The standardized NEFSC Winter Bottom Trawl Survey was initiated in 1992 and covered offshore areas from the Mid-Atlantic to Georges Bank. Inshore strata were covered from 1992-2007 but were later dropped, as few flatfish of interest were captured. Deep strata (183-366 m) were not covered consistently until 1998.

The deep water biodiversity surveys explore and describe the biodiversity of the bathy- and bentho-pelagic nekton using Midwater and bottom trawls. The covered area includes the western North Atlantic between the vicinity of Bear Seamount and Physalia Seamount, and areas surrounding the northern Mid-Atlantic Ridge (MAR-ECO), focusing on the Charlie Gibbs Fracture Zone.

Fisheries and Oceans Canada (DFO) conducts an annual multidisciplinary scientific survey with a bottom trawl in the Estuary and the northern Gulf of St. Lawrence since 1978. Over the years this survey has been conducted on cinq vessels: the MV Gadus Atlantica (1978-1994), the MV Lady Hammond (1984-1990), the CCGS Alfred Needler (1990-2005), the CCGS Teleost (2004-2022) and the CCGS Cabot (2022-present). It is important to note that the objectives, the methods used and the identification of the species during these surveys have improved over time in response to DFO requests and mandates. The data are therefore not directly comparable between these surveys. The specificities of the missions onboard the CCGS Teleost are described below. Objectives: 1. Assess groundfish and northern shrimp population abundance and condition 2. Assess environmental conditions 3. Inventory species biodiversity 4. Assess phytoplankton and mesozooplankton abundance 5. Monitor the pelagic ecosystem 6. Inventory marine mammals populations 7. Inventory seabirds populations 8. Collect samples for various research projects Survey description The survey covers the Estuary and the northern Gulf of St. Lawrence, that is the divisions 4R, 4S and the northern part of division 4T of the Northwest Atlantic Fisheries Organization (NAFO). Since 2008, coverage of division 4T has been increased in the upstream part of the Lower Estuary in order to sample the depths between 37 and 183 m. A stratified random sampling strategy is used for this survey and the area of the study area is 118,587 km². The fishing gear used on the CCGS Teleost is a four-sided Campelen 1800 shrimp trawl equipped with a Rockhopper footgear (“bicycle”). The trawl lengthening and codend are equipped with a 12.7-mm knotless nylon lining. Standard trawling tows last 15 minutes, starting from the time the trawl touches the sea floor. The aimed towing speed is 3 knots. Data For each fishing tow, the catch is sorted and weighed by taxa; individual are then count and biological data are then collected on a subsample. For fish, crab and squid, size and weight are gathered by individual and, for some species, sex, gonad maturity, and the weight of certain organs (stomach, liver, gonads) are also evaluated. The soft rays of the anal fin are counted for redfish, and the otoliths are sampled for several species such as Atlantic cod, Atlantic halibut, and witch flounder. A roughly 2-kg shrimp sample is sorted and weighed by species (and by stage of maturity for northern shrimp). The shrimps are measured individually. The other invertebrates are counted (no individual measurements) and photographed. The catches per tow for fish taxa are available below. This data is also available via the 'Biodiversity' application on the St. Lawrence Global Observatory (SLGO). For more information please contact the data management team (gddaiss-dmsaisb@dfo-mpo.gc.ca).