Separable Virtual Population Analysis of Pacific Salmon with Application to Marked Chinook Salmon, Oncorhynchus tshawytscha, from California's Central Valley

Publisher Website
Google Scholar
Abstract
A separable virtual population analysis model is developed for Pacific salmon which utilizes aged catch and spawning scapement data. This model is applied to marked chinook salmon, Oncorhynchus tshawytscha, from California''s Central Valley hatcheries using weighted least squares criteria for goodness of fit. Structural inadequacies of the model apparently produce discrepancies between predicted values and observed data that are of about the same magnitude as the observational errors in estimating the recoveries of marked fish. Some of the inadequacy of the model may be due to environmentally induced variability in population parameters, but for the marked fish used in this analysis, some of the variability is probably due to year-to-year variability in hatchery practices. From this analysis it appears that although nominal fishing effort has been relatively stable or even declining in recent years, fishing mortality has been increasing with the exception of 1983 and 1984.

This publication has 4 references indexed in Scilit: