Survival and Production of Pink and Chum Salmon in a Coastal Stream

Abstract

A study of the propagation of pink and chum salmon in the central coastal region of British Columbia was made for the years 1947 to 1956.Timing, distribution and movement of the adults and fry are discussed. The effects of temperature, stream discharge, sex ratio and population density were considered in relation to survival of egg to fry. Within the limits observed, temperature, stream discharge and sex ratio were not affecting the population perceptibly, but population density was an important factor. The density of spawners in preceding years also affected the survival in subsequent years.Predation was an important factor in keeping the fry output low: the number of fry consumed was approximately 500,000 during each migration.Ocean survival, including the effect of fishing mortality, ranged from 5.2% down to 0.7% for pink salmon, and from 2.6% to 0.85% for chum salmon. Ocean survival for pink salmon before fishing mortality occurred ranged from 10.8% down to 1.0%.Combination of freshwater and ocean survival rates indicate that a variation up to 190 times the lowest rate recorded is possible.