Scallops: Sea

Giant scallop

Sea scallop is an economically-important species in the Atlantic Ocean, with active fisheries in both the United States and Canada. Sea scallops occur from Cape Hatteras, North Carolina in the US to the north shores of the Gulf of St. Lawrence and Newfoundland, Canada. They typically occur in waters 20-110 metres depth. Scallops become increasingly restricted to deeper waters in the southern portion of their range due to their sensitivity to high water temperatures.

Sea scallops (Placopecten magellanicus) exhibit a high intrinsic population growth rate, high individual growth rate, low age at first maturity, and high egg production. Scallops reach harvestable size between the ages 4-7 (based on shell size) and live as long as 29 years.

Despite a long fishing record, offshore sea scallops stocks in Canada seem currently healthy. The stocks tend to go in cycles, with periodic strong year classes resulting in high catches. The targeted biomass of scallops (> 100 mm shell height) has decreased since 2002, but ranges above the long-term average of 1981-2005. Stock status is more variable in inshore waters, where the inshore fleet has recently moved to new areas because of low abundance in historically fished areas. Knowledge of the overall population abundances of Canadian wild scallop stocks remains fragmentary as Canadian stock assessments cover one region at a time, and stocks and data are not always reported in the same fashion, increasing the difficulty of comparison between fishing areas and between inshore and offshore scallop fisheries.

Quantitative bycatch data from observers or scientific surveys is difficult to obtain and is not recorded in most cases. Bycatch reports exist for commercially targeted species. All groundfish species, except monkfish, must be returned to the water. Monkfish have accounted for approximately 85% of the groundfish bycatch landed by offshore scallop vessels. Lobster bycatch is considered minimal, however recent exploitation of new grounds that are primarily fished for lobster, has resulted in catch of soft shelled adults. Over 100 other species have been recorded as bycatch in the inshore scallop fishery and impacts on these species has not been researched further. Canada has no reported bycatch of endangered sea turtles or barndoor skates. A complete picture of the bycatch problem is lacking. Some management measures are in place to address yellowtail flounder bycatch. Impacts of dumping of scallop shells has also not been investigated.

Scallop dredging has severe impacts on benthic populations, communities, and habitats. Some fishing areas, such as Georges Bank may recover from short-term impacts of scallop dredging. The long-term impacts from scallop fishing gear must be considered a serious conservation concern, due to potential effects on the seafloor including reduction of species densities, shifts in spatial distributions, removal of epifauna, reduction of habitat complexity, shift in seafloor community structure, redistribution of grain sizes in sediments and increases in water column silt load. The offshore scallop fishery industry conducts sea-bed mappings, which has allowed fishers and scientists to determine the exact location of scallops, enabling the industry to fish more efficiently and decrease disturbance to the ocean floor. Conversely, this has also allowed the exploitation of brood stocks and dredging of areas previously protected because of rough ground.

Canadian management has been faulted for ignoring scientific advice on managing the Bay of Fundy scallop fishery, but, overall, has implemented strong management practices such as limited entry, gear restrictions, the establishment of fishing areas and seasons, and meat counts. Catches are monitored through an industry-funded dockside monitoring program, and vessels are required to carry “black boxes”, or vessel monitoring systems. The industry also participates in and funds the research vessel surveys, collects data through a port sampling program and conducts sea-bed mapping to determine the exact locations of scallops, thus decreasing overall disturbance to the ocean floor by focusing catch effort on areas with high biomass. Management has not comprehensively addressed or monitored bycatch or impacts of dredging on the seafloor.

How and where are these scallop caught?

Contaminant levels do not warrant a consumption advisory.