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Research Document 2021/054

Preliminary results from the ecosystemic survey in August 2020 in the Estuary and northern Gulf of St. Lawrence

By Bourdages, H., Brassard, C., Desgagnés, M., Galbraith, P., Gauthier, J., Isabel, L. et Senay, C.


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 2020, the survey was conducted between August 12 and September 5 on board the CCGS Teleost. Due to the context of the Covid-19 pandemic, the number of days at sea and the number of scientists on board the ship had to be reduced. The survey successfully carried out 147 trawl tows as well as 66 CTD water column casts, and 34 zooplankton samples.

This report presents the results of the 147 tows. In total, 78 fish taxa and 206 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 2020 shows that conditions have warmed at 150 m and deeper, reaching new records since 1915 at 200 and 300 m. The cold intermediate layer was warmer in 2020 than in 2019 except in the Estuary where it remained stable. Surface waters were also warmer than normal, by 1.5°C, in July-August.

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