Science Advisory Report 2018/044

Assessment of rock crab stock status in Quebec in 2016

Summary

• In Quebec, landings of rock crab from the directed fishery totalled 923 t in 2016. Fifty-two percent of these landings came from the Magdalen Islands (477 t), 21% from the northern part of the Gaspé Peninsula (192 t), 20% from the southern part of the Gaspé Peninsula (186 t), and 7% from the North Shore (68 t). Landings have been declining since 2009 (1,777 t) and have dropped by 42% since the last assessment in 2012 (1,587 t). The relative decline in landings was much more pronounced in the Gaspé Peninsula and on the North Shore (53-59%) than in the Magdalen Islands (15%).
• The sharp decrease in landings since 2012 is mainly explained by a reduction in quotas in the Magdalen Islands and a decrease in fishing effort and, sometimes, catch rate in other areas. From 2013 to 2016, quotas, if applicable, were not approached or reached, except in the Magdalen Islands.
• Since 2012, catch rates have decreased or have apparently stabilized at very low levels in most areas. In particular, in the Magdalen Islands, the 2016 CPUE was 36%–43% below the 1995–2015 average. However, in certain areas of the Gaspé Peninsula and the North Shore where fishing effort and landings have dropped sharply, the CPUE was rather stable or even increased in one case.
• Size structures and average sizes have remained generally stable or have even improved compared to 2012 in the Gaspé Peninsula and the North Shore where fishing effort and landings saw a sharp decline. However, they are still deteriorated in the Magdalen Islands and, in 2016, the average size was less than or equal to historical lows.
• The decrease in fishing effort and deterioration of the rock crab population indicators seem inversely correlated to the increase in landings of its main predator, the American lobster. Natural mortality resulting from predation by lobster has certainly increased sharply, adding to mortality caused by fishing.
• For all of Quebec, it is recommended not to increase the intensity of the directed fishery and to better document rock crab by-catches. Quotas should be reduced in the Magdalen Islands, given the decrease in the catch rate and the average size. Quotas in the Gaspé Peninsula should be reduced, given the decline in CPUE in the northern region and in a sub-area of the southern region, or because they are set so high that they have no preventive value.
• Lastly, to assess the impact of the rock crab fishery on the ecosystem, in accordance with the DFO Sustainable Fisheries Framework, it is recommended that by-catches of the rock crab directed fishery be recorded.

This science advisory report is from the meeting of February 28 – March 1, 2017, on the Stock Assessment of Rock Crab in Quebec Inshore Waters. 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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