1. Temporal patterns and ecosystem correlates of chum salmon (Oncorhynchus keta) migration phenology in the Pacific Northwest
- Author
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Agha, Mickey, Losee, James P., Litz, Marisa N.C., Smith, Craig, Schaffler, Jason J., Patton, William S., Dufault, Aaron M., and Madel, Gabe M.
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Pacific salmon -- Environmental aspects ,Earth sciences - Abstract
Understanding and quantifying migration phenology of commercially harvested Pacific salmon (Oncorhynchus spp.) is a cornerstone for managing sustainable populations. Here, we use a multidecadal data time series together with a hypothesis-driven framework to evaluate migration phenology in adult fall and winter ecotype chum salmon (O. keta) in a poorly studied but highly managed system--the South Puget Sound (SPS) of Washington State, USA. Using generalized additive mixed models that accounted for temporal autoregressive dynamics, we examined the effect of commercial harvest, climate variation, intra-specific density dependence, and predator buffering on migration timing and run duration. SPS chum salmon are migrating earlier over time, especially the winter ecotype that showed the strongest temporal shift from historical timing. Migration timing shifts were closely associated with regional marine climate regimes, local scale freshwater availability, and increasing pinniped abundance. We conclude that there is potential for the winter ecotype migration converging with that of the fall ecotype and that directional change in migration phenology may be driven by a unique combination of ecosystem factors. La comprehension et la quantification de la phenologie des migrations des saumons du Pacifique (Oncorhynchus spp.) faisant l'objet d'une exploitation commerciale constituent un des elements essentiels de la gestion de populations perennes. Nous utilisons une serie de donnees multidecennale jumelee a un cadre module par differentes hypotheses pour evaluer la phenologie de la migration de saumons ketas (O. keta) adultes des ecotypes automnal et hivernal dans un systeme peu etudie, mais faisant l'objet d'une gestion intense, le sud du Puget Sound (SPS, Etat de Washington, Etats-Unis). En utilisant des modeles mixtes additifs generalises qui tiennent compte de la dynamique autoregressive temporelle, nous examinons les effets de l'exploitation commerciale, des variations climatiques, de la dependance intraspecifique sur la densite et de la modulation par les predateurs sur le moment et la duree des migrations. Les saumons ketas du SPS migrent de plus en plus tot, en particulier ceux de l'ecotype hivernal, qui presentent le plus grand decalage temporel par rapport aux observations passees. Les changements du moment de la migration sont etroitement associes aux regimes climatiques marins regionaux, a la disponibilite locale d'eau douce et a l'augmentation de l'abondance de pinnipedes. En conclusion, il est possible que la migration de l'ecotype hivernal converge avec celle de l'ecotype automnal et que les changements directionnels de la phenologie des migrations soient modules par une combinaison unique de facteurs ecosystemiques. [Traduit par la Redaction], Introduction Predicting migratory behavior of commercially harvested salmonids is important for managing and maintaining sustainable populations. However, evaluating the underlying biotic and abiotic mechanisms that drive migration phenology remains complex, [...]
- Published
- 2021
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