Research Document - 2010/003
Assessment of the Bay of Fundy sea urchin fishery, Lobster Fishing Area 38
By David Robichaud
Abstract
The green sea urchin (Strongylocentrotus droebachiensis) commercial fishery was initiated along the coast of southwestern New Brunswick, in the Bay of Fundy, in 1989. The sea urchin fishery was separated into 2 management areas. These 2 areas were assigned the same boundaries as Lobster Fishing Areas (LFAs) 36 and 38. In LFA 38, the existing sea urchin fishery is based on a total allowable catch (TAC) system and under non transferable individual boat quota. The urchins are harvested by dragging. Presently, there are 13 licensed dragging operators. It is currently managed using a minimum legal size limit of 51 mm test diameter (TD) and by a fishing season. A TAC of 979 t was set in 1996. Since then, the TAC has been reduced 3 times and presently the fleet operates under a TAC of 176.9 t. In this assessment, fishing effort, landings trends, and catch rates were evaluated using logbook information. In addition, sea urchin size structure, densities, and biomass were re-evaluated, using diver based sea urchin survey information. The traditional fishing grounds on the east side of Grand Manan Island were re-surveyed in 2005, and the results were compared with the previous results from the 1992 survey. During 2006 and 2007, a selected subset of transects were sampled and the survey results from these specific transects compared with the corresponding transects that were surveyed in 1992 and 2005. The TAC and harvesting rates were reviewed. By-catch was evaluated by at-sea observer during the 2007-08 fishing season.
Since 1996, there has been a consistent decrease in catch per unit effort (CPUE) until it reached its lowest during the 2006-07 fishing season. During the 2007-08 fishing season, catch rates increased for the first time since 1996. The number of fishing trips has declined to a low of 179 trips during the 2007-08 fishing season. Total biomass and estimated fishable biomass have declined between 1992 and 2005. However, there is no statistically significant difference in the density of legal-sized sea urchin between the 2 survey periods due to a high degree of variability. Nevertheless, on a selected subset of transects the density of legal-size sea urchins was significantly lower in 2006 and 2007 compared to 1992. Based on the established TAC of 176.9 t, the present exploitation rate is estimated to be 1.5%, which is lower than the harvesting rate of 3.3% set in 1996. Implementation of the new logbook format will facilitate collection and analysis of effort and harvesting rate. At-sea observer sampling showed that the by-catch amount varies between sampling periods and fishing areas, but was consistent in the species type present. Most of the by-catch consisted of kelp and of blue mussels. All other species combined made up only 3% and 4% of the catch. A review of the survey design and another survey in the next 2-3 years is recommended.
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