A comparison of catches of the European lobster (Homarus gammarus) in a lobster reserve using traditional pots and scuba diving technique

Abstract

Abstract Lobster research and the management of lobster fisheries are often dependent on catch-and tag-data obtained from fishermen using lobster pots. Therefore, understanding lobster pot selectivity is crucial. In this study, the carapace lengths (CL) of 135 pot-caught European lobsters (Homarus gammarus) are compared to the CL of 137 dive-caught lobsters inside the Kåvra lobster reserve on the Swedish west coast during summer 2017. The Carapax pot used was strongly size-selective for both small individuals and large males, and pot CL was between 63 and 149 mm. Dive-caught lobsters had a CL between 46 and 170 mm and 25% of the males were larger than the largest pot male. We conclude, for the reasons discussed here, that interpretation of size-data in pot-based monitoring and research should be made with caution. Our results show that scuba diving, especially during the night, is essential when it comes to studies of size distribution, behaviour, and choice of microhabitat.