Effect of smolt size on postrelease survival of hatcheryreared masu salmon Oncorhynchus masou

Abstract

The relationship between mean weights of hatchery-reared masu salmon Oncorhynchus masou smolts at release and the subsequent recovery rates by coastal commercial fisheries in Hokkaido, northern Japan, was investigated using the maximum likelihood method. A strongly positive correlation was observed, showing smolts with a mean of 32.6 g obtained an approximately 20-fold recovery rate of those with a mean of 14.8 g. The model with log-transformed independent variable (Y_i=-11.237 + 4.239 ln X_i) was selected as the most parsimonious model to represent the release size (X_i) and recovery rate (Y_i) relationship.