Estimation of Fish Production Rates and Associated Variances

Abstract

Variance estimators for fish production rates are explicitly derived for two production models: the instantaneous growth rate and increment summation methods. Statistics for standing stock, mean interval standing stock, instantaneous growth rate, and production:mean standing stock [Formula: see text] ratio are presented. The use of a jackknife estimator is proposed for estimating the variance of instantaneous growth rate. Comparison of the results from both production models provides a method of cross-validating results. The use of these statistics is illustrated in example calculations with trout population data. Brook trout (Salvelinus fontinalis) annual production in 1969 was significantly higher than combined annual production of brook trout, brown trout (Salmo trutta), and rainbow trout (Salmo gairdneri) in 1977. Variance estimates are affected by population and mean weight estimates. Validity of the production estimates is based on the validity of model assumptions.