Science Advisory Report 2008/039

Assessment of Scallops (Placopecten magellanicus) in Scallop Fishing Area (SFA) 29 West of Longitude 65°30′W

Summary

• This is the seventh consecutive year that a scallop fishery has been conducted in the portion of Scallop Fishing Area (SFA) 29 west of longitude 65°30′ W.  Starting in 2002, the TAC was shared between the Full Bay Fleet and a limited number of inshore East of Baccaro licence holders who are eligible to fish in SFA 29 west of longitude 65˚30′ W (i.e., East of Baccaro Fleet).
• During 2007, a total of 246 t (183 t Full Bay; 63 t East of Baccaro) was landed against a TAC of 250 t.
• Average meat weights from the 2007 fishery ranged from 21.9 g to 29.7 g. Overall, average meat weights are higher this year with the larger meat weights coming from Subareas B and D.
• Commercial catch rates have declined since the first years of the fishery but have stabilized since 2005 in Subareas A, B and C and since 2006 in Subarea D.
• Estimates from the daily commercial catch rate in 2007 indicated that median exploitation rate was highest for Subarea A (0.54). This high rate may be more indicative of local conditions than the whole subarea as fishing was limited to just a few locations in A. The median exploitation rates for the other subareas were 0.21 for C, 0.16 for D and 0.13 for B.
• Survey abundance estimates for commercial size scallops (≥100 mm) and recruits (90–99 mm) have declined since the first years of the fishery. The survey indices do not appear to track year-classes which makes it difficult to interpret trends.
• Survey catches of 1 and 2 year old scallops (shell heights ≤ 50 mm) were widely distributed, with the highest densities in Subarea A. Abundance estimates of this size class are qualitative at best given the selectivity of the survey gear and the actual strength of these year-classes will need to be confirmed by the 2008 survey.
• Based upon the survey estimates of scallops in the 90–99 mm shell height range, the abundance of commercial size scallops in 2008 is not expected to be greater than it was in 2007. The next above-average year-class expected to recruit to the fishery will not be commercial size until 2010 or 2011. Therefore the population numbers are expected to stay the same or decline until then depending upon the rates of exploitation and natural mortality over the next two years.
• Keeping exploitation rates in 2008 at levels in the range of the expected growth in biomass in Subareas B, C and D should result in small or negligible declines in population biomass. That is, catches for 2008 should be in the order of 65, 22, and 61 t for Subareas B, C and D, respectively. Applying the same rationale to Subarea A would result in a recommended catch of less than 1 t. As noted earlier, the exploitation estimate for Subarea A probably does not reflect the area as a whole and the recommended catch could be higher. However, given the high densities of the scallops with shell heights less than 50 mm that were observed in Subarea A, the fishery should be limited to improve the survival of the young scallops in this area.
• There was not enough survey information to recommend catch levels for Subarea E.  Scallop landings from this subarea have ranged from 0 to 11 t since this fishery opened in 2001, and it is likely that the habitat in this subarea is marginal for scallop.
• Bycatch of lobster by the SFA 29 scallop fishery in 2007 was estimated at less than 0.1% of the number of lobsters landed by the Lobster Fishing Area (LFA) 34 lobster fishery in the SFA 29 area. The majority of the lobsters caught in the scallop fishery were released back into the water alive and uninjured.

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