Early sea mortality of mark‐recaptured juvenile chum salmon in open coastal waters

Abstract

Estimates of instantaneous mortality rate of mark‐recaptured chum salmon Oncorhynchus keta juveniles in coastal waters of the Sea of Japan ranged from 0·033 to 0·268 day −1 in the 14–43 days after release. High mortality rate may have been caused by size‐selective mortality or poor ability to adapt to the coastal environment inhabited by chum salmon juveniles soon after release. The results indicated that large‐scale mark‐recapture experiments are useful for estimating mortality during the early sea life that is considered to be a critical period for Pacific salmon.