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Survival and life history characteristics among wild and hatchery coho salmon (Oncorhynchus kisutch) returns: how do unfed fry differ from smolt releases?

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Abstract:

Survival and life history characteristics were evaluated for a coho salmon (Oncorhynchus kisutch) integrated hatchery program using two stocking strategies. Fish were released as unfed fry or smolts and returned as adults, and then molecular analysis was employed to pedigree the entire population. We showed that mean adult survival of individuals released as unfed fry was less than that of individuals released as smolts (0.03% vs. 2.39%). The relative reproductive success (RRS) of the fry release strategy to wild spawning was significantly greater for one of two cohorts, whereas the smolt release strategy to wild RRS was significantly greater for both cohorts. Fish released as smolts were significantly smaller upon returning as adults than either those released as unfed fry or wild returns. Mean run timing was also significantly biased towards an earlier run time for hatchery-released fish when compared with the wild component. The incidence of jacking (males maturing at age 2) was greater among fish stocked as smolts than for fish stocked as fry. Differences in survival, RRS, and life history appeared to be the result of hatchery practices and indicated that a fry stocking strategy produced fish more similar to the wild component of the population than to that of fish released as smolts.

Nous avons déterminé la survie et les caractéristiques du cycle biologique de saumons coho (Oncorhynchus kisutch) dans un programme de pisciculture intégré qui utilise deux stratégies d’empoissonnement. Les poissons ont été ensemencés comme alevins ou saumoneaux à jeun et recapturés au stade adulte; des analyses moléculaires ont alors servi à établir la filiation de toute la population. Nous avons démontré que les poissons ensemencés au stade alevin à jeun avaient un taux de survie moyen jusqu’à l’âge adulte inférieur à celui des poissons ensemencés au stade saumoneau (0,03 % vs 2,39 %). Le succès reproducteur relatif (RRS) de la stratégie alevin par rapport aux individus en milieu naturel était supérieur pour une année, mais inférieur pour l’autre année. Le RRS de la stratégie saumoneau était supérieur pour les deux années. Les poissons ensemencés au stade saumoneau avaient une taille corporelle inférieure à l’âge adulte à celle des poissons relâchés en tant qu’alevins à jeun et des poissons sauvages. La date de montaison moyenne était significativement devancée pour les poissons d’élevage. L’incidence de la maturation sexuelle précoce («jacking») était plus grande parmi les poissons ensemencés au stade saumoneau que parmi les poissons relâchés au stade alevin. Ces différences dans la survie, le RRS et les traits d’histoire de vie semblent découler des pratiques d’élevage en captivité et indiquent que la stratégie d’ensemencement d’alevins produit des poissons qui sont plus semblables à l’âge adulte aux poissons sauvages que les ensemencements de saumoneaux.

Document Type: Research Article

Publication date: March 1, 2010

More about this publication?
  • Published continuously since 1901 (under various titles), this monthly journal is the primary publishing vehicle for the multidisciplinary field of aquatic sciences. It publishes perspectives (syntheses, critiques, and re-evaluations), discussions (comments and replies), articles, and rapid communications, relating to current research on cells, organisms, populations, ecosystems, or processes that affect aquatic systems. The journal seeks to amplify, modify, question, or redirect accumulated knowledge in the field of fisheries and aquatic science. Occasional supplements are dedicated to single topics or to proceedings of international symposia.
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