COMPARATIVE REVIEW OF PACIFIC SALMON SURVIVAL RATES

I collated estimates of survival from the literature for naturally rep roducing populations of the five major commercially harvested species of Pacific salmon (Oncorhynchus spp.) and compared the mean and variab ility of survival across species and life-history stages. The conclusi on that survival rates can be described with a lognormal distribution was extended to include both the marine and freshwater stages. Average egg-fry survival of pink (O. gorbuscha), chum (O. keta), and sockeye (O. nerka) salmon was similar (average 7%) but was significantly lower than that of coho salmon (O. kisutch, 19%). The egg-smelt survival of chinook (O. tshawytscha) was much higher than coho or sockeye that al so rear in freshwater for similar periods (T compared with 1-2%). No d irect estimates exist for the marine survival rate of naturally spawni ng chinook stocks; however, from fecundity and freshwater survival dat a a species average of 1-2% was derived. Across all species freshwater contributes slightly more to total variation in egg-adult survival th an does the ocean, and the schedule of mortality during the egg-adult interval depends on the natural history of each species.