Seasonal and sexual differences in the thermal preferences and movements of American lobsters

Abstract

Thermal preferences of lobsters (Homarus americanus) were determined in the laboratory and compared with seasonal movements and distribution of lobsters in the Great Bay Estuary, New Hampshire. Lobsters preferred 11.0 ± 0.6 °C, or 2.8 ± 0.7 °C warmer than ambient temperature, during the colder months of the year. However, during the warmer months they selected 15.7 ± 0.4 °C, which was 0.2 ± 0.4 °C warmer than the ambient temperature. Overall, the lobsters tested had a final preferred temperature of 15.9 °C, and males selected warmer temperatures than females. Catch per unit effort was highest at sites where temperatures were similar to the temperatures lobsters preferred in the laboratory studies and lowest at sites ≥18 °C or <12 °C. Significantly more males than females were captured in areas with temperatures >16 °C. Lobsters tagged, and subsequently recaptured within 7–35 days, moved relatively little when released into areas where temperatures were similar to their preferred temperatures. Thermal preferences may influence the movement of lobsters in thermally heterogeneous habitats, and climate change is expected to have a major impact on lobster distribution, especially in estuarine and coastal habitats.