Research Document 2023/074
Preliminary results from the ecosystemic survey in August 2022 in the Estuary and northern Gulf of St. Lawrence
By Bourdages, H., Chamberland, J.-M., Desgagnés, M., Galbraith, P., Isabel, L., Ouellette-Plante, J., Roux, M.-J., and Senay, C.
Abstract
Fisheries and Oceans Canada conducts an annual multidisciplinary survey in the Estuary and northern Gulf of St. Lawrence. The objectives of this survey are varied; assess the biodiversity of species found near the bottom; estimate the abundance of groundfish and invertebrates; assess physical and biological (phytoplankton and zooplankton) oceanographic conditions; monitor the pelagic ecosystem; and collect samples for various research projects. In 2022, the survey was conducted between August 7 and September 15 on board the CCGS Teleost and the CCGS John Cabot. During this mission, 181 and 176 trawl tows were completed, respectively on the Teleost and the John Cabot. In addition, 92 vertical profiles of the water column were carried out in order to characterize the oceanographic conditions and 63 zooplankton samples were also collected.
This report presents the results of catches of 194 tows. In total, 78 fish taxa and 208 invertebrate taxa were identified during the mission. Historical perspectives (catch rates, spatial distribution and length frequency) are presented for 25 taxa. These commercial fishery-independent data will be used in several stock assessments including cod (Gadus morhua), redfish (Sebastes spp.), Greenland halibut (Reinhardtius hippoglossoides), Atlantic halibut (Hippoglossus hippoglossus), witch flounder (Glyptocephalus cynoglossus), and northern shrimp (Pandalus borealis).
A preliminary analysis of water temperature data collected in 2022 shows that conditions have warmed at depths greater than 150 m, establishing new records since 1915 at 150 m, 200 m and 300 m. The August cold intermediate layer minimum temperature was only slightly cooler in 2022 than in 2021 when it attained the highest recorded values observed in contemporary CTD era. Surface water temperatures were above normal in July-August.
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