Effects of an autocorrelated stochastic environment and fisheries on the age at maturity of Chinook salmon
- 90 Downloads
Chinook salmon (Oncorhynchus tshawytscha) reproduce only once in their lifetime, and their age at reproduction varies among individuals (indeterminate semelparous). However, the factors that determine their spawning age still remain uncertain. Evidence from recent studies suggests that individual growth and reproduction of Chinook salmon are affected by the rate of coastal upwelling, which is shown to be positively autocorrelated between years. Therefore, the serially autocorrelated environmental is expected to play an important role in determining their spawning age. In the present study, I demonstrate the advantage of an indeterminate maturation strategy under a stochastic environment. I then present theoretical evidence for the advantage of adjusting the maturation probability based on the environment they experienced and demonstrate that fisheries reduce the fitness of the strategy to delay maturation. The results presented herein emphasize the importance of incorporating detailed life-history strategies of organisms when undertaking population management.
KeywordsAge of maturity Environmental autocorrelation Life-history evolution Matrix population model Maturation adjustment strategy
I thank Michael Mohr, Eric Bjorkstedt, and two anonymous reviewers for constructive comments on the manuscript and Marc Mangel for comments at the initial stage of this study. I also extend a special thanks to Morgan Knechtle at the California Department of Fish and Game for providing me with his preliminary result related to the maturation rate of Chinook salmon.
- Caswell H (2001) Matrix population models: construction, analysis and interpretation, 2nd edn. Sinauer Associates, Sunderland, MA, USAGoogle Scholar
- Fujiwara M, Mohr MS (2007) Effects of environmental factors on fall-run chinook salmon (Oncorhynchus tshawytscha) within the Klamath Basin. (in press)Google Scholar
- Gallager RG (1995) Discrete stochastic processes. Kluwer Academic Publishers, Boston, MA, USAGoogle Scholar
- Hankin DG, Nicholas JW, Downey TW (1993) Evidence for inheritance of age of maturity in Chinook salmon (Oncorhynchus tshawytscha). Can J Fish Aquat Sci 50:343–358Google Scholar
- Healey MC (1991) Life history of Chinook salmon (Oncorhynchus tshawytscha). In: Groot C, Margolis L (eds) Pacific Salmon: life histories. UBS Press, Vancouver, British Columbia, CanadaGoogle Scholar
- Healey MC, Heard WR (1984) Inter-population and intra-population variation in the fecundity of Chinook salmon (Oncorhynchus tshawytscha) and its relevance to life-history theory. Can J Fish Aquat Sci 41:476–483Google Scholar
- McGregor EA (1922) Observations on the egg yield of Klamath River king salmon. Calif Fish Game Report 8:161–164Google Scholar
- Quinn TP (2005) The behavior and ecology of Pacific salmon & Trout. University of Washington Press, Seattle, WA, USAGoogle Scholar
- Ricker WE (1958) Handbook of computations for biological statistics of fish populations. The Fisheries Research Board of Canada, Ottawa, CanadaGoogle Scholar