Hoenig, J.M. 1987. Estimation of growth and mortality parameters for use in length-structured stock

The suggestion of some authors that linear methods of fitting von Bertalanffy growth curves generate biases may be premature, at least in one case discussed here, where the direction of the ob-served bias is explainable by the use of a predictive instead of a functional regression. When growth parameters are needed for length-converted catch curves or length-based cohort analysis, an inverse regression (age on length) may be appropriate. This can be computed through ordinary linear regression. An estimator for the total mortality, based on mean length, is derived for use when recruitment occurs periodically rather than continuously. Surplus-production models employing total mortality as the independent variable may become tilted to the left if natural mortality is compensatory. When growth parameters are unknown, surplus production can be modelled as a function of Z/K. When available data are limited to a small portion of the surplus production curve, fitting curves by regression may give unreasonable results. In this case, one can constrain a parameter to the value of an independent estimate so that the other estimates become more reasonable