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Science Response 2014/016

Stock Status Update of Atlantic Halibut on the Scotian Shelf and Southern Grand Banks (NAFO Divs. 3NOPs4VWX5Zc)

Context

The Atlantic Halibut (Hippoglossus hippoglossus) is the largest of the flatfishes and ranges widely over Canada's East Coast. The management unit definition (3NOPs4VWX5Zc) is based largely on tagging results which indicate that Atlantic Halibut move extensively throughout the Canadian North Atlantic with smaller fish moving further than larger fish.

The Atlantic Halibut fishery was unregulated until a total allowable catch (TAC) was implemented in 1988 and a legal size limit (≥81 cm total length) was set in 1994. While the Fisheries and Oceans Canada (DFO) research vessel (RV) survey provides a useful index of abundance for incoming recruitment, an index for exploitable biomass (≥81 cm total length) is not available since larger fish are captured infrequently. An industry-DFO longline halibut survey on the Scotian Shelf and southern Grand Banks (3NOPs4VWX5Zc) was initiated in 1998 to better estimate adult biomass. A commercial index is conducted in conjunction with the longline halibut survey. The longline halibut survey and commercial index generate indices for exploitable biomass of halibut from the Scotian Shelf and southern Grand Banks, as well as estimates of population size structure. A tagging study was initiated in 2006, in which both recruits and commercial sized fish were tagged and released. Recoveries are used to estimate exploitation rate.

The last assessment of Atlantic Halibut was conducted in November 2010 (DFO 2011). This assessment used a new assessment framework and produced estimates of spawning stock biomass (SSB) and fishing mortality (F). The consequences of different harvest levels and the risk to the productivity of the stock were assessed in 2012 (DFO 2012).

This stock status update was requested to inform Fisheries and Aquaculture Management and the Scotia-Fundy Groundfish Advisory Committee of the status of the Halibut resource. The objectives are to evaluate and update trends in abundance/biomass indicators, including: standardized catch rates from the halibut survey, standardized catch rates from the commercial index, and stratified mean numbers per tow from the ecosystem RV survey, and to evaluate landings and trends in F estimated from tagging data.

This Science Response Report results from the Science Response Process of December 10, 2013, on the Status Update of 3NOPs4VWX+5 Atlantic Halibut.

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