WorldWideScience

Sample records for alevins

  1. Histologic and skeletal abnormalities in benzo(a)pyrene-treated rainbow trout alevins

    Energy Technology Data Exchange (ETDEWEB)

    Hose, J.E.; Hannah, J.B.; Puffer, H.W.; Landolt, M.L.

    1984-11-01

    Histological and skeletal examinations were performed on rainbow trout (Salmo gairdneri Richardson) alevins reared in 0.00, 0.08, 0.21, 0.39, 1.48, 2.40 or 2.99 ng/ml aqueous benzo(a)pyrene (BaP). Nuclear pycnosis and karyorrhexis were most common in neuroectodermal and mesodermal derivatives and in liver of BaP-treated alevins. Microphthalmia was observed in 17% of the test fish and was frequently associated with a patent optic fissure. Depressed mitotic rates in the retina and brain (but not liver) were observed in alevins reared in 0.21 to 1.48 ng/ml aqueous BaP. Test alevins had a significantly higher incidence of skeletal malformations in the skull and vertebral column, and abnormalities of vertebral arcualia often corresponded to areas of kyphoscoliotic flexures. 43 references, 3 figures, 4 tables.

  2. Survival of Apache Trout eggs and alevins under static and fluctuating temperature regimes

    Science.gov (United States)

    Recsetar, Matthew S.; Bonar, Scott A.

    2013-01-01

    Increased stream temperatures due to global climate change, livestock grazing, removal of riparian cover, reduction of stream flow, and urbanization will have important implications for fishes worldwide. Information exists that describes the effects of elevated water temperatures on fish eggs, but less information is available on the effects of fluctuating water temperatures on egg survival, especially those of threatened and endangered species. We tested the posthatch survival of eyed eggs and alevins of Apache Trout Oncorhynchus gilae apache, a threatened salmonid, in static temperatures of 15, 18, 21, 24, and 27°C, and also in treatments with diel fluctuations of ±3°C around those temperatures. The LT50 for posthatch survival of Apache Trout eyed eggs and alevins was 17.1°C for static temperatures treatments and 17.9°C for the midpoints of ±3°C fluctuating temperature treatments. There was no significant difference in survival between static temperatures and fluctuating temperatures that shared the same mean temperature, yet there was a slight difference in LT50s. Upper thermal tolerance of Apache Trout eyed eggs and alevins is much lower than that of fry to adult life stages (22–23°C). Information on thermal tolerance of early life stages (eyed egg and alevin) will be valuable to those restoring streams or investigating thermal tolerances of imperiled fishes.

  3. Genetic variation of resistance to mercury poisoning in steelhead (Oncorhynchus mykiss) alevins.

    Science.gov (United States)

    Blanc, J M; McIntyre, J D; Simon, R C

    2003-09-01

    Newly hatched steelhead alevins were obtained from the factorial breeding of 24 male and 10 female steelhead trout, Oncorhynchus mykiss. Each set of offspring were in a separate cell. They were tested for resistance to intoxication by methylmercuric chloride (CH3HgCl) in water at a nearly constant mercury concentration of 8 microg l(-1). High mortality (81% of the tested alevins) occurred within 2 weeks. Resistance to intoxication, as measured by the time to death, as well as by the survival rate, shared high paternal and maternal variation with negligible interaction. Heritability of time to death was 0.59 +/- 0.17; heritability of survival (all-or-none trait) was lower (0.26 +/- 0.09). Mercury in dead alevins increased with time to death, exhibiting a large environmental variation and (comparatively) negligible genetic influence. At the end of the bioassay, the mercury content in survivors varied widely (3-21 microg g(-1) wet weight). The content was greater than, but correlated with that of dead alevins from the same cells, and it showed little relation with survival rate. Thus, it seems that resistance to poisoning implies a tolerance to high levels of mercury rather than a limitation of its accumulation.

  4. Evaluation of the use of cypermethrin in the control of predatory insects of alevins in aquaculture ponds

    OpenAIRE

    Plaul, Silvia E.; García Romero, N.; Barbeito, Claudio Gustavo

    2010-01-01

    Los emprendimientos acuícolas semi-intensivos de cría de peces ornamentales, basan su producción en la siembra de alevines en cavas fertilizadas para el desarrollo de grandes cantidades de zooplancton, alimento de los peces. Los piretroides como la cipermetrina, constituyen una opción económica para combatir distintos insectos que depredan a los alevines. Se utilizaron cuatro cavas las cuales fueron fertilizadas 10 días antes del tratamiento. En ellas, se dispusieron jaulas con alevines de Ca...

  5. Crecimiento de alevines de Ictalurus Balsanus (pisces:ictaluridae) en condiciones de laboratorio.

    OpenAIRE

    Jorge Luna-Figueroa; Elsah Arce Uribe

    2016-01-01

    Se realizó un estudio para evaluar el efecto de tres dietas sobre el crecimiento de alevines de Ictalurus balsanus en condiciones de laboratorio. La talla inicial de los peces fue 39.68 ± 2.0 mm de longitud total y 411.47 ± 17.00 mg de peso corporal, colocados en grupos de 10 peces por acuario de 80L. Los bagres fueron alimentados con tres dietas diferentes: I(31,13% proteína, 2,70% grasa, 56,53% carbohidratos), II(39,12%, 3,0%, 35,0%), III(53,57%, 19,37%, 4,17%). Los resultados indican que e...

  6. Crecimiento de alevines de Ictalurus Balsanus (pisces:ictaluridae en condiciones de laboratorio.

    Directory of Open Access Journals (Sweden)

    Jorge Luna-Figueroa

    2016-03-01

    Full Text Available Se realizó un estudio para evaluar el efecto de tres dietas sobre el crecimiento de alevines de Ictalurus balsanus en condiciones de laboratorio. La talla inicial de los peces fue 39.68 ± 2.0 mm de longitud total y 411.47 ± 17.00 mg de peso corporal, colocados en grupos de 10 peces por acuario de 80L. Los bagres fueron alimentados con tres dietas diferentes: I(31,13% proteína, 2,70% grasa, 56,53% carbohidratos, II(39,12%, 3,0%, 35,0%, III(53,57%, 19,37%, 4,17%. Los resultados indican que el incremento en el peso y en la longitud total de I. balsanus fueron mayores (P0.05 entre los peces nutridos con los distintos alimentos. Por lo que se concluye que las características propias del alimento vivo y, en particular, la alta concentración proteica de Daphnia sp. Generaron mayor incremento en la tasa de crecimiento especifico de I. balsanus.

  7. Otolith micro-structure analysis of rainbow trout alevins (Oncorhynchus mykiss under rearing conditions Análisis de la micro-estructura de otolitos en alevines de trucha arcoiris (Oncorhynchus mykiss en cautiverio

    Directory of Open Access Journals (Sweden)

    Guillermo Moyano

    2012-09-01

    Full Text Available Otolith microstructure (MO analysis was used to back-calculate growth patterns from hatching to the yolk-sac absorption in Rainbow trout alevins (Oncorhynchus mykiss, under experimental conditions, from winter to spring in Central-Chile. MO showed the following main features: (i occurrences of multiple primordia in the central region of otolith (MP; (ii several increments (22 ± 3 rings before a prominent hatch check surrounding MP and (iii existence of a very distinctive check associated to yolk-sac absorption. Further findings were the validation of daily periodicity of micro-increments and a significant linear relationship (P La micro-estructura de otolitos (MO fue utilizada para retro-calcular los patrones de crecimiento, desde la eclosión hasta la absorción del saco vitelino, en alevines de trucha arcoiris (Oncorhynchus mykiss, en la zona central de Chile. La MO mostró tres características principales: (i ocurrencia de múltiples primordios en la región central de los otolitos (MP, (ii formación de varios micro-incrementos antes de la eclosión (22 ± 3 micro-incrementos (iii y existencia de una marca distintiva correspondiente a la absorción del saco vitelino. Otros resultados fueron la validación de la periodicidad diaria de micro-incrementos y la existencia de una relación lineal significativa (P < 0,001; r2 = 0,91 entre la longitud máxima del otolito (LMO y la longitud total de los alevines (L T. La relación lineal L MO-L T validó el uso del método de intercepto biológico, para retro-calcular las tasas diarias de crecimiento (TDC. Las TDC mostraron una tendencia decreciente desde la eclosión hasta 6 días después de la absorción del saco vitelino (16 ± 1 días, las TDC variaron desde los 0,22 mm d-1 a los 0,34 mm d-1 (0,30 ± 0,037. La MO demostró ser una herramienta efectiva para el análisis retrospectivo de los patrones de crecimiento en alevins una vez absorbido su saco vitelino.

  8. Hatching time and alevin growth prior to the onset of exogenous feeding in farmed, wild and hybrid Norwegian Atlantic salmon.

    Directory of Open Access Journals (Sweden)

    Monica Favnebøe Solberg

    Full Text Available The onset of exogenous feeding, when juveniles emerge from the gravel, is a critical event for salmonids where early emergence and large size provide a competitive advantage in the wild. Studying 131 farmed, hybrid and wild Norwegian Atlantic salmon families, originating from four wild populations and two commercial strains, we investigated whether approximately 10 generations of selection for faster growth has also resulted in increased somatic growth prior to the onset of exogenous feeding. In addition, we tested whether relaxed selection in farms has allowed for alterations in hatching time between farmed and wild salmon. Across three cohorts, wild salmon families hatched earlier than farmed salmon families, while hybrid families displayed intermediate hatching times. While the observed differences were small, i.e., 1-15 degree-days (0-3 days, as water temperatures were c. 5-6°C, these data suggest additive genetic variation for hatching time. Alevin length prior to exogenous feeding was positively related to egg size. After removal of egg size effects, no systematic differences in alevin length were observed between the wild and farmed salmon families. While these results indicate additive genetic variation for egg development timing, and wild salmon families consistently hatched earlier than farmed salmon families, these differences were so small they are unlikely to significantly influence early life history competition of farmed and wild salmon in the natural environment. This is especially the case given that the timing of spawning among females can vary by several weeks in some rivers. The general lack of difference in size between farmed and wild alevins, strongly suggest that the documented differences in somatic growth rate between wild and farmed Norwegian Atlantic salmon under hatchery conditions are first detectable after the onset of exogenous feeding.

  9. Dévalaison et survie d'alevins de saumon atlantique (Salmo salar L. en milieu semi-naturel contrôlé

    Directory of Open Access Journals (Sweden)

    BEALL E.

    1983-04-01

    Full Text Available Dans un chenal artificiel expérimental, des œufs de saumon atlantique (Salmo salar L. ont été pondus naturellement ou ont été enfouis au stade embryonné. A la fin de la résorption de la vésicule, une fraction importante des alevins survivants dévale de la zone de frayère. La dévalaison semble stimulée par des baisses de niveau ou des hausses de température et ralentie en période de pleine lune. D'autres facteurs pouvant être responsables de cette dévalaison sont discutés. La survie jusqu'à la collecte de tous les alevins est estimée à 74 p. 100 pour les sujets issus de la reproduction naturelle et est égale à 80 p. 100 pour ceux issus d'œufs introduits dans le gravier au stade embryonné. Des comparaisons entre ces résultats et ceux obtenus dans d'autres chenaux de fraie ou en milieu naturel montrent la validité de cette méthode pour la production d'alevins de saumon atlantique destinés au repeuplement.

  10. Efecto del calcio sobre la toxicidad aguda de aluminio en alevines de trucha arcoiris (Oncorhynchus mykiss expuestos en aguas de diferente pH

    Directory of Open Access Journals (Sweden)

    Rolando Vega

    2015-05-01

    Full Text Available En la producción de alevines de salmón de la región de la Araucanía (sur de Chile se presentan importantes eventos de mortalidad aguda sin rasgos patológicos aparentes. El problema se focaliza en ejemplares de 0,2 a 1 g y las causas apuntan a procesos de acidificación del pH del agua y a la presencia de ciertos metales pesados, entre los cuales destaca el aluminio, que alcanza concentraciones más allá de los rangos de tolerancia de los peces. La información científica indica que concentraciones de 5 mg Ca L-1 en el afluente son suficientes para mantener a salvo los peces del efectos tóxico del aluminio. Sin embargo, los problemas en la producción de alevines de salmón indican que se requiere un mayor conocimiento científico y evidencia experimental que soporte el desarrollo de procesos y tecnologías para el tratamiento de los afluentes de las pisciculturas chilenas. En este trabajo se evaluó el efecto de cuatro concentraciones de calcio (0, 5, 10 y 20 mg Ca L-1 sobre la toxicidad aguda de 500 μg Al L-1 en alevines de trucha arcoiris (Oncorhynchus mykiss de 0,1 g en agua de cultivo a pH 5, 6 y 7. El objetivo del trabajo fue determinar la dosis de calcio que reduce la toxicidad aguda de aluminio y los tiempos mínimos de reacción que podrían disponer los piscicultores para tomar medidas preventivas ante una concentración aguda de aluminio en el agua de cultivo. Los resultados indican que antes de 8 h de exposición a una concentración tóxica de aluminio los piscicultores deberían asegurar en el agua de cultivo una dosis superior a 10 mg Ca L-1 y un pH >6 como medida remedial para reducir el efecto de intoxicación aguda causada por aluminio.

  11. Study on Techniques of Artifical Breedingand Alevins Culture of Dolly Varden Charr (S. malma)%花羔红点鲑人工繁殖和仔鱼培育技术研究

    Institute of Scientific and Technical Information of China (English)

    黄权; 吴莉芳; 张东鸣; 李月红

    2001-01-01

    The techniques of artifical breeding and alevins culture of dolly varden charr (Salvelinus malma) were developed. Rel ationships between the size o f the parent fish and their reproductivity; developmental time of fertilized eggs and water temperture; the size of mature eggs and the time of the first feeding of alevins; and the effect of cultivated population on natural population were also discussed.%对花羔红点鲑人工繁殖和仔鱼培育技术进行了研究,并探讨了亲鱼大小与绝对繁殖力、受精卵发育时间与温度、成熟卵大小与初次摄食仔鱼大小等问题以及人工养殖群体对野生种群的影响。

  12. Flavobacterium psychrophilum y su patología en alevines de Onchorhynchus mykiss del centro piscícola El Ingenio, Huancayo

    Directory of Open Access Journals (Sweden)

    Jorge León

    2008-12-01

    Full Text Available En el presente trabajo se reporta la presencia de Flavobacterium psychrophilum, como agente causante de la patología “enfermedad bacteriana del agua fría” en alevines de Onchorhynchus mykiss “trucha arco iris” del Centro Piscícola El Ingenio, Junín (3250 m de altitud. La lesión macroscópica externa más frecuente fue la ulceración profunda de la región dorsal del pez acompañado de un ennegrecimiento localizado de la piel. Internamente se observó una marcada esplenomegalia, palidez del hígado, riñón y branquias, inflamación del intestino y acumulación de líquido ascítico en el peritoneo. No se detectó hemorragia interna. En Agar Cytophaga Modificado (ACM según Anaker & Ordal (1959 fueron aisladas inicialmente 29 Gram negativas, de las cuales según la caracterización fenotípica y pruebas bioquímicas 9 fueron consideradas como F. psychrophilum. Pruebas de susceptibilidad antibiótica mostraron alta sensibilidad de las cepas a Gentamicina, Ceftazidina, oxitetraciclina, Norfloxacina, furazolidona, Ciprofloxacina y Cefoxitina.

  13. REPEUPLEMENTS EN ALEVINS NOURRIS ET DÉMOGRAPHIE DE LA POPULATION DE TRUITE (SALMO TRUTTA L. DANS LE REDON, UN AFFLUENT DU LAC LÉMAN INTERROMPU PAR UN OBSTACLE

    Directory of Open Access Journals (Sweden)

    CHAMPIGNEULLE A.

    2003-01-01

    Full Text Available La démographie d’une population de truite (Salmo trutta L. a été étudiée, dans un contexte de repeuplements en alevins nourris, sur le Redon, un affluent du lac Léman. On trouve sur le Redon une situation typique de nombreux affluents du Léman : une zone aval ouverte sur le lac mais rapidement interrompue par un obstacle empêchant la remontée des truites de lac. Des relâchers d’alevins nourris issus d’œufs de géniteurs sauvages de truite de lac ou de géniteurs domestiques, pratiqués en fin de printemps-début été à des densités de 40-60 ind./100 m2, fournissent un recrutement additionnel important pouvant constituer la part dominante du peuplement automnal en 0 +, puis 1 +. Sur les zones ouvertes à la pêche, colonisées ou non par la truite de lac, la densité de la population automnale en place s’effondre entre le stade 1 + et les stades > 1 +. Les résultats comparatifs entre zones ouvertes ou fermées à la pêche indiquent que la pêche peut être un facteur de mortalité important. La dynamique comparée des truites d’origine lacustre ou sédentaire suggère l’existence d’un taux de sédentarisation plus faible pour les 1 + issus de truites de lac comparativement aux 1 + issus de la fraie de truites sédentaires en zone de réserve. Une expérimentation suggère l’existence de mouvements de dévalaison ayant lieu avant octobre et touchant préférentiellement les 0 + d’origine lacustre ayant eu la croissance initiale la plus forte. L’étude montre que : - des alevins nourris d’origine lacustre ou domestique, relâchés en fin de printemps-début été, fournissent des géniteurs de truite de lac remontant dans la rivière de relâcher, avec cependant une proportion moindre (4 fois dans le cas de l’origine domestique comparativement à l’origine lacustre. Malgré leur forte contribution aux stades de juvéniles 0 + et 1 +, les alevins domestiques de pisciculture contribuent peu aux retours de g

  14. RÉTENTION DES OVULES APRÈS OVULATION DANS LA CAVITÉ OVARIENNE DE LA CARPE HERBIVORE : COMPOSITION DES OVULES ET CAPACITÉ DE DÉVELOPPEMENT DES ŒUFS ET DES ALEVINS.

    Directory of Open Access Journals (Sweden)

    KHARROUBI M.

    2002-04-01

    Full Text Available Pour étudier l’effet de rétention prolongée des ovules dans la cavité ovarienne (in vivo de la carpe herbivore, des extractions d’ovules de 15 femelles (3 à 5,6 kg ont eu lieu à différents intervalles de temps après ovulation (0, 30, 60, 90 et 120 min. Le taux de fécondation, le taux de survie embryonnaire, le taux d’éclosion et la croissance en longueur totale des alevins jusqu’à 5 semaines après éclosion (L1 = Longueur totale mesurée 2 semaines après éclosion, L2 = Longueur totale mesurée 3 semaines après éclosion, L3 = Longueur totale mesurée 4 semaines après éclosion, L4 = Longueur totale mesurée 5 semaines après éclosion sont déterminés pour chaque temps d’extraction des ovules. Il n’y a pas eu de différences significatives entre ces paramètres biologiques observés juste après ovulation et ceux observés 120 min après ovulation. Sont déterminées également quelques caractéristiques de la composition des ovules à savoir la teneur en eau, le poids sec, les cendres brutes, le fer, le calcium, les protéines totales, les lipides totaux, les phospholipides et les sucres. Ces composés demeurent constants quand les ovules sont maintenus au sein de la femelle pour deux heures après ovulation. Chez la carpe herbivore, la rétention post ovulatoire des ovules pendant 2 heures in vivo n’a pas d’effet ni sur leur composition biochimique examinée, ni sur la capacité de développement des œufs ni sur la croissance des alevins en terme de longueur totale. L’absence de changements des constituants des ovules pourrait expliquer la maintenance de la viabilité des œufs et celle de la croissance des alevins. Cependant, il importe de signaler une certaine différence de cette capacité de développement des œufs et des alevins entre les femelles reproduites (p < 0,05 pour chaque paramètre examiné.

  15. Microhabitats utilisés par les alevins 0+ d'une communauté de cyprins rhéophiles : analyse de l'évolution de la communauté et des densités de population

    Directory of Open Access Journals (Sweden)

    BARAS E.

    1995-04-01

    Full Text Available L'évolution de l'occupation des microhabitats par les alevins de la communauté de cyprins rhéophiles de l'Ourthe a été étudiée au cours de l'été et de l'automne 1994 par échantillonnage ponctuel d'abondance (électrodes fixes prépositionnées, courant continu. 16155 poissons (10-75 mm appartenant à 15 espèces ont été recensés sur 78 sites d'échantillonnage de 2 m2 . Les espèces les plus représentées étaient Leuciscus cephalus, Leuciscus leuciscus et Chondrostoma nasus (respectivement 43,6 %, 20,7 % et 16,7 % des captures estivales. L'analyse factorielle des correspondances d'une matrice site x (espèce x taille met en évidence une subdivision progressive de la communauté au cours de l'été en espèces d'eau vive (B. barbus et L. leuciscus et d'eau lente, davantage associées à un couvert végétal (L. cephalus et C. nasus. La densité maximale observée (fin juin est de 1500 alevins (25 mm m-2, correspondant à une biomasse de 250 g m-2. Le modèle explicatif de la densité généré par analyse de régression multiple pas-à-pas explique 60,0 % de la variabilité de la densité par les variables vitesse de courant, température de l'eau et date d'échantillonnage, cette variable intégrant le concept de mortalité-dispersion au cours de la saison de croissance. Les implications de la méthodologie et des résultats présentés au plan de la gestion des écosystèmes lotiques sont brièvement discutés.

  16. Sistema energéticamente eficiente y de bajo costo para controlar la temperatura y aumentar el oxígeno en estanques de cultivo de alevines de tilapia roja

    Directory of Open Access Journals (Sweden)

    Rubén Darío Vásquez-Salazar

    2014-01-01

    Full Text Available El artículo expone un sistema automático para controlar la temperatura y aumentar el oxígeno en estanques de cultivo de alevines de tilapia roja en la granja John Jairo González, del Politécnico Colombiano Jaime Isaza Cadavid. El control se realiza a través de un PLC que recibe dos señales de temperatura ubicadas en puntos diferentes del estanque, y una señal de un sensor de nivel. Ejecutando un algoritmo de control, activa o desactiva diferentes circuitos de agua fría, proveniente de la quebrada Guaracú, o caliente, a través de un proceso de bombeo de agua del estanque hacia los colectores solares, y regresándola al estanque, recirculación que se hace hasta obtener una temperatura de 29 °C, un poco por encima de la ideal de 28 °C. El sistema de control es validado comparando temperatura y oxígeno con un tanque sin control. 

  17. Influence du débit de base et de la durée des éclusées sur la dérive d'alevins de truite commune : expérimentations en canal semi-naturel

    Directory of Open Access Journals (Sweden)

    LIEBIG H.

    1998-07-01

    Full Text Available Le fonctionnement par éclusées de certains ouvrages hydroélectriques installés sur des rivières de montagne à peuplement salmonicole est souvent considéré comme responsable du déficit en alevins observé sur les secteurs à l'aval immédiat du rejet. Une des causes majeures avancée de ce déficit est l'entraînement forcé des alevins dès l'émergence. Une approche expérimentale de ce phénomène est apparue nécessaire pour identifier et quantifier les facteurs mis en jeu. Un ancien bras de la rivière Oriège a été ainsi aménagé au niveau du canal de fuite de l'usine hydroélectrique d'Orlu, en Ariège (09. Ce système semi-naturel permet, sur un substrat et des abris naturels, de simuler des éclusées et de quantifier la dérive des alevins résultante. Sur un bief à faciès d'écoulement mixte radier-plat, nous avons testé deux modalités pour la durée des éclusées (10 minutes et 3 heures, associées à deux modalités pour la valeur du débit de base (débit précédant l'éclusée, soit 150 et 250 l/s. Le débit plafond des éclusées a été fixé à 1 500 l/s, ce qui correspond à un facteur de 6 à 10 par rapport aux débits de base, situation fréquemment rencontrée sur l'Oriège. Les résultats sont comparés et discutés. En définitive, il apparaît que les éclusées entraînent systématiquement une dérive forcée des alevins. Cette dérive intervient principalement au démarrage de l'éclusée et est d'autant plus forte que le débit de base est faible.

  18. Efecto de tres ambientes de transporte sobre el tiempo de aparición de la autólisis en muestras de alevines de trucha arcoíris (Oncorhynchus mykiss Effect of three transport conditions on the appearance time of autolysis in samples of rainbow trout fry (Oncorhynchus mykiss

    Directory of Open Access Journals (Sweden)

    AR Ortloff

    2011-01-01

    Full Text Available El objetivo de este trabajo fue comparar el efecto de tres tipos de ambiente de transporte sobre el tiempo de aparición y progreso de los cambios autolíticos de muestras de alevines muertos, enviados para ser procesados para análisis histopatológico. Para ello se depositaron 300 cadáveres de alevines completos en tres ambientes de transporte: sumergidos agua a 4 °C, sumergidos agua a 15 °C y ambiente seco a 4 °C. Cada una hora, desde el tiempo cero hasta las 24 horas, grupos de 4 alevines por ambiente fueron fijados en formalina al 10% y procesados con la técnica histológica convencional de hematoxilina&eosina. En todos los grupos se determinó el tiempo de aparición de los cambios autolíticos en los distintos segmentos del riñón e hígado, clasificándose en cambios autolíticos tempranos, avanzados y autólisis completa. Se observó que los cambios autolíticos se evidencian primero en los hígados de los cadáveres a 4 °C en ambiente seco y al último en los cadáveres sumergidos en agua a 4 °C (1 y 6 horas, respectivamente. Respecto al riñón, los primeros cambios autolíticos se presentaron en cadáveres a 4 °C en ambiente seco y al último en los cadáveres sumergidos en agua a 4 °C (3 y 9 horas, respectivamente. De este estudio se concluye que de los tres ambientes de transporte comparados, el que conserva por más tiempo la estructura histológica y citológica de los tejidos de los peces para análisis histológico es la conservación sumergidos en agua a 4 °C, evidenciando el rol clave de la temperatura y humedad ambiental en el progreso de la autólisis de peces.The aim of this work was to compare three types of transport conditions on the appearance and progress of autolytic changes in samples of dead fry sent to be processed for histopathological analysis. 300 whole fry corpses were subjected to three transport conditions: submerged in water at 4 °C, submerged in water at 15 °C and dry atmosphere at 4

  19. Efeito da vitamina C sobre o hematócrito e glicemia de alevinos de tilápia-do-nilo (Oreochromis niloticus em transporte simulado Effect of vitamin C over the haematocrit and glycemia of nile tilapia (Oreochromis niloticus alevins in simulated transport

    Directory of Open Access Journals (Sweden)

    D. Okamura

    2007-08-01

    Full Text Available Avaliou-se o efeito do ascorbato sobre o hematócrito e glicemia em alevinos de tilápia nilótica (Oreochromis niloticus submetidos à simulação de práticas relacionadas ao transporte. Foram utilizadas três dietas experimentais com diferentes níveis de vitamina C (16, 500 e 1000mg de vitamina C/kg, fornecidas durante os 14 dias anteriores à simulação do transporte que se estendeu por 14 horas. O tratamento que continha 16mg de vitamina C/kg foi o que apresentou a glicemia mais elevada logo após a simulação, 108,5mg/dl imediatamente após a simulação e 91mg/dl 12 horas após a simulação. A concentração de 1000mg de vitamina C/kg foi a mais eficiente no controle do aumento da glicemia, 94,6mg/dl imediatamente após a simulação e 74,4mg/dl 12 horas após a simulação. Para a concentração de 500mg de vitamina C/kg foram observados os níveis de 91,4mg/dl imediatamente após a simulação e 103,8mg/dl 12 horas após a simulação. Os valores do hematócrito não apresentaram variação significativa (P>0,05. A suplementação com 1000mg de vitamina C/kg por 14 dias anteriores ao transporte pode ser utilizada de forma profilática em alevinos de tilápia nilótica para amenizar o aumento da glicemia relacionado ao estresse.The effects of ascorbate on the haematocrit and blood glucose level were evaluated in Nile tilapia alevins (Oreochromis niloticus submitted to a transport simulation. Three experimental diets with different levels of vitamin C (16, 500 and 1000mg/kg were given for 14 days before the simulation of the transport. The treatment containing 16mg of vitamin C showed the highest level of glucose after the simulation (108.5mg/dl immediately after the transport and 91mg/dl 12 hours after the transport. The vitamin C concentration of 1000mg/kg was the most efficient treatment to control glycemia increases (94.6mg/dl immediately after the simulation and 74.4mg/dl 12 hour after simulation. In the 500mg/kg treatment, the

  20. Comparaison des performances de deux souches de truite commune (Salmo trutta L. (domestique et hybride sauvage x domestique introduites au stade alevin dans un ruisseau

    Directory of Open Access Journals (Sweden)

    NIHOUARN A.

    1990-10-01

    Full Text Available La production d'un hybride mâle sauvage x femelle domestique, chez la truite commune (Salmo trutta a parfois été proposée pour le repeuplement (CUINAT, 1971. Nos précédents travaux (MAISSE et al., 1983 ont montré que ces sujets sont plus difficiles à élever que ceux dont les deux parents sont domestiques. La présente étude a porté sur la comparaison des performances des hybrides et des domestiques déversés simultanément dans un ruisseau où la reproduction de la truite est compromise par le colmatage du fond. Les déversements ont été effectués sur la totalité du ruisseau, en mai, deux années de suite. Des inventaires ont été réalisés sur des secteurs représentatifs en mai, avant les déversements, et en octobre. Les résultats ont montré que les taux d'implantation, tant en 0+ qu'en 1+, ne différaient pas suivant l'origine des poissons. De plus, sur chacun des secteurs inventoriés, les individus d'origine domestique ont gardé l'avantage de taille qu'ils avaient au moment du déversement. L'intérêt d'un tel croisement est discuté en fonction des diverses stratégies de repeuplement à mettre en œuvre.

  1. Evaluation de l'effet de l'environnement et de l'alimentation sur l'apparition d'anomalies de développement chez l'alevin de bar (Dicentrarchus labrax

    Directory of Open Access Journals (Sweden)

    MENU B.

    1998-07-01

    Full Text Available Une ponte naturelle de bar, obtenue dans les installations expérimentales de Palavas, est mise en élevage dans ce même laboratoire et dans celui de Brest, après un transport fictif ou réel. Les protocoles spécifiques de chacun des deux laboratoires sont utilisés sans changer le contexte d'élevage particulier de chacun des deux sites : mise à jeun à l'obscurité jusqu'à 160 degrés jours et première alimentation sur Artemia à Palavas en bacs de 500 litres et, première alimentation à 75 degrés jours sur rotifères à Brest en bacs de 250 litres et de 35 litres. Dans les conditions d'environnement comparables (bacs de 250 litres à Brest une période de jeûne est également testée, de 75 à 160 degrés jours, soit en obscurité sans aération, soit sous éclairage continu avec aération. Les malformations des vertèbres, des maxillaires, des opercules (courts et soulevés, la non-inflation de la vessie natatoire et la présence de calculs urinaires sont relevées à 3 mois sur tous les lots. Plusieurs malformations apparaissent inféodées à un site ou un traitement particulier : cristaux urinaires à Palavas, vessies natatoires non fonctionnelles à Brest, maxillaires anormaux en bac de 35 litres. Les opercules soulevés sont observés dans deux installations utilisant des méthodologies différentes mais sont négligeables dans la ligne d'élevage où les tests méthodologiques ont été effectués. Les taux de survie sont significativement influencés par les traitements. La répartition des fréquences des lordoses entre les sites ou les différents traitements peut s'interpréter comme une conséquence de mortalités sélectives. L'association entre les lordoses et les vessies natatoires non fonctionnelles, déjà connue chez le bar, est observée. L'étude des fréquences croisées des malformations montre également que les opercules courts sont 10 fois plus fréquents chez les individus dont les vessies natatoires ne sont pas fonctionnelles. L'étude séparée des populations de juvéniles possédant ou non une vessie natatoire fonctionnelle montre que la répartition des fréquences des opercules courts est indépendante des traitements ou du site d'élevage. Les fréquences élevées des opercules courts sur la majorité des traitements du site de Brest ne peuvent être dissociées des taux importants de non-fonctionnalité des vessies natatoires.

  2. Premiers résultats de sex-ratio, puberté et dimorphisme sexuel chez le Paraha peue (Platax orbicularis) en élevage.

    OpenAIRE

    Gasset, Eric; Joufoques, Vaiana; David, Rarahu; Maamaatuaiahutapu, Moana; Teissier, Alexandre; Tamata, Thierry; Dupieux, Sylvain

    2009-01-01

    Cette première étude du sex-ratio menée chez Platax orbicularis en élevage donne d’importantes indications dans l’optique d’optimiser la gestion des productions (1) de lots de futurs géniteurs issus d’un plan de croisement et (2) des lots d’alevins destinés à la production en cages. La poursuite du suivi des lots en cours et des nouvelles familles produites (sans tri des alevins et avec marquage magnétique individuel des poissons) permettra de confirmer sans doute ces indications et d’oriente...

  3. Developmental toxicity of selenium to Dolly Varden char (Salvelinus malma).

    Science.gov (United States)

    McDonald, Blair G; deBruyn, Adrian M H; Elphick, James R F; Davies, Martin; Bustard, David; Chapman, Peter M

    2010-12-01

    Gametes were collected from Dolly Varden char (Salvelinus malma) from waterbodies in a region exposed to mining-related selenium (Se) releases in British Columbia, Canada. Fertilized eggs were incubated in a laboratory and deformities were assessed on newly-hatched alevins using a graduated severity index. No effects were observed on egg or alevin survival or larval weight across the studied exposure range of 5.4 to 66 mg/kg dry weight in egg. Length of some larvae was reduced at the highest egg Se concentrations and a clear residue-response relationship was observed for larval deformity. The egg concentration corresponding to a 10% increase in the frequency of deformity (EC10) was 54 mg/kg dry weight, which is substantially higher than reported for other cold-water fish species.

  4. Impacts of Water Level Fluctuations on Kokanee Reproduction in Flathead Lake, 1985 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Beattie, Will; Fraley, John J.; Decker-Hess, Janet (Montana Department of Fish, Wildlife and Parks, Kalispell, MT)

    1986-06-01

    This study has investigated the effects of the operation of Kerr Dam on the reproductive success of kokanee that spawn along the shores of Flathead Lake. We have estimated the spawning escapement to the lakeshore, characterized spawning habitat, monitored egg and alevin survival in redds, and related survival to length of redd exposure due to lake drawdown. Groundwater discharge apparently attracts kokanee to spawning sites along the lakeshore and is responsible for prolonging egg survival in redds above minimum pool. We have quantified and described the effect of lake drawdown on groundwater flux in spawning areas. This report defines optimal lakeshore spawning habitat and discusses eqg and alevin survival both in and below the varial zone.

  5. Water balance trumps ion balance for early marine survival of juvenile pink salmon (Oncorhynchus gorbuscha).

    Science.gov (United States)

    Sackville, M; Wilson, J M; Farrell, A P; Brauner, C J

    2012-08-01

    Smolting salmonids typically require weeks to months of physiological preparation in freshwater (FW) before entering seawater (SW). Remarkably, pink salmon (Oncorhynchus gorbuscha) enter SW directly following yolk absorption and gravel emergence at a size of 0.2 g. To survive this exceptional SW migration, pink salmon were hypothesized to develop hypo-osmoregulatory abilities prior to yolk absorption and emergence. To test this, alevins (pre-yolk absorption) and fry (post-yolk absorption) were transferred from FW in darkness to SW under simulated natural photoperiod (SNP). Ionoregulatory status was assessed at 0, 1 and 5 days post-transfer. SW alevins showed no evidence of hypo-osmoregulation, marked by significant water loss and no increase in gill Na⁺/K⁺-ATPase (NKA) activity or Na⁺:K⁺:2Cl⁻ cotransporter (NKCC) immunoreactive (IR) cell frequency. Conversely, fry maintained water balance, upregulated gill NKA activity by 50 %, increased the NKA α1b/α1a mRNA expression ratio by sixfold and increased NKCC IR cell frequency. We also provide the first evidence of photoperiod-triggered smoltification in pink salmon, as fry exposed to SNP in FW exhibited preparatory changes in gill NKA activity and α1 subunit expression similar to fry exposed to SNP in SW. Interestingly, fry incurred larger increases in whole body Na⁺ than alevins following both SW and FW + SNP exposure (40 and 20 % in fry vs. 0 % in alevins). The ability to incur and tolerate large ion loads may underlie a novel mechanism for maintaining water balance in SW prior to completing hypo-osmoregulatory development. We propose that pink salmon represent a new form of anadromy termed "precocious anadromy".

  6. Quantifying Temperature Effects on Fall Chinook Salmon

    Energy Technology Data Exchange (ETDEWEB)

    Jager, Yetta [ORNL

    2011-11-01

    The motivation for this study was to recommend relationships for use in a model of San Joaquin fall Chinook salmon. This report reviews literature pertaining to relationships between water temperature and fall Chinook salmon. The report is organized into three sections that deal with temperature effects on development and timing of freshwater life stages, temperature effects on incubation survival for eggs and alevin, and temperature effects on juvenile survival. Recommendations are made for modeling temperature influences for all three life stages.

  7. Early decrease in dietary protein:energy ratio by fat addition and ontogenetic changes in muscle growth mechanisms of rainbow trout: short- and long-term effects.

    Science.gov (United States)

    Alami-Durante, Hélène; Cluzeaud, Marianne; Duval, Carine; Maunas, Patrick; Girod-David, Virginia; Médale, Françoise

    2014-09-14

    As the understanding of the nutritional regulation of muscle growth mechanisms in fish is fragmentary, the present study aimed to (1) characterise ontogenetic changes in muscle growth-related genes in parallel to changes in muscle cellularity; (2) determine whether an early decrease in dietary protein:energy ratio by fat addition affects the muscle growth mechanisms of rainbow trout (Oncorhynchus mykiss) alevins; and (3) determine whether this early feeding of a high-fat (HF) diet to alevins had a long-term effect on muscle growth processes in juveniles fed a commercial diet. Developmental regulation of hyperplasia and hypertrophy was evidenced at the molecular (expression of myogenic regulatory factors, proliferating cell nuclear antigen and myosin heavy chains (MHC)) and cellular (number and diameter of white muscle fibres) levels. An early decrease in dietary protein:energy ratio by fat addition stimulated the body growth of alevins but led to a fatty phenotype, with accumulation of lipids in the anterior part, and less caudal muscle when compared at similar body weights, due to a decrease in both the white muscle hyperplasia and maximum hypertrophy of white muscle fibres. These HF diet-induced cellular changes were preceded by a very rapid down-regulation of the expression of fast-MHC. The present study also demonstrated that early dietary composition had a long-term effect on the subsequent muscle growth processes of juveniles fed a commercial diet for 3 months. When compared at similar body weights, initially HF diet-fed juveniles indeed had a lower mean diameter of white muscle fibres, a smaller number of large white muscle fibres, and lower expression levels of MyoD1 and myogenin. These findings demonstrated the strong effect of early feed composition on the muscle growth mechanisms of trout alevins and juveniles.

  8. ÉVOLUTION SPATIO-TEMPORELLE DE LA CONTRIBUTION DU REPEUPLEMENT EN TRUITE (SALMO TRUTTA L. RÉALISÉ A DES STADES PRÉCOCES DANS LE BASSIN AMONT DU FIER (74.

    Directory of Open Access Journals (Sweden)

    CAUDRON A.

    2002-04-01

    Full Text Available Les pratiques de repeuplement en truite à des stades précoces (alevins nourris et truitelles 3-5 cm ont été évaluées par la technique de fluoromarquage des otolithes sur le bassin amont du Fier pour trois cohortes (1995, 1996, 1997. La contribution du repeuplement et du recrutement naturel a été suivie à la fois dans la population en place et dans les captures par pêche à la ligne. Au stade 0+ en place à l’automne, la contribution des poissons alevinés est relativement importante pour les trois cohortes considérées. Cependant, l’analyse du rapport entre le nombre d’alevins introduits au printemps et le nombre de truitelles recapturées à l’automne fait apparaître un taux d’implantation très faible des 0+ marqués quelle que soit la densité alevinée. La contribution des marqués chute brutalement au stade 1+ en place (cohorte 95 et 96 et devient très faible. Cette tendance se poursuit au stade 2+ en place pour la cohorte 95 avec des taux de marqués qui diminuent encore. Dans les captures par pêche à la ligne le taux de 2+ marqués est supérieur à celui observé dans la population en place à l’automne mais la contribution du recrutement naturel reste toujours dominante. Ensuite, la contribution de repeuplement suit la même dynamique que dans la population en place puisqu’il diminue avec l’âge. Elle devient négligeable au stade 3+ et nulle à partir de 4+.

  9. Recherches biologiques et pisciculture expérimentale du goujon (Gobio gobio L.

    Directory of Open Access Journals (Sweden)

    BRUNET R.

    1972-07-01

    Full Text Available 1.1. Le goujon Gobio gobio L. (sous-espèce gobio est un poisson de rivières peu rapides, à instinct grégaire, vivant sur fond de gravier entre la région salmonicole et la région cyprinicole. Il peut vivre de 5 à 7 années et se reproduire dès la seconde année. 1.2. Le goujon n'est pas un poisson migrateur comme les expériences réalisées par marquage tendent à le démontrer, mais ce poisson à forte capacité reproductrice peut passer par des périodes de prolifération ou de raréfaction. 1.3. Le goujon est un poisson de type Carnivore qui s'alimente normalement durant toute l'année. Les adultes se nourissent principalement à partir du benthos ; les proies sont, en ordre d'importance décroissante, des larves d'Insectes, des Crustacés, des Mollusques, des Vers et des Algues ou détritus végétaux. Les alevins s'alimentent principalement à partir du plancton ; la nourriture est de même nature qualitativement, mais quantitativement les Crustacés y sont beaucoup plus abondants que les Insectes. 1.4. Le goujon est fréquemment parasité par le Plathelminte Monogène du genre Diplozoon ; ce parasite peut infester 90 % de la population. Il est parfois parasité par un grand Nématode du genre Philometra qui envahit la cavité générale. 1.5. Le goujon pond au printemps et en été, mais le début de la ponte est nettement lié à la température de l'eau (minimum de + 16°C à + 17°C; la ponte est fractionnée, mais peut atteindre 4 000 à 5 000 œufs par femelle et par saison. L'œuf, blanc translucide, mesure 1,5 mm de diamètre; l'incubation est de 125 degrés/jour. L'essai d'élevage en aquarium prouve qu'une alimentation artificielle adaptée doit être possible. 1.6. La pisciculture des alevins est réalisée dans la région toulousaine et permet d'indiquer les normes souhaitables. Pour la ponte, des bassins de 1 000 m2 , avec pente de 1 % et fond de gravier, peuvent recevoir 500 géniteurs. La croissance des alevins d'un

  10. Ionocyte Immunolocalization and the Effects of Ultraviolet Radiation on Their Abundance and Distribution in the Alenins of Caspian Sea Salmon,Salmo Trutta Caspius

    Directory of Open Access Journals (Sweden)

    Saber Khodabandeh

    2011-01-01

    Full Text Available Objective: On a global scale, stratospheric ozone depletion has caused an increase inUV-B radiation reaching the earth's surface. Ultraviolet radiation has long been suspectedto be harmful to aquatic organisms.Materials and Methods: In order to study ionocyte localization (by Na+/K+-ATPase immunolocalizationand the effects of UV radiation on the ionocytes of skin and gills, the alevinsof Salmo trutta caspius were exposed to different doses of UV radiation [unit low doses(ULD of: 60 μw/cm2 UVC; 100 μw/cm2 UVB and 40 μw/cm2 UVA and unit high doses(UHD of: 90 μw/cm2 UVC; 130 μw/cm2 UVB and 50 μw/cm2 UVA] using two adjustableF8T5 UV-B, 302 nm lamps (Japan for 15 minutes once a day in laboratory conditions.Alevins not subjected to UV exposure served as a control group.Results: In both UV exposure groups, all the alevins died on the ninth day. No mortalitywas observed in the control group. The Na+/K+-ATPase immunolocalization study indicatedthat ionocytes were located, in lessening order, on the yolk sac, trunk, gills, operculaand rarely on the head skin. Immunohistochemical results showed significant reductionin the number of ionocytes on the yolk sac, with lesser reduction on the trunk in both UVexposure groups. In contrast, the number of immunofluorescence cells on the gill wassignificantly elevated. Our results also showed that the size of ionocytes was reduced onthe trunk and yolk sac in the UV exposure groups, but not significantly. Deformation anddestruction of ionocytes on the yolk sac and trunk were observed with scanning electronmicroscope (SEM in the UV exposure groups.Conclusion: Our results showed that ionocytes were located mainly on the yolk sac,in lesser amounts on the trunk, gills and opercula, and rarely also on the head skinof alevins. UV radiation caused deformation and reduction in the number and size ofionocytes on the trunk and yolk sac. As the skin cells of trout alevins possess essentialfunctions for respiration

  11. Etude comparative du développement des larves de poissons élevées en conditions intensives et semi-extensives : Ontogénèse et performances zootechniques

    OpenAIRE

    2012-01-01

    Le développement de l’aquaculture repose avant tout sur l’approvisionnement en specimens à élever mais pour la majorité des espèces, le recrutement naturel est insuffisant pour constituer une base d’élevages à grandes échelles. La production aquacole tunisienne est essentiellement piscicole et l’élevage extensif dans les barrages y contribue de façon importante. L'élevage des larves de poissons constitue une étape incontournable pour la production d’alevins destinés à la pisciculture et aux e...

  12. Importance of the proportions of dietary polyunsaturated fatty acids and antioxoidants in larval development of marine fish

    OpenAIRE

    Atalah, Eyad

    2008-01-01

    La acuicultura es uno de los sectores con mayor crecimiento en la producción animal mundial, con una tasa superior al 5% anual en la última década (Izquierdo et al., 2008). En la acuicultura, el éxito del cultivo de cualquier especie de peces marinos está limitado por la cantidad y la calidad de la producción en masa de sus alevines (Izquierdo y Fernández - Palacios, 1997). Por lo tanto, para cubrir las crecientes demandas de la producción de semillas, es necesario mejorar l...

  13. Bilan de la première période d'élevage du silure glane (Silurus glanis) en condition tropicale et en circuit recyclé. (Collaboration Ifremer Palavas/Les Viviers de la Castillonne)

    OpenAIRE

    Gasset, Eric; Aubry, J P; Blancheton, Jean-Paul

    2002-01-01

    La production Française du Silure glane stagne depuis plusieurs années pour plusieurs raisons principales: la qualité des alevins produits par les entreprises existantes n'est pas optimale, notamment pour un élevage intensif; les techniques de production extensives et semi-intensives en bassins de terre se heurtent à un profil d'évolution thermique naturelle inadapté à cette espèce d'origine continentale, ce qui ce traduit par des croissances aléatoires, des pathologies difficiles à maîtriser...

  14. Evaluación de diferentes proporciones de proteína animal en la dieta de Clarias gariepinus (Burchell, 1822

    Directory of Open Access Journals (Sweden)

    Llanes Iglesias, José

    2008-05-01

    Full Text Available ResumenEl objetivo de este trabajo fue evaluar tres dietas experimentales usando diferentes porcentajes de harina de pescado (0, 10 y 20% de inclusión que representan tres proporciones de proteína animal (0, 25 y 45% respectivamente en relación a la proteína total de la dieta. Las dietas se emplearon en la alimentación de alevines de Clarias gariepinus de 11+0.05 g de peso promedio inicial distribuidos en un diseño completamente aleatorizado durante 60 días. Los resultados mostraron que los peces alimentados con la dieta D3 (45% de proteína animal, Pa obtuvieron los mejores crecimientos, conversión y eficiencia alimentaría, significativamente diferente (P 0,05. Se concluye que 45% debe ser la fracción de proteína de origen animal y es imprescindible para alevines de Clarias gariepinus.

  15. Evidence of Olfactory Imprinting at an Early Life Stage in Pink Salmon (Oncorhynchus gorbuscha).

    Science.gov (United States)

    Bett, Nolan N; Hinch, Scott G; Dittman, Andrew H; Yun, Sang-Seon

    2016-11-09

    Pacific salmon (Oncorhynchus spp.) navigate towards spawning grounds using olfactory cues they imprinted on as juveniles. The timing at which imprinting occurs has been studied extensively, and there is strong evidence that salmon imprint on their natal water during the parr-smolt transformation (PST). Researchers have noted, however, that the life histories of some species of Pacific salmon could necessitate imprinting prior to the PST. Juvenile pink salmon (O. gorbuscha) spend less time in fresh water than any other species of Pacific salmon, and presumably must imprint on their natal water at a very young age. The time at which imprinting occurs in this species, however, has not been experimentally tested. We exposed juvenile pink salmon as alevins to phenethyl alcohol (PEA) or control water, reared these fish to adulthood, and then tested their behavioural responses to PEA to determine whether the fish successfully imprinted. We found that pink salmon exposed to PEA as alevins were attracted to the chemical as adults, suggesting that imprinting can occur during this stage. Our finding provides some of the first evidence to support the long-standing belief that imprinting can occur in pink salmon prior to the PST.

  16. Validación del Protocolo de Reproducción de Colossoma macropomum, Piaractus brachypomus y Prochilodus nigricans en Condiciones Controladas

    Directory of Open Access Journals (Sweden)

    Lorgio Verdi-Olivares

    2014-07-01

    Full Text Available Protocolos aplicados a las diferentes etapas de la reproducción  inducida: tratamiento hormonal, incubación, manejo de larvas, y manejo de alevines en los peces de consumo humano Colossoma macropomum (gamitana, Piaractus brachypomus (paco y Prochilodus nigricans (boquichico fueron evaluados en el marco del proyecto UNAP “Cátedra CONCYTEC en Acuicultura Tropical” con el propósito de establecer los adecuados procedimientos en la búsqueda de una óptima productividad acuícola y una mejor rentabilidad económica en Loreto. Con este objetivo se utilizaron como inductores: para gamitana, Pituitaria de Carpa con dosis total de 6,0 mg/kg en hembras y 2,0 mg/kg en machos; Para machos y hembras de paco, Conceptal en dosis total de 2,6 ml/kg en hembras y 1,0 ml/kg en machos; y para boquichico, Pituitaria de Carpa con dosis total de 4,0 mg/kg en hembras y 2,0 mg/kg en machos. El desove se produjo en 11±2 horas; la eclosión ocurre después de 22 horas a partir de la fecundación, con  tasas promedios superiores al 70% y tasas de sobrevivencia, aún cundo por debajo del 50%, garantiza una alta producción de alevines.

  17. Validación del Protocolo de Reproducción de Colossoma macropomum, Piaractus brachypomus y Prochilodus nigricans en Condiciones Controladas

    Directory of Open Access Journals (Sweden)

    Lorgio Verdi Olivares

    2014-06-01

    Full Text Available Protocolos aplicados a las diferentes etapas de la reproducción  inducida: tratamiento hormonal, incubación, manejo de larvas, y manejo de alevines en los peces de consumo humano Colossoma macropomum (gamitana, Piaractus brachypomus (paco y Prochilodus nigricans (boquichico fueron evaluados en el marco del proyecto UNAP “Cátedra CONCYTEC en Acuicultura Tropical” con el propósito de establecer los adecuados procedimientos en la búsqueda de una óptima productividad acuícola y una mejor rentabilidad económica en Loreto. Con este objetivo se utilizaron como inductores: para gamitana, Pituitaria de Carpa con dosis total de 6,0 mg/kg en hembras y 2,0 mg/kg en machos; Para machos y hembras de paco, Conceptal en dosis total de 2,6 ml/kg en hembras y 1,0 ml/kg en machos; y para boquichico, Pituitaria de Carpa con dosis total de 4,0 mg/kg en hembras y 2,0 mg/kg en machos. El desove se produjo en 11±2 horas; la eclosión ocurre después de 22 horas a partir de la fecundación, con tasas promedios superiores al 70% y tasas de sobrevivencia, aún cundo por debajo del 50%, garantiza una alta producción de alevines.

  18. INVESTIGATIONS ON TECHNOLOGICAL PARAMETERS IN INTENSIVE REARING OF PIKE-PERCH (STIZOSTEDION LUCIOPERCA

    Directory of Open Access Journals (Sweden)

    Tamás Molnár

    2000-06-01

    Full Text Available Market demands and competition force the production of high quality freshwater fish in European aquaculture. In Hungary pike-perch is the most „noble” and perhaps the most sensitive fish species. One of the constraints of the increasing its production in natural waters, reservoirs and ponds is the shortage in adequate sized alevins. The possible solution of this problem can be the elaboration of intensive rearing technics of pond prereared fry. The aims of the present work were to test the growing capacity, feed conversion and survival of pike-perch in intensive circumstances. Fish were kept in 130 l aquaria working in recirculation system at an average water temperature of 220.5 C. Two stocking densities were applied (18 and 36 fish/aquarium. Minced fish (test and live prey (control were offered twice a day till satiation in two replications. The experiment lasted 4 weeks. According to our results minced fish is suitable feed in the intensive rearing of pike-perch alevins. Daily food intake was only influenced significantly by different feeds (2.01g vs.4.53 g, test and control, respectively. Feeding and stocking density had significant effect (P=0.001 and 0.017 on the average weight gain (0.52 g and 1.40 g for minced fish and live feed, respectively, 1.02 g in lower and 0.90 g in higher density. Owning to the high variances treatment effect on feed conversion proved to be not significant. Average survival of the minced fish fed group was 62.2 % vs. 78.8 % of the live fish fed alevins. This difference was significant (P<0.01 in the first two weeks when almost all of the losses happened due to cannibalism and other unknown reasons. Based on our results a period of 10–14 days is needed for pre-reared pike-perch to change gradually their feeding from zooplankton to minced fish diet.

  19. Uso estratégico del espacio en categorías de formación de pelota vasca. [Strategic use of space in basque pelota training categories].

    Directory of Open Access Journals (Sweden)

    Oidui Usabiaga

    2014-04-01

    Full Text Available La pelota vasca es un deporte de pelota compuesto por varias especialidades. La pelota a mano es una de las más practicadas y se juega tanto en duelos individuales como por equipos. El presente estudio pretende analizar y comparar algunos indicadores de juego del uso estratégico del espacio por parte de jugadores benjamines (8-10 años y alevines (10-12 años que participan en un programa de deporte escolar. La muestra estuvo compuesta por doce partidos, seis de benjamines (30 participantes y seis de alevines (30 participantes. El registro se llevó a cabo mediante un instrumento observacional ad hoc diseñado para analizar el uso estratégico del espacio por parte de los participantes, tanto cuando golpean la pelota como cuando están en situación de espera. Los resultados muestran que los participantes de las dos categorías usan el espacio de la misma forma respecto a las zonas de golpe, la ubicación espacial en situación de espera durante los duelos por parejas y los tipos de saque. Los alevines, en comparación a los benjamines, se posicionan más a la derecha del jugador que golpea durante los duelos individuales, dirigen la pelota a distancias medias y cometen menos faltas tanto en el resto del saque como en el juego de intercambio, dando mayor continuidad al juego (p Abstract The basque pelota is a ball sport composed of various specialties. The hand pelota is one of the most popular and is played in both individual and team matchups. The aim of this study was to analyze and compare some indicators of the strategic use of space by young players, 8-10- and 10-12-year-old students, participating in a school sport program. The sample consisted of twelve games, six for each level (30 participants for each level. Data were recorded with an ad hoc observational instrument designed to analyze the strategic use of space by the participants, both when they hit the ball and when they are on standby. The results show that the participants of

  20. Reversion sexual de las Tilapias Roja (Oreochromis Sp, una guía básica para el acuacultor

    Directory of Open Access Journals (Sweden)

    Duván Andrés Arboleda Obregón

    2005-12-01

    Full Text Available La tilapia roja es un híbrido distribuido en todo el mundo; atractivo por su color y sus características zootécnicas lo que la convierte en una especie con gran mercado y de gran importancia para investigación, en tilapia es importante el cultivo de machos, para obtener machos se usa la 17alfametiltestosterona que es una hormona que cuando suministrada con el alimento a los alevines los transforma en machos. The red tilapia is a hybrid distribuided in all the world; it is attractive due to its color and its zootechnical characteristic convert in a specie with big market and of many importance for research, in tilapia is important the males culture, for obtain males is used 17alfamethyltestosterone that is an hormone when is supplied with the food to the fingerlings transform in males

  1. Early enrichment effects on brain development in hatchery-reared Atlantic salmon (Salmo salar): no evidence for a critical period

    DEFF Research Database (Denmark)

    Näslund, Joacim; Aarestrup, Kim; Thomassen, Søren T.;

    2012-01-01

    In hatcheries, fish are normally reared in barren environments, which have been reported to affect their phenotypic development compared with wild conspecifics. In this study, Atlantic salmon (Salmo salar) alevins were reared in conventional barren hatchery trays or in either of two types...... of structurally enriched trays. We show that increased structural complexity during early rearing increased brain size in all investigated brain substructures. However, these effects disappeared over time after transfer to barren tanks for external feeding. Parallel to the hatchery study, a group of salmon parr...... was released into nature and recaptured at smoltification. These stream-reared smolts developed smaller brains than the hatchery reared smolts, irrespective of initial enrichment treatment. These novel findings do not support the hypothesis that there is a critical early period determining the brain growth...

  2. Salmo salar: morfología ultraestructural de la pared del corion en ovas normales y con problemas de eclosión Salmo salar: ultrastructural morphology of chorion, from normal and with hatching problems ova

    Directory of Open Access Journals (Sweden)

    R Jaramillo

    2009-01-01

    Full Text Available El “corion duro” es un fenómeno de reciente ocurrencia y se caracteriza porque algunos alevines con ojo no son capaces de degradar el corion que les rodea o lo hacen sólo de manera parcial, produciéndose en ambos casos la muerte del alevín. Este fenómeno ha causado fracasos reproductivos importantes en algunas pisciculturas del sur de Chile, desconociéndose hasta ahora la razón de su ocurrencia. En este estudio se realizaron mediciones del grosor del corion de Salmo salar así como de las fibras que forman parte de éste en ovas fertilizadas, no fertilizadas, con desarrollo normal y ovas que no lograron eclosionar. Los resultados obtenidos indican que las leves variaciones observadas en el grosor del corion entre los diferentes estados de desarrollo de las ovas estudiadas no explican la ocurrencia del “corion duro”. Sin embargo, la disposición de las fibras proteicas que forman el estrato interno del corion parece ser la respuesta a este fenómeno. Las ovas que no eclosionan presentan “corion duro” y exhiben un estrato interno carente de poros a diferencia de lo que se observa en las ovas que desarrollan normalmente y que logran la eclosión. Se propone que problemas en la síntesis de alguna de las sub-unidades que forman la coriogenina serían los responsables de la formación de un estrato interno carente de poros, siendo ésta la razón del “corion duro”.Either eyed alevins unable to digest the chorion or those digesting it partially, are both suffering the “hard chorion” phenomenon; in both cases alevins can not survive producing high mortality rates. During recent years, the salmon farming industry in Southern Chile has been facing massive mortality events caused by “hard chorion”. Since “hard chorion” is a recently observed phenomenon there are no literature reporting its origin. The aim of this study was to find differences in the ultrastructure of chorion fibers from Salmo salar ova at different

  3. Natural selection constrains personality and brain gene expression differences in Atlantic salmon (Salmo salar)

    DEFF Research Database (Denmark)

    Thörnqvist, Per-Ove; Höglund, Erik; Winberg, Svante

    2015-01-01

    In stream-spawning salmonid fishes there is a considerable variation in the timing of when fry leave the spawning nests and establish a feeding territory. The timing of emergence from spawning nests appears to be related to behavioural and physiological traits, e.g. early emerging fish are bolder...... and more aggressive. In the present study, emerging Atlantic salmon (Salmo salar L.) alevins were sorted into three fractions: early, intermediate and late emerging. At the parr stage, behaviour, stress responses, hindbrain monoaminergic activity and forebrain gene expression were explored in fish from...... the early and late emerging fractions (first and last 25%). The results show that when subjected to confinement stress, fish from the late emerging fraction respond with a larger activation of the brain serotonergic system than fish from the early fraction. Similarly, in late emerging fish, stress resulted...

  4. Temperature and Water Depth Monitoring Within Chum Salmon Spawning Habitat Below Bonneville Dam : Annual Report October 2007-September 2008

    Energy Technology Data Exchange (ETDEWEB)

    Arntzen, E.V. [Pacific Northwest National Laboratory

    2009-07-14

    The overall goal of the project described in this report is to provide a sound scientific basis for operation of the Federal Columbia River Power System (FCRPS) in ways that will effectively protect and enhance chum salmon populations - a species listed in March 1999 as threatened under the Endangered Species Act of 1973 (ESA). The study objective during fiscal year 2008 was to provide real-time data on Ives Island area water temperature and water surface elevations from the onset of chum salmon spawning through the end of chum salmon emergence. Sampling locations included areas where riverbed temperatures were elevated, potentially influencing alevin development and emergence timing. In these locations, hydrosystem operation caused large, frequent changes in river discharge that affected salmon habitat by dewatering redds and altering egg pocket temperatures. The 2008 objective was accomplished using temperature and water-level sensors deployed inside piezometers. Sensors were integrated with a radio telemetry system such that real-time data could be downloaded remotely and posted hourly on the Internet. During our overall monitoring period (October 2007 through June 2008), mean temperature in chum spawning areas was nearly 2 C warmer within the riverbed than in the overlying river. During chum salmon spawning (mid-November 2007 through December2007), mean riverbed temperature in the Ives Island area was 14.5 C, more than 5 C higher than in the river, where mean temperature was 9.4 C. During the incubation period (January 2008 through mid-May 2008), riverbed temperature was approximately 3 C greater than in the overlying river (10.5 C and 7.2 C, respectively). Chum salmon preferentially select spawning locations where riverbed temperatures are elevated; consequently the incubation time of alevin is shortened before they emerge in the spring.

  5. Performance of juvenile steelhead trout (Oncorhynchus mykiss) produced from untreated and cryopreserved milt

    Science.gov (United States)

    Hayes, Michael C.; Rubin, Stephen P.; Hensleigh, Jay E.; Reisenbichler, Reginald R.; Wetzel, Lisa A.

    2005-01-01

    Despite the expanding use of milt cryopreservation in aquaculture, the performance of fish produced from this technique has not been fully explored beyond initial rearing stages. We compared the performance of juvenile steelhead Oncorhynchus mykiss produced from untreated (UM) and cryopreserved milt (CM) and reared for 4–9 months. For the 1996 brood, CM alevins were heavier (∼ 1.7%, P influenced by a significant milt-by-family interaction (P families. No significant differences were found in length or weight (P > 0.05) for 1997 brood alevins and percent yolk was similar for both broods (P > 0.34). In growth and survival experiment I (GSE-I, 1996), UM and CM juveniles reared in separate tanks and fed to satiation (130 days) showed no significant differences in survival, length or weight (P > 0.05) between milt groups. In contrast, for UM and CM siblings reared in the same tank for 210 days on a low food ration (GSE-II), survival was similar (P > 0.05), but length (UM 4% > CM, P  CM, P = 0.08), were influenced by cryopreservation. Fish from the 1997 brood (GSE-III) were reared for 313 days in a repeat of GSE-II and no differences were found in survival (P = 0.47), length (P = 0.75) or weight (P = 0.76) suggesting considerable heterogeneity between broods. Performance of the 1996 brood was also tested for response to stress and a disease challenge. Cortisol responses of juveniles exposed to acute stress were not significantly different (P = 0.19), but mean cortisol was consistently and significantly greater (P families and suggests a cautionary approach to the widespread use of cryopreservation for steelhead.

  6. Morfologia e crescimento do músculo estriado esquelético no pirarucu Arapaima gigas Cuvier, 1817 (Teleostei, Arapaimidae = Morphology and skeletal muscle growth in pirarucu Arapaima gigas Cuvier, 1817 (Teleostei, Arapaimidae

    Directory of Open Access Journals (Sweden)

    Fernanda Regina Carani

    2008-04-01

    Full Text Available O objetivo deste trabalho foi avaliar as características morfológicas e de crescimento do músculo estriado esquelético no pirarucu (Arapaima gigas. Foram utilizados animais em duas fases de crescimento: alevinos, com 50 dias de idade, e juvenis, com umano de idade. Após eutanásia dos animais, fragmentos musculares das regiões dorsal, lateral cranial e lateral caudal foram coletados e congelados em nitrogênio líquido. Cortes histológicos (10 mm foram submetidos às colorações HE e Tricrômico de Gomori, para a análise morfológica, e NADH-TR, para a análise do metabolismo oxidativo das fibras musculares. Foi calculado o menor diâmetro das fibras musculares brancas nas regiões dorsal e lateral cranial. A musculatura dorsal branca mostrou-se mais desenvolvida e, namusculatura lateral, observaram-se compartimentos distintos: superficial vermelho e profundo branco. Nos alevinos, o crescimento muscular ocorreu predominantemente por hiperplasia das fibras e, nos juvenis, predominou o crescimento muscular por hipertrofia.The aim of this work was to evaluate the morphological and growth characteristics of skeletal muscle tissue in pirarucu (Arapaimagigas using alevins (50 days old and juveniles (1 year old. Muscle samples were collected from dorsal, lateral cranial and lateral caudal regions, and then frozen in liquid nitrogen. Histological frozen sections (10μm were stained with HE and Gomori Trichrome formorphological analysis, and NADH-TR to evaluate muscle fiber oxidative metabolism. Morphometric analysis samples were obtained from dorsal and lateral cranial regions, and the smallest-diameter white fibers were measured. White dorsal muscle was thicker, andtwo muscle fiber compartments were identified in the lateral cranial region: red (superficial and white (deep muscle. Hyperplasia muscle growth predominated in alevins and hypertrophy in juveniles.

  7. Morfologia e crescimento do músculo estriado esquelético no pirarucu Arapaima gigas Cuvier, 1817 (Teleostei, Arapaimidae - DOI: 10.4025/actascibiolsci.v30i2.3640 Morphology and skeletal muscle growth in pirarucu Arapaima gigas Cuvier, 1817 (Teleostei, Arapaimidae - DOI: 10.4025/actascibiolsci.v30i3.3640

    Directory of Open Access Journals (Sweden)

    Maeli Dal Pai Silva

    2008-05-01

    Full Text Available O objetivo deste trabalho foi avaliar as características morfológicas e de crescimento do músculo estriado esquelético no pirarucu (Arapaima gigas. Foram utilizados animais em duas fases de crescimento: alevinos, com 50 dias de idade, e juvenis, com um ano de idade. Após eutanásia dos animais, fragmentos musculares das regiões dorsal, lateral cranial e lateral caudal foram coletados e congelados em nitrogênio líquido. Cortes histológicos (10 µm foram submetidos às colorações HE e Tricrômico de Gomori, para a análise morfológica, e NADH-TR, para a análise do metabolismo oxidativo das fibras musculares. Foi calculado o menor diâmetro das fibras musculares brancas nas regiões dorsal e lateral cranial. A musculatura dorsal branca mostrou-se mais desenvolvida e, na musculatura lateral, observaram-se compartimentos distintos: superficial vermelho e profundo branco. Nos alevinos, o crescimento muscular ocorreu predominantemente por hiperplasia das fibras e, nos juvenis, predominou o crescimento muscular por hipertrofia.The aim of this work was to evaluate the morphological and growth characteristics of skeletal muscle tissue in pirarucu (Arapaima gigas using alevins (50 days old and juveniles (1 year old. Muscle samples were collected from dorsal, lateral cranial, and lateral caudal regions, and then frozen in liquid nitrogen. Histological frozen sections (10 µm were stained with HE and Gomori Trichrome for morphological analysis, and NADH-TR to evaluate muscle fiber oxidative metabolism. Morphometric analysis samples were obtained from dorsal and lateral cranial regions, and smallest diameter white fibers were measured. White dorsal muscle was thicker and two muscle fiber compartments were identified in the lateral cranial region: red (superficial and white (deep muscle. Hyperplasia muscle growth predominated in alevins and hypertrophy in juveniles.

  8. Ontogeny of the Digestive System of Atlantic Salmon (Salmo salar L. and Effects of Soybean Meal from Start-Feeding.

    Directory of Open Access Journals (Sweden)

    Christian Sahlmann

    Full Text Available Despite a long history of rearing Atlantic salmon in hatcheries in Norway, knowledge of molecular and physiological aspects of juvenile development is still limited. To facilitate introduction of alternative feed ingredients and feed additives during early phases, increased knowledge regarding the ontogeny of the digestive apparatus in salmon is needed. In this study, we characterized the development of the gastrointestinal tract and accessory digestive organs for five months following hatch by using histological, biochemical and molecular methods. Furthermore, the effects of a diet containing 16.7% soybean meal (SBM introduced at start-feeding were investigated, as compared to a fishmeal based control diet. Salmon yolk sac alevins and fry were sampled at 18 time points from hatch until 144 days post hatch (dph. Histomorphological development was investigated at 7, 27, 46, 54 and 144 dph. Ontogenetic expression patterns of genes encoding key digestive enzymes, nutrient transporters, gastrointestinal peptide hormones and T-cell markers were analyzed from 13 time points by qPCR. At 7 dph, the digestive system of Atlantic salmon alevins was morphologically distinct with an early stomach, liver, pancreas, anterior and posterior intestine. About one week before the yolk sac was internalized and exogenous feeding was started, gastric glands and developing pyloric caeca were observed, which coincided with an increase in gene expression of gastric and pancreatic enzymes and nutrient transporters. Thus, the observed organs seemed ready to digest external feed well before the yolk sac was absorbed into the abdominal cavity. In contrast to post-smolt Atlantic salmon, inclusion of SBM did not induce intestinal inflammation in the juveniles. This indicates that SBM can be used in compound feeds for salmon fry from start-feeding to at least 144 dph and/or 4-5 g body weight.

  9. Effects of shortened photoperiod on gonadotropin-releasing hormone, gonadotropin, and vitellogenin gene expression associated with ovarian maturation in rainbow trout.

    Science.gov (United States)

    Choi, Sungchang; Lee, Cheul Ho; Park, Woodong; Kim, Dae-Jung; Sohn, Young Chang

    2010-01-01

    Reproductive activities of salmonids are synchronized by changes in photoperiod, which control the endocrine system via the brain-pituitary-gonadal axis. Gonadotropin-releasing hormone (GnRH) in the brain regulates synthesis and release of the pituitary gonadotropins (GTHs; FSH and LH). FSH and LH in turn stimulate the production of sex steroids for oocyte growth and maturation-Inducing steroid hormones for oocyte maturation and ovulation, respectively, in female salmonids. To clarify effects of long-term photoperiod manipulations on the reproductive activity of salmonids from early recrudescence to ovulation, we Investigated the gene expression profiles of GnRH, GTHs, and vitellogenin (VTG), and plasma sex steroids in female rainbow trout (Oncorhynchus mykiss). In addition, the percentages of eyed embryos and hatched alevins were examined together with the number of ovulated eggs to evaluate the effects of photoperiod regimes on egg quality. During late summer, the mRNA levels of GnRHs, GTHalpha, and LHbeta, and the plasma level of a maturational steroid (17alpha,20beta-dihydroxy-4-pregnen-3-one; 17,20beta-P) were significantly elevated by a gradually shortened photoperiod under constant temperature, in accordance with accelerated sexual maturation. The percentages of eyed embryos and hatched alevins from fish ovulated in August were comparable to those of control fish observed in December. These results clearly indicate that syntheses of GnRHs, LH, VTG, and 17,20beta-P are effectively accelerated by a programmed long-short photoperiod regime in early recrudescent female rainbow trout, without a marked deterioration in egg quality.

  10. Effets négatifs de pH extrêmes sur le développement embryonnaire et larvaire du brochet Esox lucius L.

    Directory of Open Access Journals (Sweden)

    LE LOUARN H.

    1998-07-01

    Full Text Available Parmi les facteurs abiotiques conditionnant la survie au cours de la vie embryonnaire et larvaire des poissons, le pH semble jouer un rôle primordial. La motivation de ce travail provient d'observations sur les importantes variations de ses valeurs au printemps, l'existence de pH très acides en étangs forestiers et des mortalités importantes de brochetons au cours de la même période. L'expérimentation s'est déroulée en aquariums avec une gamme de valeurs allant de 4,5 à 10,5 unités pH. Des tests en bains, continus ou momentanés (1 heure, sont effectués. Deux stades sont étudiés : les oeufs fécondés suivis jusqu'après l'éclosion ; les alevins incubés à pH neutre suivis jusqu'à la résorption de la vésicule vitelline. Les paramètres suivants sont étudiés : survie, déroulement de l'embryogenèse, anomalies éventuelles, performances de nage. Le rythme cardiaque de l'embryon a été mesuré. Les résultats sont les suivants : - Les valeurs létales sont respectivement de 6 et 10 (alevins et 4,5 et 10,5 (embryons. - L'action sur les oeufs est moins forte, même si une mortalité importante (46,7 % et de faibles performances de nage pour un pH inférieur à 6 semblent hypothéquer la réussite du recrutement. La valeur de 10,5 provoque un développement déficient des quelques individus survivants. - Sur les alevins, même en bains d'une heure, la survie est faible : 42,6 % à pH 5, 29,3 % à pH 10. Le rythme cardiaque ne variait pas de façon notable entre les seuils de tolérance. Ces résultats permettent de récapituler pour une espèce largement distribuée les conditions de recrutement liées à l'acidité du milieu. Il faut noter que les hausses brutales du pH au printemps dans des plans d'eau sur substrat cristallin rendent aléatoires la réussite des empoissonnements en brochetons des premiers stades.

  11. Lake Roosevelt Fisheries Monitoring Program; Measurement of Thyroxin Concentration as an Indicator of the Critical Period for Imprinting in the Kokanee Salmon (Orcorhynchus Nerka) Implications for Operating Lake Roosevelt Kokanee Hatcheries; 1991 Supplement Report.

    Energy Technology Data Exchange (ETDEWEB)

    Scholz, Allan T.; White, Ronald J.; Koehler, Valerie A. (Eastern Washington University, Upper Columbia United Tribes Fisheries Research Center, Cheney, WA)

    1992-05-01

    Previous investigations have determined that thyroid hormone surges activate olfactory imprinting in anadromous salmonid smolts. The mechanism of action appears to require binding of thyroid hormones to receptors in brain cell nuclei, which stimulates neuron differentiation and wires a pattern of neuron circuitry that allows for the permanent storage of the imprinted olfactory memory. In this study, thyroxine concentrations [T{sub 4}] were measured in 487 Lake Whatcom stock and 70 Lake Roosevelt stock Kokanee salmon to indicate the critical period for imprinting. Eggs, alevins and fry, reared at the Spokane Indian Kokanee Hatchery, were collected from January through August 1991. Sampled fish were flash frozen on dry ice and stored at {minus}80{degrees}C until T{sub 4} was extracted and concentrations determined by radioimmunassay. Mean concentration {+-} SEM of 10--20 individual fish (assayed in duplicate) were determined for each time period. T{sub 4} concentration peaked on the day of hatch at 16.8 ng/g body weight and again at swim-up at 16.0 {+-} 4.7 ng/g body weight. T{sub 4} concentration was 12.5 to 12.9 ng/g body weight in eggs, 7.1 to 15.2 ng/g body weight in. alevins, 4.5 to 11.4 ng/g body weight in 42 to 105 day old fry and 0.1 to 2.9 ng/g body weight in 112 to 185 day old fry. T{sub 4} concentrations were highest in eggs at 13.3 {+-} 2.8 ng/g body weight, then steadily decreased to 0.1 {+-} 0.1 ng/g body weight in older fry. Fry were released in Lake Roosevelt tributaries in July and August 1991, at about 170--180 days post hatching, in order to imprint them to those sites. The results of this study indicate that the time of release was not appropriate for imprinting. If T{sub 4} levels are an accurate guide for imprinting in kokanee, our results suggest that the critical period for imprinting in kokanee is at hatching or swim-up stages.

  12. Evaluación del ensilado químico de pescado en la alimentación de Clarias gariepinus (Burchell, 1822 - Fish chemical silage evaluation in Clarias gariepinus (Burchell, 1822 feeding

    Directory of Open Access Journals (Sweden)

    Toledo Pérez, J

    2007-09-01

    Full Text Available ResumenCon el objetivo de evaluar el efecto biológico y económico del ensilado químico de pescado, como única fuente de proteína animal en la alimentación de alevines de Clarias gariepinus, se ensilo manchuelo entero (Opisthonema oglinum, con tres combinaciones de ácidos orgánicos e inorgánicos: 3% de ácido fórmico; 2% ácido sulfúrico 98% y 2% de ácido fórmico y un tercer ensilado con 2,6% de ácido fosfórico y 2,6% de ácido cítrico. Con cada ensilado se confecciono una dieta húmeda, las cuales fueron comparadas con un Alimento Comercial en la alimentación de alevines de Clarias gariepinus durante 60 días. En los resultados obtenidos no hubo diferencias significativas (P>0.05 en los indicadores de crecimiento, utilización del alimento y supervivencia al sustituir totalmente la harina de pescado por los ensilados químicos de pescado. El análisis económico mostró un ahorro de 20 a 30% de los costos de producción por concepto de alimentaciónAbstractThe objetive of this work was to evaluate the biologic and economic effects of chemical fish silage as a unique animal protein source in Clarias gariepinus feeding. Ensiled Opisthonema oglinum with three combinations of organic and inorganic acids: 3% of formic acid; 2% sulfuric acid 98% and 2% formic acid and other with 2,6% phosphoric acid and 2,6% of citric acid. From each silage moist diets was prepared and were compared with comercial foods in Clarias gariepinus feeding during 60 days. There were not significant differences (P>0.05, in growth, feed utilization and survival indicators. The economic analysis showed a cost production sabe between 20 and 30%.

  13. Temperature and Water Depth Monitoring Within Chum Salmon Spawning Habitat Below Bonneville Dam -- Annual Report -- October 2007-September 2008

    Energy Technology Data Exchange (ETDEWEB)

    Arntzen, Evan V.

    2009-07-14

    The overall goal of the project described in this report is to provide a sound scientific basis for operation of the Federal Columbia River Power System (FCRPS) in ways that will effectively protect and enhance chum salmon populations----a species listed in March 1999 as threatened under the Endangered Species Act of 1973 (ESA). The study objective during fiscal year 2008 was to provide real-time data on Ives Island area water temperature and water surface elevations from the onset of chum salmon spawning through the end of chum salmon emergence. Sampling locations included areas where riverbed temperatures were elevated, potentially influencing alevin development and emergence timing. In these locations, hydrosystem operation caused large, frequent changes in river discharge that affected salmon habitat by dewatering redds and altering egg pocket temperatures. The 2008 objective was accomplished using temperature and water-level sensors deployed inside piezo¬meters. Sensors were integrated with a radio telemetry system such that real-time data could be downloaded remotely and posted hourly on the Internet.

  14. Máximo porcentaje de ensilado químico de pescado en la dieta de clarias gariepinus (Burchell, 1822 - Maximum percent of chemical fish silage in Clarias gariepinus (Burchell, 1822, diet.

    Directory of Open Access Journals (Sweden)

    Llanes Iglesias, José

    2007-09-01

    Full Text Available ResumenEl objetivo de este estudio fue evaluar cinco dietas húmedas con diferentes porcentajes de inclusión (40, 50, 60, 70 y 80 de ensilado químico de pescado, preparado con 2% de ácido sulfúrico 98% (peso/volumen, como única fuente de proteína animal, las que fueron comparadas con un Alimento Comercial (20% de harina de pescado en la alimentación de alevines de Clarias gariepinus. Se utilizó un diseño experimental completamente aleatorizado durante 60 días. Los resultados mostraron que los indicadores de crecimiento, utilización del alimento y supervivencia no presentaron diferencias significativas (P>0,05 hasta 80% de inclusión de esta materia prima, representando un ahorro de 302,00 USD/ tonelada de pescado producidoAbstractThe objetive of this study was to evaluate five moist diets with graded levels (40, 50, 60, 70 and 80 of chemical fish silage prepared with 2% sulfuric acid 98% (weigth/volumen, as a unique animal protein source. They were compared with comercial foods (20% of fish meal, Clarias gariepinus feeding. A completely randomised experimental design was development during 60 days. The results of the indicators such as: growth, feed utilization and suvival rate did not differ significantly (P> 0,05, until 80% chemical fish silage, representing a $ 302,00/ ton saving fish produced

  15. Paternal reproductive strategy influences metabolic capacities and muscle development of Atlantic salmon (Salmo salar L.) embryos.

    Science.gov (United States)

    Morasse, Sébastien; Guderley, Helga; Dodson, Julian J

    2008-01-01

    Male Atlantic salmon follow a conditional strategy, becoming either "combatants" that undertake a seaward migration and spend at least a year at sea or "sneakers" that remain in freshwater and mature as parr. A variety of physiological indices showed significant but small differences between the offspring of males that use these two reproductive tactics. Offspring fathered by anadromous male Atlantic salmon (Salmo salar L.) showed greater muscular development and muscle metabolic capacities but lower spontaneous movements than those fathered by mature male parr. At hatch and at maximum attainable wet weight (MAWW), offspring fathered by anadromous males had higher activities of mitochondrial (cytochrome C oxidase and citrate synthase) and glycolytic (lactate dehydrogenase [LDH]) enzymes than progeny of mature male parr. Enzymatic profiles of progeny of anadromous fathers also suggested greater nitrogen excretion capacity (glutamate dehydrogenase) and increased muscular development (creatine kinase and LDH) than in the progeny of mature parr. At MAWW, juveniles fathered by mature parr made considerably more spontaneous movements, presumably increasing their energy expenditures. For juveniles fathered by anadromous males, total cross-sectional areas of white and red muscle at hatch were higher due to the greater number of large-diameter fibers. We suggest that the slightly lower metabolic capacities and muscular development of alevins fathered by mature parr could reflect differences in energy partitioning during their dependence on vitellus. Greater spontaneous movements of offspring of mature male parr could favor feeding and growth after the resorption of the vitellus.

  16. Stages in the early and larval development of the African catfish Clarias gariepinus (Teleostei, Clariidae).

    Science.gov (United States)

    Olaniyi, Wasiu Adekunle; Omitogun, Ofelia Galman

    2014-08-01

    The African catfish Clarias gariepinus Burchell 1822 is a favourite aquaculture fish in many parts of Africa and Asia because of its hardiness and fast growth rate. In this study, early, post-embryonic and larval developmental stages of C. gariepinus were examined chronologically and described. Photomicrographs of unfertilized matured oocytes from 0 min of fertilization through all cell stages to alevin, to complete yolk absorption, to free swimming larval stages are shown and documented live from lateral and top views, with the aid of a light microscope. Extruded oocytes had a mean diameter of 1 ± 0.1 mm, and possessed a thin perivitelline membrane whose space was filled with a protoplasmic layer. Heartbeat was in the range of 115-160/min prior to hatching. Hatchability rate was 85% and hatching occurred at 17 h at a controlled temperature of 28.5 ± 0.5°C, while ontogeny of the eyes and other organs were discernible. At day 4, larvae mean length was 9.3 ± 0.5 mm, exogenous feeding had commenced fully and melanophores spread cephalocaudally but were concentrated significantly on the head parts. This paper, for the first time, presents the significant chronological developmental stages of C. gariepinus embryology that will have significant implications for genetic manipulation and catfish seed production for aquaculture.

  17. Effects of Coded-Wire Tagging on the Survival of Spring Chinook Salmon : Annual Report FY 1990-1991.

    Energy Technology Data Exchange (ETDEWEB)

    Blankenship, H. Lee; Volk, Eric

    1991-09-01

    The second study year encompassed similar activities to the first, with some modification. In terms of otolith marking, all spring chinook at each facility were marked by a series of scheduled incubation water depressions. Modifications to our work plan included a somewhat later initiation of otolith marking, a shortening of cold water exposure duration for Cowlitz fish at the alevin stage, and the use of on-station personnel for conducting actual water manipulations for otolith marking. Protocols for efficient computerized collection of otolith band data were established and exploratory data collections initiated. Most of this was aimed at documentation of variability in the induced otolith pattern as a result of measurement technique and inherent biological variation in growth rates of individual otoliths. When fish has reached their appropriate size, Coded-Wire Tags were applied in specific proportions to untagged fish at each hatchery, and all untagged fish were electronically counted. Separate tag codes were applied to groups representing various rearing or release strategies at each hatchery. 11 refs., 3 tabs.

  18. Lake Roosevelt Fisheries Monitoring Program; Artificial Imprinting and Smoltification in Juvenile Kokanee Salmon Implications for Operating Lake Roosevelt Kokanee Salmon Hatcheries; 1994 Supplement Report.

    Energy Technology Data Exchange (ETDEWEB)

    Tilson, Mary Beth; Scholz, Allan T.; White, Ronald J. (Eastern Washington University, Upper Columbia United Tribes Fisheries Research Center, Cheney, WA)

    1995-02-01

    At the kokanee salmon hatcheries on Lake Roosevelt, constructed as partial mitigation for effects from Grand Coulee Dam, adult returns have been poor. The reason may be in the imprinting or in the smoltification. A study was initiated in 1992 to determine if there was a critical period for thyroxine induced alfactory imprinting in kokanee salmon; experiments were conducted on imprinting to morpholine and phenethyl alcohol. Other results showed that chemical imprinting coincided with elevated thyroxine levels in 1991 kokanee exposed to synthetic chemicals in 1992. In this report, imprinting experiments were repeated; results showed that imprinting occurred concomitant with elevated thyroxine levels in 1991 kokanee exposed to synthetic chemicals in 1992 and tested in 1994 as age 3 spawners. Imprinting also occurred at the same time as thyroxine peaks in 1992 kokanee exposed to synthetic chemicals in 1993 and tested as age 2 spawners. In both groups fish that had the highest whole body thyroxine content (swimup stage) also had the highest percentage of fish that were attracted to their exposure odor in behavioral tests. So, kokanee salmon imprinted to chemical cues during two sensitive periods during development, at the alevin/swimup and smolt stages. A field test was conducted in Lake Roosevelt on coded wire tagged fish. Smoltification experiments were conducted from 1992 to 1994. Recommendations are made for the Lake Roosevelt kokanee hatcheries.

  19. Relationship between reasons for practicing and sportpersonship behaviors in young handball players

    Directory of Open Access Journals (Sweden)

    David Sánchez Oliva

    2010-11-01

    Full Text Available AbstractThe main aim of this work was to analyze the relationships among Self-Determination Theory and sportsmanlike and antisocial behaviors in low categories. However, we recruited 127 handball players from alevine, infantile and cadet categories who filled several questionnaires to measure motivation in sport (SMS: Pelletier, Fortier, Vallerand, Tudson, Brière y Blais, 1995, satisfaction of the three psychological needs (EMM: García Calvo, Sánchez Miguel, Leo, Sánchez Oliva, y Gómez, 2010 and sportspersonship behaviors y (MSOS: Vallerand, Brière, Blanchard, y Provencher, 1997. Through the data analysis, we could demonstrate that greater self-determination levels were significantly associated with sportsmanlike conducts, as well as lower self-determination reasons were related with antisocial behaviors. Furthermore, we highlighted the autonomy as the strongest predictor of an adequate participation, whereas external regulation predicted negative critic. Finally, we emphasized the importance to promote self-determinated behaviors in young participants in the sport context, getting more adaptative conducts during the game. Keywords: Self-determination, psychological mediators, sportsmanlike, handball.

  20. Postlarval muscle growth in fish: a DNA flow cytometric and morphometric analysis.

    Science.gov (United States)

    Alfei, L; Maggi, F; Parvopassu, F; Bertoncello, G; De Vita, R

    1989-01-01

    The mechanism of postlarval fish myotomal growth was investigated in trout (Salmo gairdneri) by means of morphometric and cytofluorometric analysis. The mechanism by which new fibres are added during postlarval growth (hyperplasia) is not fully understood. In histological cross sections these new fibres have a small diameter which give the muscle a "mosaic" appearance. One hypothesis suggested that they could be derived from the proliferative activity of satellite cells. DNA cytofluorometric analysis of nuclei suspensions obtained from trout white myotomal muscle during different developmental stages (eleutherembyronic; alevin; yearling and adult) showed a consistently low S-cytometric phase during all stage in which myofibres of small diameters were present. The percentage of such small fibres, determined by morphometric analysis, suggested that satellite cells are the proliferative population. In fact, their percentages, as determined by morphometric analysis in histological section, bear a linear relationship with the S-cytometric phase percent nuclei (R = 0.927). Only in adults (67 cm in size) there was a significant decrease in the S-cytometric phase. At this stage, in histological sections, the myotomal muscle no longer had a "mosaic" appearance because of the disappearance of the small fibres. It may, therefore, be supposed that in the cm 67 adult specimens, the proliferative population is entering the G0 phase. It is known, in fact, that muscle growth proceeds only by fibre hypertrophy in trout longer than 70 cm in length (Stickland, 1983).

  1. Classification et clé de détermination des faciès d'écoulements en rivières de montagne

    Directory of Open Access Journals (Sweden)

    DELACOSTE M.

    1995-04-01

    Full Text Available La diversité hydromorphodynamique de 294 faciès d'écoulement appartenant à 15 rivières des Pyrénées a été analysée. A partir d'une Analyse Factorielle des Correspondances Multiples et d'une classification hiérarchique sur les coordonnées des individus, 6 groupes principaux puis 18 sous-groupes de faciès d'écoulement ont pu être différenciés. Une clé de détermination des faciès d'écoulement pour rivière de montagne est proposée. Cinq niveaux de discrimination successifs, quantitatifs ou qualitatifs, permettent d'identifier sur le terrain les 18 sous-groupes de faciès d'écoulement. La validité écologique de cette classification de faciès a été testée sur les biomasses et densités de truites ainsi que sur les densités de frayères. L'appartenance aux 18 sous-groupes explique de 45,6 % de la variabilité des biomasses totales à 18,8 % (p<0.05 de la variabilité des biomasses d'alevins (p<0.05.

  2. CONCENTRACIONES DE ARSÉNICO EN AGUA POTABLE Y SUS IMPLICACIONES DE BIOACUMULACIÓN Y TERATOGÉNESIS EN EL PEZ CEBRA (Danio rerio

    Directory of Open Access Journals (Sweden)

    Francisco Prieto

    2011-01-01

    Full Text Available En esta investigación se evalúan los efectos de la bioacumulación de arsénico contenido en el "agua potable" de Zimapán, Hidalgo en el pez cebra ( Danio rerio y como indicador del posible daño genotóxico sobre la población de Zimapán, expuesta a la contaminación por arsénico. Los ejemplares fueron estudiados durante 180 días en tres tratamientos: agua del pozo de referencia, agua de referencia adicionada con 5 mg As (V/L, y agua del pozo Zimapán, con 65 especimenes por lote. Se colocó una hembra y un macho en apareamiento en las mismas condiciones de tratamientos, obteniendo que a mayor concentración de As en el agua mayor porcentaje de huevos no viables y óvulos, menor porcentaje de huevos viables y de eclosión, mayor porcentaje de alevines recién eclosionados y juveniles con malformaciones, y menor porcentaje de juveniles sobrevivientes. Los resultados demuestran la genotoxicidad del As en Danio rerio .

  3. Activity determination of Na+ K+ - ATPase and Mg++ - ATPase enzymes in the gill of Poecilia vivipara (Osteichthyes, Cyprinodontiformes in different salinities

    Directory of Open Access Journals (Sweden)

    Marcelo da Cunha Amaral

    2001-03-01

    Full Text Available This work aimed to know the tolerance mechanisms through the salinity variation by Na+ K+ - ATPase and Mg++ - ATPase and enzymes encountered in the gills of Poecilia vivipara. In field, the presence of this species was observed in salinities of 0 and 28‰. In laboratory, these fish were maintained in aquarium with mean salinity of 30‰ and positive responses were obtained. Some adult specimens, collected in a lagoon of the Coqueiros Beach, were utilized as matrixes. In the experiments the specimens used were those born in the test aquarium. For each salinity studied three replicates were made with three specimens for each one. The alevins were maintained in salinities of 5, 10, 15, 20, 25, 30 and 35‰ during a month for adaptation. Gills were extracted in appropriate buffer for isolation of plasma membrane and used for specific dosage of the total enzymatic activity of Na+ K+ - ATPase and Mg++ - ATPase. The relation of alevins to their adaptation towards the salinity variation was also studied. The activity of the two enzymes showed a different result. The major expression of Na+ K+ - ATPase was observed in 20‰ (35 µmoles Pi.mg protein.h-1, the best salinity to cultivate P. vivipara.Este trabalho teve como objetivo conhecer os mecanismos de tolerância às variações de salinidade, pelas enzimas Mg++ - ATPase e Na+ K+ - ATPase, encontrada nas brânquias de Poecilia vivipara. No campo, foi observada a presença desta espécie em salinidades entre 0 e 28‰. No laboratório, os indivíduos foram mantidos em salinidade de 30‰ e responderam positivamente. Os indivíduos adultos, coletados em uma lagoa na praia dos Coqueiros, foram utilizados como matrizes. Nos experimentos foram usados alevinos que nasceram nos aquários testes. Para cada salinidade estudada foram feitas três réplicas com três espécimens em cada uma. Os alevinos foram mantidos em salinidades de 5, 10, 15, 20, 25, 30 e 35‰, durante um mês para total adaptação. As br

  4. Comparison of the growth of males and females of tilapia Oreochromis Niloticus cultured in cages

    Directory of Open Access Journals (Sweden)

    Carlos Alvarado-Ruiz

    2015-01-01

    Full Text Available With the purpose of evaluating productive performance and potential weight gain capacity of snapper O. Niloticus without reversing, we evaluated the growth of males and females raised in floating cages in captivity grouped by gender. The experiment was conducted for a term of 150 days.  We used a simple 4 836 alevins of 26.2±19.7g, fish that were nourished until they visibly reached sexual differentiation to 119.3±56.5 g to be separated by sex and nourished in floating cages to a final average weight of 387.0±128.9g (harvestto determine differences in growth. The weight distribution of the undefined gender sample showed a decrease in the coefficient of variation (CV of 75.13% to 31.49 and 30.22 for males and females respectively. This indicates that the distribution of sizes of the samples tended to become normal during the cycle of harvest. Significant differences (P=0.05 for the weight of harvest 429.2±135.1g and 339.65±102.64 g.   For the growth rate 2.74±0.86g day y 2.18±0.68 g day were determined between males and females respectively. The standard error of the estimation of the difference of average weight between males and females was 89.62±7.23g for an accuracy level of 95%. Males displayed  better growth rate and weight gain for harvest.

  5. Genotype-temperature interaction in the regulation of development, growth, and morphometrics in wild-type, and growth-hormone transgenic coho salmon.

    Directory of Open Access Journals (Sweden)

    Mare Lõhmus

    Full Text Available BACKGROUND: The neuroendocrine system is an important modulator of phenotype, directing cellular genetic responses to external cues such as temperature. Behavioural and physiological processes in poikilothermic organisms (e.g. most fishes, are particularly influenced by surrounding temperatures. METHODOLOGY/PRINCIPAL FINDINGS: By comparing the development and growth of two genotypes of coho salmon (wild-type and transgenic with greatly enhanced growth hormone production at six different temperatures, ranging between 8 degrees and 18 degrees C, we observed a genotype-temperature interaction and possible trend in directed neuroendocrine selection. Differences in growth patterns of the two genotypes were compared by using mathematical models, and morphometric analyses of juvenile salmon were performed to detect differences in body shape. The maximum hatching and alevin survival rates of both genotypes occurred at 12 degrees C. At lower temperatures, eggs containing embryos with enhanced GH production hatched after a shorter incubation period than wild-type eggs, but this difference was not apparent at and above 16 degrees C. GH transgenesis led to lower body weights at the time when the yolk sack was completely absorbed compared to the wild genotype. The growth of juvenile GH-enhanced salmon was to a greater extent stimulated by higher temperatures than the growth of the wild-type. Increased GH production significantly influenced the shape of the salmon growth curves. CONCLUSIONS: Growth hormone overexpression by transgenesis is able to stimulate the growth of coho salmon over a wide range of temperatures. Temperature was found to affect growth rate, survival, and body morphology between GH transgenic and wild genotype coho salmon, and differential responses to temperature observed between the genotypes suggests they would experience different selective forces should they ever enter natural ecosystems. Thus, GH transgenic fish would be expected to

  6. Evaluación de los desechos de pescado frescos y ensilados en la alimentación de híbridos de Clarias gariepinus X C. macrocephalus (Fresh fishing offals and silage evaluation for hybrid of Clarias gariepinus X C. macrocephalus feeding

    Directory of Open Access Journals (Sweden)

    Llanes Iglesias, José E

    2007-09-01

    Full Text Available ResumenSe evaluó el uso de los desechos frescos de pescado y sus respectivos ensilados por vías biológica y bioquímica, como única fuente de proteína animal en dietas húmedas para alevines de híbridos de Clarias gariepinus X C. macrocephalus (4,53+ 0,05g, las que fueron comparadas con un Alimento Comercial (20% de harina de desechos de pescado durante 60 días. Los resultados mostraron que los mejores indicadores de crecimiento y utilización de la proteína fueron obtenidos con los desechos frescos, los que difirieron significativamente (P85%, fue similar entre las dietas. Los ensilados y la harina de pescado no difirieron significativamente en los indicadores evaluados, siendo una alternativa para la producción de alimentos acuícola para países en vía de desarrollo. AbstractThis study evaluated the use of fresh fishes wastes and their respectives silages by biologic and quimic methodogies like only one source of animal protein in moist diets for hybrid of Clarias gariepinus X C. macrocephalus (4,53+ 0,05g. These were compared with a comercial foods (20% of fish wastes meal, during 60 days. The results showed that better growth and use of protein were obtened with fresh waste, what were differed significatively (P<0.05, to silage and fish meal. Beside, the use of food conversión was similar between the diets. The silage and fish meal did not differ significatively in the indicators evaluated.

  7. Viabilidad y crecimiento de poblaciones diploides y triploides de tilapia nilotica, oreochromis niloticus, línea Ghana

    Directory of Open Access Journals (Sweden)

    Celis M. Cesar

    1995-11-01

    Full Text Available The principal aim of this research was to produce triploid offspring of O. niloticus, applying warm thermic shocks (41A-42 oC to eggs during 3,5-4 min., 3,5 mino after fertilization, or cold shocks (10,8-11,3 oC to oocytes during one hour, 5 min after their fertilization. The best tissue to confirm triploids was kidney and brain of larvae and alevines. Then, the survival of fertilized eggs and growth rate were determined. The results show that the warm and cold shocks are efficient to produce 100% triploids, with different rates of survival. Also, that 25,5% oftspring was deformed when cold shocks were applyed, and 32,5% deformities with warm shocks. There were not significant difterences in growth between triploid and diploid populations
    after three months of age.La triploidía se obtuvo aplicando choques térmicos calientes (41.4 - 42 OC a oocitos durante 3.5 - 4 minutos, 3.5 min. después de la fertilización, y choques térmicos fríos (10.8 - 11.3 oC a oocitos durante una hora, 5 minutos de su fertilización. La triploidía se comprobó por análisis cromosomal en larvas y alevinos. Luego se monitoreó la tasa de crecimiento y sobrevivencia de los huevos fertilizados. Los resultados indican que los choques calientes y fríos fueron eficientes para producir ciento por ciento de triploidía, con tasas variables de sobrevivencia. Se observaron deformidades de peces trioloides (25.5% con choques frfos, y 32.5% con choques calientes. No se encontraron diferencias significativas en el crecimiento entre poblaciones triploides y diploides luego de tres meses de cultivo.

  8. Relationship between fish size and upper thermal tolerance

    Science.gov (United States)

    Recsetar, Matthew S.; Zeigler, Matthew P.; Ward, David L.; Bonar, Scott A.; Caldwell, Colleen A.

    2012-01-01

    Using critical thermal maximum (CTMax) tests, we examined the relationship between upper temperature tolerances and fish size (fry-adult or subadult lengths) of rainbow trout Oncorhynchus mykiss (41-200-mm TL), Apache trout O. gilae apache (40-220-mm TL), largemouth bass Micropterus salmoides (72-266-mm TL), Nile tilapia Oreochromis niloticus (35-206-mm TL), channel catfish Ictalurus punctatus (62-264 mm-TL), and Rio Grande cutthroat trout O. clarkii virginalis (36-181-mm TL). Rainbow trout and Apache trout were acclimated at 18°C, Rio Grande cutthroat trout were acclimated at 14°C, and Nile tilapia, largemouth bass, and channel catfish were acclimated at 25°C, all for 14 d. Critical thermal maximum temperatures were estimated and data were analyzed using simple linear regression. There was no significant relationship (P > 0.05) between thermal tolerance and length for Nile tilapia (P = 0.33), channel catfish (P = 0.55), rainbow trout (P = 0.76), or largemouth bass (P = 0.93) for the length ranges we tested. There was a significant negative relationship between thermal tolerance and length for Rio Grande cutthroat trout (R2 = 0.412, P 2 = 0.1374, P = 0.028); however, the difference was less than 1°C across all lengths of Apache trout tested and about 1.3°C across all lengths of Rio Grande cutthroat trout tested. Because there was either no or at most a slight relationship between upper thermal tolerance and size, management and research decisions based on upper thermal tolerance should be similar for the range of sizes within each species we tested. However, the different sizes we tested only encompassed life stages ranging from fry to adult/subadult, so thermal tolerance of eggs, alevins, and larger adults should also be considered before making management decisions affecting an entire species.

  9. Research on Captive Broodstock Programs for Pacific Salmon, 2001-2002 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Berejikian, Barry; Tezak, E.; Endicott, Rick

    2002-08-01

    The efficacy of captive broodstock programs depends on high in-culture survival and the fitness of cultured salmon after release, either as adults or juveniles. Continuing captive broodstock research designed to improve technology is being conducted to cover all major life history stages of Pacific salmon. The following summarizes some of the work performed and results from the FY 2001 performance period: (1) The incidence of male maturation of age-1 chinook salmon was significantly reduced by reducing growth in the first year of rearing. (2) Experimentally manipulated growth rates of captively-reared coho salmon had significant effects on female maturation rate, egg size, and fecundity, and the effects were stage-specific (i.e., pre-smolt vs. post-smolt). (3) A combination of Renogen and MT239 vaccination of yearling chinook salmon given an acute R. salmoninarum challenge had a significantly longer survival time than the mock-vaccinated group. The survival time was marginally higher than was seen in acutely challenged fish vaccinated with either Renogen or MT239 alone and suggests that a combination vaccine of Renogen and MT239 may be useful as both a prophylactic and therapeutic agent against BKD. (4) Full-sib (inbred) groups of chinook salmon have thus far exhibited lower ocean survival than half-sib and non-related groups. Effects of inbreeding on fluctuating asymmetry did not follow expected patterns. (5) Sockeye salmon were exposed to specific odorants at either the alevin/emergent fry stage or the smolt stage to determine the relative importance of odorant exposure during key developmental periods and the importance of exposure duration. (6) Experimental studies to determine the effects of exercise conditioning on steelhead reproductive behavior and the effects of male body size on chinook salmon fertilization success during natural spawning were completed.

  10. Cultivo de cachama blanca en altas densidades y en dos sistemas cerrados

    Directory of Open Access Journals (Sweden)

    Germán Poleo

    2011-04-01

    Full Text Available El objetivo de este trabajo fue evaluar la tolerancia de la cachama blanca, Piaractus brachypomus, a cultivos en altas densidades en sistemas cerrados. Novecientos alevines de 44,3±26 g de peso, se distribuyeron en seis tanques de concreto, con 4,8 m³ de agua. Tres tanques presentaron cero recambio de agua (SCR, y en otros tres, el agua se hizo circular a través de un bioclarificador (SRA. Ambos tratamientos presentaron fuerte aireación para mantener los sólidos en suspensión y suministrar aire. Los peces se alimentaron a saciedad con pienso comercial por 192 días. Los parámetros de calidad de agua como: oxígeno disuelto, amonio total, nitritos, nitratos, alcalinidad, dureza, temperatura y pH, se midieron semanalmente. Los peces en el SCR crecieron a una tasa de 2,34±0,05 g por día, y tuvieron conversión alimenticia de 1,5±0,06, densidad final de 12,96±0,53 kg m-3, y peso final de 449,5±99 g. En el SRA, los peces crecieron 2,33±0,03 g por día, con conversión alimenticia de 1,6±0,07, densidad final de 12,13±1,12 kg m-3, y peso final de 446,5±10 g. La cachama blanca puede ser cultivada en sistemas cerrados con cero recambio de agua en altas densidades.

  11. Natural selection constrains personality and brain gene expression differences in Atlantic salmon (Salmo salar).

    Science.gov (United States)

    Thörnqvist, Per-Ove; Höglund, Erik; Winberg, Svante

    2015-04-01

    In stream-spawning salmonid fishes there is a considerable variation in the timing of when fry leave the spawning nests and establish a feeding territory. The timing of emergence from spawning nests appears to be related to behavioural and physiological traits, e.g. early emerging fish are bolder and more aggressive. In the present study, emerging Atlantic salmon (Salmo salar L.) alevins were sorted into three fractions: early, intermediate and late emerging. At the parr stage, behaviour, stress responses, hindbrain monoaminergic activity and forebrain gene expression were explored in fish from the early and late emerging fractions (first and last 25%). The results show that when subjected to confinement stress, fish from the late emerging fraction respond with a larger activation of the brain serotonergic system than fish from the early fraction. Similarly, in late emerging fish, stress resulted in elevated expression of mRNA coding for serotonin 1A receptors (5-HT1A), GABA-A receptor-associated protein and ependymin, effects not observed in fish from the early emerging fraction. Moreover, fish from the early emerging fraction displayed bolder behaviour than their late emerging littermates. Taken together, these results suggest that time of emergence, boldness and aggression are linked to each other, forming a behavioural syndrome in juvenile salmon. Differences in brain gene expression between early and late emerging salmon add further support to a relationship between stress coping style and timing of emergence. However, early and late emerging salmon do not appear to differ in hypothalamus-pituitary-interrenal (HPI) axis reactivity, another characteristic of divergent stress coping styles.

  12. Incidences des extractions de matériaux alluvionnaires et de l'aménagement des cours d'eau sur l'écosystème aquatique

    Directory of Open Access Journals (Sweden)

    BOUCHAUD B.

    1979-04-01

    Full Text Available Les exploitations de granulats (dragages dans le lit mineur, et/ou rejets, mal décantés, d'eau de lavage des sables et graviers extraits et certains travaux hydrauliques (rectifications, recalibrages, provoquent d'importantes perturbations dans l'écosystème aquatique. Nous avons essayé, entre 1974 et 1978, de les mettre en évidence sur trois cours d'eau du MASSIF CENTRAL : la LOIRE, l'ALLIER, la DORE. LES MODIFICATIONS DU BIOTOPE portent essentiellement sur l'uniformisation et la déstabilisation du lit, l'augmentation du taux de matières en suspension et de la turbidité de l'eau, la réduction de la transmission de lumière en profondeur, le « colmatage » du fond. LES MODIFICATIONS DES COMMUNAUTES VIVANTES résultant des altérations précédentes sont : la réduction des densités numériques de Diatomées et de Macroinvertébrés benthiques (la diversité spécifique est peu affectée, une réduction de la teneur du Périphyton en pigments photosynthétiques, un abaissement de la production primaire, une réduction de la biomasse des Macroinvertébrés un ralentissement de la colonisation du substrat par cette faune, une augmentation de la mortalité des oeufs et alevins de Truites, incubés sous graviers (« colmatage » par les limons déposés, un ralentissement des éclosions des oeufs de Truites, une réduction des effectifs et de la biomasse des populations ichtyaires (prédatrices des Macroinvertébrés. LES MOYENS DE LUTTE contre ce type de nuisances résident dans l'application de la Législation, notamment des nouveaux textes concernant les Carrières. La principale mesure technique pouvant supprimer la pollution mécanique, due aux effluents de lavage des granulats, consiste à laver les matériaux extraits en circuit fermé (recyclage de l'eau. Il convient également d'interdire les extractions dans le lit mineur des cours d'eau. Quant aux aménagements hydrauliques, il est indispensable que leur conception tienne compte

  13. Composición del mercado nacional de alimentos balanceados para tilapia en Costa Rica

    Directory of Open Access Journals (Sweden)

    Ruth Vargas

    2003-01-01

    Full Text Available Se evaluó el origen y proceso de fabricación de los alimentos balanceados para tilapias comercializados en el país e inscritos en el Programa de Registro y Control de Calidad de Alimentos Balanceados para Animales del Ministerio de Agricultura y Ganadería. Además, se determinaron las prescripciones según la fase fisiol ógica y su composición química, así como las relaciones proteína cruda versus energía metabolizable y calcio – fósforo para compararlos contra los requerimientos recomendados. La calidad física fue evaluada en términos del tamaño de part ícula versus el tamaño del pez. El estudio de mercado consider ó el precio de venta de cada unidad de nutriente y su relaci ón que aportan los alimentos disponibles. Se determinó que un 82,35% de los registros son de origen nacional, un 88,23% de los alimentos son producidos por extrusión, y un 41% de las fórmulas son ofrecidas para todos los estadios, lo que provoca poca sustentación para comparar contra los requerimientos; a manera de ejemplo metodológico se determinó que los contenidos de proteína cruda de aquéllas fórmulas que son ofrecidas para alevines concuerdan con los niveles recomendados por la literatura. La situación de la calidad fí- sica es más crítica, por cuanto solamente un 23,53% de las garantías indican el tamaño del gránulo. Dado que el estudio de mercado arrojó que de las 17 garantías solamente se comercializan cinco se concluyó que comparar los alimentos por los precios unitarios de los nutrientes no coadyuva tampoco en la escogencia del alimento de manera importante.

  14. Detección “in vivo” mediante RAPD de alteraciones en el ADN producidas por benzo(apireno

    Directory of Open Access Journals (Sweden)

    C Becerril

    2004-01-01

    Full Text Available La técnica de RAPD (Amplificación al Azar de ADN Polimórfico permite detectar alteraciones inespecíficas en el ADN procedente de células que poseen una dotación genética idéntica, como son las líneas celulares establecidas, mediante la comparación del patrón de bandas de las células expuestas y no expuestas a la acción de genotóxicos. En los últimos años hemos desarrollado una metodología sensible y reproducible utilizando la línea celular RTG-2, derivada de trucha arco iris (Oncorhynchus mykiss. Sin embargo, es preciso comprobar la capacidad predictiva de este ensayo mediante estudios in vivo. La línea celular RTG-2, como se ha evidenciado en trabajos anteriores, presenta una gran similitud genética con la especie de la que procede. Por ello, en este trabajo, se ha llevado a cabo una exposición subletal a benzo(apireno mediante inyección intraperitoneal de 69 μg/g de p.c. en alevines de trucha arco iris, valorando la aparición de mutaciones mediante la comparación del patrón de bandas obtenido a partir del ADN de células de sangre periférica, a diferentes tiempos (1 - 3 meses. Debido a que la presencia de bandas polimórficas dificulta el análisis entre los grupos de individuos tratados y no tratados, las comparaciones se realizaron en un mismo individuo antes y después del tratamiento. Los análisis cualitativos y cuantitativos mostraron tanto la aparición de nuevas bandas, como alteraciones en su intensidad confirmando, de esta manera, los resultados que previamente habíamos obtenido in vitro tras exposiciones a este mismo genotóxico

  15. Reproducción natural controlada del black bass Micropterus salmoides - Controlled natural reproduction of black bass Micropterus salmoides

    Directory of Open Access Journals (Sweden)

    Amaral Junior, Hilton

    2009-09-01

    Full Text Available ResumenPara viabilizar la reproducción, larvicutura y alevinaje del Black bass, en la región sur de Brasil, se ha buscado adaptar una tecnología, desarrollada por el Centro Nacional de Acuicultura Piscifactoría las Vegas del Guadiana Badajoz/España. Consiste en controlar el ambiente de desove, utilizando estanques con nidales, para el desove del Black bass. Optimizando esta tecnología, desarrollamos una técnica de adaptación del Black bass al cultivo intensivo durante el período de invierno, ofreciendo un pienso de un 40% de proteína cruda y zooplancton (Daphnia sp.. Se dejan los reproductores en un mismo estanque de engorda en sistema extensivo, y son adaptados para un sistema intensivo de cultivo, en estanques de hormigón con entrada y salida del agua. Se acondicionan reproductores machos y hembras, durante los meses de invierno. En la primavera, se abren sucesivamente las compuertas de comunicación del departamentocentral, con los estanques frezaderos. En estos estanques frezaderos,se colocan nidales de grava para la puesta de las hembras. Pasado elperíodo de ocupación cíclica de los estanques de desove, losreproductores vuelven al departamento central. Después de laeclosión, las larvas son alimentadas con pienso molido a un 48% deproteína cruda con una oferta de un 10% de su peso y zooplancton Daphina sp. Los alevines se quedan alojados en estanques de tierrapara el período de engorda.SummaryIn order to make reproduction, larval and fingerling rearing of BlackBass in the south region of Brazil, we try to adapt a technologydeveloped by Centro Nacional de Aquicultura Piscifactoria Las Vegasdel Guadiana, Badajoz, Espanha. The technique consists in controllingthe spawning environment with a tank containing nests. To optimizethis technology, we develop a technique to adapt the black bass in aintensive culture during winter, providing food with 40% proteine andzooplankton (Daphnia sp.. The spawners are manteined in the

  16. SURVIE EMBRYONNAIRE DU SAUMON ATLANTIQUE (SALMO SALAR L. DANS UN COURS D’EAU DU SUD DE SON AIRE DE RÉPARTITION, LA NIVELLE

    Directory of Open Access Journals (Sweden)

    DUMAS J.

    2007-01-01

    Full Text Available L’évaluation de la survie du saumon Atlantique entre la ponte et l’émergence des alevins hors des graviers est réalisée dans le bassin de la Nivelle dans les domaines accessible (trois tronçons et non accessible (trois tronçons aux géniteurs. Pour ce faire, des capsules d’incubation de 12 cm3, contenant des œufs fraîchement fécondés, sont insérées dans des frayères artificielles et naturelles. Le débit et la température de l’eau de surface, l’oxygène dissous des eaux de surface et interstitielle et les caractéristiques granulométriques du substrat des frayères sont contrôlés pendant toute la durée de l’expérience. La survie, de 28,6 % en moyenne dans l’ensemble des sites, est plus élevée dans les tronçons de l’amont (52,7 % dans la Très Haute Nivelle et son affluent, le Lapitxuri que dans les autres sites, dont ceux actuellement colonisés par l’espèce (21,5 %. Il n’est pas observé de différence de survie entre les frayères artificielles et naturelles. Les mortalités interviennent essentiellement lors des épisodes de crues avant l’éclosion. Une corrélation positive forte existe entre la saturation en oxygène de l’eau interstitielle et la survie. Pour une saturation minimum en oxygène au-dessous de 62 %, la survie reste inférieure à 27 %. En revanche, la composition granulométrique du substrat ne semble pas agir directement sur la survie. Ce facteur n’étant pas corrélé avec l’oxygène dissous, ceci suggère que dans ce cours d’eau, le flux circulant dans les frayères ne provient pas uniquement de l’eau de surface, mais aussi de la nappe alluviale pauvre en oxygène dissous.

  17. Rapid diagnosis and identification by PCR of Yersinia ruckeri isolated of Oncorhynchus mykiss from Canta, Lima, Peru Diagnóstico e identificación rápidos por PCR de Yersinia ruckeri aislada de Oncorhynchus mykiss procedentes de Canta, Lima, Perú

    Directory of Open Access Journals (Sweden)

    Susana Sirvas-Cornejo

    2012-02-01

    Full Text Available Twenty individuals of rainbow trout were sampled (fry and juveniles from Acochinchan Fishfarm (Canta, Lima - Peru, and analyzed with the Polimerase Chain Reaction test (PCR in order to achieve a rapid identification of Yersinia ruckeri, which is the pathogen agent that causes the enteric red mouth disease (ERM and produces high rates of mortality. Nine fish samples were asymptomatic, while 11 of them showed signs of ERM. In addition, 22 bacterial strains were isolated from the liver, spleen and kidney. PCR and specific primers (16S rRNA, were used to amplified a specific 575 bp DNA fragment of Yersinia ruckeri. Nineteen strains were identified as Yersinia ruckeri by PCR in symptomatic and asymptomatic fishes. It was established a diagnosis time of 26 hours, compared with the 2 or 3 days that would take the diagnosis using biochemical tests.Se muestrearon 20 ejemplares (alevines y juveniles de trucha arco iris cultivados en la piscifactoría Acochinchán (Canta, Lima, Perú, y se les aplico la técnica de la Reacción en Cadena de la Polimerasa (PCR con la finalidad de obtener una identificación rápida del agente patógeno Yersinia ruckeri que produce la enfermedad entérica de la boca roja (ERM y genera elevadas tasas de mortalidad. Nueve ejemplares fueron asintomáticos mientras que 11 presentaron signos de ERM. Se aislaron 22 cepas bacterianas del hígado, bazo y riñón. Se empleó la técnica de la PCR para la amplificación y cebadores específicos (ARNr 16S, que permitieron amplificar un fragmento de ADN de 575 pb de Yersinia ruckeri. Diecinueve cepas fueron identificadas como Yersinia ruckeri mediante la PCR, tanto en peces sintomáticos como asintomáticos. Se estableció un tiempo de diagnóstico de 26 horas, en comparación con los 2 ó 3 días que duraría el diagnóstico empleando las pruebas bioquímicas.

  18. Premiers résultats de l'élevage intensif de la perche européenne (Perca fluviatilis en bassin : effet de la température et du tri sur la croissance

    Directory of Open Access Journals (Sweden)

    MÉLARD C.

    1995-01-01

    Full Text Available Malgré un marché potentiel important, peu d'études ont examiné les possibilités de développement de l'élevage intensif de la perche (Perca fluviatilis en bassins ou en cages. L'objectif de cette étude initiale était d'évaluer l'effet de la température et du tri en fonction du poids corporel sur la croissance de perches élevées en conditions intensives. Les essais ont été réalisés avec des alevins de perche sevrés (1,9 g sur une alimentation artificielle, placés en bassins alimentés par de l'eau du système de refroidissement d'une centrale nucléaire. La croissance est légèrement supérieure (+ 14,5 % à une température de 26,5 °C par rapport à celle enregistrée à 22,9 °C. Cette différence est non significative (p>0,05, probablement parce que ces 2 températures se situent dans la gamme des températures optimales pour la croissance de la perche. Une infestation (taux de contamination : 24,5 % par le cilié Heteropolaria sp est apparue à une température de 26,5 °C. Les perches, triées et séparées en 3 groupes distincts en fonction du poids corporel au début de l'expérience, ont présenté, après 234 jours d'élevage, une augmentation du polymorphisme de la croissance dans chaque groupe se traduisant par une superposition partielle des distributions des poids corporels. Une analyse de covariance indique que les 3 groupes ont présenté des vitesses de croissance comparables (F = 1,2. En élevage intensif, il apparaît que la perche présente une grande variabilité de croissance, ce qui renforce la nécessité de trier fréquemment les poissons.

  19. Índices de calidad ambiental de aguas del Arroyo Caañabe mediante tests microbiológicos y ecotoxicológico

    Directory of Open Access Journals (Sweden)

    Tomás López Arias

    2016-06-01

    Full Text Available El Arroyo Caañabe, es un curso de agua que corre a través de los Departamentos Central y Paraguarí (República del Paraguay. Las descargas de origen agropecuario, urbano e industrial contaminan sus aguas. En este trabajo se evalúa la calidad del arroyo mediante sus características fisicoquímicas, ecotoxicológicas, microbiológicas y se la comparan con la legislación vigente. Se colectaron muestras en los meses de Julio y Setiembre del año 2014. Se estudiaron tres sitios denominados S1, ubicado en aguas arriba de la Ciudad de Carapegua; S2 en la intersección del arroyo con la Ruta 1, y S3, en la zona límite de las ciudades de Carapegua y Nueva Italia. Se realizaron ensayos de toxicidad aguda con Daphnia magna, Lactuca sativa, y alevines de Danio rerio; además de ensayos crónicos en Tetradesmus wisconsinenesis, D. rerio y Allium cepa. Se evaluaron los grupos y especies microbianos siguientes: aerobios mesófilos, enterobacterias, coliformes totales, coliformes fecales, E. coli, Pseudomona aeruginosa, mohos y levaduras; además se determinaron índices de calidad y de contaminación. Los resultados indican que las aguas del arroyo presentaron características de clase II y de clase III según el padrón establecido por la Secretaría del Ambiente del Paraguay. El índice de calidad de agua (ICA arrojó valores comprendidos entre 52 y 62 lo que otorga la clasificación de "regular"; mientras que el índice de contaminación trófica (ICOTRO presentó valores entre 0,12 y 0.26, indicando "eutrofización". Los recuentos de coliformes fueron superiores en el segundo muestreo, aunque dentro lo establecido por la norma. La presencia de P. aeruginosa en los tres puntos constituye un riesgo para la salud. Ensayos ecotoxicológicos agudos mostraron que las aguas presentan escasos efectos letales, no obstante los ensayos crónicos en A. cepa y el test de micronúcleos en D. rerio indican potenciales efectos citotóxicos y genotóxicos de las

  20. Environmental performance of aquaculture in Rondônia state, Brazil

    Directory of Open Access Journals (Sweden)

    Aurélio Ferreira Borges

    2015-04-01

    Full Text Available The objective of this study was to analyze the environmental performance of aquaculture in the city of Colorado do Oeste, Rondônia State, Brazil. Fifteen fish farmers were interviewed. For data collection, structured interviews were carried out, using a questionnaire based on information supplied by the United Nations Food and Agriculture Organization (FAO. The questionnaire considered 12 items, organized into three main topics: a social and legal standards b environmental standards c standards of food safety and hygiene. The questionnaire considered 12 items, organized into three main topics: a social and legal standards b environmental standards c standards of food safety and hygiene. Aquaculture in the city of Colorado do Oeste, Rondônia presents two fish production systems: extensive and semi-intensive. In the semi-intensive system, stocking rate was one fish per m3, on average; tambaqui (Colossoma macropomum, tilapias (Oreochromis spp., pirarucu (Arapaima gigas and pintado (Pseudoplatystoma spp. were the species farmed at the largest number. The rate of water renewal was due to the greater availability of natural food in this system. Water renewal was constant in the ponds (1,500 liters per minute. In the semi-intensive system using dug ponds, alevins were stocked and fed during the entire rearing time with natural and exogenous food. The extensive system relied on the natural production of the pond, with stocking density limited by the production of natural food. The little renewal of water made the cultivation tank itself acted as a decantation lake, with the occurrence of oxidation and sedimentation of residual organic matter, consisting of feces, debris and organic fertilizer. Production of reduced effluent volume took place in the extensive system, compared to the cultivation area. In addition, there was high water turbidity, caused by high concentration of planktonic organisms, and low concentrations of dissolved oxygen in the water

  1. LES POISSONS CARNASSIERS LOCAUX PEUVENT-ILS CONTENIR L’EXPANSION DES ÉCREVISSES ÉTRANGÈRES INTRODUITES ? EFFICACITÉ DE 3 ESPÈCES DE POISSONS FACE À 2 ESPÈCES D’ÉCREVISSES DANS DES CONDITIONS EXPÉRIMENTALES.

    Directory of Open Access Journals (Sweden)

    NEVEU A.

    2001-04-01

    Full Text Available Les écrevisses sont potentiellement une source de nourriture pour les poissons. Le développement géographique et démographique de fortes populations de Pacifastacus leniusculus et de Procambarus clarkii ces 10 dernières années dans les eaux françaises pose le problème des relations avec les populations de poissons en place. En particulier au niveau des espèces carnassières : Esox lucius, Perca fluviatilis et Stizostedion lucioperca. Les interactions entre ces différentes espèces ont été étudiées dans des conditions expérimentales : en mésocosmes, en enclos dans des étangs, dans de petits étangs naturels. En mésocosme, des brochets de 16 à 46 cm consomment régulièrement des Procambarus au cours de l’année. Il y a une relation entre la taille des brochets et celle des Procambarus ingérées. Des brochets de 40 à 50 cm peuvent consommer les adultes d’écrevisses supérieurs à 8 cm. La consommation des écrevisses est régulière même en présence de poissons fourrages et même si chaque individu peut différer dans l’intensité de ses choix. L’intensité de la prédation dépend de la température mais elle perdure l’hiver. En enclos, des alevins de brochets associés à des juvéniles de Pacifastacus détruisent ces dernières au cours de l’été, malgré une croissance en parallèle. La protection par des abris n’est pas efficace, de même que la distribution de poissons fourrages. La même expérience effectuée en étang naturel donne les mêmes résultats, malgré la présence de la protection par des macrophytes. La confrontation de brochets de 1 été avec des Pacifastacus de 1 été donne des résultats semblables : les brochets éliminent la plupart des écrevisses. Dans tous les cas, les quelques écrevisses survivantes ont une croissance réduite et éventuellement une maturité retardée. L’association d’alevins de perches avec des juvéniles de Pacifastacus montre une survie normale des

  2. RELACIÓN ENTRE LOS MOTIVOS DE PRÁCTICA Y LOS COMPORTAMIENTOS DE DEPORTIVIDAD EN JÓVENES JUGADORES DE BALONMANO [Relationship between reasons for practicing and sportpersonship behaviors in young handball players] Relationship between reasons for practicing and sportpersonship behaviors in young handball players

    Directory of Open Access Journals (Sweden)

    David Sánchez Oliva

    2010-11-01

    Full Text Available

    Resumen

    El principal objetivo del presente estudio fue analizar las relaciones existentes entre la Teoría de la Autodeterminación y los comportamientos deportivos y antideportivos en categoría inferiores. Para ello, seleccionamos 127 jugadores de balonmano de categorías alevín, infantil y cadete, los cuales rellenaron diversos cuestionarios encaminados a analizar la motivación en el deporte (SMS: Pelletier, Fortier, Vallerand, Tudson, Brière y Blais, 1995, la satisfacción de las necesidades psicológicas básicas (EMM: García Calvo, Sánchez Miguel, Leo, Sánchez Oliva, y Gómez, 2010 y los comportamientos de deportividad (MSOS: Vallerand, Brière, Blanchard, y Provencher, 1997. Tras el análisis de nuestros resultados, se pudo comprobar cómo los niveles altos de autodeterminación se relacionan significativamente con los comportamientos deportivos, así como los motivos de práctica menos autodeterminados con las conductas antideportivas. Del mismo modo, destaca el mediador autonomía como el principal predictor de la participación adecuada, mientras que ocurre lo mismo con la regulación externa al predecir la crítica negativa. Como conclusión, dentro del contexto deportivo, destaca la importancia de fomentar entre los jóvenes comportamientos autodeterminados, consiguiendo que los participantes desarrollen durante el juego conductas más adaptativas. 

    Palabras clave: autodeterminación, mediadores psicológicos, deportividad, balonmano. 

     

    Abstract

    The main aim of this work was to analyze the relationships among Self-Determination Theory and sportsmanlike and antisocial behaviors in low categories. However, we recruited 127 handball players from alevine, infantile and cadet categories who filled several questionnaires to measure motivation in sport (SMS: Pelletier, Fortier, Vallerand, Tudson, Brière y Blais, 1995, satisfaction of the

  3. Early ontogenesis of the angelfish, Pterophyllum scalare Schultze, 1823 (Cichlidae

    Directory of Open Access Journals (Sweden)

    Agata Korzelecka-Orkisz

    2012-09-01

    alevines desarrollándose. Adicionalmente, se ha estudiado el efecto del pH básico del agua sobre los primeros estadios de desarrollo y la dependencia entre la cantidad de alimento y la supervivencia de los alevines. Las túnicas ovulares del escalar son finas (1,67-2,18 mm, transparentes, cubiertas de una sustancia viscosa. Los huevos de color ámbar tienen forma ovalada de diámetros medios 1,436 y 1,171 mm y de un volumen medio de 1,033 ± 0,095mm³. El porcentaje de supervivencia de embriones y de larvas en agua con pH aumentado, ligeramente básico, fue muy bajo, ya que sólo el 2% de los embriones sobrevivió, mientras que en agua de parámetros óptimos sólo algunos huevos palidecieron. Las larvas recién salidas del huevo medían 2,60 ± 0,093 mm por término medio y poseían grandes (0,64 ± 0,077 mm³ sacos vitelinos. Se han adherido al substrato mediante una secreción en forma de filamentos finos y viscosos. Esta secreción se ha desprendido de las glándulas ubicadas en la cumbre de la cabeza. Las glándulas desaparecieron al 5º día de vida de las larvas. Las larvas de un día poseían ya las primeras células pigmentarias en el cuerpo, los ojos de las larvas de dos días estaban pigmentadas plenamente. Entre el 4º y 5º día de vida las larvas empezaron a tomar alimento. Las larvas de 23 días se parecían a una versión miniaturizada de los adultos. La mortalidad de las larvas del escalar alimentadas durante los primeros días a partir del desove con larvas de artemia salina (Artemia salina fue mayor que la de las alimentadas con protozoarios y rotíferos.

  4. Biologia do saguirú (Characidae, Curimatinae

    Directory of Open Access Journals (Sweden)

    P. de Azevedo

    1938-01-01

    stomach are but delineated; the intestine is formed by a cylindric tube, all closed. At the place, where later on there will open the mouth, we find a group of ciliary hairs that produce a liquid current, very evident by the semi-circle formed by attached solid particles. After 36 hours, opening of the mouth and formation of the gill slits begin. At the age of 90 hours (4 mm. the larvas swim well and start to feed themselves; the digestive tube is now all open and the swimbladder works already. During the first days of life, larvas have an adhesive organ situated at their frontal region (fig. 7 in form of a crescent, by means of which they hang to surrounding vegetation (fig. 6. When the larva begins to swim and to feed itself and its yolk are having been absorbed. the adhesive organ retracts and disappears. While larvas and alevins feed themselves with plancton, they have small eye-teeth, which disappear,. when fishes become « ilyophagus ». There exist too, during their life as larvas, pharyngeal-teeth. The lateral line appears in the larva after 16 to 18 days; more or less at the same time all fins are completely developed. Shortly after, first scales appear (20 to 23 days. Evolution of intestines twisting followed (fig. 9. Larvas show at different parts of their bodies small of organs excretory functions, that are constituted by bottons in serial disposition, every one with an excretory canal that opens towards the outside. These formations disappear suddenly when larvas attain their phase of alevin. The existence of a great number of said formations at the caudal fin (fig. 12 is of great interest. In our experiences of breeding we have employed several thousands of C. elegans larvas in different environs and we made conditions of surrounding change (illumination, depth of water, temperature, presence of sand at bottom of aquariums and without sand, food. In this way we could compare the results obtained, estimate the action of each factor for the realisation of a

  5. Rice-fish farming in Guinée Forestière – outcome of a rural development project

    Directory of Open Access Journals (Sweden)

    D. Simon

    2010-09-01

    Full Text Available The rice-fish farming project in Guinée Forestière launched in 2000 was, at the outset, a pilot project for the purpose of testing the introduction of a new production technique in an impoverished and landlocked region. It aimed to improve food security for people living in the region and to promote the creation of income through a diversification of activity and better land use. The intervention strategy followed the template used in Côte d’Ivoire for a similar project. It consisted in supporting groups of voluntary producers who were ready to accept the risk of financing lowland developments to produce fish and rice. The project was supported by a small group, mainly composed of volunteers (expatriates and local facilitators recruited as the project activities progressed. A € 1.8 million grant was donated by the Agence Française de Développement, raised between 2000 and 2008, to cover technical assistance and training expenditures. The project gave precedence to the concept of actor autonomy for the development of lowlands and ponds. Investments were financed and implemented by the producers themselves depending on their available resources in funds and labour. Animal husbandry methods, based on extensive mixed cropping, used no other inputs than those available on the farm itself. The fish farmers themselves supplied alevins. To ensure the sustainability of rice-fish farming activities after the project ended, special emphasis was given to providing a structure for the profession in the future by encouraging the members of the groups to sponsor and train new candidates. Although results exceeded the initial targets since, by the end of the project, 350 farmers and 500 ponds were active, lowland rice and fish production is still limited. It does provide, however, regular supplies of fish to approximately 6000 people, calculated according to the low level of local consumption (10 kg/per year/per person.The impact of the

  6. Adaptando el baloncesto al niño de 12-13 años: análisis observacional del lanzamiento de tiro libre

    Directory of Open Access Journals (Sweden)

    Belén Garzón Echevarría

    2012-06-01

    Full Text Available En la competición organizada por la Federación Riojana de Baloncesto, el jugador pasa de practicar en la categoría alevín la modalidad de minibasket, a jugar en la categoría infantil un baloncesto adulto –con el mismo balón, terreno de juego y altura de la canasta que lo hacen actualmente en la ACB–. Con este trabajo se pretende, a partir del estudio del tiro libre de los integrantes de la selección riojana masculina de minibasket alevín, adaptar el baloncesto a las características propias del niño de 12-13 años, en contra de la tendencia hegemónica actual de adaptar el niño al baloncesto de los adultos. La investigación sigue una metodología cuasi-experimental y observacional, que en este caso son complementarias, si bien la metodología observacional predomina, lo que justifica el diseño observacional realizado; a través del cual se ha analizado la ejecución técnica del tiro libre en la modalidad alevín, en la infantil y en las cinco situaciones que resultan de combinar: canasta infantil (3,05 metros y balón alevín (n.º 5, canasta infantil (3,05 m y balón intermedio (n.º 6, canasta intermedia (2,80 m y balón alevín (n.º 5, canasta intermedia (2,80 m y balón intermedio (n.º 6, y canasta intermedia (2,80 m y balón infantil (n.º 7. En este sentido, para satisfacer los objetivos del estudio, se han realizado dos tipos de análisis: uno estadístico descriptivo e inferencial –mediante el programa SPSS, versión 15.0–, y otro en busca de patrones temporales –mediante el programa Theme, versión 5.0–. El trabajo de investigación concluye que todos los participantes mantienen una ejecución técnica del tiro libre alevín estable. Además, de las modalidades sometidas a estudio, la ejecución correspondiente a los tiros libre alevines es la que más se acerca al gesto técnico ideal, mientras que la situación infantil es aquella cuya ejecución de los tiros libres se aleja más del modelo técnico correcto

  7. Pyrethroid toxicity in silver catfish, Rhamdia quelen

    Directory of Open Access Journals (Sweden)

    Francisco P. Montanha

    2012-12-01

    Full Text Available This study aimed to determine both the lethal and sublethal concentrations of Cypermethrin in young Silver Catfish (Brazilian "Jundiá", Rhamdia quelen on aquatic environment during 96 hours, as well as to determine the Cypermethrin and Deltamethrin sublethal concentrations during the initial embryonic development period of Rhamdia quelen, and to verify their respective rates of fertilization, hatching and survival. Pyrethroid nowadays is a widely used insecticide, which presents a high toxicity to fish. In order to determine lethal and sublethal concentrations, 120 silver catfish were used; each one had an average weight of 59.58±4.50g and an average size of 20.33±2.34cm. Concentrations used were 0, 1.0, 1.5, 2.0, 2.5, 3.0, 5.0, 10.0, 15.0 and 20.0mg of Cypermethrin per liter of water (mg/L. Fish were exposed to the product in 30-liter fish tanks. In each fish tank there were four fishes and the product was applied three times, i.e., a total of twelve fish were exposed to the product at each application, and a total of 120 fish during the entire experiment (n=120. In order to determine the Cypermethrin and Deltamethrin sublethal concentrations during the initial embryonic development, ovulation induction was performed on female fishes using hormones, and then and egg collection was performed. The eggs were then hydrated and fertilized in Cypermethrin and Deltamethrin in different concentrations: 0.001, 0.01, 0.1, 1.0 and 10.0mg/L of Cypermethrin and 0.001, 0.01, 0.1, 0.5 and 1.0mg/L of Deltamethrin, in addition to the control group (0mg/L. After fertilization, the eggs were kept in containers with the respective pesticides of Cypermethrin and Deltamethrin until hatching, when hatching rate was verified. Then the alevins, from the hatching, were kept on their respective concentrations of Cypermethrin and Deltamethrin so that the survival rate could be analyzed regarding the tested insecticides, during both 12-hour and 24-hour periods

  8. La «loi pêche» (Code rural et l'introduction des espèces piscicoles

    Directory of Open Access Journals (Sweden)

    GUEVEL B.

    1997-01-01

    Full Text Available Les introductions d'espèces piscicoles non représentées et/ou susceptibles de créer des déséquilibres biologiques se développent, ici ou là, pour des considérations halieutiques ou accessoirement scientifiques, ou tout simplement pour se débarrasser de spécimens devenus encombrants. Face à ce phénomène, le droit de la pêche continentale n'offre qu'une réponse partielle qui n'est pas suffisante, à ce jour, pour assurer son contrôle. Ainsi, le chapitre II du titre troisième (pêche en eau douce et gestion des ressources piscicoles du livre II (nouveau du Code rural organise le contrôle des peuplements (section IV : articles L.232-10 à L.232-12, R.*232-3 à R.*232-25 du Code rural. Ce dispositif comporte un ensemble d'interdictions assorties, le cas échéant, d'autorisations : - interdiction d'introduire dans les eaux libres et les piscicultures, et de transporter sans autorisation, des poissons susceptibles de provoquer des déséquilibres biologiques ; - interdiction d'introduire sans autorisation des espèces de poissons qui ne sont pas officiellement représentées dans les eaux douces nationales ; - interdiction d'introduire, dans les eaux classées en 1ère catégorie piscicole, des poissons des espèces carnassières (brochet, perche, sandre et black-bass ; - interdiction d'introduire dans les eaux libres, pour rempoissonner ou aleviner, des poissons qui ne proviennent pas d'établissements agréés. Cette législation est perfectible en tant qu'elle suscite des difficultés d'application : la notion d'introduction n'est pas explicitée par les textes et doit être distinguée de l'emploi d'appâts vifs ou de la remise à l'eau ; le transport des espèces non représentées - autres que celles qui sont de nature à créer des déséquilibres biologiques - n'est pas soumis à autorisation et s'effectue donc librement ; le système de listes d'espèces présente une certaine rigidité et ne permet pas de pr

  9. Differences in survival and growth in hatchery and stream environments, and in maturation of residuls in a stream, between progeny of hatchery and wild steelhead (Study sites: Brushy Fork Creek and Dworshak Hatchery; Stocks:Dworshak hatchery and Fish Creek wild; Year classes: 1992 and 1993): Chapter 1

    Science.gov (United States)

    Rubin, Stephen P.; Reisenbichler, Reginald R.; Wetzel, Lisa A.; Hensleigh, Jay E.; Leonetti,; Rubin, Stephen P.; Reisenbichler, Reginald R.; Wetzel, Lisa A.; Hayes, Michael C.

    2012-01-01

    ). Differences between progeny groups were also found for growth (H>W) and condition (H>W) in the hatchery and downstream migration success of hatchery-reared fish after release (H>W), and for growth (HW for the other), condition (H>W), downstream dispersal (H>W for one year-class; H=W for the other), and maturation of residuals (ovaries weight was greater for H than for W females at ages 4 and 5; testes weight was less for H than for W age-3 males of one year-class) in Brushy Fork. A thunderstorm-induced power outage interrupted flow to the incubation trays at the hatchery and compromised a major tenet of the common garden design for the second year-class, possibly contributing to the inconsistency in relative survivals in Brushy Fork between year-classes. The storm caused the incubation environment to differ between the stocks as a result of reduced oxygen levels and substantially higher densities for H alevins. This difference was illustrated by a 55% loss for H fish during the event, about twice that for W fish.

  10. Research on Captive Broodstock Programs for Pacific Salmon, 2003-2004 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Berejikian, Barry A.; Athos, Jaime I.; Dittman, Andrew H. (National Marine Fisheries Service)

    2004-07-01

    The success of captive broodstock programs depends on high in-culture survival, appropriate development of the reproductive system, and the behavior and survival of cultured salmon after release, either as adults or juveniles. Continuing captive broodstock research designed to improve technology is being conducted to cover all major life history stages of Pacific salmon. We were able to develop an analytical method for optimizing the detection of spawning events in Chinook salmon using EMG signals. The method developed essentially captured the consistently greater frequency of higher EMG values associated with females cover digging immediately following spawning. However, females implanted with EMG tags retained the majority of their eggs, which significantly reduced their reproductive success compared to non-tagged females. Future work will include increased sample sizes, and modified tagging methods to reduce negative effects on reproductive success. Upper Columbia River sockeye salmon exposed to the odorants PEA, L-threonine, Larginine and L-glutamate were able to learn and remember these odorants as maturing adults up to 2.5 years after exposure. These results suggest that the alevin and smolt stages are both important developmental periods for successful olfactory imprinting. Furthermore, the period of time that fish are exposed to imprinting odors may be important for successful imprinting. Experimental fish exposed to imprinting odors as smolts for six or one weeks successfully imprinted to these odors but imprinting could not be demonstrated in smolts exposed to odors for only one day. A 2-3 C reduction in seawater rearing temperature during the fall and winter prior to final maturation had little effect on reproductive development of spring Chinook salmon. Body size at spawning and total ovary mass were similar between temperature treatments. The percentage of fertilized eggs was significantly higher for females exposed to the ambient temperature compared

  11. Aclimatação do híbrido da tilápia vermelha Oreochromis niloticus sp. e utilização em ambientes marinhos como isca viva para a pesca de tunideos - Acclimatization of red tilápia hybrids, Oreochromis niloticus sp., and use in sea environments as lively bait in the baitboat fishery of tuna

    Directory of Open Access Journals (Sweden)

    Hilton Amaral Junior

    2010-03-01

    Full Text Available ResumenLa tilápia roja de Florida Oreochromis sp, obtenido mediante el cruce de O.mossambicus y O. urulepis hornorum, se caracteriza por tener altaresistencia a la salinidad y ser muy tolerante a una variedad de condiciones climáticas. Por lo tanto, es ampliamente utilizado en los cultivos comerciales en algunas partes del mundo tanto en agua dulce y salobre. Se enfrenta actualmente a un problema importante en relación a la disponibilidad de cebo vivo, que usa sardina como atracción a los atunes. Además, crea un conflicto con los pescadores industriales que utilizan el mismo recurso, así como los pescadores artesanales y la sociedad. Este trabajo consistió en una evaluaciónde la resistencia a la salinidad de la tilápia roja, lo que sugiere una nueva técnica para la aclimatación de los juveniles de esta especie. Los lotes de alevines de tilápia roja sexualmente invertido se crearon en el Campo Experimental de Piscicultura de Camboriú - CEPC/Epagri y recreado en el laboratorio de maricultura UNIVALI - EMC, Penha SC. Los parámetros analizados fueron: la tolerancia a la salinidad, la supervivencia y la capacidad de almacenamiento. Los resultados de esta experiencia indican que esta especie responde a las necesidades requeridas para este tipo de pesca. Losjuveniles adaptados a la salinidad, se han utilizado para los ensayos como cebo vivo en la pesca de atún. Este trabajo ofrece una alternativa a cebo vivo en la pesca de atún.ResumoA tilápia vermelha da Flórida (Oreochromis sp, obtida através do cruzamento de O. mossambicus e O. urulepis hornorum, se caracteriza por apresentar grande resistência à salinidade e ser bastante tolerante a uma diversidade de condições climáticas. Sendo assim, é bastante utilizada em cultivos comerciais em algumas partes do mundo, tanto em água doce como salobra. A pesca de atum e afins com vara e isca-viva, atualmente vem enfrentando um grande problema em relação à disponibilidade da isca

  12. Utilización de un anticuerpo monoclonal en el diagnóstico directo e indirecto del virus IPN en peces infectados experimentalmente Utilization of a monoclonal antibody in the diagnosis of infectious pancreatic necrosis virus in fish

    Directory of Open Access Journals (Sweden)

    F. CIFUENTES

    1999-01-01

    Full Text Available El virus de la necrosis pancreática infecciosa, virus IPN, es el agente causal de una enfermedad altamente contagiosa que afecta a peces salmonídeos jóvenes, éstos cuando sobreviven pueden convertirse en portadores que pueden transmitir la enfermedad. Para contribuir al diagnóstico rápido y efectivo del virus tanto en peces con la infección aguda, como en peces portadores, es que ensayamos la aplicación de un anticuerpo monoclonal en la detección del virus en animales infectados experimentalmente. Utilizamos alevines de truchas arcoiris (Oncorhynchus mykiss y de salmones coho (Oncorhynchus kisutch infectados con virus IPN aislado en Chile. Para detectar a los antígenos virales empleamos ensayos de ELISA inmunodot e inmunofluorescencia. Los resultados muestran que en los peces con la enfermedad aguda el virus se detecta aplicando directamente los inmunoensayos en extractos de peces enteros. En cambio, para detectar al virus en los peces portadores fue necesario incorporar un paso adicional para amplificar al virus en cultivos celulares. A pesar de lo cual, sin embargo, los métodos se optimizaron de manera que el procedimiento completo se realizó en menos de tres días para ELISA e inmunodot y menos de un día y medio para la inmunofluorescencia. Debido a que la técnica de inmunofluorescencia permite la identificación inequívoca de una o pocas células infectadas, es que ensayamos condiciones para diagnosticar al virus IPN desde improntas de peces portadores del virus. Demostramos que los antígenos virales pueden ser facilmente identificados por medio de la tinción directa de improntas de órganos de peces con el tamaño adecuadoThe infectious pancreatic necrosis virus, IPNV, is the etiological agent of a highly contagious disease that affects young salmon. If they survive, they become carriers and can transmit the disease. To contribute to the fast and effective diagnosis in fish with the acute infection, as well as of carrier

  13. (Danio rerio

    Directory of Open Access Journals (Sweden)

    F Prieto García

    2007-01-01

    y de eclosión, mayor porcentaje de alevines recién eclosionados y juveniles con malformaciones, y menor porcentaje de juveniles sobrevivientes.

  14. Pyrethroid toxicity in silver catfish, Rhamdia quelen Toxicidade dos piretróides sobre Jundiás, Rhamdia quelen

    Directory of Open Access Journals (Sweden)

    Francisco P. Montanha

    2012-12-01

    Full Text Available This study aimed to determine both the lethal and sublethal concentrations of Cypermethrin in young Silver Catfish (Brazilian "Jundiá", Rhamdia quelen on aquatic environment during 96 hours, as well as to determine the Cypermethrin and Deltamethrin sublethal concentrations during the initial embryonic development period of Rhamdia quelen, and to verify their respective rates of fertilization, hatching and survival. Pyrethroid nowadays is a widely used insecticide, which presents a high toxicity to fish. In order to determine lethal and sublethal concentrations, 120 silver catfish were used; each one had an average weight of 59.58±4.50g and an average size of 20.33±2.34cm. Concentrations used were 0, 1.0, 1.5, 2.0, 2.5, 3.0, 5.0, 10.0, 15.0 and 20.0mg of Cypermethrin per liter of water (mg/L. Fish were exposed to the product in 30-liter fish tanks. In each fish tank there were four fishes and the product was applied three times, i.e., a total of twelve fish were exposed to the product at each application, and a total of 120 fish during the entire experiment (n=120. In order to determine the Cypermethrin and Deltamethrin sublethal concentrations during the initial embryonic development, ovulation induction was performed on female fishes using hormones, and then and egg collection was performed. The eggs were then hydrated and fertilized in Cypermethrin and Deltamethrin in different concentrations: 0.001, 0.01, 0.1, 1.0 and 10.0mg/L of Cypermethrin and 0.001, 0.01, 0.1, 0.5 and 1.0mg/L of Deltamethrin, in addition to the control group (0mg/L. After fertilization, the eggs were kept in containers with the respective pesticides of Cypermethrin and Deltamethrin until hatching, when hatching rate was verified. Then the alevins, from the hatching, were kept on their respective concentrations of Cypermethrin and Deltamethrin so that the survival rate could be analyzed regarding the tested insecticides, during both 12-hour and 24-hour periods

  15. Effect of the Operation of Kerr and Hungry Horse Dams on the Reproductive Success of Kokanee in the Flathead System, 1987 Final Report.

    Energy Technology Data Exchange (ETDEWEB)

    Beattie, Will; Zubik, Raymond; Clancey, Patrick

    1988-05-01

    reproductive success in few sites. Studies of the effects of hydroelectric operations on the reproductive success of kokanee in the Flathead system have been ongoing since 1980. Results of these studies have been published in a series of annual progress reports which are detailed in Appendix G. The reports summarize spawning site inventories and spawning escapement, egg and alevin mortality rates and the mechanisms by which water level fluctuations influence mortality, creel surveys, and investigation of the population dynamics of Flathead kokanee. The Region 1 offices of the Montana Department of Fish, Wildlife and Parks distribute this material to the scientific community and the general public. Until recently, it was considered feasible to recover losses to the Flathead kokanee fishery by enhancing and diversifying natural reproduction. But the establishment of opossum shrimp (M. relicta) in Flathead Lake has reduced the availability of zooplankton forage in the spring and summer, and may reduce the viability of juvenile kokanee. In 1986, research was redirected to quantify this competitive interaction and to investigate artificial means of enhancing the kokanee fishery. The average density of mysid shrimp in Flathead Lake has increased to 108/m{sup 2} in 1987, and at some locations density exceeds 500/m2. Mysid grazing pressure has delayed the pulse of zooplankton production in the spring and reduced zooplankton standing crop in the summer. Cladocerans such as Daphnia thorata, the preferred food of kokanee of all ages, are the most markedly affected species. The peak density of D. thorata in the summer has declined from 4.8/liter in 1983 to O.9/liter in 1987. Growth rates of underyearling and yearling kokanee have declined, apparently as a result of the reduction in their food supply. Spawning escapement has also declined, falling from 150,000 in 1985. to 25,000 in 1986, to 600 in 1987. Fry-to-adult survival has declined from 2.5 percent to near zero. The causes of high