DFO Quebec Region Multispecies bottom trawl surveys (OBIS Canada)

Data collection containing the principle biological characteristics of fishes and invertebrates caught in trawl tows during stratified random sampling surveys carried out in the northern Gulf of St. Lawrence, NAFO Areas 4RST. The data provide a source of information used in preparing scientific advice on the stock status of demersal fishes and invertebrates in these areas.

The annual survey is carried out by Fisheries and Oceans Canada scientists on large trawlers and provides important information on the status of marine resources exploited in the estuary and northern Gulf of St. Lawrence. The main objective of the survey is to estimate the abundance and biomass of five important commercial species: Atlantic cod (Gadus morhua), Greenland halibut (Reinhardtius hippoglossoides), two redfishes (Sebastes fasciatus and Sebastes mentella), and northern shrimp (Pandalus borealis). During the past few years, the biologists have aimed at combining stock status and ecosystem information, demanding a greater effort in describing the catches of the other species of fish and invertebrates. The protocol of observation and sampling that was long time in place has gradually evolved into a greatly more detailed and complex protocol. Certain difficulties, however, have arisen during the application of this protocol in the correct identification of the dozen or so species caught at each sampling station.

Trawling gear: a four-sided shrimp trawl, the Campelen 1800, equipped with a Rockhopper footgear; the extension and codend were fit with a 12.7 mm knotless nylon lining; standard tows lasted 15 minutes on the bottom.

The OBIS view of this dataset includes only presence information for the various species at the survey station locations.