Science Advisory Report  2013/030

Assessment of the Rock Crab (Cancer irroratus) fishery in the southern Gulf of St. Lawrence for 2006 to 2011

Summary

• The rock crab fishery in the southern Gulf of St. Lawrence is comprised of three components: the bycatch fishery, the bait fishery, and the directed fishery. The bycatch and the bait fisheries are conducted during the lobster fishery by lobster licence holders.
• Between 2006 and 2011, total annual recorded landings averaged 4,734 t, with an average of 4,300 t from the directed fishery and 434 t from the bycatch fishery.
• Bycatch landings (sold, not personal use) of rock crab during the lobster fishery from 2000 to 2011 represented 7% to 24% of the total directed fishery landings with a declining trend since 2004.
• There is no estimate of quantities of rock crab caught and used as bait during the lobster fishery. The extent of the bait bycatch in lobster gear may be decreasing with the adjustment of escape mechanisms in lobster traps which could reduce the retention of smaller rock crabs.
• Catch rates derived from logbooks in 2011 were above the average of the 2000 to 2010 period for every fishing area.
• The percentages of active licence holders reaching 90% or more of their individual allocation were highest in lobster fishing areas 25 and 26A (51% and 71%, respectively), with a large amount of latent effort remaining in this fishery.
• A wide size frequency distribution and a balanced sex ratio of rock crab were observed based on the trawl survey.
• The minimum legal size used in the directed fishery is above the size at 50% and 95% maturity for males.
• Rock crab plays a major role in ecosystem structure and functioning. It is abundant and widely distributed in the coastal areas of the southern Gulf of St. Lawrence and is an important prey of a wide variety of organisms including lobster.
• There is no estimate of total biomass of rock crab in the southern Gulf of St. Lawrence, in terms of male biomass available to the fishery or estimates of exploitation rate. Landings are unlikely to be a proxy of biomass due to the limits placed on individual catches. Trawl surveys in 2010 and 2011 provided a snapshot of relative biomass in the two most heavily fished areas.
• Measuring effectiveness of management measures is limited due to lack of stock indicators against which to assess them.

This Science Advisory Report is from the regional peer review meeting of February 26 to 28, 2013 on the assessment of the status of the lobster (Homarus americanus) and rock crab (Cancer irroratus) stocks of the southern Gulf of St. Lawrence. Additional publications from this meeting will be posted on the Fisheries and Oceans Canada (DFO) Science Advisory Schedule as they become available.

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