Research Document - 2011/112

Preliminary results from the groundfish and shrimp multidisciplinary survey in August 2011 in the Estuary and northern Gulf of St. Lawrence

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

Abstract

In 2011, 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 August 1st to 29th onboard the CCGS Teleost. One of the primary objectives was to estimate abundance indices for the main groundfish species (cod, Greenland halibut, Atlantic halibut and redfishes – 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 oceanographic conditions observed in August for the sampling area.

This report describes preliminary results on the catch rates and distribution of 25 taxa, as well as their size frequency distribution. These results were compared with results from the historical survey series that 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 2011, the abundance and biomass indices of many species were stable or decreased compared to 2010. In fact, the two redfish species, cod, black dogfish and longfin hake showed index values below their respective means calculated for the comparative period of 1990-2010. Even if Atlantic halibut, witch, thorny skate, hagfish, northern shrimp and snow crab indices decreased from 2010 to 2011, they were comparable or higher than the mean estimated for the 1990-2010 period. Five species (Greenland halibut, white hake, American plaice, capelin and herring) showed an increase for their indices in 2011. Except for white hake, the indices for these species were similar or higher than the 1990-2010 period means. The geographic distributions of catches recorded for the different species in 2011 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 (Greenland halibut, thorny skate, white hake, witch, American plaice, hagfish and northern shrimp), some size classes observed in 2011 were clearly dominant, and their abundance well above the calculated average for the comparative period.

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