Latitudinal variation in growth rates of American lobseter (Homarus americanus) at the scale of the commercial range

Abstract

Accurate life history information is essential for stock assessment and management of the American lobster (Homarus americanus) fishery in the Northwest Atlantic. To evaluate conservation measures adopted by lobster harvesters, a growth model is required to provide estimates of egg production and reproductive value. This study examines inconsistencies among previous estimates of growth rates and combines historical data with current tag-recapture studies to develop a general model to estimate growth rates. Growth rates calculated using multiple techniques differed substantially in a single dataset; therefore, a single technique must be used consistently in all locations. A general von Bertalanffy growth model for the entire species' range was developed and growth rates showed a steady decrease with increasing latitude within the range of 41.543600ﾟ and 50.722915ﾟ N. The decrease in growth rate per degree of latitude was approximately 0.3% for both male and female lobsters when using a regression weighted by the inverse variance. Growth parameters for American lobster can now be estimated on a site-specific basis using latitude, reducing the need for resource-intensive tag-recapture field studies.