ryan M; Egeberg, Channing A; Hart, Nathan S; Ryan, Laura; Chapuis, Lucille; Kerr, Caroline C; Schmidt, Carl; Huveneers, Charlie; Gennari, Enrico; Yopak, Kara E; Meeuwig, Jessica J; Collin, Shaun P

2016-01-01

Sharks play a vital role in the health of marine ecosystems, but the potential threat that sharks pose to humans is a reminder of our vulnerability when entering the ocean. Personal shark deterrents are being marketed as the solution to mitigate the threat that sharks pose. However, the effectiveness claims of many personal deterrents are based on our knowledge of shark sensory biology rather than robust testing of the devices themselves, as most have not been subjected to independent scientific studies. Therefore, there is a clear need for thorough testing of commercially available shark deterrents to provide the public with recommendations of their effectiveness. Using a modified stereo-camera system, we quantified behavioural interactions between white sharks (Carcharodon carcharias) and a baited target in the presence of a commercially available, personal electric shark deterrent (Shark Shield Freedom7™). The stereo-camera system enabled an accurate assessment of the behavioural responses of C. carcharias when encountering a non-lethal electric field many times stronger than what they would naturally experience. Upon their first observed encounter, all C. carcharias were repelled at a mean (± std. error) proximity of 131 (± 10.3) cm, which corresponded to a mean voltage gradient of 9.7 (± 0.9) V/m. With each subsequent encounter, their proximity decreased by an average of 11.6 cm, which corresponded to an increase in tolerance to the electric field by an average of 2.6 (± 0.5) V/m per encounter. Despite the increase in tolerance, sharks continued to be deterred from interacting for the duration of each trial when in the presence of an active Shark Shield™. Furthermore, the findings provide no support to the theory that electric deterrents attract sharks. The results of this study provide quantitative evidence of the effectiveness of a non-lethal electric shark deterrent, its influence on the behaviour of C. carcharias, and an accurate method for testing

How Close is too Close? The Effect of a Non-Lethal Electric Shark Deterrent on White Shark Behaviour.

Directory of Open Access Journals (Sweden)

Ryan M Kempster

Full Text Available Sharks play a vital role in the health of marine ecosystems, but the potential threat that sharks pose to humans is a reminder of our vulnerability when entering the ocean. Personal shark deterrents are being marketed as the solution to mitigate the threat that sharks pose. However, the effectiveness claims of many personal deterrents are based on our knowledge of shark sensory biology rather than robust testing of the devices themselves, as most have not been subjected to independent scientific studies. Therefore, there is a clear need for thorough testing of commercially available shark deterrents to provide the public with recommendations of their effectiveness. Using a modified stereo-camera system, we quantified behavioural interactions between white sharks (Carcharodon carcharias and a baited target in the presence of a commercially available, personal electric shark deterrent (Shark Shield Freedom7™. The stereo-camera system enabled an accurate assessment of the behavioural responses of C. carcharias when encountering a non-lethal electric field many times stronger than what they would naturally experience. Upon their first observed encounter, all C. carcharias were repelled at a mean (± std. error proximity of 131 (± 10.3 cm, which corresponded to a mean voltage gradient of 9.7 (± 0.9 V/m. With each subsequent encounter, their proximity decreased by an average of 11.6 cm, which corresponded to an increase in tolerance to the electric field by an average of 2.6 (± 0.5 V/m per encounter. Despite the increase in tolerance, sharks continued to be deterred from interacting for the duration of each trial when in the presence of an active Shark Shield™. Furthermore, the findings provide no support to the theory that electric deterrents attract sharks. The results of this study provide quantitative evidence of the effectiveness of a non-lethal electric shark deterrent, its influence on the behaviour of C. carcharias, and an accurate

Allometric relationships of the dentition of the great White Shark, Carcharodon carcharias, in forensic investigations of shark attacks.

Science.gov (United States)

Nambiar, P; Bridges, T E; Brown, K A

1991-06-01

As a result of a systematic morphometric study of shark dentitions, a system of notation for describing the location of shark teeth has been developed and is proposed as a standard to be adopted for use in similar studies in the future. The macroscopic morphology of White Shark teeth has been characterised in order to gain quantitative data which might assist in identification of these sharks from bite marks on victims or objects or from shark carcasses. Using these data, a nomogram has been developed which can be used to estimate the body length of a White Shark from measurements of tooth or bite mark morphology. An example of the forensic application of such allometric data is provided as it applied to a recent fatal attack on a diver by a White Shark.

Killer Whale (Orcinus orca) Predation on Beaked Whales (Mesoplodon spp.) in the Bremer Sub-Basin, Western Australia.

Science.gov (United States)

Wellard, Rebecca; Lightbody, Keith; Fouda, Leila; Blewitt, Michelle; Riggs, David; Erbe, Christine

2016-01-01

Observations of killer whales (Orcinus orca) feeding on the remains of beaked whales have been previously documented; however, to date, there has been no published account of killer whales actively preying upon beaked whales. This article describes the first field observations of killer whales interacting with, hunting and preying upon beaked whales (Mesoplodon spp.) on four separate occasions during 2014, 2015 and 2016 in the Bremer Sub-Basin, off the south coast of Western Australia.

The Ecological Role of Sharks on Coral Reefs.

Science.gov (United States)

Roff, George; Doropoulos, Christopher; Rogers, Alice; Bozec, Yves-Marie; Krueck, Nils C; Aurellado, Eleanor; Priest, Mark; Birrell, Chico; Mumby, Peter J

2016-05-01

Sharks are considered the apex predator of coral reefs, but the consequences of their global depletion are uncertain. Here we explore the ecological roles of sharks on coral reefs and, conversely, the importance of reefs for sharks. We find that most reef-associated shark species do not act as apex predators but instead function as mesopredators along with a diverse group of reef fish. While sharks perform important direct and indirect ecological roles, the evidence to support hypothesised shark-driven trophic cascades that benefit corals is weak and equivocal. Coral reefs provide some functional benefits to sharks, but sharks do not appear to favour healthier reef environments. Restoring populations of sharks is important and can yet deliver ecological surprise. Copyright © 2016 Elsevier Ltd. All rights reserved.

How Close is too Close? The Effect of a Non-Lethal Electric Shark Deterrent on White Shark Behaviour

OpenAIRE

Kempster, Ryan M.; Egeberg, Channing A.; Hart, Nathan S.; Ryan, Laura; Chapuis, Lucille; Kerr, Caroline C.; Schmidt, Carl; Huveneers, Charlie; Gennari, Enrico; Yopak, Kara E.; Meeuwig, Jessica J.; Collin, Shaun P.

2016-01-01

Sharks play a vital role in the health of marine ecosystems, but the potential threat that sharks pose to humans is a reminder of our vulnerability when entering the ocean. Personal shark deterrents are being marketed as the solution to mitigate the threat that sharks pose. However, the effectiveness claims of many personal deterrents are based on our knowledge of shark sensory biology rather than robust testing of the devices themselves, as most have not been subjected to independent scienti...

Cyanobacterial Neurotoxin BMAA and Mercury in Sharks

Directory of Open Access Journals (Sweden)

Neil Hammerschlag

2016-08-01

Full Text Available Sharks have greater risk for bioaccumulation of marine toxins and mercury (Hg, because they are long-lived predators. Shark fins and cartilage also contain β-N-methylamino-l-alanine (BMAA, a ubiquitous cyanobacterial toxin linked to neurodegenerative diseases. Today, a significant number of shark species have found their way onto the International Union for Conservation of Nature (IUCN Red List of Threatened Species. Many species of large sharks are threatened with extinction due in part to the growing high demand for shark fin soup and, to a lesser extent, for shark meat and cartilage products. Recent studies suggest that the consumption of shark parts may be a route to human exposure of marine toxins. Here, we investigated BMAA and Hg concentrations in fins and muscles sampled in ten species of sharks from the South Atlantic and Pacific Oceans. BMAA was detected in all shark species with only seven of the 55 samples analyzed testing below the limit of detection of the assay. Hg concentrations measured in fins and muscle samples from the 10 species ranged from 0.05 to 13.23 ng/mg. These analytical test results suggest restricting human consumption of shark meat and fins due to the high frequency and co-occurrence of two synergistic environmental neurotoxic compounds.

Cyanobacterial Neurotoxin BMAA and Mercury in Sharks.

Science.gov (United States)

Hammerschlag, Neil; Davis, David A; Mondo, Kiyo; Seely, Matthew S; Murch, Susan J; Glover, William Broc; Divoll, Timothy; Evers, David C; Mash, Deborah C

2016-08-16

Sharks have greater risk for bioaccumulation of marine toxins and mercury (Hg), because they are long-lived predators. Shark fins and cartilage also contain β-N-methylamino-l-alanine (BMAA), a ubiquitous cyanobacterial toxin linked to neurodegenerative diseases. Today, a significant number of shark species have found their way onto the International Union for Conservation of Nature (IUCN) Red List of Threatened Species. Many species of large sharks are threatened with extinction due in part to the growing high demand for shark fin soup and, to a lesser extent, for shark meat and cartilage products. Recent studies suggest that the consumption of shark parts may be a route to human exposure of marine toxins. Here, we investigated BMAA and Hg concentrations in fins and muscles sampled in ten species of sharks from the South Atlantic and Pacific Oceans. BMAA was detected in all shark species with only seven of the 55 samples analyzed testing below the limit of detection of the assay. Hg concentrations measured in fins and muscle samples from the 10 species ranged from 0.05 to 13.23 ng/mg. These analytical test results suggest restricting human consumption of shark meat and fins due to the high frequency and co-occurrence of two synergistic environmental neurotoxic compounds.

Allometric relationships of the dentition of the great White Shark, Carcharodon carcharias, in forensic investigations of shark attacks

OpenAIRE

Nambiar, P.; Bridges, T. E.; Brown, K. A.

2017-01-01

As a result of a systematic morphometric study of shark dentitions, a system of notation for describing the location of shark teeth has been developed and is proposed as a standard to be adopted for use in similar studies in the future. The macroscopic morphology of White Shark teeth has been characterised in order to gain quantitative data which might assist in identification of these sharks from bite marks on victims or objects or from shark carcasses. Using these data, a nomogram has been ...

77 FR 21540 - Whaling Provisions; Aboriginal Subsistence Whaling Quotas

Science.gov (United States)

2012-04-10

... 230.4(c), forbid the taking of calves or any whale accompanied by a calf. NOAA regulations (at 50 CFR... which are summarized here: Only licensed whaling captains or crew under the control of those captains... crew, supplies, and equipment to engage in an efficient operation. Crew may not receive money for...

War of the Whales

DEFF Research Database (Denmark)

Blok, Anders

2011-01-01

This article examines some of the difficulties of universalistic science in situations of deep conflict over global nature, using empirical material pertaining to ongoing controversies in the context of Japanese whaling practices. Within global-scale whaling assemblages since the 1970s, science has...... become a ‘‘post-sovereign’’ authority, unable to impose any stable definition of nature on all actors. Instead, across spaces of deep antagonistic differences, anti- and pro-whalers now ontologically enact a multiplicity of mutually irreconcilable versions of whales. Empirically, the article attempts...... to map out a ‘‘cosmogram’’ of Japanese pro-whaling enactments of abundant and ‘‘killable’’ whales. Following the political ecology of Bruno Latour, the global-scale situation is conceptualized as one of cosmopolitics, the politics of forging a common world across divergences in nature-cultures....

76 FR 16388 - Whaling Provisions; Aboriginal Subsistence Whaling Quotas

Science.gov (United States)

2011-03-23

... well as the NOAA regulation at 50 CFR 230.4(c), forbid the taking of calves or any whale accompanied by... captains or crew under the control of those captains may engage in whaling. They must follow the provisions... aboriginal hunters must have adequate crew, supplies, and equipment. They may not receive money for...

75 FR 10223 - Whaling Provisions; Aboriginal Subsistence Whaling Quotas

Science.gov (United States)

2010-03-05

... well as the NOAA regulation at 50 CFR 230.4(c), forbid the taking of calves or any whale accompanied by... captains or crew under the control of those captains may engage in whaling. They must follow the provisions... aboriginal hunters must have adequate crew, supplies, and equipment. They may not receive money for...

Tread-water feeding of Bryde's whales.

Science.gov (United States)

Iwata, Takashi; Akamatsu, Tomonari; Thongsukdee, Surasak; Cherdsukjai, Phaothep; Adulyanukosol, Kanjana; Sato, Katsufumi

2017-11-06

Many previous studies have shown that rorqual whales (Balaenopteridae), including the blue whale (Balaenoptera musculus), fin whale (B. physalus), sei whale (B. borealis), Bryde's whale (B. edeni), minke whale (B. acutorostrata), and humpback whale (Megaptera novaeangliae), employ a strategy called lunge feeding to capture a large amount of krill and/or fish for nourishment [1]. Lunge feeding entails a high energetic cost due to the drag created by an open mouth at high speeds [1,2]. In the upper Gulf of Thailand, Bryde's whales, which feed on small fish species [3], predominantly anchovies, demonstrated a range of feeding behaviors such as oblique, vertical, and lateral lunging. Moreover, they displayed a novel head-lifting feeding behavior characterized by holding the vertical posture for several seconds with an open mouth at the water surface. This study describes the head-lifting feeding by Bryde's whales, which is distinct from the typical lunge feeding of rorqual whales. Whales showing this behavior were observed on 58 occasions, involving 31 whales and including eight adult-calf pairs. Whales caught their prey using a series of coordinated movements: (i) lifting the head above the water with a closed mouth, (ii) opening the mouth until the lower jaw contacted the sea surface, which created a current of water flowing into the mouth, (iii) holding their position for several seconds, (iv) waiting for the prey to enter the mouth, and (v) closing the mouth and engulfing the prey underwater (Figure 1A-F, Movie S1 in Supplemental Information published with this article online). When a whale kept its upper jaw above the sea surface, many anchovies in the targeted shoal appeared to lose orientation and flowed passively into the mouth of the whale by the current created by the lower mandible breaking the surface of the water. We measured the duration of feeding events when the whales had a wide-open mouth mostly above the sea surface. The mean and maximum feeding

78 FR 13028 - Whaling Provisions; Aboriginal Subsistence Whaling Quotas

Science.gov (United States)

2013-02-26

... The IWC regulations, as well as the NOAA regulation at 50 CFR 230.4(c), forbid the taking of calves or... whaling captains or crew under the control of those captains may engage in whaling. Captains and crew must... operation. Crew may not receive money for participating in the hunt. No person may sell or offer for sale...

Rafinesque's Sicilian whale, Balena gastrytis

Science.gov (United States)

Woodman, Neal; Mead, James G.

2017-01-01

In 1815, the naturalist Constantine S. Rafinesque described a new species of cetacean, Balena gastrytis, from Sicily, based on a whale that stranded on Carini beach near Palermo. In comparing the characteristics of his new whale with known species, Rafinesque also took the opportunity to name a new genus, Cetoptera, to replace Balaenoptera Lacépède, 1804. Unfortunately, few of Rafinesque's contemporaries saw his article, which appeared in Il Portafoglio, a local journal that he published and distributed. The journal remains rare, and awareness of the whale remains minimal, despite its relevance to cetacean taxonomy and understanding of whale diversity and distribution in the Mediterranean. We describe the circumstances of the stranding of the Sicilian whale and provide Rafinesque's original description of the whale, as well as an evaluation of its reported characteristics and its current identity.

Fatal tiger shark, Galeocerdo cuvier attack in New Caledonia erroneously ascribed to great white shark, Carcharodon carcharias

OpenAIRE

Tirard, P.; Maillaud, C.; Borsa, Philippe

2015-01-01

International audience; To understand the causes and patterns of shark attacks on humans, accurate identification of the shark species involved is necessary. Often, the only reliable evidence for this comes from the characteristics of the wounds exhibited by the victim. The present case report is intended as a reappraisal of the Luengoni, 2007 case (International Shark Attack File no. 4299) where a single shark bite provoked the death of a swimmer by haemorrhagic shock. Our examination of the...

Abundancia, tamaño y estructura poblacional del tiburón punta blanca de arrecife, Triaenodon obesus (Carcharhiniformes: Carcharhinidae, en Bahía Chatham, Parque Nacional Isla del Coco, Costa Rica Abundance, size and population structure of whitetip reef sharks, Triaenodon obesus (Carcharhiniformes: Carcharhinidae, in Bahía Chatham, Parque Nacional Isla del Coco, Costa Rica

Directory of Open Access Journals (Sweden)

Ilena Zanella

2012-11-01

Full Text Available Doce especies de tiburones habitan las aguas del Parque Nacional Isla del Coco (PNIC y uno de los más abundantes es el tiburón punta blanca de arrecife, Triaenodon obesus. El presente estudio determinó la abundancia, tallas y estructura de la población de esta especie en la zona de Bahía Chatham, PNIC. Se utilizó el método de marcaje y recaptura y se realizaron conteos subacuáticos visuales, con el fin de determinar su abundancia relativa y contabilizar recapturas visuales. Los tiburones punta blanca de Bahía Chatham no presentan segregación ontogénica espacial definida; pero si una alta fidelidad a los a sitios de residencia dentro de esta bahía. La longitud total promedio de los tiburones marcados fue de 101.8±12.1cm, con una longitud total máxima de 130.0cm y una mínima de 71.0cm. La mediana de las longitudes totales de los tiburones machos (103.5±21.33cm y hembras (100.1±11.2cm no difirieron significativamente (H = 1.78; p=0.1818. La abundancia relativa en Bahía Chatham, PNIC fue de 49.5±10.4 tiburones/h. El tamaño estimado de la población usando el método de de captura-recaptura fue de 408 (IC=181-1050.Approximately 12 species of shark inhabit at Coco Island National Park (PNIC; some are migratory, such as the hammerhead shark (Sphyrna lewini and whale shark (Rincodon typus, and others are resident, like the whitetip shark (Triaenodon obesus. The whitetip shark is a species related to coral reefs, it inhabits coastal environments and is nocturnal and, it is very common in tropical waters, but there are few studies worldwide. In fact, only short researches have been done about their behavior at PNIC. Therefore, this study aimed to give data about the abundance, size and population structure of the whitetip shark at Chatham Bay in Coco Island National Park, providing baseline information for monitoring its population which is also very vulnerable to climate change. In order to accomplish this aim, a mark-recapture method

Swimming strategy and body plan of the world’s largest fish: implications for foraging efficiency and thermoregulation

Directory of Open Access Journals (Sweden)

Mark eMeekan

2015-09-01

Full Text Available The largest animals in the oceans eat prey that are orders of magnitude smaller than themselves, implying strong selection for cost-effective foraging to meet their energy demands. Whale sharks (Rhincodon typus may be especially challenged by warm seas that elevate their metabolism and contain sparse prey resources. Using a combination of biologging and satellite tagging, we show that whale sharks use four strategies to save energy and improve foraging efficiency: 1 fixed, low power swimming, 2 constant low speed swimming, 3 gliding and 4 asymmetrical diving. These strategies increase foraging efficiency by 22 – 32% relative to swimming horizontally and resolve the energy-budget paradox of whale sharks. However, sharks in the open ocean must access food resources that reside in relatively cold waters (up to 20oC cooler than the surface at depths of 250-500 m during the daytime, where long, slow gliding descents, continuous ram ventilation of the gills and filter-feeding could rapidly cool the circulating blood and body tissues. We suggest that whale sharks may overcome this problem through their large size and a specialized body plan that isolates highly vascularized red muscle on the dorsal surface, allowing heat to be retained near the centre of the body within a massive core of white muscle. This could allow a warm-adapted species to maintain enhanced function of organs and sensory systems while exploiting food resources in deep, cool water.

Calcitonin produces hypercalcemia in leopard sharks.

Science.gov (United States)

Glowacki, J; O'Sullivan, J; Miller, M; Wilkie, D W; Deftos, L J

1985-02-01

Calcitonin was detected by RIA in sera from four marine species, leopard sharks (Triakis semifasciata), horn sharks (Heterodontus francisci), thornback rays (Platyrhinoides triseriata), and kelp bass (Paralabrax clathratus). These animals have levels of calcitonin and calcium higher than freshwater and terrestrial species have. The administration of salmon calcitonin to bass (4 micrograms/kg BW) produced hypocalcemia and hypophosphatemia as has been reported for other bony vertebrates. In marked contrast, calcitonin produced a prompt hypercalcemia in sharks; the average was 9.8% increase in serum calcium in nine animals with no attendant change in phosphorus. These findings demonstrate that calcitonin can increase serum calcium in sharks. Because shark skeleton is composed of cartilage, this hypercalcemic effect of calcitonin does not require a bony skeleton.

Shark hunting - An indiscriminate trade endangering elasmobranchs to extinction

Digital Repository Service at National Institute of Oceanography (India)

Verlecar, X.N.; Snigdha; Desai, S.R.; Dhargalkar, V.K.

- head/round headed shark (Sphyrna zygaena), grey dog shark (R. acutus), sharp-nosed/yellow dog shark (S. lati- caudus) and black-finned/blacktip shark (C. melanop- terus). Most of the shark fin exports have been directed to Hong Kong and Singapore...

Chemotaxis of nurse shark leukocytes.

Science.gov (United States)

Obenauf, S D; Smith, S H

1985-01-01

Studies were conducted to determine the ability of leukocytes from the nurse shark to migrate in an in vitro micropore filter chemotaxis assay and to determine optimal assay conditions and suitable attractants for such an assay. A migratory response was seen with several attractants: activated rat serum, activated shark plasma, and a pool of shark complement components. Only the response to activated rat serum was chemotactic, as determined by the checkerboard assay.

Looking for North Atlantic Baleen Whales: When are they coming to the Azores?

Directory of Open Access Journals (Sweden)

Laura González

2014-06-01

Full Text Available The archipelago of the Azores is like an oasis in the middle of the Atlantic Ocean. Surrounded by deep waters, those islands are a “must stop” place for every traveler, including, of course, cetaceans. Around the archipelago more than 24 different species of whales and dolphins can be seen. Some of them are resident such as the common dolphin or the emblematic sperm whale. But others are seasonal or sporadic, such as the spotted dolphin or the big baleen whales. The aim of this study is to assess the temporal distribution of the baleen whales sighted off Azores. We analyzed data gathered off the south coast of São Miguel (Azores from 2006 to 2013 from whale watching vessels. The whale watching company is located in Ponta Delgada and it works all throughout the year, always when the weather, the sea state and the number of tourists allow doing it. In Azores, whale watching companies use to locate cetaceans from land, with specialized lookouts spotting the animals from strategic points on the shore (as whalers did. These lookouts use powerful binoculars to locate the animals, and then give instructions to the boats to get to them. Once there, the boat registers date, hour, sea state, visibility, position (GPS, species, number of individuals, number of adults, juveniles and calves, behavior, association with other species and if there are other boats in the area. Photos are taken whenever it is possible and they are analyzed when the quality is good enough to distinguish natural marks and shapes. Most of the photos used in this study were taken in the last 5 years. Photo-Id catalogues were created for blue whales, fin whales and humpback whales. Data collected are more complete and frequent since 2009. In this case we have analyzed a total of 7691 sightings, belonging to 20 different species of cetaceans, 14 Odontoceti and 6 Mysticeti. In the latter group we recorded 491 sightings. The three most sighted Mysticeti species were the three great

Sharks of the order Carcharhiniformes

National Research Council Canada - National Science Library

Compagno, L.J.V

1988-01-01

This book is a general review, taxonomic revision, and phylogenetic analysis of the carcharhinoids, the largest group of living sharks, which comprises almost 60 percent or 200 of known shark species...

Shark Interactions With Directed and Incidental Fisheries in the Northeast Pacific Ocean: Historic and Current Encounters, and Challenges for Shark Conservation.

Science.gov (United States)

King, Jackie; McFarlane, Gordon A; Gertseva, Vladlena; Gasper, Jason; Matson, Sean; Tribuzio, Cindy A

For over 100 years, sharks have been encountered, as either directed catch or incidental catch, in commercial fisheries throughout the Northeast Pacific Ocean. A long-standing directed fishery for North Pacific Spiny Dogfish (Squalus suckleyi) has occurred and dominated shark landings and discards. Other fisheries, mainly for shark livers, have historically targeted species including Bluntnose Sixgill Shark (Hexanchus griseus) and Tope Shark (Galeorhinus galeus). While incidental catches of numerous species have occurred historically, only recently have these encounters been reliably enumerated in commercial and recreational fisheries. In this chapter we present shark catch statistics (directed and incidental) for commercial and recreational fisheries from Canadian waters (off British Columbia), southern US waters (off California, Oregon, and Washington), and northern US waters (off Alaska). In total, 17 species of sharks have collectively been encountered in these waters. Fishery encounters present conservation challenges for shark management, namely, the need for accurate catch statistics, stock delineation, life history parameter estimates, and improved assessments methods for population status and trends. Improvements in management and conservation of shark populations will only come with the further development of sound science-based fishery management practices for both targeted and incidental shark fisheries. © 2017 Elsevier Ltd All rights reserved.

Two intense decades of 19th century whaling precipitated rapid decline of right whales around New Zealand and East Australia.

Directory of Open Access Journals (Sweden)

Emma L Carroll

Full Text Available Right whales (Eubalaena spp. were the focus of worldwide whaling activities from the 16th to the 20th century. During the first part of the 19th century, the southern right whale (E. australis was heavily exploited on whaling grounds around New Zealand (NZ and east Australia (EA. Here we build upon previous estimates of the total catch of NZ and EA right whales by improving and combining estimates from four different fisheries. Two fisheries have previously been considered: shore-based whaling in bays and ship-based whaling offshore. These were both improved by comparison with primary sources and the American offshore whaling catch record was improved by using a sample of logbooks to produce a more accurate catch record in terms of location and species composition. Two fisheries had not been previously integrated into the NZ and EA catch series: ship-based whaling in bays and whaling in the 20th century. To investigate the previously unaddressed problem of offshore whalers operating in bays, we identified a subset of vessels likely to be operating in bays and read available extant logbooks. This allowed us to estimate the total likely catch from bay-whaling by offshore whalers from the number of vessels seasons and whales killed per season: it ranged from 2,989 to 4,652 whales. The revised total estimate of 53,000 to 58,000 southern right whales killed is a considerable increase on the previous estimate of 26,000, partly because it applies fishery-specific estimates of struck and loss rates. Over 80% of kills were taken between 1830 and 1849, indicating a brief and intensive fishery that resulted in the commercial extinction of southern right whales in NZ and EA in just two decades. This conforms to the global trend of increasingly intense and destructive southern right whale fisheries over time.

Pelagic shark fisheries of Indonesia's Eastern Indian Ocean ...

African Journals Online (AJOL)

Sharks are commonly caught in Indonesian waters both by target fisheries and as bycatch. Fishers targeting sharks mostly employ drift longlines, whereas tuna longlines and gillnets are the gear mostly responsible for shark bycatch. Our studies on shark fisheries have been conducted since 2006 and have focused on the ...

Seasonal and long-term changes in relative abundance of bull sharks from a tourist shark feeding site in Fiji.

Science.gov (United States)

Brunnschweiler, Juerg M; Baensch, Harald

2011-01-27

Shark tourism has become increasingly popular, but remains controversial because of major concerns originating from the need of tour operators to use bait or chum to reliably attract sharks. We used direct underwater sampling to document changes in bull shark Carcharhinus leucas relative abundance at the Shark Reef Marine Reserve, a shark feeding site in Fiji, and the reproductive cycle of the species in Fijian waters. Between 2003 and 2009, the total number of C. leucas counted on each day ranged from 0 to 40. Whereas the number of C. leucas counted at the feeding site increased over the years, shark numbers decreased over the course of a calendar year with fewest animals counted in November. Externally visible reproductive status information indicates that the species' seasonal departure from the feeding site may be related to reproductive activity.

Japanese Small Type Coastal Whaling

Directory of Open Access Journals (Sweden)

Sue Fisher

2016-07-01

Full Text Available 2016 marks the 70th anniversary of the International Convention for the Regulation of Whaling (ICRW as well as the 30th anniversary of the International Whaling Commission’s (IWC moratorium on commercial whaling. It also marks three decades of effort by Japan to overturn this ban. Its strategy to circumvent the moratorium by issuing permits to kill protected whales for scientific research is famous—even the subject of a 2014 lawsuit at the International Court of Justice. Less well known is Japan’s strategy to overturn the ban by persuading the Commission to authorise a category of commercial whaling known as Small Type Coastal Whaling (STCW that is conducted on minke and other small whales in Japanese waters but has never been regulated, or even formally recognised, by the IWC. For three decades Japan has sought STCW catch limits for four communities which it claims are still suffering distress as a result of the moratorium. While the Commission has rejected each proposal, mainly citing concerns that the commercial nature and purpose of STCW violates the moratorium, Japan has persisted, exhibiting great flexibility in its approach. Its tactics changed significantly in 2014; it no longer denied (or defended the commerciality of the hunt, but argued that it is irrelevant since it sought only a small exemption to the moratorium which would remain intact for all other populations. This is a perspective on Japan’s evolving STCW strategy and the risk that lifting, or modifying, the moratorium would pose to the conservation of whales.

A whale of an opportunity

DEFF Research Database (Denmark)

Laidre, Kristin L.; Heide-Jørgensen, Mads Peter; Logsdon, Miles L.

2010-01-01

Sixty hours of direct measurements of fluorescence were collected from six bowhead whales (Balaena mysticetus) instrumented with fluorometers in Greenland in April 2005 and 2006. The data were used to (1) characterize the three-dimensional spatial pattern of chlorophyll-a (Chl-a) in the water...... column, (2) to examine the relationships between whale foraging areas and productive zones, and (3) to examine the correlation between whale-derived in situ values of Chl-a and those from concurrent satellite images using the NASA MODIS (Moderate Resolution Imaging Spectroradiometer) EOS-AQUA satellite...... (MOD21, SeaWifs analogue OC3M and SST MOD37). Bowhead whales traversed 1600 km2, providing information on diving, Chl-a structure and temperature profiles to depths below 200 m. Feeding dives frequently passed through surface waters (>50 m) and targeted depths close to the bottom, and whales did...

Digestive enzyme activities are higher in the shortfin mako shark, Isurus oxyrinchus, than in ectothermic sharks as a result of visceral endothermy.

Science.gov (United States)

Newton, Kyle C; Wraith, James; Dickson, Kathryn A

2015-08-01

Lamnid sharks are regionally endothermic fishes that maintain visceral temperatures elevated above the ambient water temperature. Visceral endothermy is thought to increase rates of digestion and food processing and allow thermal niche expansion. We tested the hypothesis that, at in vivo temperatures, the endothermic shortfin mako shark, Isurus oxyrinchus, has higher specific activities of three digestive enzymes-gastric pepsin and pancreatic trypsin and lipase-than the thresher shark, Alopias vulpinus, and the blue shark, Prionace glauca, neither of which can maintain elevated visceral temperatures. Homogenized stomach or pancreas tissue obtained from sharks collected by pelagic longline was incubated at both 15 and 25 °C, at saturating substrate concentrations, to quantify tissue enzymatic activity. The mako had significantly higher enzyme activities at 25 °C than did the thresher and blue sharks at 15 °C. This difference was not a simple temperature effect, because at 25 °C the mako had higher trypsin activity than the blue shark and higher activities for all enzymes than the thresher shark. We also hypothesized that the thermal coefficient, or Q 10 value, would be higher for the mako shark than for the thresher and blue sharks because of its more stable visceral temperature. However, the mako and thresher sharks had similar Q 10 values for all enzymes, perhaps because of their closer phylogenetic relationship. The higher in vivo digestive enzyme activities in the mako shark should result in higher rates of food processing and may represent a selective advantage of regional visceral endothermy.

SHARK LONGLINE FISHERY IN TANJUNGLUAR-EAST LOMBOK

Directory of Open Access Journals (Sweden)

Dharmadi Dharmadi

2013-06-01

longline fishing was conducted every month. The trend of shark catches relates to the number of fishing vessels, fishing ground, and weather conditions at sea. The period between July and September is a transitional season from East to West seasons. During this season, the wind strength is weakened and a good fishing season for the fishers. The lowest catch occurs in January (1.06 tonnes and the highest catch in September with the total catch of 24.6 tonnes. Sharks caught by surface longline were dominated by Silky shark, Carcharhinus falciformis (40-90% with the size range of 100-125 cm. The catch of bottom longline was mostly consisting of fish in mature condition that dominated by Grey reef shark (Carcharhinus amblyrhynchos, Common black tip shark (C. limbatus, Spot tail shark (C. sorrah, and Scalloped hammerhead shark (Sphyrna lewini, with the size range of 125-200 cm, 170- 250 cm, 100-150 cm, and 170-300 cm, respectively. Surface longline fishing occurs in the offshore waters in depth more than 200 m to 3000 m, whereas bottom longline fishing is operated at a depth of 50-100 m around islands.

Responses of male sperm whales (Physeter macrocephalus) to killer whale sounds: implications for anti-predator strategies.

Science.gov (United States)

Curé, Charlotte; Antunes, Ricardo; Alves, Ana Catarina; Visser, Fleur; Kvadsheim, Petter H; Miller, Patrick J O

2013-01-01

Interactions between individuals of different cetacean species are often observed in the wild. Killer whales (Orcinus orca) can be potential predators of many other cetaceans, and the interception of their vocalizations by unintended cetacean receivers may trigger anti-predator behavior that could mediate predator-prey interactions. We explored the anti-predator behaviour of five typically-solitary male sperm whales (Physeter macrocephalus) in the Norwegian Sea by playing sounds of mammal-feeding killer whales and monitoring behavioural responses using multi-sensor tags. Our results suggest that, rather than taking advantage of their large aerobic capacities to dive away from the perceived predator, sperm whales responded to killer whale playbacks by interrupting their foraging or resting dives and returning to the surface, changing their vocal production, and initiating a surprising degree of social behaviour in these mostly solitary animals. Thus, the interception of predator vocalizations by male sperm whales disrupted functional behaviours and mediated previously unrecognized anti-predator responses.

Habitat features influence catch rates of near-shore bull shark (Carcharhinus leucas) in the Queensland Shark Control Program, Australia 1996-2012

Science.gov (United States)

Haig, Jodie A.; Lambert, Gwladys I.; Sumpton, Wayne D.; Mayer, David G.; Werry, Jonathan M.

2018-01-01

Understanding shark habitat use is vital for informing better ecological management of coastal areas and shark populations. The Queensland Shark Control Program (QSCP) operates over ∼1800 km of Queensland coastline. Between 1996 and 2012, catch, total length and sex were recorded from most of the 1992 bull shark (Carcharhinus leucas) caught on drum lines and gill-nets as part of the QSCP (sex and length was not successfully recorded for all individuals). Gear was set at multiple sites within ten locations. Analysis of monthly catch data resulted in a zero-inflated dataset for the 17 years of records. Five models were trialled for suitability of standardising the bull shark catch per unit effort (CPUE) using available habitat and environmental data. Three separate models for presence-absence and presence-only were run and outputs combined using a delta-lognormal framework for generalized linear and generalized additive models. The delta-lognormal generalized linear model approach resulted in best fit to explain patterns in CPUE. Greater CPUE occurred on drum lines, and greater numbers of bull sharks were caught on both gear types in summer months, with tropical sites, and sites with greater adjacent wetland habitats catching consistently more bull sharks compared to sub-tropical sites. The CPUE data did not support a hypothesis of population decline indicative of coastal overfishing. However, the total length of sharks declined slightly through time for those caught in the tropics; subtropical catches were dominated by females and a large proportion of all bull sharks caught were smaller than the size-at-maturity reported for this species. These factors suggest that growth and sex overfishing of Queensland bull shark populations may be occurring but are not yet detectable in the available data. The data highlight available coastal wetlands, river size, length of coastline and distance to the 50 m depth contour are important for consideration in future whole of

Sharks in Captivity: The Role of Husbandry, Breeding, Education, and Citizen Science in Shark Conservation.

Science.gov (United States)

Grassmann, Michael; McNeil, Bryan; Wharton, Jim

The role of public aquariums in promoting conservation has changed substantially over the decades, evolving from entertainment attractions to educational and research centres. In many facilities, larger sharks are an essential part of the collection and represent one of the biggest draws for the public. Displaying healthy elasmobranchs comes with many challenges, but improvements in husbandry techniques have enabled aquariums to have success with a variety of species. The establishment of organisations such as the Association of Zoos and Aquariums, and the completion of texts like the Elasmobranch Husbandry Manual, has helped set high standards of care for sharks in captivity and promoted international conservation efforts. Aquariums keeping sharks are in a unique position to influence local, regional, and international attitudes and policies by acting as both educational and research facilities. Interactions with multiple stakeholders of diverse educational and demographic backgrounds through the use of in-house advocacy, public outreach, media interviews, and partnerships with academic and government institutions enable these facilities to engage and share information with a broad audience. Although the data collected on sharks in captivity often cannot be directly translated to animals in the wild, it offers better insight into a number of life history traits and poorly understood behaviours, and has been the foundation for many captive breeding programs. Several Northeast Pacific (NEP) shark species are commonly displayed for long durations or bred in aquariums, while other less studied species have been held for short periods to collect valuable data that can be applied towards ongoing studies and conservation measures. Here, we discuss past and current tangible benefits of holding NEP sharks in captivity, as well as noting several ways in which future research and education activities will continue to inform and shape public opinions on shark management and

Correction: Two intense decades of 19th century whaling precipitated rapid decline of right whales around New Zealand and east Australia.

Directory of Open Access Journals (Sweden)

Emma L Carroll

Full Text Available Right whales (Eubalaena spp. were the focus of worldwide whaling activities from the 16th to the 20th century. During the first part of the 19th century, the southern right whale (E. australis was heavily exploited on whaling grounds around New Zealand (NZ and east Australia (EA. Here we build upon previous estimates of the total catch of NZ and EA right whales by improving and combining estimates from four different fisheries. Two fisheries have previously been considered: shore-based whaling in bays and ship-based whaling offshore. These were both improved by comparison with primary sources and the American offshore whaling catch record was improved by using a sample of logbooks to produce a more accurate catch record in terms of location and species composition. Two fisheries had not been previously integrated into the NZ and EA catch series: ship-based whaling in bays and whaling in the 20th century. To investigate the previously unaddressed problem of offshore whalers operating in bays, we identified a subset of vessels likely to be operating in bays and read available extant logbooks. This allowed us to estimate the total likely catch from bay-whaling by offshore whalers from the number of vessels seasons and whales killed per season: it ranged from 2,989 to 4,652 whales. The revised total estimate of 53,000 to 58,000 southern right whales killed is a considerable increase on the previous estimate of 26,000, partly because it applies fishery-specific estimates of struck and loss rates. Over 80% of kills were taken between 1830 and 1849, indicating a brief and intensive fishery that resulted in the commercial extinction of southern right whales in NZ and EA in just two decades. This conforms to the global trend of increasingly intense and destructive southern right whale fisheries over time.

Tracing the spatio-temporal dynamics of endangered fin whales (Balaenoptera physalus) within baleen whale (Mysticeti) lineages: a mitogenomic perspective.

Science.gov (United States)

Yu, Jihyun; Nam, Bo-Hye; Yoon, Joon; Kim, Eun Bae; Park, Jung Youn; Kim, Heebal; Yoon, Sook Hee

2017-12-01

To explore the spatio-temporal dynamics of endangered fin whales (Balaenoptera physalus) within the baleen whale (Mysticeti) lineages, we analyzed 148 published mitochondrial genome sequences of baleen whales. We used a Bayesian coalescent approach as well as Bayesian inferences and maximum likelihood methods. The results showed that the fin whales had a single maternal origin, and that there is a significant correlation between geographic location and evolution of global fin whales. The most recent common female ancestor of this species lived approximately 9.88 million years ago (Mya). Here, North Pacific fin whales first appeared about 7.48 Mya, followed by a subsequent divergence in Southern Hemisphere approximately 6.63 Mya and North Atlantic about 4.42 Mya. Relatively recently, approximately 1.76 and 1.42 Mya, there were two additional occurrences of North Pacific populations; one originated from the Southern Hemisphere and the other from an uncertain location. The evolutionary rate of this species was 1.002 × 10 -3 substitutions/site/My. Our Bayesian skyline plot illustrates that the fin whale population has the rapid expansion event since ~ 2.5 Mya, during the Quaternary glaciation stage. Additionally, this study indicates that the fin whale has a sister group relationship with humpback whale (Meganoptera novaeangliae) within the baleen whale lineages. Of the 16 genomic regions, NADH5 showed the most powerful signal for baleen whale phylogenetics. Interestingly, fin whales have 16 species-specific amino acid residues in eight mitochondrial genes: NADH2, COX2, COX3, ATPase6, ATPase8, NADH4, NADH5, and Cytb.

Pre-whaling genetic diversity and population ecology in eastern Pacific gray whales: insights from ancient DNA and stable isotopes.

Directory of Open Access Journals (Sweden)

S Elizabeth Alter

Full Text Available Commercial whaling decimated many whale populations, including the eastern Pacific gray whale, but little is known about how population dynamics or ecology differed prior to these removals. Of particular interest is the possibility of a large population decline prior to whaling, as such a decline could explain the ~5-fold difference between genetic estimates of prior abundance and estimates based on historical records. We analyzed genetic (mitochondrial control region and isotopic information from modern and prehistoric gray whales using serial coalescent simulations and Bayesian skyline analyses to test for a pre-whaling decline and to examine prehistoric genetic diversity, population dynamics and ecology. Simulations demonstrate that significant genetic differences observed between ancient and modern samples could be caused by a large, recent population bottleneck, roughly concurrent with commercial whaling. Stable isotopes show minimal differences between modern and ancient gray whale foraging ecology. Using rejection-based Approximate Bayesian Computation, we estimate the size of the population bottleneck at its minimum abundance and the pre-bottleneck abundance. Our results agree with previous genetic studies suggesting the historical size of the eastern gray whale population was roughly three to five times its current size.

Cross matching of blood in carcharhiniform, lamniform, and orectolobiform sharks.

Science.gov (United States)

Hadfield, Catherine A; Haines, Ashley N; Clayton, Leigh A; Whitaker, Brent R

2010-09-01

The transfusion of whole blood in elasmobranchs could provide cardiovascular support following hemorrhage. Since donor and recipient compatibility is not known, a technique was established to allow cross matching of red blood cells and serum in sharks. Cross matching was carried out among 19 individuals from seven species: the nurse shark (Ginglymostoma cirratum), sandbar shark (Carcharhinus plumbeus), sandtiger shark (Carcharias taurus), white-spotted bamboo shark (Chiloscyllium plagiosum), brown-banded bamboo shark (Chiloscyllium punctatum), zebra shark (Stegostoma fasciatum), and spotted wobbegong (Orectolobus maculatus). Negative cross-matches showed no agglutination or hemolysis, suggesting that donor and recipient would be compatible. Cross-matches between conspecifics were all negative (sandbar, sandtiger, nurse, and white-spotted bamboo sharks). All cross-matches between sandbar and sandtiger sharks were also negative. Positive crossmatches consisted of agglutination or hemolysis of red blood cells, suggesting that the donor and recipient would be incompatible. Strong positive reactions occurred, for example, with red blood cells from sandtiger and sandbar sharks and serum from nurse sharks. Cross matching should be carried out in elasmobranchs prior to any blood transfusion.

An integrated approach to historical population assessment of the great whales: case of the New Zealand southern right whale.

Science.gov (United States)

Jackson, Jennifer A; Carroll, Emma L; Smith, Tim D; Zerbini, Alexandre N; Patenaude, Nathalie J; Baker, C Scott

2016-03-01

Accurate estimation of historical abundance provides an essential baseline for judging the recovery of the great whales. This is particularly challenging for whales hunted prior to twentieth century modern whaling, as population-level catch records are often incomplete. Assessments of whale recovery using pre-modern exploitation indices are therefore rare, despite the intensive, global nature of nineteenth century whaling. Right whales (Eubalaena spp.) were particularly exploited: slow swimmers with strong fidelity to sheltered calving bays, the species made predictable and easy targets. Here, we present the first integrated population-level assessment of the whaling impact and pre-exploitation abundance of a right whale, the New Zealand southern right whale (E. australis). In this assessment, we use a Bayesian population dynamics model integrating multiple data sources: nineteenth century catches, genetic constraints on bottleneck size and individual sightings histories informing abundance and trend. Different catch allocation scenarios are explored to account for uncertainty in the population's offshore distribution. From a pre-exploitation abundance of 28 800-47 100 whales, nineteenth century hunting reduced the population to approximately 30-40 mature females between 1914 and 1926. Today, it stands at less than 12% of pre-exploitation abundance. Despite the challenges of reconstructing historical catches and population boundaries, conservation efforts of historically exploited species benefit from targets for ecological restoration.

Dramatic increase in sea otter mortality from white sharks in California

Science.gov (United States)

Tinker, M. Tim; Hatfield, Brian B.; Harris, Michael D.; Ames, Jack A.

2016-01-01

Although southern sea otters (Enhydra lutris nereis) are not considered prey for white sharks (Carcharodon carcharias), sharks do nonetheless bite sea otters. We analyzed spatial and temporal trends in shark bites on sea otters in California, assessing the frequency of shark bite wounds in 1,870 carcasses collected since 1985. The proportion of stranded sea otters having shark bites has increased sharply since 2003, and white shark bites now account for >50% of recovered carcasses. The trend was most pronounced in the southern part of the range, from Estero Bay to Point Conception, where shark bite frequency has increased eightfold. Seasonal trends were also evident: most shark-bitten carcasses are recovered in late summer and fall; however, the period of elevated shark bite frequency has lengthened. The causes of these trends are unclear, but possible contributing factors include increased white shark abundance and/or changes in white shark behavior and distribution. In particular, the spatiotemporal patterns of shark-bitten sea otters match increases in pinniped populations, and the increased availability of marine mammal prey for white sharks may have led to more sharks spending more time in nearshore waters utilized by both sea otters and pinnipeds.

Stable isotope and trace element status of subsistence-hunted bowhead and beluga whales in Alaska and gray whales in Chukotka

Energy Technology Data Exchange (ETDEWEB)

Dehn, Larissa-A. [Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK 99775-7000 (United States)]. E-mail: ftld@uaf.edu; Follmann, Erich H. [Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK 99775-7000 (United States); Rosa, Cheryl [Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK 99775-7000 (United States); Duffy, Lawrence K. [Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK 99775-7000 (United States); Thomas, Dana L. [Department of Mathematical Sciences, University of Alaska Fairbanks, Fairbanks, AK 99775-6660 (United States); Bratton, Gerald R. [Department of Veterinary Anatomy and Public Health, Texas A and M University, College Station, TX 77843 (United States); Taylor, Robert J. [Department of Veterinary Anatomy and Public Health, Texas A and M University, College Station, TX 77843 (United States); O' Hara, Todd M. [Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK 99775-7000 (United States); Department of Wildlife Management, North Slope Borough, Barrow, AK 99725 (United States)

2006-03-15

Tissues of bowhead, beluga, and gray whales were analyzed for Ag, Cd, Cu, Se, Zn, THg and MeHg (belugas only). {delta}{sup 15}N and {delta}{sup 13}C in muscle were used to estimate trophic position and feeding habitat, respectively. Trace element concentrations in tissues were significantly different among whale species. Hepatic Ag was higher in belugas than bowheads and gray whales. Gray whales had lower Cd concentrations in liver and kidney than bowhead and belugas and a sigmoid correlation of Cd with length was noted for all whales. Renal and hepatic Se and THg were higher in belugas than in baleen whales. The hepatic molar ratio of Se:THg exceeded 1:1 in all species and was negatively correlated to body length. Hepatic and renal Zn in subsistence-harvested gray whales was lower than concentrations for stranded whales. Se:THg molar ratios and tissue concentrations of Zn may show promise as potential indicators of immune status and animal health.

Stable isotope and trace element status of subsistence-hunted bowhead and beluga whales in Alaska and gray whales in Chukotka

International Nuclear Information System (INIS)

Dehn, Larissa-A.; Follmann, Erich H.; Rosa, Cheryl; Duffy, Lawrence K.; Thomas, Dana L.; Bratton, Gerald R.; Taylor, Robert J.; O'Hara, Todd M.

2006-01-01

Tissues of bowhead, beluga, and gray whales were analyzed for Ag, Cd, Cu, Se, Zn, THg and MeHg (belugas only). δ 15 N and δ 13 C in muscle were used to estimate trophic position and feeding habitat, respectively. Trace element concentrations in tissues were significantly different among whale species. Hepatic Ag was higher in belugas than bowheads and gray whales. Gray whales had lower Cd concentrations in liver and kidney than bowhead and belugas and a sigmoid correlation of Cd with length was noted for all whales. Renal and hepatic Se and THg were higher in belugas than in baleen whales. The hepatic molar ratio of Se:THg exceeded 1:1 in all species and was negatively correlated to body length. Hepatic and renal Zn in subsistence-harvested gray whales was lower than concentrations for stranded whales. Se:THg molar ratios and tissue concentrations of Zn may show promise as potential indicators of immune status and animal health

The Gray whale: Eschrichtius robustus

National Research Council Canada - National Science Library

Jones, Mary Lou; Leatherwood, Stephen; Swartz, Steven L

1984-01-01

.... Section II documents historical aspects of gray whale exploitation and the economic importance of these whales to humans, beginning with aboriginal societies in Asia and North America, and leading...

On two abnormal sharks from Gujarat

Digital Repository Service at National Institute of Oceanography (India)

Gopalan, U.K.

The description of the two abnormal sharks, Carchariaswalbeehmi and Eulamia dussumieri collected from Gujarat, India, is given Of these C walbeehmi was double-headed The other shark E dussumieri had thumb snouted albino...

Bacteriology of the teeth from a great white shark: potential medical implications for shark bite victims.

Science.gov (United States)

Buck, J D; Spotte, S; Gadbaw, J J

1984-11-01

Bacteria were cultured for the first time from the teeth of a great white shark (Carcharodon carcharias). Isolates included Vibrio alginolyticus, Vibrio fluvialis, Vibrio parahaemolyticus, and other genera. All are common in the marine environment and some may be associated with wound infections in humans. Shark bite lacerations may serve as a source of these potentially infectious bacteria, particularly Vibrio spp., and should be treated immediately. Antibiotic susceptibility patterns are shown for representatives of Vibrio isolates and indicate that a variety of new agents may be appropriate chemotherapy for shark bite victims.

High post-capture survival for sharks, rays and chimaeras discarded in the main shark fishery of Australia?

Science.gov (United States)

Braccini, Matias; Van Rijn, Jay; Frick, Lorenz

2012-01-01

Most sharks, rays and chimaeras (chondrichthyans) taken in commercial fisheries are discarded (i.e. returned to the ocean either dead or alive). Quantifying the post-capture survival (PCS) of discarded species is therefore essential for the improved management and conservation of this group. For all chondrichthyans taken in the main shark fishery of Australia, we quantified the immediate PCS of individuals reaching the deck of commercial shark gillnet fishing vessels and applied a risk-based method to semi-quantitatively determine delayed and total PCS. Estimates of immediate, delayed and total PCS were consistent, being very high for the most commonly discarded species (Port Jackson shark, Australian swellshark, and spikey dogfish) and low for the most important commercial species (gummy and school sharks). Increasing gillnet soak time or water temperature significantly decreased PCS. Chondrichthyans with bottom-dwelling habits had the highest PCS whereas those with pelagic habits had the lowest PCS. The risk-based approach can be easily implemented as a standard practice of on-board observing programs, providing a convenient first-step assessment of the PCS of all species taken in commercial fisheries.

The shark's fin

International Nuclear Information System (INIS)

Listinsky, J.L.; Griffiths, H.J.

1989-01-01

Initial plain film studies of seven patients with facet fracture-dislocations of the cervical spine were examined retrospectively. Rotation of the cross-table lateral film from a standard vetical viewing orientation to a simulated brow-down position allowed easier appreciation of the dislocated pillar in six of the seven patients. The displaced pillar had an appearance similar to that of the dorsal fin of a shark. We conclude that the finding of a shark's fin appearance of an articular pillar in a traumatized patient warrants further radiographic studies. (author). 8 refs.; 3 figs

Preferred conservation policies of shark researchers.

Science.gov (United States)

Shiffman, David S; Hammerschlag, Neil

2016-08-01

There is increasing concern about the conservation status of sharks. However, the presence of numerous different (and potentially mutually exclusive) policies complicates management implementation and public understanding of the process. We distributed an online survey to members of the largest professional shark and ray research societies to assess member knowledge of and attitudes toward different conservation policies. Questions covered society member opinions on conservation and management policies, personal histories of involvement in advocacy and management, and perceptions of the approach of conservation nongovernmental organizations (NGOs) to shark conservation. One hundred and two surveys were completed (overall response rate 21%). Respondents considered themselves knowledgeable about and actively involved in conservation and management policy; a majority believed scientists have a responsibility to advocate for conservation (75%), and majorities have sent formal public comments to policymakers (54%) and included policy suggestions in their papers (53%). They believe sustainable shark fisheries are possible, are currently happening today (in a few places), and should be the goal instead of banning fisheries. Respondents were generally less supportive of newer limit-based (i.e., policies that ban exploitation entirely without a species-specific focus) conservation policy tools, such as shark sanctuaries and bans on the sale of shark fins, than of target-based fisheries management tools (i.e., policies that allow for sustainable harvest of species whose populations can withstand it), such as fishing quotas. Respondents were generally supportive of environmental NGO efforts to conserve sharks but raised concerns about some NGOs that they perceived as using incorrect information and focusing on the wrong problems. Our results show there is an ongoing debate in shark conservation and management circles relative to environmental policy on target-based natural

Reef sharks: recent advances in ecological understanding to inform conservation.

Science.gov (United States)

Osgood, G J; Baum, J K

2015-12-01

Sharks are increasingly being recognized as important members of coral-reef communities, but their overall conservation status remains uncertain. Nine of the 29 reef-shark species are designated as data deficient in the IUCN Red List, and three-fourths of reef sharks had unknown population trends at the time of their assessment. Fortunately, reef-shark research is on the rise. This new body of research demonstrates reef sharks' high site restriction, fidelity and residency on coral reefs, their broad trophic roles connecting reef communities and their high population genetic structure, all information that should be useful for their management and conservation. Importantly, recent studies on the abundance and population trends of the three classic carcharhinid reef sharks (grey reef shark Carcharhinus amblyrhynchos, blacktip reef shark Carcharhinus melanopterus and whitetip reef shark Triaenodon obesus) may contribute to reassessments identifying them as more vulnerable than currently realized. Because over half of the research effort has focused on only these three reef sharks and the nurse shark Ginglymostoma cirratum in only a few locales, there remain large taxonomic and geographic gaps in reef-shark knowledge. As such, a large portion of reef-shark biodiversity remains uncharacterized despite needs for targeted research identified in their red list assessments. A research agenda for the future should integrate abundance, life history, trophic ecology, genetics, habitat use and movement studies, and expand the breadth of such research to understudied species and localities, in order to better understand the conservation requirements of these species and to motivate effective conservation solutions. © 2015 The Fisheries Society of the British Isles.

Biomimetic shark skin: design, fabrication and hydrodynamic function.

Science.gov (United States)

Wen, Li; Weaver, James C; Lauder, George V

2014-05-15

Although the functional properties of shark skin have been of considerable interest to both biologists and engineers because of the complex hydrodynamic effects of surface roughness, no study to date has successfully fabricated a flexible biomimetic shark skin that allows detailed study of hydrodynamic function. We present the first study of the design, fabrication and hydrodynamic testing of a synthetic, flexible, shark skin membrane. A three-dimensional (3D) model of shark skin denticles was constructed using micro-CT imaging of the skin of the shortfin mako (Isurus oxyrinchus). Using 3D printing, thousands of rigid synthetic shark denticles were placed on flexible membranes in a controlled, linear-arrayed pattern. This flexible 3D printed shark skin model was then tested in water using a robotic flapping device that allowed us to either hold the models in a stationary position or move them dynamically at their self-propelled swimming speed. Compared with a smooth control model without denticles, the 3D printed shark skin showed increased swimming speed with reduced energy consumption under certain motion programs. For example, at a heave frequency of 1.5 Hz and an amplitude of ± 1 cm, swimming speed increased by 6.6% and the energy cost-of-transport was reduced by 5.9%. In addition, a leading-edge vortex with greater vorticity than the smooth control was generated by the 3D printed shark skin, which may explain the increased swimming speeds. The ability to fabricate synthetic biomimetic shark skin opens up a wide array of possible manipulations of surface roughness parameters, and the ability to examine the hydrodynamic consequences of diverse skin denticle shapes present in different shark species. © 2014. Published by The Company of Biologists Ltd.

Acoustic Ecology of Minke Whales

National Research Council Canada - National Science Library

Costa, Daniel

1998-01-01

Calls of minke whales, Balaenoptera acutorostrata, off the coast of NE Australia in July of 1997 were recorded utilizing a newly described population, where minke whales maintain long contacts with vessels...

Blue whales respond to anthropogenic noise.

Directory of Open Access Journals (Sweden)

Mariana L Melcón

Full Text Available Anthropogenic noise may significantly impact exposed marine mammals. This work studied the vocalization response of endangered blue whales to anthropogenic noise sources in the mid-frequency range using passive acoustic monitoring in the Southern California Bight. Blue whales were less likely to produce calls when mid-frequency active sonar was present. This reduction was more pronounced when the sonar source was closer to the animal, at higher sound levels. The animals were equally likely to stop calling at any time of day, showing no diel pattern in their sensitivity to sonar. Conversely, the likelihood of whales emitting calls increased when ship sounds were nearby. Whales did not show a differential response to ship noise as a function of the time of the day either. These results demonstrate that anthropogenic noise, even at frequencies well above the blue whales' sound production range, has a strong probability of eliciting changes in vocal behavior. The long-term implications of disruption in call production to blue whale foraging and other behaviors are currently not well understood.

Survey of shark fisheries and preparation of a National Plan of Action (NPOA) for conservation and management of shark resources in Bangladesh

OpenAIRE

2014-01-01

The report presents; terms of reference; work progress; surveys of shark fishers and traders; shark biodiversity survey; and a National Plan of Action (NPOA) for conservation and management of shark resources in Bangladesh.

Unprovoked fatal shark attack in Lifou Island (Loyalty Islands, New Caledonia, South Pacific) by a great white shark, Carcharodon carcharias.

Science.gov (United States)

Clua, Eric; Séret, Bernard

2010-09-01

The case of a fatal, unprovoked shark attack is reported and analyzed. The incident took place on the 30th of September 2007, in the lagoon of Luengoni Bay, Lifou Island (Loyalty Islands, New Caledonia). A young French woman who was snorkeling was severely bitten on the right thigh and died of hemorrhage. An analysis based in particular on the size and color of the shark, the characteristics of the wounds, and the behavior of the shark before and after the bite suggests that the aggressor was a great white shark, Carcharodon carcharias.

Smells Like Home: The Role of Olfactory Cues in the Homing Behavior of Blacktip Sharks, Carcharhinus limbatus.

Science.gov (United States)

Gardiner, Jayne M; Whitney, Nicholas M; Hueter, Robert E

2015-09-01

Animal navigation in the marine environment is believed to be guided by different sensory cues over different spatial scales. Geomagnetic cues are thought to guide long-range navigation, while visual or olfactory cues allow animals to pinpoint precise locations, but the complete behavioral sequence is not yet understood. Terra Ceia Bay is a primary nursery area for blacktip sharks, Carcharhinus limbatus, on southwestern Florida's Gulf of Mexico coast. Young-of-the-year animals show strong fidelity to a specific home range in the northeastern end of the bay and rapidly return when displaced. Older juveniles demonstrate annual philopatry for the first few years, migrating as far south as the Florida Keys each fall, then returning to Terra Ceia Bay each spring. To examine the sensory cues used in homing, we captured neonate (sharks from within their home range, fitted them with acoustic tags, and translocated them to sites 8 km away in adjacent Tampa Bay and released them. Intact animals returned to their home range, within 34 h on average, and remained there. With olfaction blocked, fewer animals returned to their home range and they took longer to do so, 130 h on average. However, they did not remain there but instead moved throughout Terra Ceia Bay and in and out of Tampa Bay. Since sharks from both treatments returned at night in tannic and turbid water, vision is likely not playing a major role in navigation by these animals. The animals in this study also returned on incoming or slack tides, suggesting that sharks, like many other fish, may use selective tidal stream transport to conserve energy and aid navigation during migration. Collectively, these results suggest that while other cues, possibly geomagnetic and/or tidal information, might guide sharks over long distances, olfactory cues are required for recognizing their specific home range. © The Author 2015. Published by Oxford University Press on behalf of the Society for Integrative and Comparative

Humans, Fish, and Whales: How Right Whales Modify Calling Behavior in Response to Shifting Background Noise Conditions.

Science.gov (United States)

Parks, Susan E; Groch, Karina; Flores, Paulo; Sousa-Lima, Renata; Urazghildiiev, Ildar R

2016-01-01

This study investigates the role of behavioral plasticity in the variation of sound production of southern right whales (Eubalaena australis) in response to changes in the ambient background noise conditions. Data were collected from southern right whales in Brazilian waters in October and November 2011. The goal of this study was to quantify differences in right whale vocalizations recorded in low background noise as a control, fish chorus noise, and vessel noise. Variation in call parameters were detected among the three background noise conditions and have implications for future studies of noise effects on whale sound production.

Effects of species, sex, length, and locality on the mercury content of school shark Galeorhinus australis (Macleay) and gummy shark Mustelus antarcticus Guenther from south-eastern Australian waters

Energy Technology Data Exchange (ETDEWEB)

Walker, T.I.

1976-12-01

The mercury levels detected in the muscle tissues of sharks ranged from 0.01 to 2.7 ppM wet weight for school shark Galeorhinus australis (Macleay) and from 0.07 to 3.0 ppM for gummy shark Mustelus antarcticus Guenther. Estimates of the mean mercury levels for the 1971 Victorian landed commercial shark catch were found to be 0.90 ppM for the school shark and 0.37 ppM for the gummy shark. The analyses for total mercury determinations were carried out by five independent laboratories. Preliminary analyses carried out by one indicated that most of the mercury in school sharks and about two-thirds of the mercury in gummy sharks was present as methylmercury. The mercury concentrations varied exponentially with shark length. School sharks had statistically significant higher mercury levels than gummy sharks of the same length and for both the medium-sized and large individuals of each species males had significantly higher levels than females. Levels in male gummy sharks were found to be affected by locality.

Re-creating missing population baselines for Pacific reef sharks.

Science.gov (United States)

Nadon, Marc O; Baum, Julia K; Williams, Ivor D; McPherson, Jana M; Zgliczynski, Brian J; Richards, Benjamin L; Schroeder, Robert E; Brainard, Russell E

2012-06-01

Sharks and other large predators are scarce on most coral reefs, but studies of their historical ecology provide qualitative evidence that predators were once numerous in these ecosystems. Quantifying density of sharks in the absence of humans (baseline) is, however, hindered by a paucity of pertinent time-series data. Recently researchers have used underwater visual surveys, primarily of limited spatial extent or nonstandard design, to infer negative associations between reef shark abundance and human populations. We analyzed data from 1607 towed-diver surveys (>1 ha transects surveyed by observers towed behind a boat) conducted at 46 reefs in the central-western Pacific Ocean, reefs that included some of the world's most pristine coral reefs. Estimates of shark density from towed-diver surveys were substantially lower (sharks observed in towed-diver surveys and human population in models that accounted for the influence of oceanic primary productivity, sea surface temperature, reef area, and reef physical complexity. We used these models to estimate the density of sharks in the absence of humans. Densities of gray reef sharks (Carcharhinus amblyrhynchos), whitetip reef sharks (Triaenodon obesus), and the group "all reef sharks" increased substantially as human population decreased and as primary productivity and minimum sea surface temperature (or reef area, which was highly correlated with temperature) increased. Simulated baseline densities of reef sharks under the absence of humans were 1.1-2.4/ha for the main Hawaiian Islands, 1.2-2.4/ha for inhabited islands of American Samoa, and 0.9-2.1/ha for inhabited islands in the Mariana Archipelago, which suggests that density of reef sharks has declined to 3-10% of baseline levels in these areas. ©2012 Society for Conservation Biology No claim to original US government works.

Fisheries management and conservation of sharks in Indonesia ...

African Journals Online (AJOL)

Indonesian waters have a high diversity of sharks and rays, with at least 118 species belonging to 25 families found throughout the vast archipelago. Indonesia also has the highest shark landings globally and nearly all high-value shark species are overexploited and could be considered threatened. This situation is of ...

High Post-Capture Survival for Sharks, Rays and Chimaeras Discarded in the Main Shark Fishery of Australia?

Science.gov (United States)

Braccini, Matias; Van Rijn, Jay; Frick, Lorenz

2012-01-01

Most sharks, rays and chimaeras (chondrichthyans) taken in commercial fisheries are discarded (i.e. returned to the ocean either dead or alive). Quantifying the post-capture survival (PCS) of discarded species is therefore essential for the improved management and conservation of this group. For all chondrichthyans taken in the main shark fishery of Australia, we quantified the immediate PCS of individuals reaching the deck of commercial shark gillnet fishing vessels and applied a risk-based method to semi-quantitatively determine delayed and total PCS. Estimates of immediate, delayed and total PCS were consistent, being very high for the most commonly discarded species (Port Jackson shark, Australian swellshark, and spikey dogfish) and low for the most important commercial species (gummy and school sharks). Increasing gillnet soak time or water temperature significantly decreased PCS. Chondrichthyans with bottom-dwelling habits had the highest PCS whereas those with pelagic habits had the lowest PCS. The risk-based approach can be easily implemented as a standard practice of on-board observing programs, providing a convenient first-step assessment of the PCS of all species taken in commercial fisheries. PMID:22384270

Epidemiological investigation of tattoo-like skin lesions among bottlenose dolphins in Shark Bay, Australia.

Science.gov (United States)

Powell, Sarah N; Wallen, Megan M; Bansal, Shweta; Mann, Janet

2018-07-15

Bottlenose dolphins are excellent bioindicators of ocean ecosystem health for three reasons: (a) as long-lived apex predators they accumulate biotoxins and contaminants; (b) they are visible, routinely appearing at the water's surface in coastal areas, often coming into close contact with humans; and, (c) they exhibit a range of pathogenic lesions attributable to environmental degradation. In this study, we analyzed tattoo-like skin lesions in a population of Tursiops aduncus studied for 30+years in Shark Bay, Australia, a UNESCO World Heritage Site. We provide important baseline data by documenting epidemiological patterns of tattoo-like skin lesions in a healthy, free-ranging population that builds on the previous data of tattoo skin disease (TSD) derived from free ranging, stranded, and dead dolphins. Individual dolphins were classified as symptomatic with tattoo-like skin disease if at least one photograph showed a lesion similar to TSD. The average age of infection was 26.6months (±34.8months) with the symptomatic period lasting 137±29.8days. Overall prevalence of tattoo-like skin disease in the population was 19.4%. Age, but not sex, was significant, with yearlings (1-2years) exhibiting tattoo-like lesions more than younger and older calves. Tattoo-like lesions were rare among juvenile and adult dolphins (N=68 calves, 4 juveniles, and 3 adults). We hypothesize that the lower prevalence in youngest calves (2years) have infection-acquired immunity, as reported for other small cetaceans. The low prevalence of tattoo-like lesions in Shark Bay compared to other populations with poxvirus is consistent with reproductive and demographic viability analyses. Furthermore, by documenting the demography of the disease, we can monitor changes in the prevalence of tattoo-like lesions as a sentinel indicator of ecosystem health. Copyright © 2018 Elsevier B.V. All rights reserved.

Morphometry, gross morphology and available histopathology in North Atlantic right whale (Eubalaena glacialis) mortalities (1970 to 2002)

Science.gov (United States)

Moore, M.J.; Knowlton, A.R.; Kraus, S.D.; McLellan, W.A.; Bonde, R.K.

2005-01-01

Fifty-four right whale mortalities have been reported from between Florida, USA and the Canadian Maritimes from 1970 to 2002. Thirty of those animals were examined: 18 adults and juveniles, and 12 calves. Morphometric data are presented such that prediction of body weight is possible if the age, or one or more measurements are known. Calves grew approximately linearly in their first year. Total length and fluke width increased asymptotically to a plateau with age, weight increased linearly with age, weight and snout to blowhole distance increased exponentially with total length, whereas total length was linearly related to fluke width and flipper length. Among the adults and juveniles examined in this study, human interaction appeared to be a major cause of mortality, where in 14/18 necropsies, trauma was a significant finding. In 10/14 of these, the cause of the trauma was presumed to be vessel collision. Entanglement in fishing gear accounted for the remaining four cases. Trauma was also present in 4/12 calves. In the majority of calf mortalities (8/12) the cause of death was not determined. Sharp ship trauma included propeller lacerations inducing multiple, deep lacerations that often incised vital organs including the brain, spinal cord, major airways, vessels and musculature. Blunt ship trauma resulted in major internal bruising and fractures often without any obvious external damage. In at least two cases fatal gear entanglements were extremely protracted: where the entanglements took at least 100 and 163 days respectively to be finally lethal. The sum of these findings show two major needs: (1) that extinction avoidance management strategies focused on reducing trauma to right whales from ship collisions and fishing gear entanglement are highly appropriate and need to be continued and; (2) that as mitigation measures continue to be introduced into shipping and fishing industry practices, there is a strong effort to maximise the diagnostic quality of post

Acoustic Behaviour of Bottlenose Dolphins and Pilot Whales

DEFF Research Database (Denmark)

Jensen, Frants Havmand

2011-01-01

and review for the topics addressed in the subsequent chapters, with discussions of these chapters where appropriate. In this thesis, I have undertaken a series of acoustic studies on two species of toothed whales, the bottlenose dolphin and the short-finned pilot whale. The bottlenose dolphin (Tursiops sp.......) is one of the best known toothed whales due to studies in captivity over the last 50 years. In contrast, the short-finned pilot whale (Globicephala macrorhynchus) is a larger, deep-diving toothed whale that has been studied rather little, in part because their deep-diving ecology regularly takes them out...... their vocal behaviour and sound production to their different ecological niches and habitats. Toothed whales find and capture prey using a sophisticated biosonar system. Little is known about how toothed whales use their biosonar during a complex three-dimensional task of locating and capturing prey...

Thresher sharks use tail-slaps as a hunting strategy.

Science.gov (United States)

Oliver, Simon P; Turner, John R; Gann, Klemens; Silvosa, Medel; D'Urban Jackson, Tim

2013-01-01

The hunting strategies of pelagic thresher sharks (Alopias pelagicus) were investigated at Pescador Island in the Philippines. It has long been suspected that thresher sharks hunt with their scythe-like tails but the kinematics associated with the behaviour in the wild are poorly understood. From 61 observations recorded by handheld underwater video camera between June and October 2010, 25 thresher shark shunting events were analysed. Thresher sharks employed tail-slaps to debilitate sardines at all times of day. Hunting events comprised preparation, strike, wind-down recovery and prey item collection phases, which occurred sequentially. Preparation phases were significantly longer than the others, presumably to enable a shark to windup a tail-slap. Tail-slaps were initiated by an adduction of the pectoral fins, a manoeuvre that changed a thresher shark's pitch promoting its posterior region to lift rapidly, and stall its approach. Tail-slaps occurred with such force that they may have caused dissolved gas to diffuse out of the water column forming bubbles. Thresher sharks were able to consume more than one sardine at a time, suggesting that tail-slapping is an effective foraging strategy for hunting schooling prey. Pelagic thresher sharks appear to pursue sardines opportunistically by day and night, which may make them vulnerable to fisheries. Alopiids possess specialist pectoral and caudal fins that are likely to have evolved, at least in part, for tail-slapping. The evidence is now clear; thresher sharks really do hunt with their tails.

Interacting with wildlife tourism increases activity of white sharks.

Science.gov (United States)

Huveneers, Charlie; Watanabe, Yuuki Y; Payne, Nicholas L; Semmens, Jayson M

2018-01-01

Anthropogenic activities are dramatically changing marine ecosystems. Wildlife tourism is one of the fastest growing sectors of the tourism industry and has the potential to modify the natural environment and behaviour of the species it targets. Here, we used a novel method to assess the effects of wildlife tourism on the activity of white sharks ( Carcharodon carcharias ). High frequency three-axis acceleration loggers were deployed on ten white sharks for a total of ~9 days. A combination of multivariate and univariate analysis revealed that the increased number of strong accelerations and vertical movements when sharks are interacting with cage-diving operators result in an overall dynamic body acceleration (ODBA) ~61% higher compared with other times when sharks are present in the area where cage-diving occurs. Since ODBA is considered a proxy of metabolic rate, interacting with cage-divers is probably more costly than are normal behaviours of white sharks at the Neptune Islands. However, the overall impact of cage-diving might be small if interactions with individual sharks are infrequent. This study suggests wildlife tourism changes the instantaneous activity levels of white sharks, and calls for an understanding of the frequency of shark-tourism interactions to appreciate the net impact of ecotourism on this species' fitness.

Mercury accumulation in sharks from the coastal waters of southwest Florida.

Science.gov (United States)

Rumbold, Darren; Wasno, Robert; Hammerschlag, Neil; Volety, Aswani

2014-10-01

As large long-lived predators, sharks are particularly vulnerable to exposure to methylmercury biomagnified through the marine food web. Accordingly, nonlethal means were used to collect tissues for determining mercury (Hg) concentrations and stable isotopes of carbon (δ(13)C) and nitrogen (δ(15)N) from a total of 69 sharks, comprising 7 species, caught off Southwest Florida from May 2010 through June 2013. Species included blacknose (Carcharhinus acronotus), blacktip (C. limbatus), bull (C. leucas), great hammerhead (Sphyrna mokarran), lemon (Negaprion brevirostris), sharpnose (Rhizoprionodon terraenovae), and tiger sharks (Galeocerdo cuvier). The sharks contained Hg concentrations in their muscle tissues ranging from 0.19 mg/kg (wet-weight basis) in a tiger shark to 4.52 mg/kg in a blacktip shark. Individual differences in total length and δ(13)C explained much of the intraspecific variation in Hg concentrations in blacknose, blacktip, and sharpnose sharks, but similar patterns were not evident for Hg and δ(15)N. Interspecific differences in Hg concentration were evident with greater concentrations in slower-growing, mature blacktip sharks and lower concentrations in faster-growing, young tiger sharks than other species. These results are consistent with previous studies reporting age-dependent growth rate can be an important determinant of intraspecific and interspecific patterns in Hg accumulation. The Hg concentrations observed in these sharks, in particular the blacktip shark, also suggested that Hg may pose a threat to shark health and fitness.

36 CFR 13.1174 - Whale water restrictions.

Science.gov (United States)

2010-07-01

... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Whale water restrictions. 13... Vessel Operating Restrictions § 13.1174 Whale water restrictions. (a) May 15 through September 30, the following waters are designated as whale waters. (1) Waters north of a line drawn from Point Carolus to...

Detection and Classification of Whale Acoustic Signals

Science.gov (United States)

Xian, Yin

This dissertation focuses on two vital challenges in relation to whale acoustic signals: detection and classification. In detection, we evaluated the influence of the uncertain ocean environment on the spectrogram-based detector, and derived the likelihood ratio of the proposed Short Time Fourier Transform detector. Experimental results showed that the proposed detector outperforms detectors based on the spectrogram. The proposed detector is more sensitive to environmental changes because it includes phase information. In classification, our focus is on finding a robust and sparse representation of whale vocalizations. Because whale vocalizations can be modeled as polynomial phase signals, we can represent the whale calls by their polynomial phase coefficients. In this dissertation, we used the Weyl transform to capture chirp rate information, and used a two dimensional feature set to represent whale vocalizations globally. Experimental results showed that our Weyl feature set outperforms chirplet coefficients and MFCC (Mel Frequency Cepstral Coefficients) when applied to our collected data. Since whale vocalizations can be represented by polynomial phase coefficients, it is plausible that the signals lie on a manifold parameterized by these coefficients. We also studied the intrinsic structure of high dimensional whale data by exploiting its geometry. Experimental results showed that nonlinear mappings such as Laplacian Eigenmap and ISOMAP outperform linear mappings such as PCA and MDS, suggesting that the whale acoustic data is nonlinear. We also explored deep learning algorithms on whale acoustic data. We built each layer as convolutions with either a PCA filter bank (PCANet) or a DCT filter bank (DCTNet). With the DCT filter bank, each layer has different a time-frequency scale representation, and from this, one can extract different physical information. Experimental results showed that our PCANet and DCTNet achieve high classification rate on the whale

A global perspective on the trophic geography of sharks

DEFF Research Database (Denmark)

Bird, Christopher S.; Verissimo, Ana; Magozzi, Sarah

2018-01-01

Sharks are a diverse group of mobile predators that forage across varied spatial scales and have the potential to influence food web dynamics. The ecological consequences of recent declines in shark biomass may extend across broader geographic ranges if shark taxa display common behavioural trait...

Possible link between Hg and Cd accumulation in the brain of long-finned pilot whales (Globicephala melas)

Energy Technology Data Exchange (ETDEWEB)

Gajdosechova, Zuzana [Trace Element Speciation Laboratory, Department of Chemistry, Meston Walk, University of Aberdeen, Aberdeen AB24 3UE (United Kingdom); Brownlow, Andrew [SAC Wildlife Unit, Inverness (United Kingdom); Cottin, Nicolas T.; Fernandes, Mariana [Trace Element Speciation Laboratory, Department of Chemistry, Meston Walk, University of Aberdeen, Aberdeen AB24 3UE (United Kingdom); Read, Fiona L. [Oceanlab, University of Aberdeen, Main Street, Newburgh AB41 6AA (United Kingdom); Urgast, Dagmar S.; Raab, Andrea; Feldmann, Jörg; Krupp, Eva M. [Trace Element Speciation Laboratory, Department of Chemistry, Meston Walk, University of Aberdeen, Aberdeen AB24 3UE (United Kingdom)

2016-03-01

The bioaccumulation of metals was investigated by analysis of liver, kidney, muscle and brain tissue of a pod of 21 long-finned pilot whales (Globicephala melas) of all ages stranded in Scotland, UK. The results are the first to report cadmium (Cd) passage through the blood–brain barrier of pilot whales and provide a comprehensive study of the long-term (up to 35 years) mammalian exposure to the environmental pollutants. Additionally, linear accumulation of mercury (Hg) was observed in all studied tissues, whereas for Cd this was only observed in the liver. Total Hg concentration above the upper neurochemical threshold was found in the sub-adult and adult brains and methylmercury (MeHg) of 2.2 mg/kg was found in the brain of one individual. Inter-elemental analysis showed significant positive correlations of Hg with selenium (Se) and Cd with Se in all studied tissues. Furthermore, differences in the elemental concentrations in the liver and brain tissues were found between juvenile, sub-adult and adult groups. The highest concentrations of manganese, iron, zinc, Se, Hg and MeHg were noted in the livers, whereas Cd predominantly accumulated in the kidneys. High concentrations of Hg and Cd in the tissues of pilot whales presented in this study reflect ever increasing toxic stress on marine mammals. - Highlights: • Trace elements were measured in a pod of 21 pilot whales stranded in Scotland. • Bioaccumulation of mercury and methyl mercury was found in all studied tissues. • Cadmium age related accumulation was observed in the liver and brain tissues. • Cadmium-selenium correlations suggest formation of cadmium-selenium complexes.

Possible link between Hg and Cd accumulation in the brain of long-finned pilot whales (Globicephala melas)

International Nuclear Information System (INIS)

Gajdosechova, Zuzana; Brownlow, Andrew; Cottin, Nicolas T.; Fernandes, Mariana; Read, Fiona L.; Urgast, Dagmar S.; Raab, Andrea; Feldmann, Jörg; Krupp, Eva M.

2016-01-01

The bioaccumulation of metals was investigated by analysis of liver, kidney, muscle and brain tissue of a pod of 21 long-finned pilot whales (Globicephala melas) of all ages stranded in Scotland, UK. The results are the first to report cadmium (Cd) passage through the blood–brain barrier of pilot whales and provide a comprehensive study of the long-term (up to 35 years) mammalian exposure to the environmental pollutants. Additionally, linear accumulation of mercury (Hg) was observed in all studied tissues, whereas for Cd this was only observed in the liver. Total Hg concentration above the upper neurochemical threshold was found in the sub-adult and adult brains and methylmercury (MeHg) of 2.2 mg/kg was found in the brain of one individual. Inter-elemental analysis showed significant positive correlations of Hg with selenium (Se) and Cd with Se in all studied tissues. Furthermore, differences in the elemental concentrations in the liver and brain tissues were found between juvenile, sub-adult and adult groups. The highest concentrations of manganese, iron, zinc, Se, Hg and MeHg were noted in the livers, whereas Cd predominantly accumulated in the kidneys. High concentrations of Hg and Cd in the tissues of pilot whales presented in this study reflect ever increasing toxic stress on marine mammals. - Highlights: • Trace elements were measured in a pod of 21 pilot whales stranded in Scotland. • Bioaccumulation of mercury and methyl mercury was found in all studied tissues. • Cadmium age related accumulation was observed in the liver and brain tissues. • Cadmium-selenium correlations suggest formation of cadmium-selenium complexes.

Shark recreational fisheries: Status, challenges, and research needs.

Science.gov (United States)

Gallagher, Austin J; Hammerschlag, Neil; Danylchuk, Andy J; Cooke, Steven J

2017-05-01

For centuries, the primary manner in which humans have interacted with sharks has been fishing. A combination of their slow-growing nature and high use-values have resulted in population declines for many species around the world, and to date the vast majority of fisheries-related work on sharks has focused on the commercial sector. Shark recreational fishing remains an overlooked area of research despite the fact that these practices are popular globally and could present challenges to their populations. Here we provide a topical overview of shark recreational fisheries, highlighting their history and current status. While recreational fishing can provide conservation benefits under certain circumstances, we focus our discourse on the relatively understudied, potentially detrimental impacts these activities may have on shark physiology, behavior, and fitness. We took this angle given the realized but potentially underestimated significance of recreational fishing for shark conservation management plans and stock assessments, in hopes of creating a dialogue around sustainability. We also present a series of broad and focused research questions and underpin areas of future research need to assist with the development of this emergent area of research.

Preliminary Assessment of Cetacean Incidental Mortality in Artisanal ...

African Journals Online (AJOL)

Three dolphin species and humpback whales were reported accidentally caught in fishing gear meant to catch sharks. Dolphins were mostly reported as to be entangled in gillnets; conversely longlines were only described to incidentally catch humpback whales. Bottlenose and spinner dolphins were respectively 48.10% ...

Transfer of 60Co from midwater squid to sperm whales

International Nuclear Information System (INIS)

Umezu, Takeshi; Minamisako, Yoko; Ebihara, Hiroshi; Watanabe, Hiroshi.

1984-01-01

Sperm whales are notable squid-eaters. They feed mainly on medium to large-sized cephalopods at midwater levels and defecate near the surface. This suggests the existence of an upward transport of 60 Co by sperm whales from the mesopelagic zone (150-1,200m). To elucidate this squid-whale route for this artificial radionuclide, 60 Co content was determined in squid and in predator whales captured by commercial whaling. In the Cephalopoda livers 60 Co levels of 30-500 mBq kg -1 wet were found and in the viscera of Odontoceti (toothed whales) 15-40 mBq kg -1 wet. About 0.3% of 60 Co ingested was estimated to be retained in a 23-year-old male sperm whale. In the livers of Bryde's whales, 60 Co levels of 40-80 mBq kg -1 wet were detected, but not in euphausiids and sardines, their possible prey. The level of Co in sperm whales was nearly the same as in Bryde's whales. Specific radioactivity 60 Co/ 59 Co in mBq μg -1 was several times higher in sperm whale (1.1-1.6) than in cephalopods (0.19-0.77). Eating prey with a high content of 60 Co in the 1960's may have contributed to the present body burden in sperm whales with a long-life span. However, the origin of 60 Co in Bryde's whales is unknown. (author)

Abundance and Distribution of Sperm Whales in the Canary Islands: Can Sperm Whales in the Archipelago Sustain the Current Level of Ship-Strike Mortalities?

Science.gov (United States)

Fais, Andrea; Lewis, Tim P.; Zitterbart, Daniel P.; Álvarez, Omar; Tejedor, Ana; Aguilar Soto, Natacha

2016-01-01

Sperm whales are present in the Canary Islands year-round, suggesting that the archipelago is an important area for this species in the North Atlantic. However, the area experiences one of the highest reported rates of sperm whale ship-strike in the world. Here we investigate if the number of sperm whales found in the archipelago can sustain the current rate of ship-strike mortality. The results of this study may also have implications for offshore areas where concentrations of sperm whales may coincide with high densities of ship traffic, but where ship-strikes may be undocumented. The absolute abundance of sperm whales in an area of 52933 km2, covering the territorial waters of the Canary Islands, was estimated from 2668 km of acoustic line-transect survey using Distance sampling analysis. Data on sperm whale diving and acoustic behaviour, obtained from bio-logging, were used to calculate g(0) = 0.92, this is less than one because of occasional extended periods when whales do not echolocate. This resulted in an absolute abundance estimate of 224 sperm whales (95% log-normal CI 120–418) within the survey area. The recruitment capability of this number of whales, some 2.5 whales per year, is likely to be exceeded by the current ship-strike mortality rate. Furthermore, we found areas of higher whale density within the archipelago, many coincident with those previously described, suggesting that these are important habitats for females and immature animals inhabiting the archipelago. Some of these areas are crossed by active shipping lanes increasing the risk of ship-strikes. Given the philopatry in female sperm whales, replacement of impacted whales might be limited. Therefore, the application of mitigation measures to reduce the ship-strike mortality rate seems essential for the conservation of sperm whales in the Canary Islands. PMID:26999791

Abundance and Distribution of Sperm Whales in the Canary Islands: Can Sperm Whales in the Archipelago Sustain the Current Level of Ship-Strike Mortalities?

Directory of Open Access Journals (Sweden)

Andrea Fais

Full Text Available Sperm whales are present in the Canary Islands year-round, suggesting that the archipelago is an important area for this species in the North Atlantic. However, the area experiences one of the highest reported rates of sperm whale ship-strike in the world. Here we investigate if the number of sperm whales found in the archipelago can sustain the current rate of ship-strike mortality. The results of this study may also have implications for offshore areas where concentrations of sperm whales may coincide with high densities of ship traffic, but where ship-strikes may be undocumented. The absolute abundance of sperm whales in an area of 52933 km2, covering the territorial waters of the Canary Islands, was estimated from 2668 km of acoustic line-transect survey using Distance sampling analysis. Data on sperm whale diving and acoustic behaviour, obtained from bio-logging, were used to calculate g(0 = 0.92, this is less than one because of occasional extended periods when whales do not echolocate. This resulted in an absolute abundance estimate of 224 sperm whales (95% log-normal CI 120-418 within the survey area. The recruitment capability of this number of whales, some 2.5 whales per year, is likely to be exceeded by the current ship-strike mortality rate. Furthermore, we found areas of higher whale density within the archipelago, many coincident with those previously described, suggesting that these are important habitats for females and immature animals inhabiting the archipelago. Some of these areas are crossed by active shipping lanes increasing the risk of ship-strikes. Given the philopatry in female sperm whales, replacement of impacted whales might be limited. Therefore, the application of mitigation measures to reduce the ship-strike mortality rate seems essential for the conservation of sperm whales in the Canary Islands.

Abundance and Distribution of Sperm Whales in the Canary Islands: Can Sperm Whales in the Archipelago Sustain the Current Level of Ship-Strike Mortalities?

Science.gov (United States)

Fais, Andrea; Lewis, Tim P; Zitterbart, Daniel P; Álvarez, Omar; Tejedor, Ana; Aguilar Soto, Natacha

2016-01-01

Sperm whales are present in the Canary Islands year-round, suggesting that the archipelago is an important area for this species in the North Atlantic. However, the area experiences one of the highest reported rates of sperm whale ship-strike in the world. Here we investigate if the number of sperm whales found in the archipelago can sustain the current rate of ship-strike mortality. The results of this study may also have implications for offshore areas where concentrations of sperm whales may coincide with high densities of ship traffic, but where ship-strikes may be undocumented. The absolute abundance of sperm whales in an area of 52933 km2, covering the territorial waters of the Canary Islands, was estimated from 2668 km of acoustic line-transect survey using Distance sampling analysis. Data on sperm whale diving and acoustic behaviour, obtained from bio-logging, were used to calculate g(0) = 0.92, this is less than one because of occasional extended periods when whales do not echolocate. This resulted in an absolute abundance estimate of 224 sperm whales (95% log-normal CI 120-418) within the survey area. The recruitment capability of this number of whales, some 2.5 whales per year, is likely to be exceeded by the current ship-strike mortality rate. Furthermore, we found areas of higher whale density within the archipelago, many coincident with those previously described, suggesting that these are important habitats for females and immature animals inhabiting the archipelago. Some of these areas are crossed by active shipping lanes increasing the risk of ship-strikes. Given the philopatry in female sperm whales, replacement of impacted whales might be limited. Therefore, the application of mitigation measures to reduce the ship-strike mortality rate seems essential for the conservation of sperm whales in the Canary Islands.

Introduction to Northeast Pacific Shark Biology, Research, and Conservation, Part B.

Science.gov (United States)

Larson, Shawn E; Lowry, Dayv

Sharks are iconic, sometimes apex, predators found in every ocean. Because of their ecological role as predators and concern over the stability of their populations, there has been an increasing amount of work focused on shark conservation around the world in recent decades. The populations of sharks that reside in the Northeast Pacific (NEP) Ocean bordering the west coast of the United States reside in one of the most economically and ecologically important oceanic regions in the world. Volume 78 of Advances in Marine Biology (AMB) is a companion to Volume 77, which focused primarily on NEP shark biodiversity, organismal biology, and ecology. Volume 78 highlights fisheries and the conservation implications of fisheries management; shark population modelling and the conservation impacts of these models given that many life history metrics of NEP sharks necessary to accurately run these models are still unknown; the value of captive sharks to the biology, outreach, and conservation of NEP sharks; and the conservation value of citizen science and shark ecotourism. Together these volumes encapsulate the current state of the knowledge for sharks in the NEP and lay the foundation for protecting, managing, and learning from these species in the face evolving natural conditions and societal opinions. © 2017 Elsevier Ltd All rights reserved.

Are baleen whales exposed to the threat of microplastics? A case study of the Mediterranean fin whale (Balaenoptera physalus).

Science.gov (United States)

Fossi, Maria Cristina; Panti, Cristina; Guerranti, Cristiana; Coppola, Daniele; Giannetti, Matteo; Marsili, Letizia; Minutoli, Roberta

2012-11-01

Baleen whales are potentially exposed to micro-litter ingestion as a result of their filter-feeding activity. However, the impacts of microplastics on baleen whales are largely unknown. In this case study of the Mediterranean fin whale (Balaenoptera physalus), we explore the toxicological effects of microplastics on mysticetes. The study included the following three steps: (1) the collection/count of microplastics in the Pelagos Sanctuary (Mediterranean Sea), (2) the detection of phthalates in surface neustonic/planktonic samples, and (3) the detection of phthalates in stranded fin whales. A total of 56% of the surface neustonic/planktonic samples contained microplastic particles. The highest abundance of microplastics (9.63 items/m(3)) was found in the Portofino MPA (Ligurian Sea). High concentrations of phthalates (DEHP and MEHP) were detected in the neustonic/planktonic samples. The concentrations of MEHP found in the blubber of stranded fin whales suggested that phthalates could serve as a tracer of the intake of microplastics. The results of this study represent the first warning of this emerging threat to baleen whales. Copyright © 2012 Elsevier Ltd. All rights reserved.

Recovery of human remains after shark attack.

Science.gov (United States)

Byard, Roger W; James, Ross A; Heath, Karen J

2006-09-01

Two cases of fatal shark attack are reported where the only tissues recovered were fragments of lung. Case 1: An 18-year-old male who was in the sea behind a boat was observed by friends to be taken by a great white shark (Carcharodon carcharias). The shark dragged him under the water and then, with a second shark, dismembered the body. Witnesses noted a large amount of blood and unrecognizable body parts coming to the surface. The only tissues recovered despite an intensive beach and sea search were 2 fragments of lung. Case 2: A 19-year-old male was attacked by a great white shark while diving. A witness saw the shark swim away with the victim's body in its mouth. Again, despite intensive beach and sea searches, the only tissue recovered was a single piece of lung, along with pieces of wetsuit and diving equipment. These cases indicate that the only tissue to escape being consumed or lost in fatal shark attacks, where there is a significant attack with dismemberment and disruption of the integrity of the body, may be lung. The buoyancy of aerated pulmonary tissue ensures that it rises quickly to the surface, where it may be recovered by searchers soon after the attack. Aeration of the lung would be in keeping with death from trauma rather than from drowning and may be a useful marker in unwitnessed deaths to separate ante- from postmortem injury, using only relatively small amounts of tissues. Early organ recovery enhances the identification of human tissues as the extent of morphologic alterations by putrefactive processes and sea scavengers will have been minimized. DNA testing is also possible on such recovered fragments, enabling confirmation of the identity of the victim.

Star-Mapping Tools Enable Tracking of Endangered Animals

Science.gov (United States)

2009-01-01

Software programmer Jason Holmberg of Portland, Oregon, partnered with a Goddard Space Flight Center astrophysicist to develop a method for tracking the elusive whale shark using the unique spot patterns on the fish s skin. Employing a star-mapping algorithm originally designed for the Hubble Space Telescope, Holmberg created the Shepherd Project, a photograph database and pattern-matching system that can identify whale sharks by their spots and match images contributed to the database by photographers from around the world. The system has been adapted for tracking other rare and endangered animals, including polar bears and ocean sunfish.

78 FR 77591 - Drawbridge Operation Regulation; Shark River, NJ

Science.gov (United States)

2013-12-24

... Operation Regulation; Shark River, NJ AGENCY: Coast Guard, DHS. ACTION: Notice of deviation from drawbridge... governs the bascule span of the Route 71 Bridge across Shark River (South Channel), mile 0.8, at Belmar... motor seals and instrumentation on the bridge. The Route 71 Bridge across Shark River (South Channel...

Temporal and spatial patterns of habitat use by juveniles of a small coastal shark (Mustelus lenticulatus in an estuarine nursery.

Directory of Open Access Journals (Sweden)

Malcolm P Francis

Full Text Available Juvenile rig (Mustelus lenticulatus were internally tagged with acoustic transmitters and tracked with acoustic receivers deployed throughout two arms of Porirua Harbour, a small (7 km(2 estuary in New Zealand. Ten rig were tracked for up to four months during summer-autumn to determine their spatial and temporal use of the habitat. The overall goal was to estimate the size of Marine Protected Areas required to protect rig nursery areas from direct human impacts. Rig showed clear site preferences, but those preferences varied among rig and over time. They spent most of their time in large basins and on shallow sand and mud flats around the margins, and avoided deep channels. Habitat range increased during autumn for many of the rig. Only one shark spent time in both harbour arms, indicating that there was little movement between the two. Rig home ranges were 2-7 km(2, suggesting that an effective MPA would need to cover the entire Porirua Harbour. They moved to outer harbour sites following some high river flow rates, and most left the harbour permanently during or soon after a river spike, suggesting that they were avoiding low salinity water. Rig showed strong diel movements during summer, although the diel pattern weakened in autumn. Persistent use of the same day and night sites indicates that diel movements are directed rather than random. Further research is required to determine the sizes of rig home ranges in larger harbours where nursery habitat is more extensive. Marine Protected Areas do not control land-based impacts such as accelerated sedimentation and heavy metal pollution, so integration of marine and terrestrial management tools across a range of government agencies is essential to fully protect nursery areas.

Temporal and spatial patterns of habitat use by juveniles of a small coastal shark (Mustelus lenticulatus) in an estuarine nursery.

Science.gov (United States)

Francis, Malcolm P

2013-01-01

Juvenile rig (Mustelus lenticulatus) were internally tagged with acoustic transmitters and tracked with acoustic receivers deployed throughout two arms of Porirua Harbour, a small (7 km(2)) estuary in New Zealand. Ten rig were tracked for up to four months during summer-autumn to determine their spatial and temporal use of the habitat. The overall goal was to estimate the size of Marine Protected Areas required to protect rig nursery areas from direct human impacts. Rig showed clear site preferences, but those preferences varied among rig and over time. They spent most of their time in large basins and on shallow sand and mud flats around the margins, and avoided deep channels. Habitat range increased during autumn for many of the rig. Only one shark spent time in both harbour arms, indicating that there was little movement between the two. Rig home ranges were 2-7 km(2), suggesting that an effective MPA would need to cover the entire Porirua Harbour. They moved to outer harbour sites following some high river flow rates, and most left the harbour permanently during or soon after a river spike, suggesting that they were avoiding low salinity water. Rig showed strong diel movements during summer, although the diel pattern weakened in autumn. Persistent use of the same day and night sites indicates that diel movements are directed rather than random. Further research is required to determine the sizes of rig home ranges in larger harbours where nursery habitat is more extensive. Marine Protected Areas do not control land-based impacts such as accelerated sedimentation and heavy metal pollution, so integration of marine and terrestrial management tools across a range of government agencies is essential to fully protect nursery areas.

Beaked Whale Habitat Characterization and Prediction

National Research Council Canada - National Science Library

Ward, Jessica A; Mitchell, Glenn H; Farak, Amy M; Keane, Ellen P

2005-01-01

The objective of this study was to characterize known beaked whale habitat and create a predictive beaked whale habitat model of the Gulf of Mexico and east coast of the United States using available...

Australian and U.S. news media portrayal of sharks and their conservation.

Science.gov (United States)

Muter, Bret A; Gore, Meredith L; Gledhill, Katie S; Lamont, Christopher; Huveneers, Charlie

2013-02-01

Investigation of the social framing of human-shark interactions may provide useful strategies for integrating social, biological, and ecological knowledge into national and international policy discussions about shark conservation. One way to investigate social opinion and forces related to sharks and their conservation is through the media's coverage of sharks. We conducted a content analysis of 300 shark-related articles published in 20 major Australian and U.S. newspapers from 2000 to 2010. Shark attacks were the emphasis of over half the articles analyzed, and shark conservation was the primary topic of 11% of articles. Significantly more Australian articles than U.S. articles treated shark attacks (χ(2) = 3.862; Australian 58% vs. U.S. 47%) and shark conservation issues (χ(2) = 6.856; Australian 15% vs. U.S. 11%) as the primary article topic and used politicians as the primary risk messenger (i.e., primary person or authority sourced in the article) (χ(2) = 7.493; Australian 8% vs. U.S. 1%). However, significantly more U.S. articles than Australian articles discussed sharks as entertainment (e.g., subjects in movies, books, and television; χ(2) = 15.130; U.S. 6% vs. Australian 1%) and used scientists as the primary risk messenger (χ(2) = 5.333; U.S. 25% vs. Australian 15%). Despite evidence that many shark species are at risk of extinction, we found that most media coverage emphasized the risks sharks pose to people. To the extent that media reflects social opinion, our results highlight problems for shark conservation. We suggest that conservation professionals purposefully and frequently engage with the media to highlight the rarity of shark attacks, discuss preventative measures water users can take to reduce their vulnerability to shark encounters, and discuss conservation issues related to local and threatened species of sharks. When integrated with biological and ecological data, social-science data may help generate a more comprehensive perspective

A recent shark radiation: molecular phylogeny, biogeography and speciation of wobbegong sharks (family: Orectolobidae).

Science.gov (United States)

Corrigan, Shannon; Beheregaray, Luciano B

2009-07-01

The elasmobranch fish are an ancient, evolutionarily successful, but under-researched vertebrate group, particularly in regard to their recent evolutionary history. Their lineage has survived four mass extinction events and most present day taxa are thought to be derived from Mesozoic forms. Here we present a molecular phylogenetic analysis of the family Orectolobidae that provides evidence for recent events of diversification in this shark group. Species interrelationships in Orectolobidae were reconstructed based on four mitochondrial and nuclear genes. In line with previous morphological work, our results do not support current taxonomic arrangements in Orectolobidae and indicate that a taxonomic revision of the family is warranted. We propose that the onset of diversification of orectolobid sharks is of Miocene age and occurred within the Indo-Australian region. Surprisingly, we also find evidence for a recent ( approximately last 2 million years) and rapid radiation of wobbegong sharks. Allopatric speciation followed by range expansion seems like the general most likely explanation to account for wobbegong relationships and distributions. We suggest that the evolution of this shark group was mostly influenced by two temporal scenarios of diversification. The oldest relates to major geological changes in the Indo-West Pacific associated with the Miocene collision of the Indo-Australian and Eurasian plates. The most recent scenario was influenced by changes in oceanography and the emergence of biogeographic barriers related to Pleistocene glacial cycles in Australian waters.

Water-tunnel studies of heat balance in swimming mako sharks.

Science.gov (United States)

Bernal, D; Sepulveda, C; Graham, J B

2001-12-01

The mako shark (Isurus oxyrinchus) has specialized vascular networks (retia mirabilia) forming counter-current heat exchangers that allow metabolic heat retention in certain regions of the body, including the aerobic, locomotor red muscle and the viscera. Red muscle, white muscle and stomach temperatures were measured in juvenile (5-13.6 kg) makos swimming steadily in a water tunnel and exposed to stepwise square-wave changes in ambient temperature (T(a)) to estimate the rates of heat transfer and to determine their capacity for the activity-independent control of heat balance. The rates of heat gain of red muscle during warming were significantly higher than the rates of heat loss during cooling, and neither the magnitude of the change in T(a) nor the direction of change in T(a) had a significant effect on red muscle latency time. Our findings for mako red muscle are similar to those recorded for tunas and suggest modulation of retial heat-exchange efficiency as the underlying mechanism controlling heat balance. However, the red muscle temperatures measured in swimming makos (0.3-3 degrees C above T(a)) are cooler than those measured previously in larger decked makos. Also, the finding of non-stable stomach temperatures contrasts with the predicted independence from T(a) recorded in telemetry studies of mako and white sharks. Our studies on live makos provide new evidence that, in addition to the unique convergent morphological properties between makos and tunas, there is a strong functional similarity in the mechanisms used to regulate heat transfer.

Night-life of Bryde's whales

DEFF Research Database (Denmark)

Izadi, Sahar; Johnson, Mark; Aguilar de Soto, Natacha

2018-01-01

logging tags on resident Bryde'swhales in a busy gulf to study their daily activity patterns. We found that, while whales were active during daytime making energetic lunges to capture tonnes of plankton, they dedicated much of the night to rest. This suggests that whales may rely on vision to find prey...

Vertebral bomb radiocarbon suggests extreme longevity in white sharks.

Science.gov (United States)

Hamady, Li Ling; Natanson, Lisa J; Skomal, Gregory B; Thorrold, Simon R

2014-01-01

Conservation and management efforts for white sharks (Carcharodon carcharias) remain hampered by a lack of basic demographic information including age and growth rates. Sharks are typically aged by counting growth bands sequentially deposited in their vertebrae, but the assumption of annual deposition of these band pairs requires testing. We compared radiocarbon (Δ(14)C) values in vertebrae from four female and four male white sharks from the northwestern Atlantic Ocean (NWA) with reference chronologies documenting the marine uptake of (14)C produced by atmospheric testing of thermonuclear devices to generate the first radiocarbon age estimates for adult white sharks. Age estimates were up to 40 years old for the largest female (fork length [FL]: 526 cm) and 73 years old for the largest male (FL: 493 cm). Our results dramatically extend the maximum age and longevity of white sharks compared to earlier studies, hint at possible sexual dimorphism in growth rates, and raise concerns that white shark populations are considerably more sensitive to human-induced mortality than previously thought.

Growth and maximum size of tiger sharks (Galeocerdo cuvier) in Hawaii.

Science.gov (United States)

Meyer, Carl G; O'Malley, Joseph M; Papastamatiou, Yannis P; Dale, Jonathan J; Hutchinson, Melanie R; Anderson, James M; Royer, Mark A; Holland, Kim N

2014-01-01

Tiger sharks (Galecerdo cuvier) are apex predators characterized by their broad diet, large size and rapid growth. Tiger shark maximum size is typically between 380 & 450 cm Total Length (TL), with a few individuals reaching 550 cm TL, but the maximum size of tiger sharks in Hawaii waters remains uncertain. A previous study suggested tiger sharks grow rather slowly in Hawaii compared to other regions, but this may have been an artifact of the method used to estimate growth (unvalidated vertebral ring counts) compounded by small sample size and narrow size range. Since 1993, the University of Hawaii has conducted a research program aimed at elucidating tiger shark biology, and to date 420 tiger sharks have been tagged and 50 recaptured. All recaptures were from Hawaii except a single shark recaptured off Isla Jacques Cousteau (24°13'17″N 109°52'14″W), in the southern Gulf of California (minimum distance between tag and recapture sites  =  approximately 5,000 km), after 366 days at liberty (DAL). We used these empirical mark-recapture data to estimate growth rates and maximum size for tiger sharks in Hawaii. We found that tiger sharks in Hawaii grow twice as fast as previously thought, on average reaching 340 cm TL by age 5, and attaining a maximum size of 403 cm TL. Our model indicates the fastest growing individuals attain 400 cm TL by age 5, and the largest reach a maximum size of 444 cm TL. The largest shark captured during our study was 464 cm TL but individuals >450 cm TL were extremely rare (0.005% of sharks captured). We conclude that tiger shark growth rates and maximum sizes in Hawaii are generally consistent with those in other regions, and hypothesize that a broad diet may help them to achieve this rapid growth by maximizing prey consumption rates.

The modelling and assessment of whale-watching impacts

Science.gov (United States)

New, Leslie; Hall, Ailsa J.; Harcourt, Robert; Kaufman, Greg; Parsons, E.C.M.; Pearson, Heidi C.; Cosentino, A. Mel; Schick, Robert S

2015-01-01

In recent years there has been significant interest in modelling cumulative effects and the population consequences of individual changes in cetacean behaviour and physiology due to disturbance. One potential source of disturbance that has garnered particular interest is whale-watching. Though perceived as ‘green’ or eco-friendly tourism, there is evidence that whale-watching can result in statistically significant and biologically meaningful changes in cetacean behaviour, raising the question whether whale-watching is in fact a long term sustainable activity. However, an assessment of the impacts of whale-watching on cetaceans requires an understanding of the potential behavioural and physiological effects, data to effectively address the question and suitable modelling techniques. Here, we review the current state of knowledge on the viability of long-term whale-watching, as well as logistical limitations and potential opportunities. We conclude that an integrated, coordinated approach will be needed to further understanding of the possible effects of whale-watching on cetaceans.

Getting to know you: Identification of pygmy killer whales (Feresa attenuata and melon-headed whales (Peponocephala electra under challenging conditions

Directory of Open Access Journals (Sweden)

Salvatore Siciliano

2015-12-01

Full Text Available Abstract Melon-headed whale (Peponocephala electra and Pygmy killer whale (Feresa attenuata are very poorly known species and are often confused with each other. We examined in detail Figure 3 in MARIGO and GIFFONI (2010 who reported that two melon-headed whales were taken in a surface driftnet about 90 nm off Santos, Brazil. We concluded they were in fact pygmy killer whales and explain our reasoning. To aid in future identifications, we illustrate and describe some of the main differences between these two species of small cetaceans. The incident reported by MARIGO and GIFFONI (2010 might represent the 'tip of the iceberg' regarding the incidental catches of cetaceans by pelagic drift nets off Brazil. Offshore driftnetting operating along the south-southeastern coast of Brazil may threaten pygmy killer whales.

White sharks Carcharodon carcharias at Bird Island, Algoa Bay ...

African Journals Online (AJOL)

We present the first quantitative study of the occurrence, size and sex of white sharks Carcharodon carcharias at Bird Island, Algoa Bay. Twenty-two boat trips were made to Bird Island between November 2009 and October 2011 to chum for sharks. A total of 53 sharks was observed over the study period, ranging in size ...

CATCH COMPOSITION AND SOME BIOLOGICAL ASPECTS OF SHARKS IN WESTERN SUMATERA WATERS OF INDONESIA

Directory of Open Access Journals (Sweden)

Dharmadi Dharmadi

2017-01-01

Full Text Available This study was conducted in western Sumatera and since October 2013 to June 2014. The sampling locations in Banda Aceh and Sibolga-North Sumatera which were the largest base of fisheries in western Sumatera region. Shark landing recorded by enumerators was used  as sampling data daily . This research aim to describ sex ratio, size composition, catch composition of sharks, and length at first maturity. In Banda Aceh, the sharks as target fish collected by  sorting the bycatch from tuna longlines and tuna handlines. In Sibolga, sharks  is bycatch from fish net, bottom gillnet and purse seine. Overall, there were 20 species of shark caught in west Indian Ocean and landed at those fish landing sites, dominated by Spot tail shark (23% and Silky shark (13%, whereas Hammerhead shark contributed about 10% and  Oceanic whitetip shark was only less than 1%. Almost of Spot tail shark, Silky shark, and Scalloped hammerhead that caught in that area were  immature, while for the almost part of Tiger shark and Pelagic thresher were  matured. The sex ratios for Spot tail shark, Silky shark, Tiger shark, Pelagic thresher, and Scalloped hammerhead caught and landed at Lampulo and Sibolga fish landing sites were not balance. The length at first maturity for Spot tail shark was Lm=87,1 cm and Lm = 213,2 cm total length for Tiger shark.

Wandering whales? : Relationships between baleen whales and the sea ice environment in the Southern Ocean

NARCIS (Netherlands)

Beekmans, Bas

2017-01-01

Each austral summer large baleen whales migrate into the Southern Ocean to feed on krill. The melting of sea ice leads to algal blooms which allow rapid growth and development of krill. In order to predict how baleen whales will respond to long-term changes in the physical environment, we need to

Blue whales Balaenoptera musculus off Angola: recent sightings ...

African Journals Online (AJOL)

Further survey work is required to better clarify the status of blue whales in Angolan waters, particularly with regard to population structure and potential calving grounds. Keywords: Antarctic blue whale, calving, catch data, pygmy blue whale, South-East Atlantic, stomach contents. African Journal of Marine Science 2014, ...

The Influence of Culture on the International Management of Shark Finning

Science.gov (United States)

Dell'Apa, Andrea; Chad Smith, M.; Kaneshiro-Pineiro, Mahealani Y.

2014-08-01

Shark finning is prohibited in many countries, but high prices for fins from the Asian market help maintain the international black-market and poaching. Traditional shark fin bans fail to recognize that the main driver of fin exploitation is linked to cultural beliefs about sharks in traditional Chinese culture. Therefore, shark finning should be addressed considering the social science approach as part of the fishery management scheme. This paper investigates the cultural significance of sharks in traditional Chinese and Hawaiian cultures, as valuable examples of how specific differences in cultural beliefs can drive individuals' attitudes toward the property of shark finning. We suggest the use of a social science approach that can be useful in the design of successful education campaigns to help change individuals' attitudes toward shark fin consumption. Finally, alternative management strategies for commercial fishers are provided to maintain self-sustainability of local coastal communities.

Bristled shark skin: a microgeometry for boundary layer control?

International Nuclear Information System (INIS)

Lang, A W; Hidalgo, P; Westcott, M; Motta, P

2008-01-01

There exists evidence that some fast-swimming shark species may have the ability to bristle their scales during fast swimming. Experimental work using a water tunnel facility has been performed to investigate the flow field over and within a bristled shark skin model submerged within a boundary layer to deduce the possible boundary layer control mechanisms being used by these fast-swimming sharks. Fluorescent dye flow visualization provides evidence of the formation of embedded cavity vortices within the scales. Digital particle image velocimetry (DPIV) data, used to evaluate the cavity vortex formation and boundary layer characteristics close to the surface, indicate increased momentum in the slip layer forming above the scales. This increase in flow velocity close to the shark's skin is indicative of boundary layer control mechanisms leading to separation control and possibly transition delay for the bristled shark skin microgeometry

Shark attack-related injuries: Epidemiology and implications for plastic surgeons.

Science.gov (United States)

Ricci, Joseph A; Vargas, Christina R; Singhal, Dhruv; Lee, Bernard T

2016-01-01

The increased media attention to shark attacks has led to a heightened fear and public awareness. Although few sharks are considered dangerous, attacks on humans can result in large soft tissue defects necessitating the intervention of reconstructive surgeons. This study aims to evaluate and describe the characteristics of shark-related injuries in order to improve treatment. The Global Shark Accident File, maintained by the Shark Research Institute (Princeton, NJ, USA), is a compilation of all known worldwide shark attacks. Database records since the 1900s were reviewed to identify differences between fatal and nonfatal attacks, including: geography, injury pattern, shark species, and victim activity. Since the 1900s, there have been 5034 reported shark attacks, of which 1205 (22.7%) were fatal. Although the incidence of attacks per decade has increased, the percentage of fatalities has decreased. Characteristics of fatal attacks included swimming (p = 0.001), boating (p = 0.001), three or more bite sites (p = 0.03), limb loss (p = 0.001), or tiger shark attack (p = 0.002). The most common attacks were bites to the legs (41.8%) or arms (18.4%), with limb loss occurring in 7% of attacks. Geographically, the majority of attacks occurred in North America (36.7%) and Australia (26.5%). Most attacks in the USA occurred in Florida (49.1%) and California (13.6%). Although rare, shark attacks result in devastating injuries to patients. As these injuries often involve multiple sites and limb loss, this creates a significant challenge for reconstructive surgeons. Proper identification of the characteristics of the attack can aid in providing optimal care for those affected. Copyright © 2015 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

Whales and dolphins (Mammalia, Cetacea) of the Cape Verde Islands, with special reference to the Humpback Whale Megaptera novaeangliae (Borowski, 1781)

NARCIS (Netherlands)

Hazevoet, Cornelis J.; Wenzel, Frederick W.

2000-01-01

Observations of whales and dolphins in the Cape Verde Islands obtained in 1995 and 1996 are reported and data on the occurrence of 14 taxa are given, including four not previously reported from the region, viz. Bryde’s Whale Balaenoptera edeni, Killer Whale Orcinus orca, Rough-toothed Dolphin Steno

Impact of biology knowledge on the conservation and management of large pelagic sharks.

Science.gov (United States)

Yokoi, Hiroki; Ijima, Hirotaka; Ohshimo, Seiji; Yokawa, Kotaro

2017-09-06

Population growth rate, which depends on several biological parameters, is valuable information for the conservation and management of pelagic sharks, such as blue and shortfin mako sharks. However, reported biological parameters for estimating the population growth rates of these sharks differ by sex and display large variability. To estimate the appropriate population growth rate and clarify relationships between growth rate and relevant biological parameters, we developed a two-sex age-structured matrix population model and estimated the population growth rate using combinations of biological parameters. We addressed elasticity analysis and clarified the population growth rate sensitivity. For the blue shark, the estimated median population growth rate was 0.384 with a range of minimum and maximum values of 0.195-0.533, whereas those values of the shortfin mako shark were 0.102 and 0.007-0.318, respectively. The maturity age of male sharks had the largest impact for blue sharks, whereas that of female sharks had the largest impact for shortfin mako sharks. Hypotheses for the survival process of sharks also had a large impact on the population growth rate estimation. Both shark maturity age and survival rate were based on ageing validation data, indicating the importance of validating the quality of these data for the conservation and management of large pelagic sharks.

77 FR 57022 - Drawbridge Operation Regulation; Shark River, Avon, NJ

Science.gov (United States)

2012-09-17

... Operation Regulation; Shark River, Avon, NJ AGENCY: Coast Guard, DHS. ACTION: Notice of temporary deviation... across the Shark River (South Channel), at Avon Township, NJ. This deviation is necessary to facilitate stringer replacement on the Shark River railroad bridge. This temporary deviation will allow the...

Chromium Is Elevated in Fin Whale (Balaenoptera physalus) Skin Tissue and Is Genotoxic to Fin Whale Skin Cells

Science.gov (United States)

Wise, Catherine F.; Wise, Sandra S.; Thompson, W. Douglas; Perkins, Christopher; Wise, John Pierce

2015-01-01

Hexavalent chromium (Cr(VI)) is present in the marine environment and is a known carcinogen and reproductive toxicant. Cr(VI) is the form of chromium that is well absorbed through the cell membrane. It is also the most prevalent form in seawater. We measured the total Cr levels in skin biopsies obtained from healthy free-ranging fin whales from the Gulf of Maine and found elevated levels relative to marine mammals in other parts of the world. The levels in fin whale biopsies ranged from 1.71 ug/g to 19.6 ug/g with an average level of 10.07 ug/g. We also measured the cytotoxicity and genotoxicity of Cr(VI) in fin whale skin cells. We found that particulate and soluble Cr(VI) are both cytotoxic and genotoxic to fin whale skin cells in a concentration-dependent manner. The concentration range used in our cell culture studies used environmentally relevant concentrations based on the biopsy measurements. These data suggest that Cr(VI) may be a concern for whales in the Gulf of Maine. PMID:25805270

Shark predation on Indian Ocean bottlenose dolphins TUTSiops ...

African Journals Online (AJOL)

1988-10-24

Oct 24, 1988 ... Four species of shark, the Zambesi (Carcharhinus leucas), the tiger (Galeocerdo ... level of shark predation on bottlenose dolphins was unknown it appeared to ..... possible examples of these adaptations. Acknowledgments.

The use of positive reinforcement in training zebra sharks (Stegostoma fasciatum).

Science.gov (United States)

Marranzino, Ashley

2013-01-01

Positive reinforcement training (PRT) was used on 4 adult zebra sharks, Stegostoma fasciatum, housed at the Downtown Aquarium, Denver, to determine the ability of zebra sharks to become desensitized to various stimuli associated with veterinary procedures. One male and 3 female sharks were trained for 12 weeks. As a result of PRT, all 4 zebra sharks were desensitized to staying within a closed holding tank off of the main exhibit, the presence of multiple trainers in the closed holding tank, and tactile stimulation. One of the 4 zebra sharks was also successfully desensitized to the presence of a stretcher being brought into the holding tank. All of these procedures are common in veterinary examinations, and it is hoped that desensitization to these stimuli will reduce the stress associated with examinations. The training accomplished has allowed for easier maintenance of the zebra sharks by the aquarium staff and an improvement in the care of the sharks.

Bacteriology of the teeth from a great white shark: potential medical implications for shark bite victims.

OpenAIRE

Buck, J D; Spotte, S; Gadbaw, J J

1984-01-01

Bacteria were cultured for the first time from the teeth of a great white shark (Carcharodon carcharias). Isolates included Vibrio alginolyticus, Vibrio fluvialis, Vibrio parahaemolyticus, and other genera. All are common in the marine environment and some may be associated with wound infections in humans. Shark bite lacerations may serve as a source of these potentially infectious bacteria, particularly Vibrio spp., and should be treated immediately. Antibiotic susceptibility patterns are sh...

Evidence of positive selection associated with placental loss in tiger sharks.

Science.gov (United States)

Swift, Dominic G; Dunning, Luke T; Igea, Javier; Brooks, Edward J; Jones, Catherine S; Noble, Leslie R; Ciezarek, Adam; Humble, Emily; Savolainen, Vincent

2016-06-14

All vertebrates initially feed their offspring using yolk reserves. In some live-bearing species these yolk reserves may be supplemented with extra nutrition via a placenta. Sharks belonging to the Carcharhinidae family are all live-bearing, and with the exception of the tiger shark (Galeocerdo cuvier), develop placental connections after exhausting yolk reserves. Phylogenetic relationships suggest the lack of placenta in tiger sharks is due to secondary loss. This represents a dramatic shift in reproductive strategy, and is likely to have left a molecular footprint of positive selection within the genome. We sequenced the transcriptome of the tiger shark and eight other live-bearing shark species. From this data we constructed a time-calibrated phylogenetic tree estimating the tiger shark lineage diverged from the placental carcharhinids approximately 94 million years ago. Along the tiger shark lineage, we identified five genes exhibiting a signature of positive selection. Four of these genes have functions likely associated with brain development (YWHAE and ARL6IP5) and sexual reproduction (VAMP4 and TCTEX1D2). Our results indicate the loss of placenta in tiger sharks may be associated with subsequent adaptive changes in brain development and sperm production.

Bristled shark skin: a microgeometry for boundary layer control?

Energy Technology Data Exchange (ETDEWEB)

Lang, A W; Hidalgo, P; Westcott, M [Aerospace Engineering and Mechanics Department, University of Alabama, Box 870280, Tuscaloosa, AL 35487 (United States); Motta, P [Biology Department, University of South Florida, 4202 East Fowler Avenue, Tampa, FL 33620 (United States)], E-mail: alang@eng.ua.edu

2008-12-01

There exists evidence that some fast-swimming shark species may have the ability to bristle their scales during fast swimming. Experimental work using a water tunnel facility has been performed to investigate the flow field over and within a bristled shark skin model submerged within a boundary layer to deduce the possible boundary layer control mechanisms being used by these fast-swimming sharks. Fluorescent dye flow visualization provides evidence of the formation of embedded cavity vortices within the scales. Digital particle image velocimetry (DPIV) data, used to evaluate the cavity vortex formation and boundary layer characteristics close to the surface, indicate increased momentum in the slip layer forming above the scales. This increase in flow velocity close to the shark's skin is indicative of boundary layer control mechanisms leading to separation control and possibly transition delay for the bristled shark skin microgeometry.

Determining Correlation between Shark Location and Atmospheric Wind and Thermal Parameters.

Science.gov (United States)

Merchant, J.

2017-12-01

Millions of people visit the nation's shorelines every summer. As recreational use of the ocean increases across the country, so too does the risk of shark attacks on people. According to George H. Burgess, curator for the International Shark Attack File and the Florida Program for Shark Research "The number of shark-human interactions occurring in a given year is directly correlated with the amount of time humans spend in the sea. As world population continues its upsurge and interest in aquatic recreation concurrently rises, we realistically should expect increases in the number of shark attacks and other aquatic recreation-related injuries". Burgess' analysis released in February of 2016, states "2015 yearly total of 98 unprovoked attacks (worldwide) was the highest on record" until 2016. Adding to the previous record number of global shark/human interactions in 2015 were 10 confirmed cases of people bitten by sharks off the shores of North Carolina and South Carolina over a five week period in June and July of 2015. The unusually high amount of attacks within close proximity over a short period of time garnered significant media attention nationwide. Preliminary data resulting from the analysis of these 2015 shark attacks and separate acoustic shark location data from Dr. Gregory Skomal's (Program Manager, Senior Marine Fisheries Biologist for the state of Massachusetts) ongoing research across Cape Code do indicate a correlation between environmental and biological factors leading up to human/shark interactions. Not only will these preliminary findings be presented, but a full description of how the use of higher resolution remote sensing and in-situ surface wind and thermal measurements would improve real time detection and prediction of these dangerous conditions, up to hours in advance, mitigating human risk and interaction with shark.

78 FR 3836 - Drawbridge Operation Regulation; Shark River, Avon, NJ

Science.gov (United States)

2013-01-17

... Operation Regulation; Shark River, Avon, NJ AGENCY: Coast Guard, DHS. ACTION: Notice of deviation from... and the railroad bridge, mile 0.9 both of which are across the Shark River (South Channel), at Avon Township, NJ. This deviation is necessary to facilitate machinery replacement on the Shark River railroad...

Movement patterns of silvertip sharks ( Carcharhinus albimarginatus) on coral reefs

Science.gov (United States)

Espinoza, Mario; Heupel, Michelle. R.; Tobin, Andrew J.; Simpfendorfer, Colin A.

2015-09-01

Understanding how sharks use coral reefs is essential for assessing risk of exposure to fisheries, habitat loss, and climate change. Despite a wide Indo-Pacific distribution, little is known about the spatial ecology of silvertip sharks ( Carcharhinus albimarginatus), compromising the ability to effectively manage their populations. We examined the residency and movements of silvertip sharks in the central Great Barrier Reef (GBR). An array of 56 VR2W acoustic receivers was used to monitor shark movements on 17 semi-isolated reefs. Twenty-seven individuals tagged with acoustic transmitters were monitored from 70 to 731 d. Residency index to the study site ranged from 0.05 to 0.97, with a mean residency (±SD) of 0.57 ± 0.26, but most individuals were detected at or near their tagging reef. Clear seasonal patterns were apparent, with fewer individuals detected between September and February. A large proportion of the tagged population (>71 %) moved regularly between reefs. Silvertip sharks were detected less during daytime and exhibited a strong diel pattern in depth use, which may be a strategy for optimizing energetic budgets and foraging opportunities. This study provides the first detailed examination of the spatial ecology and behavior of silvertip sharks on coral reefs. Silvertip sharks remained resident at coral reef habitats over long periods, but our results also suggest this species may have more complex movement patterns and use larger areas of the GBR than common reef shark species. Our findings highlight the need to further understand the movement ecology of silvertip sharks at different spatial and temporal scales, which is critical for developing effective management approaches.

Biological responses of sharks to ocean acidification.

Science.gov (United States)

Rosa, Rui; Rummer, Jodie L; Munday, Philip L

2017-03-01

Sharks play a key role in the structure of marine food webs, but are facing major threats due to overfishing and habitat degradation. Although sharks are also assumed to be at relatively high risk from climate change due to a low intrinsic rate of population growth and slow rates of evolution, ocean acidification (OA) has not, until recently, been considered a direct threat. New studies have been evaluating the potential effects of end-of-century elevated CO 2 levels on sharks and their relatives' early development, physiology and behaviour. Here, we review those findings and use a meta-analysis approach to quantify the overall direction and magnitude of biological responses to OA in the species of sharks that have been investigated to date. While embryo survival and development time are mostly unaffected by elevated CO 2 , there are clear effects on body condition, growth, aerobic potential and behaviour (e.g. lateralization, hunting and prey detection). Furthermore, studies to date suggest that the effects of OA could be as substantial as those due to warming in some species. A major limitation is that all past studies have involved relatively sedentary, benthic sharks that are capable of buccal ventilation-no studies have investigated pelagic sharks that depend on ram ventilation. Future research should focus on species with different life strategies (e.g. pelagic, ram ventilators), climate zones (e.g. polar regions), habitats (e.g. open ocean), and distinct phases of ontogeny in order to fully predict how OA and climate change will impact higher-order predators and therefore marine ecosystem dynamics. © 2017 The Author(s).

A right whale pootree: classification trees of faecal hormones identify reproductive states in North Atlantic right whales (Eubalaena glacialis).

Science.gov (United States)

Corkeron, Peter; Rolland, Rosalind M; Hunt, Kathleen E; Kraus, Scott D

2017-01-01

Immunoassay of hormone metabolites extracted from faecal samples of free-ranging large whales can provide biologically relevant information on reproductive state and stress responses. North Atlantic right whales ( Eubalaena glacialis Müller 1776) are an ideal model for testing the conservation value of faecal metabolites. Almost all North Atlantic right whales are individually identified, most of the population is sighted each year, and systematic survey effort extends back to 1986. North Atlantic right whales number trees as an alternative method of analysing multiple-hormone data sets, building on univariate models that have previously been used to describe hormone profiles of individual North Atlantic right whales of known reproductive state. Our tree correctly classified the age class, sex and reproductive state of 83% of 112 faecal samples from known individual whales. Pregnant females, lactating females and both mature and immature males were classified reliably using our model. Non-reproductive [i.e. 'resting' (not pregnant and not lactating) and immature] females proved the most unreliable to distinguish. There were three individual males that, given their age, would traditionally be considered immature but that our tree classed as mature males, possibly calling for a re-evaluation of their reproductive status. Our analysis reiterates the importance of considering the reproductive state of whales when assessing the relationship between cortisol concentrations and stress. Overall, these results confirm findings from previous univariate statistical analyses, but with a more robust multivariate approach that may prove useful for the multiple-analyte data sets that are increasingly used by conservation physiologists.

The Diet Composition of Beaked Whales and Melon-Headed Whales from the North Pacific

Science.gov (United States)

2015-09-30

description and comparison of diet composition as well as provide insight into the foraging behavior and ecology of these whales in the North...activities. Assessing diet for many species of cetaceans is difficult, given that most foraging occurs far below the surface and that stomach...furthering our understanding of the foraging behavior of this species. Such an examination of food habits from Hawaiian melon-headed whales would be

Satellite Tracking of Humpback Whales in West Greenland

DEFF Research Database (Denmark)

Dietz, R.; Teilmann, J.; Heide-Jørgensen, M.-P.

In June 2000, 6 humpback whales (Megaptere novaeangliae) were tagged with satellite transmitters off West Greenland. Contact remained for up to 42 days. The tagging revealed that within the month of June, humpback whales off West Greenland moved between Fiskenæs Banke, Fyllas Banke, Tovqussaq Banke......, Sukkertop Banke and Lille Hellefiske Banke. The whales showed a preference for the continental slopes with depths less than 200 m, however, few dives were recorded down to 500 m. The whales had a preference for dives lasting 7-8 min. (15%) and no dives lasted longer than 15 min....

Shark teeth as edged weapons: serrated teeth of three species of selachians.

Science.gov (United States)

Moyer, Joshua K; Bemis, William E

2017-02-01

Prior to European contact, South Pacific islanders used serrated shark teeth as components of tools and weapons. They did this because serrated shark teeth are remarkably effective at slicing through soft tissues. To understand more about the forms and functions of serrated shark teeth, we examined the morphology and histology of tooth serrations in three species: the Tiger Shark (Galeocerdo cuvier), Blue Shark (Prionace glauca), and White Shark (Carcharodon carcharias). We show that there are two basic types of serrations. A primary serration consists of three layers of enameloid with underlying dentine filling the serration's base. All three species studied have primary serrations, although the dentine component differs (orthodentine in Tiger and Blue Sharks; osteodentine in the White Shark). Smaller secondary serrations are found in the Tiger Shark, formed solely by enameloid with no contribution from underlying dentine. Secondary serrations are effectively "serrations within serrations" that allow teeth to cut at different scales. We propose that the cutting edges of Tiger Shark teeth, equipped with serrations at different scales, are linked to a diet that includes large, hard-shelled prey (e.g., sea turtles) as well as smaller, softer prey such as fishes. We discuss other aspects of serration form and function by making analogies to man-made cutting implements, such as knives and saws. Copyright © 2016 Elsevier GmbH. All rights reserved.

78 FR 59878 - Atlantic Highly Migratory Species; Commercial Atlantic Aggregated Large Coastal Shark (LCS...

Science.gov (United States)

2013-09-30

... Coastal Shark (LCS), Atlantic Hammerhead Shark, Atlantic Blacknose Shark, and Atlantic Non-Blacknose Small Coastal Shark (SCS) Management Groups AGENCY: National Marine Fisheries Service (NMFS), National Oceanic... closing the commercial management groups for aggregated LCS and hammerhead sharks in the Atlantic region...

75 FR 28779 - Prince of Whales Resource Advisory Committee

Science.gov (United States)

2010-05-24

... DEPARTMENT OF AGRICULTURE Forest Service Prince of Whales Resource Advisory Committee AGENCY: Forest Service, USDA. ACTION: Notice of meeting. SUMMARY: The Prince of Whales Resource Advisory... Ranger District, 504 9th Street, Craig Alaska. Send written comments to Prince of Whales Resource...

An Economical Custom-Built Drone for Assessing Whale Health

Directory of Open Access Journals (Sweden)

Vanessa Pirotta

2017-12-01

Full Text Available Drones or Unmanned Aerial Vehicles (UAVs have huge potential to improve the safety and efficiency of sample collection from wild animals under logistically challenging circumstances. Here we present a method for surveying population health that uses UAVs to sample respiratory vapor, ‘whale blow,' exhaled by free-swimming humpback whales (Megaptera novaeangliae, and coupled this with amplification and sequencing of respiratory tract microbiota. We developed a low-cost multirotor UAV incorporating a sterile petri dish with a remotely operated ‘blow' to sample whale blow with minimal disturbance to the whales. This design addressed several sampling challenges: accessibility; safety; cost, and critically, minimized the collection of atmospheric and seawater microbiota and other potential sources of sample contamination. We collected 59 samples of blow from northward migrating humpback whales off Sydney, Australia and used high throughput sequencing of bacterial ribosomal gene markers to identify putative respiratory tract microbiota. Model-based comparisons with seawater and drone-captured air demonstrated that our system minimized external sources of contamination and successfully captured sufficient material to identify whale blow-specific microbial taxa. Whale-specific taxa included species and genera previously associated with the respiratory tracts or oral cavities of mammals (e.g., Pseudomonas, Clostridia, Cardiobacterium, as well as species previously isolated from dolphin or killer whale blowholes (Corynebacteria, others. Many examples of exogenous marine species were identified, including Tenacibaculum and Psychrobacter spp. that have been associated with the skin microbiota of marine mammals and fish and may include pathogens. This information provides a baseline of respiratory tract microbiota profiles of contemporary whale health. Customized UAVs are a promising new tool for marine megafauna research and may have broad application in

Description of a new fossil beaked whale from the Late Miocene Gram Fm. in Denmark, and aspects of beaked whale evolution

DEFF Research Database (Denmark)

Ramassamy, Benjamin Fernand Guy

Modern beaked whales (Ziphiidae) are among the least known groups of mammals. This family of toothed whales forage at great depths on cephalopods, their favored prey. The origin and timing of their specialisation to deep diving is almost unknown. The discovery of a new fossil beaked whale from...... Denmark may unveil the origin of deep diving in the family. This project had two mains objectives. First, describing a new fossil specimen from the Miocene of Denmark. Second, investigating deep diving abilities in extinct beaked whales. The fossil specimen represent a new genus and species of Ziphiidae...

Morphology and evolution of the jaw suspension in lamniform sharks.

Science.gov (United States)

Wilga, C D

2005-07-01

The morphology of the jaw suspension and jaw protrusion mechanism in lamniform sharks is described and mapped onto a cladogram to investigate how changes in jaw suspension and protrusion have evolved. This has revealed that several evolutionary modifications in the musculoskeletal apparatus of the jaws have taken place among lamniform sharks. Galeomorph sharks (Carcharhiniformes, Lamniformes, Orectolobiformes, and Heterodontiformes) have paired ethmopalatine ligaments connecting the ethmoid process of the upper jaw to the ethmoid region of the cranium. Basal lamniform sharks also acquired a novel single palatonasal ligament connecting the symphysis of the upper jaw to the cranium mid-ventral to the nasal capsule. Sharks in the family Lamnidae subsequently lost the original paired ethmopalatine ligament while retaining the novel palatonasal ligament. Thus, basal lamniform taxa (Mitsukurina owstoni, Carcharius taurus, Alopias vulpinnis) have increased ligamentous support of the lateral region of the upper jaw while derived species (Lamnidae) have lost this lateral support but gained anterior support. In previous studies the morphology of the jaw suspension has been shown to play a major role in the mechanism of upper jaw protrusion in elasmobranchs. The preorbitalis is the primary muscle effecting upper jaw protrusion in squalean (sister group to galeomorphs) and carcharhiniform (sister group to lamniforms) sharks. The preorbitalis originates from the quadratomandibularis muscle and inserts onto the nasal capsule in squalean and carcharhiniform sharks. Carcharhiniform sharks have evolved a subdivided preorbitalis muscle with the new division inserting near the ethmoid process of the palatoquadrate (upper jaw). Alopid sharks have also independently evolved a partially subdivided preorbitalis with the new division inserting at the base of the ethmoid process and surrounding connective tissue. Lamnid sharks have retained the two preorbitalis divisions but have modified

Cyanobacterial Neurotoxin β-N-Methylamino-L-alanine (BMAA in Shark Fins

Directory of Open Access Journals (Sweden)

John Pablo

2012-02-01

Full Text Available Sharks are among the most threatened groups of marine species. Populations are declining globally to support the growing demand for shark fin soup. Sharks are known to bioaccumulate toxins that may pose health risks to consumers of shark products. The feeding habits of sharks are varied, including fish, mammals, crustaceans and plankton. The cyanobacterial neurotoxin β-N-methylamino-L-alanine (BMAA has been detected in species of free-living marine cyanobacteria and may bioaccumulate in the marine food web. In this study, we sampled fin clips from seven different species of sharks in South Florida to survey the occurrence of BMAA using HPLC-FD and Triple Quadrupole LC/MS/MS methods. BMAA was detected in the fins of all species examined with concentrations ranging from 144 to 1836 ng/mg wet weight. Since BMAA has been linked to neurodegenerative diseases, these results may have important relevance to human health. We suggest that consumption of shark fins may increase the risk for human exposure to the cyanobacterial neurotoxin BMAA.

Habitat use and diel vertical migration of bigeye thresher shark: Overlap with pelagic longline fishing gear.

Science.gov (United States)

Coelho, Rui; Fernandez-Carvalho, Joana; Santos, Miguel N

2015-12-01

Pelagic longliners targeting swordfish and tunas in oceanic waters regularly capture sharks as bycatch, including currently protected species as the bigeye thresher, Alopias superciliosus. Fifteen bigeye threshers were tagged with pop-up satellite archival tags (PSATs) in 2012-2014 in the tropical northeast Atlantic, with successful transmissions received from 12 tags for a total of 907 tracking days. Marked diel vertical movements were recorded on all specimens, with most of the daytime spent in deeper colder water (mean depth = 353 m, SD = 73; mean temperature = 10.7 °C, SD = 1.8) and nighttime spent in warmer water closer to the surface (mean depth = 72 m, SD = 54; mean temperature = 21.9 °C, SD = 3.7). The operating depth of the pelagic longline gear was measured with Minilog Temperature and Depth Recorders (TDRs), and the overlap with habitat utilization was calculated. Overlap is taking place mainly during the night and is higher for juveniles. The results presented herein can be used as inputs for Ecological Risk Assessments for bigeye threshers captured in oceanic tuna fisheries, and serve as a basis for efficient management and conservation of this vulnerable shark species. Copyright © 2015 Elsevier Ltd. All rights reserved.

Sex determination of baleen whale artefacts

DEFF Research Database (Denmark)

Sinding, Mikkel Holger Strander; Tervo, Outi M.; Grønnow, Bjarne

2016-01-01

to 4500 years old bowhead whale samples, and for comparison on dilution series from modern bowhead whales of known sex. DNA sequencing of PCR products obtained from the ancient material confirmed a higher proportion of successful PCR amplifications of the X homologue over the Y homologue. This potentially...

bullwinkle and shark regulate dorsal-appendage morphogenesis in Drosophila oogenesis.

Science.gov (United States)

Tran, David H; Berg, Celeste A

2003-12-01

bullwinkle (bwk) regulates embryonic anteroposterior patterning and, through a novel germline-to-soma signal, morphogenesis of the eggshell dorsal appendages. We screened for dominant modifiers of the bullwinkle mooseantler eggshell phenotype and identified shark, which encodes an SH2-domain, ankyrin-repeat tyrosine kinase. At the onset of dorsal-appendage formation, shark is expressed in a punctate pattern in the squamous stretch cells overlying the nurse cells. Confocal microscopy with cell-type-specific markers demonstrates that the stretch cells act as a substrate for the migrating dorsal-appendage-forming cells and extend cellular projections towards them. Mosaic analyses reveal that shark is required in follicle cells for cell migration and chorion deposition. Proper shark RNA expression in the stretch cells requires bwk activity, while restoration of shark expression in the stretch cells suppresses the bwk dorsal-appendage phenotype. These results suggest that shark plays an important downstream role in the bwk-signaling pathway. Candidate testing implicates Src42A in a similar role, suggesting conservation with a vertebrate signaling pathway involving non-receptor tyrosine kinases.

Long-term changes in species composition and relative abundances of sharks at a provisioning site.

Directory of Open Access Journals (Sweden)

Juerg M Brunnschweiler

Full Text Available Diving with sharks, often in combination with food baiting/provisioning, has become an important product of today's recreational dive industry. Whereas the effects baiting/provisioning has on the behaviour and abundance of individual shark species are starting to become known, there is an almost complete lack of equivalent data from multi-species shark diving sites. In this study, changes in species composition and relative abundances were determined at the Shark Reef Marine Reserve, a multi-species shark feeding site in Fiji. Using direct observation sampling methods, eight species of sharks (bull shark Carcharhinus leucas, grey reef shark Carcharhinus amblyrhynchos, whitetip reef shark Triaenodon obesus, blacktip reef shark Carcharhinus melanopterus, tawny nurse shark Nebrius ferrugineus, silvertip shark Carcharhinus albimarginatus, sicklefin lemon shark Negaprion acutidens, and tiger shark Galeocerdo cuvier displayed inter-annual site fidelity between 2003 and 2012. Encounter rates and/or relative abundances of some species changed over time, overall resulting in more individuals (mostly C. leucas of fewer species being encountered on average on shark feeding dives at the end of the study period. Differences in shark community composition between the years 2004-2006 and 2007-2012 were evident, mostly because N. ferrugineus, C. albimarginatus and N. acutidens were much more abundant in 2004-2006 and very rare in the period of 2007-2012. Two explanations are offered for the observed changes in relative abundances over time, namely inter-specific interactions and operator-specific feeding protocols. Both, possibly in combination, are suggested to be important determinants of species composition and encounter rates, and relative abundances at this shark provisioning site in Fiji. This study, which includes the most species from a spatially confined shark provisioning site to date, suggests that long-term provisioning may result in competitive

Long-term changes in species composition and relative abundances of sharks at a provisioning site.

Science.gov (United States)

Brunnschweiler, Juerg M; Abrantes, Kátya G; Barnett, Adam

2014-01-01

Diving with sharks, often in combination with food baiting/provisioning, has become an important product of today's recreational dive industry. Whereas the effects baiting/provisioning has on the behaviour and abundance of individual shark species are starting to become known, there is an almost complete lack of equivalent data from multi-species shark diving sites. In this study, changes in species composition and relative abundances were determined at the Shark Reef Marine Reserve, a multi-species shark feeding site in Fiji. Using direct observation sampling methods, eight species of sharks (bull shark Carcharhinus leucas, grey reef shark Carcharhinus amblyrhynchos, whitetip reef shark Triaenodon obesus, blacktip reef shark Carcharhinus melanopterus, tawny nurse shark Nebrius ferrugineus, silvertip shark Carcharhinus albimarginatus, sicklefin lemon shark Negaprion acutidens, and tiger shark Galeocerdo cuvier) displayed inter-annual site fidelity between 2003 and 2012. Encounter rates and/or relative abundances of some species changed over time, overall resulting in more individuals (mostly C. leucas) of fewer species being encountered on average on shark feeding dives at the end of the study period. Differences in shark community composition between the years 2004-2006 and 2007-2012 were evident, mostly because N. ferrugineus, C. albimarginatus and N. acutidens were much more abundant in 2004-2006 and very rare in the period of 2007-2012. Two explanations are offered for the observed changes in relative abundances over time, namely inter-specific interactions and operator-specific feeding protocols. Both, possibly in combination, are suggested to be important determinants of species composition and encounter rates, and relative abundances at this shark provisioning site in Fiji. This study, which includes the most species from a spatially confined shark provisioning site to date, suggests that long-term provisioning may result in competitive exclusion among shark

Multiple origins of gigantism in stem baleen whales

Science.gov (United States)

Tsai, Cheng-Hsiu; Kohno, Naoki

2016-12-01

Living baleen whales (Mysticeti) include the world's largest animals to have ever lived—blue whales ( Balaenoptera musculus) can reach more than 30 m. However, the gigantism in baleen whales remains little explored. Here, we compiled all published stem mysticetes from the Eocene and Oligocene and then mapped the estimated body size onto different phylogenies that suggest distinct evolutionary histories of baleen whales. By assembling all known stem baleen whales, we present three novel findings in early mysticete evolution. Results show that, regardless of different phylogenetic scenarios, large body size (more than 5-m long) evolved multiple times independently in their early evolutionary history. For example, the earliest known aetiocetid ( Fucaia buelli, 33-31 Ma) was small in size, about 2 m, and a later aetiocetid ( Morawanocetus-like animal, 26-23 Ma) can reach 8-m long—almost four times the size of Fucaia buelli—suggesting an independent gigantism in the aetiocetid lineage. In addition, our reconstruction of ancestral state demonstrates that the baleen whales originated from small body size (less than 5 m) rather than large body size as previously acknowledged. Moreover, reconstructing the evolution of body size in stem baleen whales suggests that the initial pulse of mysticete gigantism started at least back to the Paleogene and in turn should help to understand the origin, pattern, and process of the extreme gigantism in the crown baleen whales. This study illustrates that Cope's rule is insufficient to explain the evolution of body size in a group that comprises the largest animals in the history of life, although currently the lack of exact ancestor-descendant relationships remains to fully reveal the evolutionary history of body size.

Quantifying shark distribution patterns and species-habitat associations: implications of marine park zoning.

Science.gov (United States)

Espinoza, Mario; Cappo, Mike; Heupel, Michelle R; Tobin, Andrew J; Simpfendorfer, Colin A

2014-01-01

Quantifying shark distribution patterns and species-specific habitat associations in response to geographic and environmental drivers is critical to assessing risk of exposure to fishing, habitat degradation, and the effects of climate change. The present study examined shark distribution patterns, species-habitat associations, and marine reserve use with baited remote underwater video stations (BRUVS) along the entire Great Barrier Reef Marine Park (GBRMP) over a ten year period. Overall, 21 species of sharks from five families and two orders were recorded. Grey reef Carcharhinus amblyrhynchos, silvertip C. albimarginatus, tiger Galeocerdo cuvier, and sliteye Loxodon macrorhinus sharks were the most abundant species (>64% of shark abundances). Multivariate regression trees showed that hard coral cover produced the primary split separating shark assemblages. Four indicator species had consistently higher abundances and contributed to explaining most of the differences in shark assemblages: C. amblyrhynchos, C. albimarginatus, G. cuvier, and whitetip reef Triaenodon obesus sharks. Relative distance along the GBRMP had the greatest influence on shark occurrence and species richness, which increased at both ends of the sampling range (southern and northern sites) relative to intermediate latitudes. Hard coral cover and distance across the shelf were also important predictors of shark distribution. The relative abundance of sharks was significantly higher in non-fished sites, highlighting the conservation value and benefits of the GBRMP zoning. However, our results also showed that hard coral cover had a large effect on the abundance of reef-associated shark species, indicating that coral reef health may be important for the success of marine protected areas. Therefore, understanding shark distribution patterns, species-habitat associations, and the drivers responsible for those patterns is essential for developing sound management and conservation approaches.

"Sharks in Your Hands"--A Case Study on Effects of Teaching Strategies to Change Knowledge and Attitudes towards Sharks

Science.gov (United States)

Lee, Hung-Shan; Liu, Shiang-Yao; Yeh, Ting-Kuang

2016-01-01

This study was designed to exemplify how hands-on based teaching strategies enhanced students' knowledge and positive attitudes towards sharks. Hands-on activities for sharks' biological and morphological features were carried out. Eleven elementary school students from a remote area in Taiwan were recruited and assigned to the hands-on condition.…

76 FR 23935 - Atlantic Highly Migratory Species; Atlantic Shark Management Measures

Science.gov (United States)

2011-04-29

.... 110120049-1144-01] RIN 0648-BA69 Atlantic Highly Migratory Species; Atlantic Shark Management Measures... retention, transshipping, landing, storing, or selling of hammerhead sharks in the family Sphyrnidae (except for Sphyrna tiburo) and oceanic whitetip sharks (Carcharhinus longimanus) caught in association with...

76 FR 72383 - Atlantic Highly Migratory Species; Atlantic Shark Management Measures

Science.gov (United States)

2011-11-23

...-BA17 Atlantic Highly Migratory Species; Atlantic Shark Management Measures AGENCY: National Marine... plan (FMP) amendment that would consider catch shares for the Atlantic shark fisheries. The comment... potential catch shares programs in the Atlantic shark fisheries. Additionally, NMFS is extending the comment...

Killer whale (Orcinus orca) behavioral audiograms.

Science.gov (United States)

Branstetter, Brian K; St Leger, Judy; Acton, Doug; Stewart, John; Houser, Dorian; Finneran, James J; Jenkins, Keith

2017-04-01

Killer whales (Orcinus orca) are one of the most cosmopolitan marine mammal species with potential widespread exposure to anthropogenic noise impacts. Previous audiometric data on this species were from two adult females [Szymanski, Bain, Kiehl, Pennington, Wong, and Henry (1999). J. Acoust. Soc. Am. 108, 1322-1326] and one sub-adult male [Hall and Johnson (1972). J. Acoust. Soc. Am. 51, 515-517] with apparent high-frequency hearing loss. All three killer whales had best sensitivity between 15 and 20 kHz, with thresholds lower than any odontocete tested to date, suggesting this species might be particularly sensitive to acoustic disturbance. The current study reports the behavioral audiograms of eight killer whales at two different facilities. Hearing sensitivity was measured from 100 Hz to 160 kHz in killer whales ranging in age from 12 to 52 year. Previously measured low thresholds at 20 kHz were not replicated in any individual. Hearing in the killer whales was generally similar to other delphinids, with lowest threshold (49 dB re 1 μPa) at approximately 34 kHz, good hearing (i.e., within 20 dB of best sensitivity) from 5 to 81 kHz, and low- and high-frequency hearing cutoffs (>100 dB re μPa) of 600 Hz and 114 kHz, respectively.

Shark protection plan for the Dutch Caibbean EEZ

NARCIS (Netherlands)

Beek, van I.J.M.; Debrot, A.O.; Walker, P.A.; Kingma, I.

2014-01-01

Shark populations have steeply declined worldwide due to unsustainable overexploitation and in this the Caribbean region is no exception. Since the 1990s many initiatives have been developed to protect the most threatened species. Sharks play an important ecological role in tropical marine

Testing the feasibility of a hypothetical whaling-conservation permit market in Norway.

Science.gov (United States)

Huang, Biao; Abbott, Joshua K; Fenichel, Eli P; Muneepeerakul, Rachata; Perrings, Charles; Gerber, Leah R

2017-08-01

A cap-and-trade system for managing whale harvests represents a potentially useful approach to resolve the current gridlock in international whale management. The establishment of whale permit markets, open to both whalers and conservationists, could reveal the strength of conservation demand, about which little is known. This lack of knowledge makes it difficult to predict the outcome of a hypothetical whale permit market. We developed a bioeconomic model to evaluate the influence of economic uncertainty about demand for whale conservation or harvest. We used simulations over a wide range of parameterizations of whaling and conservation demands to examine the potential ecological consequences of the establishment of a whale permit market in Norwegian waters under bounded (but substantial) economic uncertainty. Uncertainty variables were slope of whaling and conservation demand, participation level of conservationists and their willingness to pay for whale conservation, and functional forms of demand, including linear, quadratic, and log-linear forms. A whale-conservation market had the potential to yield a wide range of conservation and harvest outcomes, the most likely outcomes were those in which conservationists bought all whale permits. © 2017 Society for Conservation Biology.

75 FR 57235 - Atlantic Highly Migratory Species; Atlantic Shark Management Measures

Science.gov (United States)

2010-09-20

.... 100825390-0431-01] RIN 0648-BA17 Atlantic Highly Migratory Species; Atlantic Shark Management Measures... on potential adjustments to the regulations governing the U.S. Atlantic shark fishery to address several specific issues currently affecting management of the shark fishery and to identify specific goals...

77 FR 37647 - Atlantic Highly Migratory Species; Silky Shark Management Measures

Science.gov (United States)

2012-06-22

.... 120416016-2151-01] RIN 0648-BB96 Atlantic Highly Migratory Species; Silky Shark Management Measures AGENCY..., transshipping, or landing of silky sharks (Carcharhinus falciformis) caught in association with ICCAT fisheries... sharks with bottom longline, gillnet, or handgear; nor would the rule affect recreational fishermen as...

75 FR 30483 - Atlantic Highly Migratory Species; Atlantic Shark Management Measures; Amendment 3

Science.gov (United States)

2010-06-01

... and 635 Atlantic Highly Migratory Species; Atlantic Shark Management Measures; Amendment 3; Final Rule... and 635 [Docket No. 080519678-0217-02] RIN 0648-AW65 Atlantic Highly Migratory Species; Atlantic Shark... available to rebuild blacknose sharks and end overfishing of blacknose and shortfin mako sharks, consistent...

Quantification of Massive Seasonal Aggregations of Blacktip Sharks (Carcharhinus limbatus) in Southeast Florida.

Science.gov (United States)

Kajiura, Stephen M; Tellman, Shari L

2016-01-01

Southeast Florida witnesses an enormous seasonal influx of upper trophic level marine predators each year as massive aggregations of migrating blacktip sharks (Carcharhinus limbatus) overwinter in nearshore waters. The narrow shelf and close proximity of the Gulf Stream current to the Palm Beach County shoreline drive tens of thousands of sharks to the shallow, coastal environment. This natural bottleneck provides a unique opportunity to estimate relative abundance. Over a four year period from 2011-2014, an aerial survey was flown approximately biweekly along the length of Palm Beach County. A high definition video camera and digital still camera mounted out of the airplane window provided a continuous record of the belt transect which extended 200 m seaward from the shoreline between Boca Raton Inlet and Jupiter Inlet. The number of sharks within the survey transect was directly counted from the video. Shark abundance peaked in the winter (January-March) with a maximum in 2011 of 12,128 individuals counted within the 75.6 km(-2) belt transect. This resulted in a maximum density of 803.2 sharks km(-2). By the late spring (April-May), shark abundance had sharply declined to 1.1% of its peak, where it remained until spiking again in January of the following year. Shark abundance was inversely correlated with water temperature and large numbers of sharks were found only when water temperatures were less than 25 °C. Shark abundance was also correlated with day of the year but not with barometric pressure. Although shark abundance was not correlated with photoperiod, the departure of the sharks from southeast Florida occurred around the vernal equinox. The shark migration along the United States eastern seaboard corresponds spatially and temporally with the spawning aggregations of various baitfish species. These baseline abundance data can be compared to future studies to determine if shark population size is changing and if sharks are restricting their southward

Vulnerability of oceanic sharks as pelagic longline bycatch

Directory of Open Access Journals (Sweden)

A.J. Gallagher

2014-08-01

Full Text Available Bycatch (the unintentional catch of non-target species or sizes is consistently ranked as one of the greatest threats to marine fish populations; yet species-specific rates of bycatch survival are rarely considered in risk assessments. Regulations often require that bycatch of threatened species be released; but, if animals are already dead, their release serves no conservation purpose. We examined the survival of 12 shark species caught as bycatch in the US Atlantic pelagic longline fishery. Shark survival was evaluated in relation to fishery target (swordfish versus tuna and four operational, environmental, and biological variables to evaluate the underlying mechanisms affecting mortality. Survival estimates ranged from 33% (night shark to 97% (tiger shark with seven of the 12 species being significantly affected by at least one variable. We placed our survival results within a framework that assessed each species’ relative vulnerability by integrating survival estimates with reproductive potential and found that the bigeye thresher, dusky, night, and scalloped hammerhead shark exhibited the highest vulnerabilities to bycatch. We suggest that considering ecological and biological traits of species shows promise for designing effective conservation measures, whereas techniques that reduce fisheries interactions in the first place may be the best strategy for highly vulnerable species.

77 FR 61562 - Atlantic Highly Migratory Species; 2013 Atlantic Shark Commercial Fishing Season

Science.gov (United States)

2012-10-10

.... 120706221-2481-01] RIN 0648-XC106 Atlantic Highly Migratory Species; 2013 Atlantic Shark Commercial Fishing... establish opening dates and adjust quotas for the 2013 fishing season for the Atlantic commercial shark... the 2011 and 2012 Atlantic commercial shark fishing seasons. We propose to keep the porbeagle shark...

Olfaction Contributes to Pelagic Navigation in a Coastal Shark.

Science.gov (United States)

Nosal, Andrew P; Chao, Yi; Farrara, John D; Chai, Fei; Hastings, Philip A

2016-01-01

How animals navigate the constantly moving and visually uniform pelagic realm, often along straight paths between distant sites, is an enduring mystery. The mechanisms enabling pelagic navigation in cartilaginous fishes are particularly understudied. We used shoreward navigation by leopard sharks (Triakis semifasciata) as a model system to test whether olfaction contributes to pelagic navigation. Leopard sharks were captured alongshore, transported 9 km offshore, released, and acoustically tracked for approximately 4 h each until the transmitter released. Eleven sharks were rendered anosmic (nares occluded with cotton wool soaked in petroleum jelly); fifteen were sham controls. Mean swimming depth was 28.7 m. On average, tracks of control sharks ended 62.6% closer to shore, following relatively straight paths that were significantly directed over spatial scales exceeding 1600 m. In contrast, tracks of anosmic sharks ended 37.2% closer to shore, following significantly more tortuous paths that approximated correlated random walks. These results held after swimming paths were adjusted for current drift. This is the first study to demonstrate experimentally that olfaction contributes to pelagic navigation in sharks, likely mediated by chemical gradients as has been hypothesized for birds. Given the similarities between the fluid three-dimensional chemical atmosphere and ocean, further research comparing swimming and flying animals may lead to a unifying paradigm explaining their extraordinary navigational abilities.

Whale Watching in the Gulf of Maine.

Science.gov (United States)

Carkin, Clayton A.

1985-01-01

Describes a variety of teaching strategies to prepare a class for a whale watching field trip. Guidelines for recording a sighting, pictures and statistics for commonly and/or occasionally seen whales, and hints for avoiding sea sickness are included. (DH)

78 FR 54195 - Atlantic Highly Migratory Species; Atlantic Commercial Shark Fisheries

Science.gov (United States)

2013-09-03

.... 110831548-3536-02] RIN 0648-XC836 Atlantic Highly Migratory Species; Atlantic Commercial Shark Fisheries...) dressed weight (dw) of non-blacknose small coastal shark (SCS) quota from the Atlantic region to the Gulf... Atlantic shark permitted vessels. DATES: The quota transfer is effective from September 2, 2013 until...

33 CFR 117.751 - Shark River (South Channel).

Science.gov (United States)

2010-07-01

... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Shark River (South Channel). 117.751 Section 117.751 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES DRAWBRIDGE OPERATION REGULATIONS Specific Requirements New Jersey § 117.751 Shark River (South...

Southern right whales Eubalaena australis visit the coasts of ...

African Journals Online (AJOL)

spamer

Counts and photographs of right whales Eubalaena australis taken on aerial surveys of the southern coast of. South Africa between ... of 0.08–2.89 km.h-1. Theodolite tracking of undisturbed groups of right whales from Cape Columbine produced ...... right whales on the coast of Argentina (Outer Coast) between 1971 and ...

ARM Aerial Facility ArcticShark Unmanned Aerial System

Science.gov (United States)

Schmid, B.; Hubbell, M.; Mei, F.; Carroll, P.; Mendoza, A.; Ireland, C.; Lewko, K.

2017-12-01

The TigerShark Block 3 XP-AR "ArcticShark" Unmanned Aerial System (UAS), developed and manufactured by Navmar Applied Sciences Corporation (NASC), is a single-prop, 60 hp rotary-engine platform with a wingspan of 6.5 m and Maximum Gross Takeoff Weight of 295 Kg. The ArcticShark is owned by the U.S. Department of Energy (DOE) and has been operated by Pacific Northwest National Laboratory (PNNL) since March 2017. The UAS will serve as an airborne atmospheric research observatory for DOE ARM, and, once fully operational, can be requested through ARM's annual call for proposals. The Arctic Shark is anticipated to measure a wide range of radiative, aerosol, and cloud properties using a variable instrument payload weighing up to 46 Kg. SATCOM-equipped, it is capable of taking measurements up to altitudes of 5.5 Km over ranges of up to 500 Km. The ArcticShark operates at airspeeds of 30 to 40 m/s, making it capable of slow sampling. With a full fuel load, its endurance exceeds 8 hours. The aircraft and its Mobile Operations Center (MOC) have been hardened specifically for operations in colder temperatures.ArcticShark's design facilitates rapid integration of various types of payloads. 2500 W of its 4000 W electrical systems is dedicated to payload servicing. It has an interior payload volume of almost 85 L and four wing-mounted pylons capable of carrying external probes. Its payload bay volume, electrical power, payload capacity, and flight characteristics enable the ArcticShark to accommodate multiple combinations of payloads in numerous configurations. Many instruments will be provided by the ARM Aerial Facility (AAF), but other organizations may eventually propose instrumentation for specific campaigns. AAF-provided measurement capabilities will include the following atmospheric state and thermodynamics: temperature, pressure, winds; gases: H2O and CO2; up- and down-welling broadband infrared and visible radiation; surface temperature; aerosol number concentration

78 FR 24148 - Atlantic Highly Migratory Species; Atlantic Shark Management Measures

Science.gov (United States)

2013-04-24

... declared that the status of the dusky shark stock is still overfished and still experiencing overfishing (i... rebuilding and ending overfishing of dusky sharks. This EIS would assess the potential effects on the human environment of action to rebuild and end overfishing of the dusky shark stock, consistent with the Magnuson...

Ocean-wide tracking of pelagic sharks reveals extent of overlap with longline fishing hotspots.

Science.gov (United States)

Queiroz, Nuno; Humphries, Nicolas E; Mucientes, Gonzalo; Hammerschlag, Neil; Lima, Fernando P; Scales, Kylie L; Miller, Peter I; Sousa, Lara L; Seabra, Rui; Sims, David W

2016-02-09

Overfishing is arguably the greatest ecological threat facing the oceans, yet catches of many highly migratory fishes including oceanic sharks remain largely unregulated with poor monitoring and data reporting. Oceanic shark conservation is hampered by basic knowledge gaps about where sharks aggregate across population ranges and precisely where they overlap with fishers. Using satellite tracking data from six shark species across the North Atlantic, we show that pelagic sharks occupy predictable habitat hotspots of high space use. Movement modeling showed sharks preferred habitats characterized by strong sea surface-temperature gradients (fronts) over other available habitats. However, simultaneous Global Positioning System (GPS) tracking of the entire Spanish and Portuguese longline-vessel fishing fleets show an 80% overlap of fished areas with hotspots, potentially increasing shark susceptibility to fishing exploitation. Regions of high overlap between oceanic tagged sharks and longliners included the North Atlantic Current/Labrador Current convergence zone and the Mid-Atlantic Ridge southwest of the Azores. In these main regions, and subareas within them, shark/vessel co-occurrence was spatially and temporally persistent between years, highlighting how broadly the fishing exploitation efficiently "tracks" oceanic sharks within their space-use hotspots year-round. Given this intense focus of longliners on shark hotspots, our study argues the need for international catch limits for pelagic sharks and identifies a future role of combining fine-scale fish and vessel telemetry to inform the ocean-scale management of fisheries.

Shark fisheries in the Southeast Pacific: A 61-year analysis from Peru

Science.gov (United States)

Gonzalez-Pestana, Adriana; Kouri J., Carlos; Velez-Zuazo, Ximena

2016-01-01

Peruvian waters exhibit high conservation value for sharks. This contrasts with a lag in initiatives for their management and a lack of studies about their biology, ecology and fishery. We investigated the dynamics of Peruvian shark fishery and its legal framework identifying information gaps for recommending actions to improve management. Further, we investigated the importance of the Peruvian shark fishery from a regional perspective. From 1950 to 2010, 372,015 tons of sharks were landed in Peru. From 1950 to 1969, we detected a significant increase in landings; but from 2000 to 2011 there was a significant decrease in landings, estimated at 3.5% per year. Six species represented 94% of landings: blue shark ( Prionace glauca), shortfin mako ( Isurus oxyrinchus), smooth hammerhead ( Sphyrna zygaena), common thresher ( Alopias vulpinus), smooth-hound ( Mustelus whitneyi) and angel shark ( Squatina californica). Of these, the angel shark exhibits a strong and significant decrease in landings: 18.9% per year from 2000 to 2010. Peru reports the highest accumulated historical landings in the Pacific Ocean; but its contribution to annual landings has decreased since 1968. Still, Peru is among the top 12 countries exporting shark fins to the Hong Kong market. Although the government collects total weight by species, the number of specimens landed as well as population parameters (e.g. sex, size and weight) are not reported. Further, for some genera, species-level identification is deficient and so overestimates the biomass landed by species and underestimates the species diversity. Recently, regional efforts to regulate shark fishery have been implemented to support the conservation of sharks but in Peru work remains to be done. PMID:27635216

Tiger sharks can connect equatorial habitats and fisheries across the Atlantic Ocean basin.

Science.gov (United States)

Afonso, André S; Garla, Ricardo; Hazin, Fábio H V

2017-01-01

Increasing our knowledge about the spatial ecology of apex predators and their interactions with diverse habitats and fisheries is necessary for understanding the trophic mechanisms that underlie several aspects of marine ecosystem dynamics and for guiding informed management policies. A preliminary assessment of tiger shark (Galeocerdo cuvier) population structure off the oceanic insular system of Fernando de Noronha (FEN) and the large-scale movements performed by this species in the equatorial Atlantic Ocean was conducted using longline and handline fishing gear and satellite telemetry. A total of 25 sharks measuring 175-372 cm in total length (TL) were sampled. Most sharks were likely immature females ranging between 200 and 260 cm TL, with few individuals shark size-distribution previously reported for coastal waters off the Brazilian mainland, where most individuals measured shark-1; SD = 65.6). These sharks exhibited a considerable variability in their horizontal movements, with three sharks showing a mostly resident behavior around FEN during the extent of the respective tracks, two sharks traveling west to the South American continent, and two sharks moving mostly along the middle of the oceanic basin, one of which ending up in the northern hemisphere. Moreover, one shark traveled east to the African continent, where it was eventually caught by fishers from Ivory Coast in less than 474 days at liberty. The present results suggest that young tiger sharks measuring sharks are able to connect marine trophic webs from the neritic provinces of the eastern and western margins of the Atlantic Ocean across the equatorial basin and that they may experience mortality induced by remote fisheries. All this information is extremely relevant for understanding the energetic balance of marine ecosystems as much as the exposure of this species to fishing pressure in this yet poorly-known region.

Survey sequencing and comparative analysis of the elephant shark (Callorhinchus milii genome.

Directory of Open Access Journals (Sweden)

Byrappa Venkatesh

2007-04-01

Full Text Available Owing to their phylogenetic position, cartilaginous fishes (sharks, rays, skates, and chimaeras provide a critical reference for our understanding of vertebrate genome evolution. The relatively small genome of the elephant shark, Callorhinchus milii, a chimaera, makes it an attractive model cartilaginous fish genome for whole-genome sequencing and comparative analysis. Here, the authors describe survey sequencing (1.4x coverage and comparative analysis of the elephant shark genome, one of the first cartilaginous fish genomes to be sequenced to this depth. Repetitive sequences, represented mainly by a novel family of short interspersed element-like and long interspersed element-like sequences, account for about 28% of the elephant shark genome. Fragments of approximately 15,000 elephant shark genes reveal specific examples of genes that have been lost differentially during the evolution of tetrapod and teleost fish lineages. Interestingly, the degree of conserved synteny and conserved sequences between the human and elephant shark genomes are higher than that between human and teleost fish genomes. Elephant shark contains putative four Hox clusters indicating that, unlike teleost fish genomes, the elephant shark genome has not experienced an additional whole-genome duplication. These findings underscore the importance of the elephant shark as a critical reference vertebrate genome for comparative analysis of the human and other vertebrate genomes. This study also demonstrates that a survey-sequencing approach can be applied productively for comparative analysis of distantly related vertebrate genomes.

Widespread utility of highly informative AFLP molecular markers across divergent shark species.

Science.gov (United States)

Zenger, Kyall R; Stow, Adam J; Peddemors, Victor; Briscoe, David A; Harcourt, Robert G

2006-01-01

Population numbers of many shark species are declining rapidly around the world. Despite the commercial and conservation significance, little is known on even the most fundamental aspects of their population biology. Data collection that relies on direct observation can be logistically challenging with sharks. Consequently, molecular methods are becoming increasingly important to obtain knowledge that is critical for conservation and management. Here we describe an amplified fragment length polymorphism method that can be applied universally to sharks to identify highly informative genome-wide polymorphisms from 12 primer pairs. We demonstrate the value of our method on 15 divergent shark species within the superorder Galeomorphii, including endangered species which are notorious for low levels of genetic diversity. Both the endangered sand tiger shark (Carcharodon taurus, N = 18) and the great white shark (Carcharodon carcharias, N = 7) displayed relatively high levels of allelic diversity. A total of 59 polymorphic loci (H(e) = 0.373) and 78 polymorphic loci (H(e) = 0.316) were resolved in C. taurus and C. carcharias, respectively. Results from other sharks (e.g., Orectolobus ornatus, Orectolobus sp., and Galeocerdo cuvier) produced remarkably high numbers of polymorphic loci (106, 94, and 86, respectively) from a limited sample size of only 2. A major constraint to obtaining much needed genetic data from sharks is the time-consuming process of developing molecular markers. Here we demonstrate the general utility of a technique that provides large numbers of informative loci in sharks.

Killer Whale Genetic Data - Southern resident killer whale pedigree analysis

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — In this project, we are using genetic variation to infer mating patterns in the southern killer whale community. In Canada, this population was listed as threatened...

Evolutionary immunology. A boost to immunity from nurse sharks.

Science.gov (United States)

Parham, P

1995-07-01

A study of the nurse shark has revealed a type of rearranging gene that has yet to be seen in mammals; it encodes a secreted 'new antigen receptor' which, unlike shark immunoglobulin, revels in somatic hypermutation.

Modulation of shark prey capture kinematics in response to sensory deprivation.

Science.gov (United States)

Gardiner, Jayne M; Atema, Jelle; Hueter, Robert E; Motta, Philip J

2017-02-01

The ability of predators to modulate prey capture in response to the size, location, and behavior of prey is critical to successful feeding on a variety of prey types. Modulating in response to changes in sensory information may be critical to successful foraging in a variety of environments. Three shark species with different feeding morphologies and behaviors were filmed using high-speed videography while capturing live prey: the ram-feeding blacktip shark, the ram-biting bonnethead, and the suction-feeding nurse shark. Sharks were examined intact and after sensory information was blocked (olfaction, vision, mechanoreception, and electroreception, alone and in combination), to elucidate the contribution of the senses to the kinematics of prey capture. In response to sensory deprivation, the blacktip shark demonstrated the greatest amount of modulation, followed by the nurse shark. In the absence of olfaction, blacktip sharks open the jaws slowly, suggestive of less motivation. Without lateral line cues, blacktip sharks capture prey from greater horizontal angles using increased ram. When visual cues are absent, blacktip sharks elevate the head earlier and to a greater degree, allowing them to overcome imprecise position of the prey relative to the mouth, and capture prey using decreased ram, while suction remains unchanged. When visual cues are absent, nurse sharks open the mouth wider, extend the labial cartilages further, and increase suction while simultaneously decreasing ram. Unlike some bony fish, neither species switches feeding modalities (i.e. from ram to suction or vice versa). Bonnetheads failed to open the mouth when electrosensory cues were blocked, but otherwise little to no modulation was found in this species. These results suggest that prey capture may be less plastic in elasmobranchs than in bony fishes, possibly due to anatomical differences, and that the ability to modulate feeding kinematics in response to available sensory information varies

Mercury in shark in western Australia: a preliminary report

Energy Technology Data Exchange (ETDEWEB)

Hancock, D.A.; Edmonds, J.S.; Edinger, J.J.

1977-01-01

Linear and curvilinear regressions relating mercury concentration and size were used in conjunction with catch data to estimate the average concentration in the three major shark species in the Western Australia fishery industry. The three species were whiskery (Furgaleus ventralis), bronze whaler (Carcharhinus obscurus) and gummy (Emissola antarctica) sharks. The averge mercury concentration for the 3 species was found to be approximately 0.75 ppM. The relevance of this to Public Health regulations was discussed and the need for information on consumption of shark stressed.

Are Caribbean reef sharks, Carcharhinus perezi, able to perceive human body orientation?

Science.gov (United States)

Ritter, Erich K; Amin, Raid

2014-05-01

The present study examines the potential capability of Caribbean reef sharks to perceive human body orientation, as well as discussing the sharks' swimming patterns in a person's vicinity. A standardized video method was used to record the scenario of single SCUBA divers kneeling in the sand and the approach patterns of sharks, combined with a control group of two divers kneeling back-to-back. When approaching a single test-subject, significantly more sharks preferred to swim outside the person's field of vision. The results suggest that these sharks are able to identify human body orientation, but the mechanisms used and factors affecting nearest distance of approach remain unclear.

Baleen whales and their prey in a coastal environment

Science.gov (United States)

Piatt, John F.; Methven, David A.; Burger, Alan E.; McLagan, Ruth L.; Mercer, Vicki; Creelman, Elizabeth

1989-01-01

Patterns of abundance of humpback (Megaptera novaeangliae), fin (Balaenoptera physalus), and minke (Balaenoptera acutorostrata) whales are described in relation to the abundance of their primary prey, capelin (Mallotus villosus), during 1982–1985 at Witless Bay, Newfoundland. The abundance ratio of the three whale species was 10:1:3.5, respectively. Abundance of all whale species was strongly correlated with abundance of capelin through each season and between years. Capelin abundance accounted for 63% of the variation in whale numbers in 1983 and 1984, while environmental parameters (e.g., water temperatures) accounted for little variance. The amount of capelin consumed by whales was small (< 2%) compared with the amount available. All three species overlapped temporally at Witless Bay, but spatial overlap was reduced as fins occurred primarily offshore, minkes primarily inshore, and humpbacks in bay habitats of intermediate depth.

Ultrastructure Organization of Collagen Fibrils and Proteoglycans of Stingray and Shark Corneal Stroma

Directory of Open Access Journals (Sweden)

Saud A. Alanazi

2015-01-01

Full Text Available We report here the ultrastructural organization of collagen fibrils (CF and proteoglycans (PGs of the corneal stroma of both the stingray and the shark. Three corneas from three stingrays and three corneas from three sharks were processed for electron microscopy. Tissues were embedded in TAAB 031 resin. The corneal stroma of both the stingray and shark consisted of parallel running lamellae of CFs which were decorated with PGs. In the stingray, the mean area of PGs in the posterior stroma was significantly larger than the PGs of the anterior and middle stroma, whereas, in the shark, the mean area of PGs was similar throughout the stroma. The mean area of PGs of the stingray was significantly larger compared to the PGs, mean area of the shark corneal stroma. The CF diameter of the stingray was significantly smaller compared to the CF diameter in the shark. The ultrastructural features of the corneal stroma of both the stingray and the shark were similar to each other except for the CFs and PGs. The PGs in the stingray and shark might be composed of chondroitin sulfate (CS/dermatan sulfate (DS PGs and these PGs with sutures might contribute to the nonswelling properties of the cornea of the stingray and shark.

Summary of Reported Whale-Vessel Collisions in Alaskan Waters

Directory of Open Access Journals (Sweden)

Janet L. Neilson

2012-01-01

Full Text Available Here we summarize 108 reported whale-vessel collisions in Alaska from 1978–2011, of which 25 are known to have resulted in the whale's death. We found 89 definite and 19 possible/probable strikes based on standard criteria we created for this study. Most strikes involved humpback whales (86% with six other species documented. Small vessel strikes were most common (<15 m, 60%, but medium (15–79 m, 27% and large (≥80 m, 13% vessels also struck whales. Among the 25 mortalities, vessel length was known in seven cases (190–294 m and vessel speed was known in three cases (12–19 kn. In 36 cases, human injury or property damage resulted from the collision, and at least 15 people were thrown into the water. In 15 cases humpback whales struck anchored or drifting vessels, suggesting the whales did not detect the vessels. Documenting collisions in Alaska will remain challenging due to remoteness and resource limitations. For a better understanding of the factors contributing to lethal collisions, we recommend (1 systematic documentation of collisions, including vessel size and speed; (2 greater efforts to necropsy stranded whales; (3 using experienced teams focused on determining cause of death; (4 using standard criteria for validating collision reports, such as those presented in this paper.

Great white sharks: the biology of Carcharodon carcharias

National Research Council Canada - National Science Library

Klimley, A.P; Ainley, D.G

1996-01-01

... Morphology 37 Systematics of the Lamnidae and the Origination Time of Carcharodon carcharias Inferred from the Comparative Analysis of Mitochondrial DNA Sequences Size and Skeletal Anatomy of the Giant "Megatooth" Shark Carcharodon megalodon 55 Paleoecology of Fossil White Sharks 67 4. 5. 6. 7. 8. 11. Temperature, Swimming Depth, and Movements ...

75 FR 8304 - Schedules for Atlantic Shark Identification Workshops and Protected Species Safe Handling...

Science.gov (United States)

2010-02-24

... Atlantic Shark Identification Workshops and Protected Species Safe Handling, Release, and Identification... gear, and have also been issued shark or swordfish limited access permits. Additional free workshops... Coastal Highway, Ocean City, MD 21842. Atlantic Shark Identification Workshop Since January 1, 2007, shark...

50 CFR 635.24 - Commercial retention limits for sharks and swordfish.

Science.gov (United States)

2010-10-01

... 50 Wildlife and Fisheries 8 2010-10-01 2010-10-01 false Commercial retention limits for sharks and... Management Measures § 635.24 Commercial retention limits for sharks and swordfish. The retention limits in this section are subject to the quotas and closure provisions in §§ 635.27 and 635.28. (a) Sharks. (1...

Field hearing measurements of the Atlantic sharpnose shark Rhizoprionodon terraenovae.

Science.gov (United States)

Casper, B M; Mann, D A

2009-12-01

Field measurements of hearing thresholds were obtained from the Atlantic sharpnose shark Rhizoprionodon terraenovae using the auditory evoked potential method (AEP). The fish had most sensitive hearing at 20 Hz, the lowest frequency tested, with decreasing sensitivity at higher frequencies. Hearing thresholds were lower than AEP thresholds previously measured for the nurse shark Ginglymostoma cirratum and yellow stingray Urobatis jamaicensis at frequencies sharks which have been observed in acoustic field attraction experiments. The sound pressure levels that would be equivalent to the particle acceleration thresholds of R. terraenovae were much higher than the sound levels which attracted closely related sharks suggesting a discrepancy between the hearing threshold experiments and the field attraction experiments.

Immunoglobulins in the eggs of the nurse shark, Ginglymostoma cirratum.

Science.gov (United States)

Haines, Ashley N; Flajnik, Martin F; Rumfelt, Lynn L; Wourms, John P

2005-01-01

Elasmobranchs, which include the sharks, skates, and rays, emerged over 450 million years ago and are the oldest vertebrates to possess an adaptive immune system. They have evolved diverse reproductive modes, with a variety of physiological adaptations that enhance reproductive success. The nurse shark, Ginglymostoma cirratum, is an aplacental, viviparous elasmobranch in which the egg and its associated vitelline vasculature are the primary route for maternal-embryonic interactions. During gestation, nurse shark embryos hatch from their eggcases and develop free in the uterus, which is flushed regularly with seawater. Similar to higher vertebrates, embryonic and neonatal nurse sharks possess an immune system that is not fully competent. In birds and bony fishes, maternal immunoglobulins (Ig) stored in the egg during oogenesis confer protective immunity to embryos during gestation. However, early research suggested that such transfer of passive immunity does not occur in sharks. To better understand how elasmobranch embryos are protected from waterborne pathogens during this potentially vulnerable time, we have re-examined the existence of Igs in elasmobranch eggs. Using monoclonal antibodies, we establish the presence of two classes of Igs in nurse shark eggs: 7S IgM and IgNAR. The potential transfer of immunoglobulins from elasmobranch eggs is discussed.

Click rates and silences of sperm whales at Kaikoura, New Zealand

Science.gov (United States)

Douglas, Lesley A.; Dawson, Stephen M.; Jaquet, Nathalie

2005-07-01

Analysis of the usual click rates of sperm whales (Physeter macrocephalus) at Kaikoura, New Zealand, confirms the potential for assessing abundance via ``click counting.'' Usual click rates over three dive cycles each of three photographically identified whales showed that 5 min averages of usual click rate did not differ significantly within dives, among dives of the same whale or among whales. Over the nine dives (n=13 728 clicks) mean usual click rate was 1.272 clicks s-1 (95% CI=0.151). On average, individual sperm whales at Kaikoura spent 60% of their time usual clicking in winter and in summer. There was no evidence that whale identity or stage of the dive recorded affects significantly the percentage of time spent usual clicking. Differences in vocal behavior among sperm whale populations worldwide indicate that estimates of abundance that are based on click rates need to based on data from the population of interest, rather than from another population or some global average.

Food and feeding of sperm whales physeter macrocephalus off the ...

African Journals Online (AJOL)

The stomach contents of 1 268 sperm whales Physeter macrocephalus processed at the Donkergat whaling station, South Africa, were examined during the 1962 and 1963 whaling seasons. Results were compared with. Clarkefs analysis of cephalopod beaks collected in 1963 (Clarke 1980). There was no significant ...

Large Whale Biology Survey (DE9908, EK500)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The large whale biology survey primarily focuses on right whales in the coastal and continental shelf areas, with the following objectives: 1) Develop a better...

Gulf of Mexico sperm whale photo-ID catalog

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Photo-identification data on sperm whales occupying the north central Gulf of Mexico have been collected during vessel surveys. Photographs of sperm whales are taken...

Propulsion of a fin whale (Balaenoptera physalus): why the fin whale is a fast swimmer.

Science.gov (United States)

Bose, N; Lien, J

1989-07-22

Measurements of an immature fin whale (Balaenoptera physalus), which died as a result of entrapment in fishing gear near Frenchmans Cove, Newfoundland (47 degrees 9' N, 55 degrees 25' W), were made to obtain estimates of volume and surface area of the animal. Detailed measurements of the flukes, both planform and sections, were also obtained. A strip theory was developed to calculate the hydrodynamic performance of the whale's flukes as an oscillating propeller. This method is based on linear, two-dimensional, small-amplitude, unsteady hydrofoil theory with correction factors used to account for the effects of finite span and finite amplitude motion. These correction factors were developed from theoretical results of large-amplitude heaving motion and unsteady lifting-surface theory. A model that makes an estimate of the effects of viscous flow on propeller performance was superimposed on the potential-flow results. This model estimates the drag of the hydrofoil sections by assuming that the drag is similar to that of a hydrofoil section in steady flow. The performance characteristics of the flukes of the fin whale were estimated by using this method. The effects of the different correction factors, and of the frictional drag of the fluke sections, are emphasized. Frictional effects in particular were found to reduce the hydrodynamic efficiency of the flukes significantly. The results are discussed and compared with the known characteristics of fin-whale swimming.

76 FR 53343 - Atlantic Highly Migratory Species; Commercial Porbeagle Shark Fishery Closure

Science.gov (United States)

2011-08-26

...-XA658 Atlantic Highly Migratory Species; Commercial Porbeagle Shark Fishery Closure AGENCY: National...: Temporary rule; fishery closure. SUMMARY: NMFS is closing the commercial fishery for porbeagle sharks. This... available quota. DATES: The commercial porbeagle shark fishery is closed effective 11:30 p.m. local time...

Northern Right Whale Survey (DE0107, EK500)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The right whale and cetacean survey primarily focuses on right whales in the coastal and continental shelf areas, with the following objectives: 1) Develop a better...

Northern Right Whale Survey (DE0306, EK500)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The right whale and cetacean survey primarily focuses on right whales in the coastal and continental shelf areas, with the following objectives: 1) Develop a better...

Acoustic telemetry validates a citizen science approach for monitoring sharks on coral reefs.

Science.gov (United States)

Vianna, Gabriel M S; Meekan, Mark G; Bornovski, Tova H; Meeuwig, Jessica J

2014-01-01

Citizen science is promoted as a simple and cost-effective alternative to traditional approaches for the monitoring of populations of marine megafauna. However, the reliability of datasets collected by these initiatives often remains poorly quantified. We compared datasets of shark counts collected by professional dive guides with acoustic telemetry data from tagged sharks collected at the same coral reef sites over a period of five years. There was a strong correlation between the number of grey reef sharks (Carcharhinus amblyrhynchos) observed by dive guides and the telemetry data at both daily and monthly intervals, suggesting that variation in relative abundance of sharks was detectable in datasets collected by dive guides in a similar manner to data derived from telemetry at these time scales. There was no correlation between the number or mean depth of sharks recorded by telemetry and the presence of tourist divers, suggesting that the behaviour of sharks was not affected by the presence of divers during our study. Data recorded by dive guides showed that current strength and temperature were important drivers of the relative abundance of sharks at monitored sites. Our study validates the use of datasets of shark abundance collected by professional dive guides in frequently-visited dive sites in Palau, and supports the participation of experienced recreational divers as contributors to long-term monitoring programs of shark populations.

Diet and condition of mesopredators on coral reefs in relation to shark abundance.

Directory of Open Access Journals (Sweden)

Shanta C Barley

Full Text Available Reef sharks may influence the foraging behaviour of mesopredatory teleosts on coral reefs via both risk effects and competitive exclusion. We used a "natural experiment" to test the hypothesis that the loss of sharks on coral reefs can influence the diet and body condition of mesopredatory fishes by comparing two remote, atoll-like reef systems, the Rowley Shoals and the Scott Reefs, in northwestern Australia. The Rowley Shoals are a marine reserve where sharks are abundant, whereas at the Scott Reefs numbers of sharks have been reduced by centuries of targeted fishing. On reefs where sharks were rare, the gut contents of five species of mesopredatory teleosts largely contained fish while on reefs with abundant sharks, the same mesopredatory species consumed a larger proportion of benthic invertebrates. These measures of diet were correlated with changes in body condition, such that the condition of mesopredatory teleosts was significantly poorer on reefs with higher shark abundance. Condition was defined as body weight, height and width for a given length and also estimated via several indices of condition. Due to the nature of natural experiments, alternative explanations cannot be discounted. However, the results were consistent with the hypothesis that loss of sharks may influence the diet and condition of mesopredators and by association, their fecundity and trophic role. Regardless of the mechanism (risk effects, competitive release, or other, our findings suggest that overfishing of sharks has the potential to trigger trophic cascades on coral reefs and that further declines in shark populations globally should be prevented to protect ecosystem health.

Diet and condition of mesopredators on coral reefs in relation to shark abundance.

Science.gov (United States)

Barley, Shanta C; Meekan, Mark G; Meeuwig, Jessica J

2017-01-01

Reef sharks may influence the foraging behaviour of mesopredatory teleosts on coral reefs via both risk effects and competitive exclusion. We used a "natural experiment" to test the hypothesis that the loss of sharks on coral reefs can influence the diet and body condition of mesopredatory fishes by comparing two remote, atoll-like reef systems, the Rowley Shoals and the Scott Reefs, in northwestern Australia. The Rowley Shoals are a marine reserve where sharks are abundant, whereas at the Scott Reefs numbers of sharks have been reduced by centuries of targeted fishing. On reefs where sharks were rare, the gut contents of five species of mesopredatory teleosts largely contained fish while on reefs with abundant sharks, the same mesopredatory species consumed a larger proportion of benthic invertebrates. These measures of diet were correlated with changes in body condition, such that the condition of mesopredatory teleosts was significantly poorer on reefs with higher shark abundance. Condition was defined as body weight, height and width for a given length and also estimated via several indices of condition. Due to the nature of natural experiments, alternative explanations cannot be discounted. However, the results were consistent with the hypothesis that loss of sharks may influence the diet and condition of mesopredators and by association, their fecundity and trophic role. Regardless of the mechanism (risk effects, competitive release, or other), our findings suggest that overfishing of sharks has the potential to trigger trophic cascades on coral reefs and that further declines in shark populations globally should be prevented to protect ecosystem health.

77 FR 32036 - Atlantic Highly Migratory Species; Commercial Porbeagle Shark Fishery Closure

Science.gov (United States)

2012-05-31

...-XC044 Atlantic Highly Migratory Species; Commercial Porbeagle Shark Fishery Closure AGENCY: National...: Temporary rule; fishery closure. SUMMARY: NMFS is closing the commercial fishery for porbeagle sharks. This... available quota. DATES: The commercial porbeagle shark fishery is closed effective 11:30 p.m. local time May...

Residency and spatial use by reef sharks of an isolated seamount and its implications for conservation.

Science.gov (United States)

Barnett, Adam; Abrantes, Kátya G; Seymour, Jamie; Fitzpatrick, Richard

2012-01-01

Although marine protected areas (MPAs) are a common conservation strategy, these areas are often designed with little prior knowledge of the spatial behaviour of the species they are designed to protect. Currently, the Coral Sea area and its seamounts (north-east Australia) are under review to determine if MPAs are warranted. The protection of sharks at these seamounts should be an integral component of conservation plans. Therefore, knowledge on the spatial ecology of sharks at the Coral Sea seamounts is essential for the appropriate implementation of management and conservation plans. Acoustic telemetry was used to determine residency, site fidelity and spatial use of three shark species at Osprey Reef: whitetip reef sharks Triaenodon obesus, grey reef sharks Carcharhinus amblyrhynchos and silvertip sharks Carcharhinus albimarginatus. Most individuals showed year round residency at Osprey Reef, although five of the 49 individuals tagged moved to the neighbouring Shark Reef (~14 km away) and one grey reef shark completed a round trip of ~250 km to the Great Barrier Reef. Additionally, individuals of white tip and grey reef sharks showed strong site fidelity to the areas they were tagged, and there was low spatial overlap between groups of sharks tagged at different locations. Spatial use at Osprey Reef by adult sharks is generally restricted to the north-west corner. The high residency and limited spatial use of Osprey Reef suggests that reef sharks would be highly vulnerable to targeted fishing pressure and that MPAs incorporating no-take of sharks would be effective in protecting reef shark populations at Osprey and Shark Reef.

Residency and spatial use by reef sharks of an isolated seamount and its implications for conservation.

Directory of Open Access Journals (Sweden)

Adam Barnett

Full Text Available Although marine protected areas (MPAs are a common conservation strategy, these areas are often designed with little prior knowledge of the spatial behaviour of the species they are designed to protect. Currently, the Coral Sea area and its seamounts (north-east Australia are under review to determine if MPAs are warranted. The protection of sharks at these seamounts should be an integral component of conservation plans. Therefore, knowledge on the spatial ecology of sharks at the Coral Sea seamounts is essential for the appropriate implementation of management and conservation plans. Acoustic telemetry was used to determine residency, site fidelity and spatial use of three shark species at Osprey Reef: whitetip reef sharks Triaenodon obesus, grey reef sharks Carcharhinus amblyrhynchos and silvertip sharks Carcharhinus albimarginatus. Most individuals showed year round residency at Osprey Reef, although five of the 49 individuals tagged moved to the neighbouring Shark Reef (~14 km away and one grey reef shark completed a round trip of ~250 km to the Great Barrier Reef. Additionally, individuals of white tip and grey reef sharks showed strong site fidelity to the areas they were tagged, and there was low spatial overlap between groups of sharks tagged at different locations. Spatial use at Osprey Reef by adult sharks is generally restricted to the north-west corner. The high residency and limited spatial use of Osprey Reef suggests that reef sharks would be highly vulnerable to targeted fishing pressure and that MPAs incorporating no-take of sharks would be effective in protecting reef shark populations at Osprey and Shark Reef.

Residency and Spatial Use by Reef Sharks of an Isolated Seamount and Its Implications for Conservation

Science.gov (United States)

Barnett, Adam; Abrantes, Kátya G.; Seymour, Jamie; Fitzpatrick, Richard

2012-01-01

Although marine protected areas (MPAs) are a common conservation strategy, these areas are often designed with little prior knowledge of the spatial behaviour of the species they are designed to protect. Currently, the Coral Sea area and its seamounts (north-east Australia) are under review to determine if MPAs are warranted. The protection of sharks at these seamounts should be an integral component of conservation plans. Therefore, knowledge on the spatial ecology of sharks at the Coral Sea seamounts is essential for the appropriate implementation of management and conservation plans. Acoustic telemetry was used to determine residency, site fidelity and spatial use of three shark species at Osprey Reef: whitetip reef sharks Triaenodon obesus, grey reef sharks Carcharhinus amblyrhynchos and silvertip sharks Carcharhinus albimarginatus. Most individuals showed year round residency at Osprey Reef, although five of the 49 individuals tagged moved to the neighbouring Shark Reef (∼14 km away) and one grey reef shark completed a round trip of ∼250 km to the Great Barrier Reef. Additionally, individuals of white tip and grey reef sharks showed strong site fidelity to the areas they were tagged, and there was low spatial overlap between groups of sharks tagged at different locations. Spatial use at Osprey Reef by adult sharks is generally restricted to the north-west corner. The high residency and limited spatial use of Osprey Reef suggests that reef sharks would be highly vulnerable to targeted fishing pressure and that MPAs incorporating no-take of sharks would be effective in protecting reef shark populations at Osprey and Shark Reef. PMID:22615782

Do White Shark Bites on Surfers Reflect Their Attack Strategies on Pinnipeds?

Directory of Open Access Journals (Sweden)

Erich Ritter

2016-01-01

Full Text Available The theory of mistaken identity states that sharks, especially white sharks, Carcharodon carcharias, mistake surfers for pinnipeds when looking at them from below and thus bite them erroneously. Photographs of surfer wounds and board damage were interpreted with special emphasis on shark size, wound severity, and extent of damage to a board. These were compared with the concurrent literature on attack strategies of white sharks on pinnipeds and their outcomes. The results show that the majority of damage to surfers and their boards is at best superficial-to-moderate in nature and does not reflect the level of damage needed to immobilize or stun a pinniped. It is further shown that the size distribution of sharks biting surfers differs from that in pinnipeds. The results presented show that the theory of mistaken identity, where white sharks erroneously mistake surfers for pinnipeds, does not hold true and should be rejected.

Humpback whale, Megaptera novaeangliae, song during the ...

African Journals Online (AJOL)

Colombia Foundation to educate the communities of the Gulf of. Tribugá about the ... humpback whales (Winn and Winn 1978). Humpback whale song. ARTICLE .... mental (e.g., wind, waves) or anthropogenic (e.g., water craft) fea- tures, as well ..... rine Sanctuary, Division of Aquatic Resources, Department of Land and Na-.

Sperm whales reduce foraging effort during exposure to 1-2 kHz sonar and killer whale sounds.

Science.gov (United States)

Isojunno, Saana; Cure, Charlotte; Kvadsheim, Petter Helgevold; Lam, Frans-Peter Alexander; Tyack, Peter Lloyd; Wensveen, Paul Jacobus; Miller, Patrick James O'Malley

2016-01-01

The time and energetic costs of behavioral responses to incidental and experimental sonar exposures, as well as control stimuli, were quantified using hidden state analysis of time series of acoustic and movement data recorded by tags (DTAG) attached to 12 sperm whales (Physeter macrocephalus) using suction cups. Behavioral state transition modeling showed that tagged whales switched to a non-foraging, non-resting state during both experimental transmissions of low-frequency active sonar from an approaching vessel (LFAS; 1-2 kHz, source level 214 dB re 1 µPa m, four tag records) and playbacks of potential predator (killer whale, Orcinus orca) sounds broadcast at naturally occurring sound levels as a positive control from a drifting boat (five tag records). Time spent in foraging states and the probability of prey capture attempts were reduced during these two types of exposures with little change in overall locomotion activity, suggesting an effect on energy intake with no immediate compensation. Whales switched to the active non-foraging state over received sound pressure levels of 131-165 dB re 1 µPa during LFAS exposure. In contrast, no changes in foraging behavior were detected in response to experimental negative controls (no-sonar ship approach or noise control playback) or to experimental medium-frequency active sonar exposures (MFAS; 6-7 kHz, source level 199 re 1 µPa m, received sound pressure level [SPL] = 73-158 dB re 1 µPa). Similarly, there was no reduction in foraging effort for three whales exposed to incidental, unidentified 4.7-5.1 kHz sonar signals received at lower levels (SPL = 89-133 dB re 1 µPa). These results demonstrate that similar to predation risk, exposure to sonar can affect functional behaviors, and indicate that increased perception of risk with higher source level or lower frequency may modulate how sperm whales respond to anthropogenic sound.

Active predation by Greenland shark Somniosus microcephalus

DEFF Research Database (Denmark)

Nielsen, Julius; hedeholm, Rasmus; Simon, Malene

2013-01-01

and show that the sharks catch epi-benthic species with Atlantic cod being the most important (% IRI = 56 ), followed by squid (% IRI= 13 ) and wolf fish (IRI=4). Furthermore seal was found in 50 % of all stomachs (% IRI= 13). In addition to providing new knowledge of feeding habits of this species......Dansk Havforskermøde 2013 Julius Nielsen, Rasmus Hedeholm, Malene Simon og John Fleng Steffensen The Greenland shark is ubiquitous in the northern part of the North Atlantic ranging from eastern Canada to northwest Russia . Although knowledge is scarce it is believed to be abundant and potentially...... important part of the ecosystem. Whether Greenland sharks in general should be considered opportunistic scavengers or active predators is therefore important in understanding ecosystem dynamics. Due to its sluggish appearance and a maximum reported swimming speed of 74 cm per second scavenging seems...

On Sharks, Trolls, and Other Patent Animals

DEFF Research Database (Denmark)

Reitzig, Markus; Henkel, Joachim; Heath, Christopher

2007-01-01

Patent trolls (or sharks) are small patent holding individuals or firms who trap R&D intense manufacturers in patent infringement situations in order to receive damage awards for the illegitimate use of their technology. While of great concern to management, their existence and impact for both...... corporate decision makers and policy makers remains to be fully analyzed from an academic standpoint. In this paper we show why patent sharks can operate profitably, why they are of growing concern, how manufacturers can forearm themselves against them, and which issues policy makers need to address. To do...... so, we map international indemnification rules with strategic rationales of small patent-holding firms within a game-theoretical model. Our central finding is that the courts’ unrealistic consideration of the trade-offs faced by inadvertent infringers is a central condition for sharks to operate...

Whale-Watching

Science.gov (United States)

Lande, Rivian

1973-01-01

Describes a program initiated by the Cabrillo Beach Museum (San Pedro, California) and the American Cetacean Society to take students of the fourth grade through high school on half-day cruises to observe gray whales. College students assist in the program with related field projects and presentations in the schools. (JR)

Thermal Imaging and Biometrical Thermography of Humpback Whales

Directory of Open Access Journals (Sweden)

Travis W. Horton

2017-12-01

Full Text Available Determining species' distributions through time and space remains a primary challenge in cetacean science and conservation. For example, many whales migrate thousands of kilometers every year between remote seasonal habitats along migratory corridors that cross major shipping lanes and intensively harvested fisheries, creating a dynamic spatial and temporal context that conservation decisions must take into account. Technological advances enabling automated whale detection have the potential to dramatically improve our knowledge of when and where whales are located, presenting opportunities to help minimize adverse human-whale interactions. Using thermographic data we show that near-horizontal (i.e., high zenith angle infrared images of humpback whale (Megaptera novaeangliae blows, dorsal fins, flukes and rostrums record similar magnitude brightness temperature anomalies relative to the adjacent ocean surface. Our results demonstrate that these anomalies are similar in both low latitude and high latitude environments despite a ~16°C difference in ocean surface temperature between study areas. We show that these similarities occur in both environments due to emissivity effects associated with oblique target imaging, rather than differences in cetacean thermoregulation. The consistent and reproducible brightness temperature anomalies we report provide important quantitative constraints that will help facilitate the development of transient temperature anomaly detection algorithms in diverse marine environments. Thermographic videography coupled with laser range finding further enables calculation of whale blow velocity, demonstrating that biometrical measurements are possible for near-horizontal datasets that otherwise suffer from emissivity effects. The thermographic research we present creates a platform for the delivery of three important contributions to cetacean conservation: (1 non-invasive species-level identifications based on whale blow

DNA barcoding reveals the diversity of sharks in Guyana coastal markets

Directory of Open Access Journals (Sweden)

Matthew A. Kolmann

2017-12-01

Full Text Available ABSTRACT A fundamental challenge for both sustainable fisheries and biodiversity protection in the Neotropics is the accurate determination of species identity. The biodiversity of the coastal sharks of Guyana is poorly understood, but these species are subject to both artisanal fishing as well as harvesting by industrialized offshore fleets. To determine what species of sharks are frequently caught and consumed along the coastline of Guyana, we used DNA barcoding to identify market specimens. We sequenced the mitochondrial co1 gene for 132 samples collected from six markets, and compared our sequences to those available in the Barcode of Life Database (BOLD and GenBank. Nearly 30% of the total sample diversity was represented by two species of Hammerhead Sharks (Sphyrna mokarran and S. lewini, both listed as Endangered by the International Union for Conservation of Nature (IUCN. Other significant portions of the samples included Sharpnose Sharks (23% - Rhizoprionodon spp., considered Vulnerable in Brazilian waters due to unregulated gillnet fisheries, and the Smalltail Shark (17% - Carcharhinus porosus. We found that barcoding provides efficient and accurate identification of market specimens in Guyana, making this study the first in over thirty years to address Guyana’s coastal shark biodiversity.

Passive acoustic detection of deep-diving beaked whales

DEFF Research Database (Denmark)

Zimmer, W.M.X.; Harwood, J.; Tyack, P.L.

2008-01-01

Beaked whales can remain submerged for an hour or more and are difficult to sight when they come to the surface to breathe. Passive acoustic detection (PAD) not only complements traditional visual-based methods for detecting these species but also can be more effective because beaked whales produce...... clicks regularly to echolocate on prey during deep foraging dives. The effectiveness of PAD for beaked whales depends not only on the acoustic behavior and output of the animals but also on environmental conditions and the quality of the passive sonar implemented. A primary constraint on the range...... at which beaked whale clicks can be detected involves their high frequencies, which attenuate rapidly, resulting in limited ranges of detection, especially in adverse environmental conditions. Given current knowledge of source parameters and in good conditions, for example, with a wind speed of 2  m...

Introduction to Northeast Pacific Shark Biology, Ecology, and Conservation.

Science.gov (United States)

Lowry, Dayv; Larson, Shawn E

Sharks are iconic, sometimes apex, predators found in every ocean and, as a result, they have featured prominently in the mythology, history, and fisheries of diverse human cultures around the world. Because of their regional significance to fisheries and ecological role as predators, and as a result of concern over long-term stability of their populations, there has been an increasing amount of work focused on shark conservation in recent decades. This volume highlights the biodiversity and biological attributes of, and conservation efforts targeted at, populations of sharks that reside in the Northeast Pacific Ocean bordering the west coast of the United States and Canada, one of the most economically and ecologically important oceanic regions in the world. A companion volume addresses details of fisheries and ecotourism in the same region, as well as delving into the relationship between captive husbandry of sharks and education/outreach efforts aimed at fostering a conservation mindset in the public at large. Together, these volumes provide readers a detailed backdrop against which to consider their own actions, and those of resource managers, academics, and educators, as they relate to the long-term conservation of sharks and their relatives. © 2017 Elsevier Ltd. All rights reserved.

The shark assemblage at French Frigate Shoals atoll, Hawai'i: species composition, abundance and habitat use.

Science.gov (United States)

Dale, Jonathan J; Stankus, Austin M; Burns, Michael S; Meyer, Carl G

2011-02-10

Empirical data on the abundance and habitat preferences of coral reef top predators are needed to evaluate their ecological impacts and guide management decisions. We used longline surveys to quantify the shark assemblage at French Frigate Shoals (FFS) atoll from May to August 2009. Fishing effort consisted of 189 longline sets totaling 6,862 hook hours of soak time. A total of 221 sharks from 7 species were captured, among which Galapagos (Carcharhinus galapagensis, 36.2%), gray reef (Carcharhinus amblyrhynchos, 25.8%) and tiger (Galeocerdo cuvier, 20.4%) sharks were numerically dominant. A lack of blacktip reef sharks (Carcharhinus melanopterus) distinguished the FFS shark assemblage from those at many other atolls in the Indo-Pacific. Compared to prior underwater visual survey estimates, longline methods more accurately represented species abundance and composition for the majority of shark species. Sharks were significantly less abundant in the shallow lagoon than adjacent habitats. Recaptures of Galapagos sharks provided the first empirical estimate of population size for any Galapagos shark population. The overall recapture rate was 5.4%. Multiple closed population models were evaluated, with Chao M(h) ranking best in model performance and yielding a population estimate of 668 sharks with 95% confidence intervals ranging from 289-1720. Low shark abundance in the shallow lagoon habitats suggests removal of a small number of sharks from the immediate vicinity of lagoonal islets may reduce short-term predation on endangered monk seal (Monachus schauinslandi) pups, but considerable fishing effort would be required to catch even a small number of sharks. Additional data on long-term movements and habitat use of sharks at FFS are required to better assess the likely ecological impacts of shark culling.

76 FR 11679 - Drawbridge Operation Regulation; Shark River (South Channel), Belmar, NJ

Science.gov (United States)

2011-03-03

... Operation Regulation; Shark River (South Channel), Belmar, NJ AGENCY: Coast Guard, DHS. ACTION: Notice of... temporary deviation from the regulations governing the operation of the S71 Bridge across Shark River (South... Bridge, a bascule lift drawbridge, across Shark River (South Channel), at mile 0.8, in Belmar, NJ, has a...

Essential and non-essential element concentrations in two sleeper shark species collected in arctic waters

Energy Technology Data Exchange (ETDEWEB)

McMeans, Bailey C. [Great Lakes Institute for Environmental Research, University of Windsor, 401 Sunset Avenue, Windsor, ON, N9B 3P4 (Canada); Borga, Katrine [Norwegian Institute for Water Research, P.O. Box 173, Kjelsas, N-0411 Oslo (Norway); Bechtol, William R. [Alaska Department of Fish and Game, Division of Commercial Fisheries, Anchorage, AK 99518-1599 (United States); Higginbotham, David [Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA 30602-2152 (United States); Fisk, Aaron T. [Great Lakes Institute for Environmental Research, University of Windsor, 401 Sunset Avenue, Windsor, ON, N9B 3P4 (Canada)]. E-mail: afisk@uwindsor.ca

2007-07-15

A number of elements/metals have increased in arctic biota and are of concern due to their potential toxicity. Most studies on elements in the Arctic have focused on marine mammals and seabirds, but concentrations in the Greenland shark (Somniosus microcephalus) and Pacific sleeper shark (Somniosus pacificus), the only two shark species known to regularly inhabit arctic waters, have never been reported. To address this data gap, concentrations and patterns of 25 elements were analyzed in liver of Greenland sharks collected about Cumberland Sound (n = 24) and Pacific sleeper sharks collected about Prince William Sound (n = 14). Several non-essential elements differed between species/locations, which could suggest geographical exposure differences or ecological (e.g., diet) differences between the species. Certain essential elements also differed between the two sleeper sharks, which may indicate different physiological requirements between these closely related shark species, although information on such relationships are lacking for sharks and fish. - Patterns of essential and non-essential elements provide insight into sleeper shark biology and physiology.

Essential and non-essential element concentrations in two sleeper shark species collected in arctic waters

International Nuclear Information System (INIS)

McMeans, Bailey C.; Borga, Katrine; Bechtol, William R.; Higginbotham, David; Fisk, Aaron T.

2007-01-01

A number of elements/metals have increased in arctic biota and are of concern due to their potential toxicity. Most studies on elements in the Arctic have focused on marine mammals and seabirds, but concentrations in the Greenland shark (Somniosus microcephalus) and Pacific sleeper shark (Somniosus pacificus), the only two shark species known to regularly inhabit arctic waters, have never been reported. To address this data gap, concentrations and patterns of 25 elements were analyzed in liver of Greenland sharks collected about Cumberland Sound (n = 24) and Pacific sleeper sharks collected about Prince William Sound (n = 14). Several non-essential elements differed between species/locations, which could suggest geographical exposure differences or ecological (e.g., diet) differences between the species. Certain essential elements also differed between the two sleeper sharks, which may indicate different physiological requirements between these closely related shark species, although information on such relationships are lacking for sharks and fish. - Patterns of essential and non-essential elements provide insight into sleeper shark biology and physiology

Seasonal and geographic variation of southern blue whale subspecies in the Indian Ocean.

Directory of Open Access Journals (Sweden)

Flore Samaran

Full Text Available Understanding the seasonal movements and distribution patterns of migratory species over ocean basin scales is vital for appropriate conservation and management measures. However, assessing populations over remote regions is challenging, particularly if they are rare. Blue whales (Balaenoptera musculus spp are an endangered species found in the Southern and Indian Oceans. Here two recognized subspecies of blue whales and, based on passive acoustic monitoring, four "acoustic populations" occur. Three of these are pygmy blue whale (B.m. brevicauda populations while the fourth is the Antarctic blue whale (B.m. intermedia. Past whaling catches have dramatically reduced their numbers but recent acoustic recordings show that these oceans are still important habitat for blue whales. Presently little is known about the seasonal movements and degree of overlap of these four populations, particularly in the central Indian Ocean. We examined the geographic and seasonal occurrence of different blue whale acoustic populations using one year of passive acoustic recording from three sites located at different latitudes in the Indian Ocean. The vocalizations of the different blue whale subspecies and acoustic populations were recorded seasonally in different regions. For some call types and locations, there was spatial and temporal overlap, particularly between Antarctic and different pygmy blue whale acoustic populations. Except on the southernmost hydrophone, all three pygmy blue whale acoustic populations were found at different sites or during different seasons, which further suggests that these populations are generally geographically distinct. This unusual blue whale diversity in sub-Antarctic and sub-tropical waters indicates the importance of the area for blue whales in these former whaling grounds.

Fin whales and microplastics: The Mediterranean Sea and the Sea of Cortez scenarios

International Nuclear Information System (INIS)

Fossi, Maria Cristina; Marsili, Letizia; Baini, Matteo; Giannetti, Matteo; Coppola, Daniele; Guerranti, Cristiana; Caliani, Ilaria; Minutoli, Roberta; Lauriano, Giancarlo; Finoia, Maria Grazia; Rubegni, Fabrizio; Panigada, Simone; Bérubé, Martine; Urbán Ramírez, Jorge; Panti, Cristina

2016-01-01

The impact that microplastics have on baleen whales is a question that remains largely unexplored. This study examined the interaction between free-ranging fin whales (Balaenoptera physalus) and microplastics by comparing populations living in two semi-enclosed basins, the Mediterranean Sea and the Sea of Cortez (Gulf of California, Mexico). The results indicate that a considerable abundance of microplastics and plastic additives exists in the neustonic samples from Pelagos Sanctuary of the Mediterranean Sea, and that pelagic areas containing high densities of microplastics overlap with whale feeding grounds, suggesting that whales are exposed to microplastics during foraging; this was confirmed by the observation of a temporal increase in toxicological stress in whales. Given the abundance of microplastics in the Mediterranean environment, along with the high concentrations of Persistent Bioaccumulative and Toxic (PBT) chemicals, plastic additives and biomarker responses detected in the biopsies of Mediterranean whales as compared to those in whales inhabiting the Sea of Cortez, we believe that exposure to microplastics because of direct ingestion and consumption of contaminated prey poses a major threat to the health of fin whales in the Mediterranean Sea. - Highlights: • Microplastics and phthalates were higher in the Mediterranean Sea than in the Sea of Cortez. • The overlap between the whale feeding areas and high microplastic density shows the risk of interaction. • Data suggest an increasing risk of chemical transfer from microplastic to whales during the foraging. • Mediterranean whales are exposed to higher ecotoxicological threat of than Sea of Cortez whales. - This study identified temporal and regional ecotoxicological variations in free-ranging fin whales inhabiting two seas different characterized by different microplastic abundance.

Whale Heart

DEFF Research Database (Denmark)

2017-01-01

Student bachelor film. Synopsis:Silas lives in an isolated whaling town, toiling for months in the harsh and bloody trade on which he and his community depend. However, in order to be capable of killing the creatures whose bone and blubber pay his wage, he has developed an ungodly method for extr...

Identification and evaluation of shark bycatch in Georgia's commercial shrimp trawl fishery with implications for management

Science.gov (United States)

Belcher, C.N.; Jennings, C.A.

2011-01-01

Many US states have recreational and commercial fisheries that occur in nursery areas occupied by subadult sharks and can potentially affect their survival. Georgia is one of few US states without a directed commercial shark fishery, but the state has a large, nearshore penaeid shrimp trawl fishery in which small sharks occur as bycatch. During our 1995–1998 investigation of bycatch in fishery-dependent sampling events, 34% of 127 trawls contained sharks. This bycatch totalled 217 individuals from six species, with Atlantic sharpnose shark, Rhizoprionodon terraenovae (Richardson), the most common and finetooth shark, Carcharhinus isodon (Müller & Henle) and spinner shark, Carcharhinus brevipinna (Müller & Henle), the least common. The highest catch rates for sharks occurred during June and July and coincided with the peak months of the pupping season for many species. Trawl tow speed and tow time did not significantly influence catch rates for shark species. Gear configurations [net type, turtle excluder device (TED), bycatch reduction device] affected catch rates for shark species. Results of this study indicate gear restrictions, a delayed season opening, or reduced bar spacing on TEDs may reduce shark bycatch in this fishery.

Endangered Right Whales Enhance Primary Productivity in the Bay of Fundy.

Directory of Open Access Journals (Sweden)

Joe Roman

Full Text Available Marine mammals have recently been documented as important facilitators of rapid and efficient nutrient recycling in coastal and offshore waters. Whales enhance phytoplankton nutrition by releasing fecal plumes near the surface after feeding and by migrating from highly productive, high-latitude feeding areas to low-latitude nutrient-poor calving areas. In this study, we measured NH4+ and PO43- release rates from the feces of North Atlantic right whales (Eubalaena glacialis, a highly endangered baleen whale. Samples for this species were primarily collected by locating aggregations of whales in surface-active groups (SAGs, which typically consist of a central female surrounded by males competing for sexual activity. When freshly collected feces were incubated in seawater, high initial rates of N release were generally observed, which decreased to near zero within 24 hours of sampling, a pattern that is consistent with the active role of gut microflora on fecal particles. We estimate that at least 10% of particulate N in whale feces becomes available as NH4+ within 24 hours of defecation. Phosphorous was also abundant in fecal samples: initial release rates of PO43- were higher than for NH4+, yielding low N/P nutrient ratios over the course of our experiments. The rate of PO43- release was thus more than sufficient to preclude the possibility that nitrogenous nutrients supplied by whales would lead to phytoplankton production limited by P availability. Phytoplankton growth experiments indicated that NH4+ released from whale feces enhance productivity, as would be expected, with no evidence that fecal metabolites suppress growth. Although North Atlantic right whales are currently rare (approximately 450 individuals, they once numbered about 14,000 and likely played a substantial role in recycling nutrients in areas where they gathered to feed and mate. Even though the NH4+ released from fresh whale fecal material is a small fraction of total whale

Comparative Chromosome Map and Heterochromatin Features of the Gray Whale Karyotype (Cetacea).

Science.gov (United States)

Kulemzina, Anastasia I; Proskuryakova, Anastasia A; Beklemisheva, Violetta R; Lemskaya, Natalia A; Perelman, Polina L; Graphodatsky, Alexander S

2016-01-01

Cetacean karyotypes possess exceptionally stable diploid numbers and highly conserved chromosomes. To date, only toothed whales (Odontoceti) have been analyzed by comparative chromosome painting. Here, we studied the karyotype of a representative of baleen whales, the gray whale (Eschrichtius robustus, Mysticeti), by Zoo-FISH with dromedary camel and human chromosome-specific probes. We confirmed a high degree of karyotype conservation and found an identical order of syntenic segments in both branches of cetaceans. Yet, whale chromosomes harbor variable heterochromatic regions constituting up to a third of the genome due to the presence of several types of repeats. To investigate the cause of this variability, several classes of repeated DNA sequences were mapped onto chromosomes of whale species from both Mysticeti and Odontoceti. We uncovered extensive intrapopulation variability in the size of heterochromatic blocks present in homologous chromosomes among 3 individuals of the gray whale by 2-step differential chromosome staining. We show that some of the heteromorphisms observed in the gray whale karyotype are due to distinct amplification of a complex of common cetacean repeat and heavy satellite repeat on homologous autosomes. Furthermore, we demonstrate localization of the telomeric repeat in the heterochromatin of both gray and pilot whale (Globicephala melas, Odontoceti). Heterochromatic blocks in the pilot whale represent a composite of telomeric and common repeats, while heavy satellite repeat is lacking in the toothed whale consistent with previous studies. © 2016 S. Karger AG, Basel.