A critical size and period hypothesis to explain natural regulation of salmon abundance and the linkage to climate and climate change

摘要: Abstract We hypothesise that salmon year class strength is determined in two stages during the first ocean. There an early natural mortality mostly related to predation, which followed by a physiologically-based mortality. Juvenile fail reach critical size end of their marine summer do not survive following winter. In this study we describe our initial tests and period hypothesis using data from ocean surveys juvenile experimental feeding studies on coho. Conservative swept volume abundance estimates for coho, possibly chinook, indicate there high fall winter sea. Studies otolith weight show length otolith-weight relationship young coho changes year. growth associated hormone levels slow growing are stunted deficient insulin-like factor-I (IGF-I). sampled September had low IGF-I values, indicative poor growth. The results these provide evidence general growth-related occurs late may be important determining (brood year). link between total climate could operating via availability nutrients regulating food supply hence competition (i.e. bottom–up regulation).