Research Document - 2012/144

Preliminary results from the groundfish and shrimp multidisciplinary survey in August 2012 in the Estuary and northern Gulf of St. Lawrence

By D. Archambault, H. Bourdages, B. Bernier, P. Galbraith, J. Gauthier, F. Grégoire, J. Lambert and L. Savard

Abstract

In 2012, the annual summer survey for the assessment of abundance and distribution of groundfish and shrimp in the Estuary and the northern Gulf of St. Lawrence was conducted from July 31st to September 2nd aboard the CCGS Teleost. One of the primary objectives was to estimate abundance and biomass indices for the main groundfish species (cod, Greenland halibut, Atlantic halibut and rockfish - Sebastes fasciatus and S. mentella -) and for the Northern shrimp, and to identify the spatial distribution and biological characteristics of these species. The two other main objectives of the survey included monitoring the biodiversity of the Estuary and the northern Gulf, and describing the environmental conditions observed in August for the sampling area.

This report describes the preliminary results on the catch rates and distribution of twenty taxa, as well their size frequency distribution. These results were conmpared with results from the historical survey series began in 1990, taking into account the equivalency factors used to convert data from the tandem CCGS Alfred Needler-URI to the tandem CCGS Teleost-Campelen. In 2012, the abundance and biomass indices of many species were stable or decreased compared to 2011. In fact, the two redfish species, longfin hake, white hake, hagfish and lumpfish showed indices values below their respective averages calculated for the comparative period of 1990-2011. Even if Atlantic halibut, herring, American plaice and Northern shrimp indices decreased from 2011 to 2012, they were comparable or higher than the averages estimated for the 1990 – 2011 period. Only black dogfish and snow crab indices increased in 2012 and showed values comparable to or higher than their respective averages for the 1990-2011 period. The geographic distribution of catches recorded for the different species in 2012 showed the same pattern as in previous years. Finally, the size distributions ranges determined for each species remains relatively stable for the entire time of the historical series. However, for some species (Atlantic and Greenland halibut, cod, witch and American plaice), some size classes observed in 2012 were clearly dominant, and their abundance well above the calculated average distribution average for the comparative period.

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