Responses of European lobster (Homarus gammarus) and lobster fishers to protective management

Abstract

Marine protected areas (MPAs) are valued for their conservation benefits to harvested species. However, potential benefits of MPAs to neighboring fisheries are less well-understood. This study quantifies how the European lobster (Homarus gammarus) and the fishery for this valued catch respond to the establishment of a relatively small (5.2 km2) MPA on the Norwegian Skagerrak coast. A series of yearly standardized trap surveys was conducted to estimate lobster abundance and catch weights both inside and outside the MPA before (2010- 2011) and after the MPA was established (2012-2016). Lobster abundance and catch weights were determined as number of catch per unit effort (CPUEN) and weight of catch per unit effort (CPUEw), respectively. Using a similar before-after study design, the lobster fishery was described from fishery diaries and by counting all lobster traps in the study area. After 4 years of protection, gradients for abundance and catch weights across the MPA boundaries have developed, but the export of benefits to neighboring fishing areas are limited. Inside the MPA, CPUEN values increased from 0.748 lobsters/trap/day before protection to 1.93 lobsters/trap/day after protection. Catch weights have also increased from 1.29 kg/trap/day to 1.54 kg/trap/day in the same period. Slight increases in CPUEw were observed in the fished areas near the boundary, but not for CPUEN. At fished areas 2-3 km away from the boundaries, CPUEN values were stable, and catch weights have increased. This suggests that fishers around the MPA are catching larger, but not more lobsters around the MPA. Increased catch weights in the fished areas are attributed to the protection of berried female lobsters from fishing mortality. Fishing pressure, mostly from recreational fishers, is increasing the most outside MPA boundaries, resulting in lowered CPUEN and catch weight values. Results from the study indicate that determining conservation and fishery benefits of an MPA should always be considered in context of existing and changing fishing pressure in order to effectively utilize MPAs as a fishery management tool. Keywords: European lobster, Homarus gammarus, MPA benefits to fisheries, lobster CPUE, recreational fisheries