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Mark W Chilcote - One of the best experts on this subject based on the ideXlab platform.
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relationship between natural productivity and the frequency of wild fish in mixed Spawning Populations of wild and hatchery steelhead oncorhynchus mykiss
Canadian Journal of Fisheries and Aquatic Sciences, 2003Co-Authors: Mark W ChilcoteAbstract:The proportion of wild fish in 12 mixed Populations of hatchery and wild steelhead (Oncorhynchus mykiss) was evaluated for its relationship to mean and intrinsic measures of Population productivity. The Population mean of ln(recruits/spawner) was used to represent mean productivity. Intrinsic productivity was represented by values for the Ricker a parameter as estimated from fits of spawner and recruit data. Significant regressions (p < 0.001) were found between both measures of productivity and the proportion of wild fish in the Spawning Population (Pw). The slopes of the two regressions were not significantly different (p = 0.55) and defined a relationship suggesting that a Spawning Population comprised of equal numbers of hatchery and wild fish would produce 63% fewer recruits per spawner than one comprised entirely of wild fish. Study findings were not sensitive to likely levels of data error or confounded by extraneous habitat correlation with Pw. Population status assessments and conservation monito...
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relationship between natural productivity and the frequency of wild fish in mixed Spawning Populations of wild and hatchery steelhead oncorhynchus mykiss
Canadian Journal of Fisheries and Aquatic Sciences, 2003Co-Authors: Mark W ChilcoteAbstract:The proportion of wild fish in 12 mixed Populations of hatchery and wild steelhead (Oncorhynchus mykiss) was evaluated for its relationship to mean and intrinsic measures of Population productivity. The Population mean of ln(recruits/spawner) was used to represent mean productivity. Intrinsic productivity was represented by values for the Ricker a parameter as estimated from fits of spawner and recruit data. Significant regressions ( p < 0.001) were found between both measures of productivity and the proportion of wild fish in the Spawning Population (Pw). The slopes of the two regressions were not significantly different ( p = 0.55) and defined a relationship suggesting that a Spawning Population comprised of equal numbers of hatchery and wild fish would produce 63% fewer recruits per spawner than one comprised entirely of wild fish. Study findings were not sensitive to likely levels of data error or confounded by extraneous habitat correlation with Pw. Population status assessments and conservation monitoring efforts should in- clude Pw as a critical variable. For natural Populations, removal rather than addition of hatchery fish may be the most effective strategy to improve productivity and resilience. Resume : La proportion de poissons sauvages dans 12 Populations mixtes de truites arc-en-ciel anadromes (Oncorhyn- chus mykiss) sauvages et de pisciculture a ete mise en relation avec des mesures de productivite moyenne et intrinseque de la Population. La moyenne de ln(recrues-reproducteurs) dans la Population represente la productivite moyenne et les valeurs du parametre a de Ricker calculees a partir d'ajustements des donnees sur les recrues et les reproducteurs, la productivite intrinseque. Il existe des regressions significatives ( p < 0,001) entre chacune des deux mesures de produc- tivite et la proportion de poissons sauvages dans la Population des reproducteurs ( PW). Les pentes des deux regressions ne different pas significativement (p = 0,55); la relation obtenue indique qu'une Population de reproducteurs composee d'un nombre egal de truites sauvages et de truites de pisciculture produirait 63 % moins de recrues par reproducteur qu'une Population composee entierement de poissons sauvages. Les resultats de l'etude ne sont pas affectes par les niveaux probables des erreurs de donnees, ni par les correlations accessoires entre l'habitat et PW. Les evaluations du statut des Populations et les efforts de surveillance des activites de conservation devraient donc utiliser PW comme variable critique. Le retrait, plutot que l'addition, de poissons de pisciculture est peut-etre la strategie la plus efficace pour augmenter la productivite et la resilience des Populations naturelles. (Traduit par la Redaction) Chilcote 1067
Jenny M Suter - One of the best experts on this subject based on the ideXlab platform.
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tank culture of yellowfin tuna thunnus albacares developing a Spawning Population for research purposes
Aquaculture, 2003Co-Authors: Jeanne B Wexler, Vernon P Scholey, Robert J Olson, Daniel Margulies, Akio Nakazawa, Jenny M SuterAbstract:Abstract A land-based culture facility for research on yellowfin tuna, Thunnus albacares , was developed at the Achotines Laboratory in the Republic of Panama. Six concrete tanks, and seawater and life support systems were built to maintain a yellowfin broodstock. On average, 50% of the yellowfin caught survived capture and handling, and approximately 30% became broodstock in Tank 1 (17 m diameter, 6 m depth) or Tank 2 (8.5 m diameter, 3 m depth). Each fish was tagged with a microchip implant tag, then weighed, measured, and injected with oxytetracycline (OTC) prior to stocking. Daily rations of primarily market squid, Loligo opalescens , and Pacific thread herring, Opisthonema spp., were regulated based on the feeding activity and energy requirements of the fish. Feeding activity of the broodstock decreased when the water temperatures decreased, and the fish ate decreasing daily rations and increasing calories with increasing size. Spawning occurred in both tanks within 6–8 months of capture. Spawning first occurred in Tank 1 when 24 females ranged in size from 6 to 16 kg and 65 to 93 cm fork length (FL). Spawning was intermittent during the first 2 months and occurred near daily thereafter. Tank size appeared to affect survival rates, the types of mortalities that occurred, and the growth of the fish. Survival rates after 1 year in captivity were higher, and the fish were larger, on average, in Tank 1 than in Tank 2. Most of the mortalities in Tank 1 were the result of wall strikes, which occurred more frequently after the fish reached their highest density of 0.64 kg m −3 and sizes greater than 96 cm FL and 19 kg. Non-linear growth models were fitted to the initial stocking sizes and final sizes of fish that died or were removed from Tank 1 during 1996–1999. Estimated growth rates in length (11–48 cm year −1 ) for fish between 51 and 150 cm FL decreased with increasing length. Estimated growth rates in weight ranged from 9 to 19 kg year −1 for fish less than 19 kg and 20–23 kg year −1 for fish greater than 19 kg. The results of this work demonstrate that the stable environment of a land-based culture facility may be the preferred system for long-term maintenance of a yellowfin broodstock.
Campbell R Davies - One of the best experts on this subject based on the ideXlab platform.
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evidence of discrete yellowfin tuna thunnus albacares Populations demands rethink of management for this globally important resource
Scientific Reports, 2015Co-Authors: Peter M Grewe, Pierre Feutry, P L Hill, Rasanthi M Gunasekera, Kurt Schaefer, David Itano, Daniel W Fuller, Scott D Foster, Campbell R DaviesAbstract:Tropical tuna fisheries are central to food security and economic development of many regions of the world. Contemporary Population assessment and management generally assume these fisheries exploit a single mixed Spawning Population, within ocean basins. To date Population genetics has lacked the required power to conclusively test this assumption. Here we demonstrate heterogeneous Population structure among yellowfin tuna sampled at three locations across the Pacific Ocean (western, central, and eastern) via analysis of double digest restriction-site associated DNA using Next Generation Sequencing technology. The differences among locations are such that individuals sampled from one of the three regions examined can be assigned with close to 100% accuracy demonstrating the power of this approach for providing practical markers for fishery independent verification of catch provenance in a way not achieved by previous techniques. Given these results, an extended pan-tropical survey of yellowfin tuna using this approach will not only help combat the largest threat to sustainable fisheries (i.e. illegal, unreported, and unregulated fishing) but will also provide a basis to transform current monitoring, assessment, and management approaches for this globally significant species.
Pierre Feutry - One of the best experts on this subject based on the ideXlab platform.
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evidence of discrete yellowfin tuna thunnus albacares Populations demands rethink of management for this globally important resource
Scientific Reports, 2015Co-Authors: Peter M Grewe, Pierre Feutry, P L Hill, Rasanthi M Gunasekera, Kurt Schaefer, David Itano, Daniel W Fuller, Scott D Foster, Campbell R DaviesAbstract:Tropical tuna fisheries are central to food security and economic development of many regions of the world. Contemporary Population assessment and management generally assume these fisheries exploit a single mixed Spawning Population, within ocean basins. To date Population genetics has lacked the required power to conclusively test this assumption. Here we demonstrate heterogeneous Population structure among yellowfin tuna sampled at three locations across the Pacific Ocean (western, central, and eastern) via analysis of double digest restriction-site associated DNA using Next Generation Sequencing technology. The differences among locations are such that individuals sampled from one of the three regions examined can be assigned with close to 100% accuracy demonstrating the power of this approach for providing practical markers for fishery independent verification of catch provenance in a way not achieved by previous techniques. Given these results, an extended pan-tropical survey of yellowfin tuna using this approach will not only help combat the largest threat to sustainable fisheries (i.e. illegal, unreported, and unregulated fishing) but will also provide a basis to transform current monitoring, assessment, and management approaches for this globally significant species.
Jeanne B Wexler - One of the best experts on this subject based on the ideXlab platform.
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tank culture of yellowfin tuna thunnus albacares developing a Spawning Population for research purposes
Aquaculture, 2003Co-Authors: Jeanne B Wexler, Vernon P Scholey, Robert J Olson, Daniel Margulies, Akio Nakazawa, Jenny M SuterAbstract:Abstract A land-based culture facility for research on yellowfin tuna, Thunnus albacares , was developed at the Achotines Laboratory in the Republic of Panama. Six concrete tanks, and seawater and life support systems were built to maintain a yellowfin broodstock. On average, 50% of the yellowfin caught survived capture and handling, and approximately 30% became broodstock in Tank 1 (17 m diameter, 6 m depth) or Tank 2 (8.5 m diameter, 3 m depth). Each fish was tagged with a microchip implant tag, then weighed, measured, and injected with oxytetracycline (OTC) prior to stocking. Daily rations of primarily market squid, Loligo opalescens , and Pacific thread herring, Opisthonema spp., were regulated based on the feeding activity and energy requirements of the fish. Feeding activity of the broodstock decreased when the water temperatures decreased, and the fish ate decreasing daily rations and increasing calories with increasing size. Spawning occurred in both tanks within 6–8 months of capture. Spawning first occurred in Tank 1 when 24 females ranged in size from 6 to 16 kg and 65 to 93 cm fork length (FL). Spawning was intermittent during the first 2 months and occurred near daily thereafter. Tank size appeared to affect survival rates, the types of mortalities that occurred, and the growth of the fish. Survival rates after 1 year in captivity were higher, and the fish were larger, on average, in Tank 1 than in Tank 2. Most of the mortalities in Tank 1 were the result of wall strikes, which occurred more frequently after the fish reached their highest density of 0.64 kg m −3 and sizes greater than 96 cm FL and 19 kg. Non-linear growth models were fitted to the initial stocking sizes and final sizes of fish that died or were removed from Tank 1 during 1996–1999. Estimated growth rates in length (11–48 cm year −1 ) for fish between 51 and 150 cm FL decreased with increasing length. Estimated growth rates in weight ranged from 9 to 19 kg year −1 for fish less than 19 kg and 20–23 kg year −1 for fish greater than 19 kg. The results of this work demonstrate that the stable environment of a land-based culture facility may be the preferred system for long-term maintenance of a yellowfin broodstock.