MEPS 483:231-243 (2013)  -  DOI: https://doi.org/10.3354/meps10282

ABSTRACT: Estimates of vital rates, at appropriate spatial scales, are essential for stock assessment and sustainable management of exploited populations. Substantial research efforts are often required to estimate vital rates, with results of unknown applicability to other locations or larger areas within the species range. We investigated whether a rate variable, growth, can be estimated across the entire range of a species. We used data from the commercial range of the American lobster Homarus americanus to develop a model to calculate von Bertalanffy growth parameters at any location in that range. Fixing the maximum size parameter (L_∞) to a biologically reasonable value resulted in more realistic estimates of growth than estimating this parameter from data at any one location. The growth parameter k decreased with latitude at a rate of 0.51% per year per degree of latitude for males and 0.40% for females. The von Bertalanffy parameters apply to individual growth; the bias in using these parameters to estimate population growth was minor. The underlying mechanism for the latitude model was investigated by GIS mapping of candidate environmental factors: depth, temperature, and salinity. Multiple regression analysis showed a significant positive relationship between the growth parameter k and temperature. Growth rates of American lobster can now be estimated on a site-specific basis without having to undertake resource-intensive tag-recapture field studies or adopting an estimate from a distant location. Similar approaches with other vital rates allow calculations at any spatial scale, from local scales to those of populations and ecosystems.

KEY WORDS: Growth modeling · American lobster · von Bertalanffy · Tag-recapture