The potential influence of habitat composition on seasonal lobster movements and their distribution in the Great Bay Estuary, New Hampshire

Abstract

Abstract Although estuaries create many physiological challenges for lobsters (Homarus americanus), there may also be some advantages for lobsters residing in these unique systems. While some lobsters in the Great Bay Estuary (GBE) make seasonal migrations into and out of the GBE, many remain year-round, including ovigerous (egg-bearing) females. Furthermore, lobsters that are resident in the GBE tend to aggregate in specific areas. The overall goal of this study was to determine why lobsters (both ovigerous and non-ovigerous) tend to spend more time in certain areas of the GBE. Specifically, we set out to test the hypothesis for two disparate areas of GBE that have features potentially making them conducive habitats for long-term lobster residency. We used a combination of habitat mapping using underwater videography and diver surveys to compare areas where lobsters aggregated compared with those areas where lobster density was known to be low. Areas where lobsters spent the most time in GBE were similar to coastal marine habitats, comprised mostly of rocky (hardbottom) complexes interspersed with macroalgae. In contrast, areas with the fewest lobsters were primarily comprised of sandy, soft sediment. The strong relationship between complex, rocky habitats and lobster residency in GBE suggest that habitat quality in other estuaries might have a strong impact on the distribution, abundance, and residency of lobsters and increases the likelihood that some estuaries may support year-round resident lobster populations.