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 Atlantic surfclam (Spisula solidissima) includes the metadata, sample weight and the shell width of the specimens measured. This dataset covers the period of 2003 to present. 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.

The dataset represents known concentration areas of harvested or unharvested Atlantic surfclam (Spisula solidissima) in the Gulf of St. Lawrence, around the Magdalen Islands. The dataset was created for the National environmental emergencies center (NEEC) for preparation and response in case of an oil spill. Concentration areas were delineated using Fisheries and Oceans Canada (DFO) inventories conducted between 2000 and 2020, commercial fisheries data (logbooks and purchase receipts from 2002 to 2020 and observations at sea from 2005 to 2017), data from exploratory fisheries as well as interviews. This layer is dependent on the inventories carried out and thus only represents the known areas of the Atlantic surfclam. This dataset does not represent the general distribution of the species nor the extent to which fishing is allowed. Most of the information comes from inventories that did not necessarily target this species, therefore its distribution is undoubtedly wider than what is recorded in this layer. In addition, the extent of shellfish beds can change over time in response to, among others, harvesting and recruitment rates. Some concentration areas were delimited based on interviews with people who locally know the resource but their delimitation remains approximate. The polygons delimited based on sampling data are more precise but might underestimate the concentration areas because sampling was made where the target resource was known to be more abundant without necessarily sampling the entire bed. Nonetheless, the precision is sufficient for resource protection and management needs in case of an environmental incident. Data sources and references: Bio-Conseil. 1986. Pêche exploratoire à la palourde (Spisula solidissima) aux Îles-de-la-Madeleine, automne 1985. Rapport final, Bio-Conseil, Pêches et Océans Canada. 24 p. Bernier, L. and L. Poirier. 1979. Evaluation sommaire du stock de mactres de l'Atlantique, Spisula solidissima Dillwyn, des Îles-de-la-Madeleine (golfe du St-Laurent). Cahier d'information, ministère de l'Industrie et du Commerce. 42 p. Bourget, E. and D. Messier. 1983. Macrobenthic density, biomass, and fauna of intertidal and subtidal sand in a Magdalen Islands lagoon, Gulf of St. Lawrence. Can. J. Zool. 61(11):2509-2518. Brulotte, S. 2013. Évaluation des stocks de la mactre de l’Atlantique, Spisula solidissima, des eaux côtières des Îles-de-la-Madeleine – méthodologies et résultats. Secr. can. de consult. sci. du MPO. Doc. de rech. 2013/082: x + 58 p . Brulotte, S. 2016. Évaluation des stocks de mactre de l’Atlantique, Spisula solidissima, des Îles-de-la-Madeleine, Québec en 2015 – méthodologie et résultats. Secr. can. de consult. sci. du MPO. Doc. de rech. 2016/074. x + 51 p. DFO. 2016. Stock Assessment of Atlantic Surfclam of the Îles-de-la-Madeleine in 2015. DFO Can. Sci. Advis. Sec. Sci. Advis. Rep. 2016/022. DFO. 2019. Assessment of the Îles-de-la-Madeleine Atlantic Surfclam stock in 2018. DFO Can. Sci. Advis. Sec. Sci. Advis. Rep. 2019/031. Fréchette, M. and M. Giguère. 1984. Rapport sur une pêche exploratoire à la palourde aux Îles-de-la-Madeleine en 1984. Pêches et Océans Canada. 17 p. Hurlbut, T and D. Clay. 1990. Protocols for research vessel cruises within the Gulf region (demersal fish) (1970-1987). Can. Manuscr. Rep. Fish. Aquat. Sci. 2082:143p. Hurtubise, S. (Fisheries Data [ZIFF] and At-Sea Observers Manager). Unpublished data. Fisheries and Oceans Canada.