Biodiversity of the Magdalen Islands Sea Scallop survey

A research survey of scallops (mainly sea scallop Placopecten magellanicus, but also Icelandic Scallop Chlamys islandica) using a dredge was carried out by DFO (Fisheries and Oceans Canada) every 1 or 2 years since 1992 in the Magdalen Islands (fishing area 20). The main objective of this research survey was to assess Sea Scallop stocks. Another objective was to document taxa associated with scallop habitat according to a fixed random sampling plan. Occurrences for the year 2021 and 2022 are presented by species (or taxon) by station. Starting in 2021, catches were weighed, and specimens photographed, with information available upon request. The taxonomic and geographical validity of the data was checked and the World Register of Marine Species served as the taxonomic authority for naming all taxa recorded during the survey. Epibenthic invertebrates (mainly molluscs, echinoderms and crustaceans) as well as demersal fish were identified from the dredge catches. The historical dataset is available at the following link : https://open.canada.ca/data/en/dataset/71732ad5-5c70-4dbf-916d-a94e1380c53b

The study area is located south of the Magdalen Islands and the sampling of scallop beds is carried out at depths of generally around 25 to 35 m. A random selection of sampling stations is carried out from a fixed station grid. Sampling is done along transects at these randomly drawn stations in the study area. Sampling is done with a lined Digby scallop dredge (20 mm mesh) over approximately 500 m along the seabed. The four baskets of the dredge are examined for all scallops, and starting in 2022, also for all fishes. One basket (first on the starboard side) is sorted and examined for associated species. Most specimens are counted by taxa. Those that are too small and numerous, or colonial, are noted for presence or relative abundance. Special cases are occasionally conserved for taxonomic analysis, for example, ascidians (to monitor for invasive species) and sponges (to document new species). The availability of photos and some conserved specimens enables future review. Changes are anticipated in the identifications, notably for Bryozoan, Hydrozoa, and Porifera, that are currently the focus of research efforts.