Differences in the size at maturity of female American lobsters (Homarus americanus) from offshore Southern New England and eastern Georges Bank, USA

Abstract

Female reproductive dynamics of the offshore American lobster fishery are not well understood due to the difficulties associated with biological sampling offshore. This lack of knowledge limits our understanding of population dynamics and the impacts of fishery removals on the offshore lobster resource. Addressing needs identified by stock assessment scientists, we determined the size at which female lobsters reach sexual maturity for two offshore areas (offshore Southern New England and eastern Georges Bank) utilizing data from commercial lobster gear and the Northeast Fisheries Science Center bottom trawl survey. A total of 491 female lobsters were collected and assigned a maturity status based on standard ovarian staging techniques. The size at which 50% of females in the population are mature (L50) occurred at a smaller size (L50 = 79.5 mm) in Southern New England compared to eastern Georges Bank (L50 = 91.9 mm). Comparisons of our results to historical data from nearby regions show only a slight decline in Southern New England, but, depending on the data source, a larger decline in size at maturity for Georges Bank. These maturity estimates for offshore lobsters provide new information for assessment scientists and managers on lobster population demographics in a data-poor region of the fishery, and reinforce the value achieved by working collaboratively with the fishing industry to address data gaps in the offshore lobster fishery.