Summary The Quebec region of the Department of Fisheries and Oceans (DFO) is responsible for the assessment of several fish and invertebrate stocks exploited in the Estuary and the northern Gulf of St. Lawrence. The commercial catches sampling program is one of the sources of information used to complete these assessments. The data collected by this program, at wharf or at sea, offers among other things the advantage of a relatively large spatio-temporal coverage and provides some of the necessary knowledge to assess the demography and the structure of the exploited populations. This program is implemented by specialized DFO staff whose main mandate is to collect biological data on groundfish, pelagic fish and marine invertebrate species that are commercially exploited in the various marine communities. Data This dataset on the redfish (Sebastes sp.) includes the metadata, sample weight, fish length, the sex and the number of specimens measured. This dataset covers the periods of 1980-1996, 1999-2013, 2015-2016 and 2019. In order to protect the confidentiality of the sources, some informations (such as those concerning the vessel) have been excluded and others (such as the date of capture) have been simplified. Entries where there was only one vessel in a fishing area for a given year were also excluded. Further information including the fishing areas coordinates can be found by clicking on the «Atlantic and Arctic commercial fisheries» and «Fishing areas» links below.

This data is from the Newfoundland and Labrador Region Multispecies Trawl survey, specific to Snow Crab from 2018-25, with only successful tows included in the database. Details of annual survey coverage and an overview of the survey program can be found in Rideout et al. (2025) and references therein. This trawl survey follows a depth-stratified random design, designated by type = 1 (Survey). From 2021-23, a comparative fishing program (i.e., direct side-by-side paired comparison between old and new vessels) was undertaken to determine differences in catchability due to vessel changes and associated modifications to the trawl gear with the retirement of the CCGS Alfred Needler and CCGS Teleost (called ‘old vessels’) and the introduction of the CCGS Capt. Jacques Cartier and CCGS John Cabot (called ‘new vessels’). During this period other set types are in the dataset (6 and 7) from paired tows and all station allocation may not have been stratified random. The DFO NL Region comparative fishing success varied by year, NAFO division, and vessel combinations and resulted in conversion factors to adjust the catches of Snow Crab in the old vessels time series into the same units as the new vessels. Methodologies and conversion factors are described in Wheeland et al. (2024), Trueman et al. (2025), Trueman et al. (2026), and Pantin et al. (in prep). Conversion factors have been applied to the numbers of Snow Crab caught, where conversion factors exist, and are in the converted_number column. An NA in the converted_number column indicates that conversion factors do not exist for this vessel/area combination and therefore direct comparisons cannot be made between old vessels and new vessels. Weights are those recorded at sea and do not have conversion factors applied. Analyses by the DFO NL Snow Crab group apply a length-weight relationship to the converted numbers to determine converted weights, which is not in this dataset. All reasonable attempts are made to standardize fishing time during trawl surveys, however there is always some variation in the actual time on bottom. The species weights and numbers in this dataset are not standardized for tow distance/duration. Spatial coverage of this survey has varied over time, therefore, not all divisions, or depths within divisions, are sampled every year or season. Biological measurements are described in Pantin et al. (2025). Tows that caught zero Snow Crab are denoted in the dataset by a ‘number’ of 0. References: McCallum, B. R., and S. J. Walsh. 1996. Groundfish survey trawls used at the Northwest Atlantic Fisheries Centre, 1971-present. NAFO Sci. Coun. Studies, 29: 93-104. Pantin, J., D. Mullowney, K. Baker, K. Lefort, W. Coffey, F. Cyr, H. Munro, and Koen-Alonso, M. 2025. An Assessment of Newfoundland and Labrador Snow Crab (Chionoecetes opilio) in 2023. DFO. Can. Sci. Advis. Sec. Res. Doc. 2025/080. iv + 152 p. Pantin, J., Charmley, K., Mullowney, D., Baker, K., Lefort, K., Coyne, J., Munro, H., and Koen-Alonso, M. In prep. An Assessment of Newfoundland and Labrador Snow Crab (Chionoecetes opilio) in 2024. DFO Can. Sci. Advis. Sec. Res. Doc. year/nnn. Rideout, R.M., Wheeland, L., Perreault, A., Regular, P., Skanes, K., Simms, L., and Makrides, J. 2025. Canadian (Newfoundland and Labrador Region) Multi-Species Research vessel Bottom Trawl Survey Report for Surveys Conducted in 2024. NAFO SCR Doc. 25/028: 1-68. Trueman, S., Wheeland, L., Benoît, H., Munro, H., Nguyen, T., Novaczek, E., Skanes, K., and Yin, Y. 2025. Results of Comparative Fishing Between the CCGS Teleost and CCGS Alfred Needler with the CCGS John Cabot and CCGS Capt. Jacques Cartier in the Newfoundland and Labrador Region in 2021 and 2022. DFO Can. Sci. Advis. Sec. Res. Doc. 2025/021. v + 237 p. Trueman, S., Wheeland, L., Pantin, J., Baker, K., and Mullowney, D. 2026. On the relative catchability of Snow Crab in the Newfoundland and Labrador Multispecies trawl surveys. DFO Can. Sci. Advis. Sec. Res. Doc. 2026/008. iv + 41 p. Wheeland, L., Skanes, K. and Trueman, S. 2024. Summary of Comparative Fishing Data Collected in Newfoundland & Labrador from 2021-2022. Can. Tech. Rep. Fish. Aquat. Sci. 3579: iv + 132 p.

To better understand patterns of temporal and spatial variation of fish assemblages in offshore waters of Lake Winnipeg (Manitoba, Canada), pelagic trawl tows were conducted at lakewide monitoring stations since 2002. Trawl samples collected during spring, summer, and fall from the south basin, channel, and north basin were used to study effects of season and geographic region within the lake on species biomass estimates.

PURPOSE: To record hourly water temperatures throughout the Margaree watershed. DESCRIPTION: The Department of Fisheries and Oceans (DFO) has been deploying water temperature monitoring equipment since spring 1993 in the Margaree River watershed. Coverage has changed throughout the time series and there is little documentation regarding equipment used. In recent years data have been collected using VEMCOs. USE LIMITATION: To ensure scientific integrity and appropriate use of the data, we would encourage you to contact the data custodian.

This record contains data on bowhead whale locations reported in Harwood, L.A. and P. Norton. 1996. Aerial survey data from the southeast Beaufort Sea, Mackenzie River estuary and west. Amundsen Gulf, July 1992. Canadian Data Report of Fisheries and Aquatic Sciences No. 964

The study involved sampling during a winter subsistence fishery at Brock Lake in November 2003, and a physical, chemical and biological assessment of the lake in July 2004 and July 2005. Data including physical, chemical and biological variables were published as Roux, M.-J., Harwood, L. A., Illasiak, J., Babaluk, J.A., and de Graff, N. 2011. Fishery resources and habitats in a headwater lake of the Brock River, NT, 2003-2005. Can. Manuscr. Rep. Fish. Aquat. Sci. 2932: viii + 61 p.

Fisheries and Oceans Canada (DFO) has conducted an annual multidisciplinary scientific survey using a bottom trawl in the Estuary and the northern Gulf of St. Lawrence during the summer since 1984. Over the years this survey has been conducted aboard four vessels: the MV Lady Hammond (1984-1990), the CCGS Alfred Needler (1990-2005), the CCGS Teleost (2004-2022) and the CCGS Cabot (2022-current). 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. However, comparative analyses have been carried out between vessels, and conversion factors are available upon request for a number of species. The specificities of the missions onboard the CCGS Cabot are described below. Objectives: 1. Assess groundfish and northern shrimp population abundance and condition 2. Assess environmental conditions 3. Conduct a biodiversity inventory of benthic and demersal megafauna 4. Assess phytoplankton and mesozooplankton abundance 5. Monitor the pelagic ecosystem 6. 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. Each year, approximately 200 sampling stations are randomly selected within depth-based strata, ranging from around 40 m near the shores to close to 500 m in the deep channels. The fishing gear used on the CCGS Cabot is a four-sided modified 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 targeted towing speed is 3 knots. Data For each fishing tow, the catch is sorted and weighed by taxa; individuals are then counted, and biological data are collected from a subsample. For fish and certain invertebrate species, size and weight are measured 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, Greenland 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 biological data are divided into 3 files: a “Stations” file containing set information, a “Catches” file containing catches per set for all species caught and a “Carbio” file containing biological and morphometric measurements per individual all species measured except shrimps. The columns source_info, no_survey, nbpc and station_number serve as a common key linking the three datasets. To further link the “Captures” and the “Carbio” files to the species level (for fish and certain invertebrate species), use the columns source_info, no_survey, nbpc, station_number, strap_code, and category. Further shrimp biological and morphometric data are available but are not presented here in order to simplify data presentation. For access to the complete information, please contact the data management team (gddaiss-dmsaisb@dfo-mpo.gc.ca). The latest published data is preliminary and will be updated at the end of January of the following year. It is important to note that this is raw data. Only sets considered successful are retained. In each set, all species are kept, with a few exceptions. For more information please contact the data management team (gddaiss-dmsaisb@dfo-mpo.gc.ca).

The objective of this project was to gather data to develop a model of the food web of the lower trophic levels of the nearshore area of the Beaufort Sea. Sampling took place from 2005 to 2008 using the CCGS Nahidik. The multidisciplinary character of the Nahidik program produced measurements of biology/ecology (primary production, phytoplankton, zooplankton, benthos, fish), chemical and physical oceanography, contaminants, geology and hydro acoustics. The data were collected in July and August of each year. The Nahidik program provided data to provide a baseline for future studies as well as an information source for environmental assessment. This record contains the geographic coordinates and station names from 2005 to 2008.

The data were collected during two research projects: Development of community-based monitoring for aquatic invasive species in the Canadian Arctic - preparing for increased shipping related to resource development and climate change; Diversity of pelagic primary producers in coastal habitats and the potential for harmful blooms in Eastern Canadian Arctic, with a focus near Iqaluit, Nunavut. Funding was provided by Polar Knowledge Canada, Fisheries and Oceans Canada (Strategic Program for Ecosystem-based Research and Advice, Aquatic Invasive Species Program and Oceans Ocean Protection Plan) and the Nunavik Marine Region Wildlife Board. These data are the abundance, richness and diversity of dinoflagellate communities in Canadian Arctic seaports to provide baseline data and to verify the presence of potential non-indigenous species and harmful taxa. These data can be used as a reference source for monitoring the introduction of potentially non-native species introduced into Arctic ports where shipping activities are high. SAMPLING Dinoflagellate samples were collected using a 20 μm (30 cm diameter) Nitex® plankton net during August in Churchill (MB) (2007 and 2015), in Deception Bay (QC ) (2016), in Iqaluit (NU) (2015 and 2019) and in Milne Inlet (2017). Samples were collected from 1 m of the surface to 1 m above the bottom. PREPARATION : Samples were stored in 4% formaldehyde. Sample preparation and counting were performed using the Utermöhl method. OBSERVATION : Samples were observed using an inverted microscope (NIKON Eclipse TE-2000-U) under a magnification of 200x. ABUNDANCE : The calculation of the abundance of dinoflagellates (cell / liter) was carried out as follows: Number of cells X Volume of the bottle / Volume of the Utermöhl chamber / (pi X Radius^2 X Depth) X 1000 ENVIRONMENTAL VARIABLES Environmental data were measured using a CTD and a Secchi disk. The time between sea ice melt and sampling was calculated by subtracting the sampling day from the breakup dates (ice concentration <1/10) which were extracted from the Canadian Ice Service records. For further information, please consult the following paper: Dhifallah F, Rochon A, Simard N, McKindsey CW, Gosselin M, Howland KL. 2022. Dinoflagellate communities in high-risk Canadian Arctic ports. Estuarine, Coastal and Shelf Science 266:107731

The Aquatic Invasive Species Surveillance Database is a compilation of fish community and habitat data from DFO’s Aquatic Invasive Species and Invasive Carp Program early detection surveillance efforts in Canadian waters of the Great Lakes basin. Data includes: sampling site location, date, fish species and counts, and associated habitat information. Annual project-specific details including purpose/objectives and study methodology are often reported in the DFO Canadian manuscript report of fisheries and aquatic sciences series.