Biodiversity of the whelk (Buccinum) dredge survey in the St. Lawrence Estuary

A research survey on the common whelk (Buccinum undatum) has been conducted biennially in three sectors of the St. Lawrence Estuary since 2005 to assess the abundance of whelk and benthic species associated with whelk habitat. Only data for benthic species associated with whelk habitat are presented in this dataset. The survey was initiated in 2005 following the intensive fishery of the early 2000s in the Upper North Shore region. The three sectors covered by the survey were based on the distribution of commercial fishing effort from 2001 to 2004.

Surveys were conducted between mid-July and early August from 2005 to 2019 on the North Shore of the St. Lawrence Estuary between Portneuf-sur-Mer and Baie-Comeau according to a fixed station sampling design. Three sectors were surveyed at each survey: Forestville (69°03'11"W-48°39'24"N and 68°56'02"W-48°46'16"N), Pointe-aux-Outardes (68°35'53"W-48°59'32"N and 68°25'30"W-49°01'06"N) and Baie-Comeau (68°06'04"W-49°08'40"N and 68°05'10"W-49°12'26"N). Since 2007, the sampling plan consists of 55 stations in Forestville, 26 stations in Pointe-aux-Outardes and 11 stations in Baie-Comeau. The targeted depth interval at the three sectors was approximately 5 to 40 m. Specimens were collected using a Digby-type scallop dredge with a total width of 3.04 m consisting of four 19 mm mesh Vexar™ lined baskets to harvest small individuals. Start and end positions were recorded to calculate the distance traveled at each tow using the geosphere library in R. Since 2011, the average tow distance was approximately 300 m. The area covered at each tow was the product of the dredge width and distance.

The three files provided (DarwinCore format) are complementary and are linked by the "eventID" key. The "event_information" file includes generic event information, including date and location. The "additional_information_event_and_occurrence" file includes sample size, sampling protocol and sampling effort, among others. The "taxon_occurrence" file includes the taxonomy of the species observed, identified to the species or lowest possible taxonomic level. For abundance and biomass estimates, contact Virginie Roy (virginie.roy@dfo-mpo.gc.ca).

For quality controls, all taxonomic names were checked against the World Register of Marine Species (WoRMS) to match recognized standards. The WoRMS match was placed in the "scientificNameID" field of the occurrence file. Special cases were noted in "identificationRemarks" and selected specimens were confirmed using field photos. Data quality checks were performed using the R obistools and worrms libraries. All sampling locations were spatially validated.