ABSTRACT
The biomass of fish in a population that is closed to migration may change due to the addition of individuals through recruitment, subtraction of individuals by mortality, or growth of the individuals in the population. Historically, growth functions were fit to mean length-at-age data. However, to fit models with appropriate estimates of variability, length measurements and age estimates from individual fish are required. Individual growth is treated as an increase in either length or weight with increasing age. Several functions have been used to model the mean length-at-age of fishes. Many models in fisheries and ecological research are nonlinear. The profile likelihood and bootstrap confidence intervals may differ dramatically if the profile is greatly curved or if the histogram of bootstrapped estimates is highly skewed. Predicted lengths-at-age are obtained from the results of the fitted von Bertalanffy growth function in a variety of ways.
