Canadian Farmed Clams
The Manila clam (Ruditapes phillippinarum) is the primary clam species farmed in Canada. Other clam species farmed include: Softshell clams (Mya arenaria), hard clams or quahaugs (Mercenaria mercenaria), Savory or Varnish clams (Nuttallia obscurata) and Geoducks (Panope abrupta).
Where they’re farmed
British Columbia is Canada’s major clam producing province. Softshell clams are farmed in Nova Scotia and Quebec, and quahaugs in Nova Scotia.
How they’re farmed…
The production cycle on a Canadian clam farm begins with the collection/production of clam larvae and juveniles. All clam larvae are produced in a hatchery from spawning adult broodstock. The larvae are kept in hatchery tanks where they transform into tiny juvenile clams (seed) within a few weeks. The seed is essentially a very small version of the adult clam. On the east coast, juvenile clams are collected in natural nursery areas using various collector substrates.
After leaving the hatchery, the young clams are transferred to nursery facilities to allow them to reach a larger size. One type of nursery system that is commonly used in British Columbia is a ‘floating upwelling system’ (referred to as a ‘flupsy’) that is housed on a raft on the ocean. The seed are kept in compartments on the flupsy where nutrient rich ocean water is circulated – thereby allowing them to reach a larger size before the final grow-out phase.
Once the nursery phase is completed, the juvenile clams are carefully spread on subtidal regions of an ocean beach where they then burrow into the substrate. Clams remain on the beach for 2 to 4 years – until they reach marketable size. Clams are usually harvested by hand using a long tined rake. Yields of clams on well-managed farm plots can reach to over 2kg per square meter each year.
What they eat…
Clams are both filter feeders and deposit feeders: they obtain all their required nutrients by drawing sea water through their gills and filtering out naturally occurring tiny plants and animals called plankton, as well as organic material on the seabed. Clam farmers therefore do not need to feed their stock, and rely solely on natural food supplies for production.
Why they’re environmentally sustainable…
Clam farming is, by definition, green and sustainable. Clams cannot tolerate the discharge of sewage or other toxins; the presence of clam farming, therefore, often results in increased awareness and monitoring of coastal waters for pollution control.
In addition to being important modulators of nutrient cycles in ecological systems, farmed clams help to reduce greenhouse gases by removing carbon dioxide from the ocean for shell formation.
Clam farming is endorsed by environmental groups such as the Audubon Society, Monterey Bay Aquarium’s Seafood Watch and Eco-Fish.
Did you know…
Aside from their food value, clams are efficient accumulators of environmental contaminants such as heavy metals and have been used in some areas for habitat remediation from industrial pollution.
Clams are excellent sources of protein and calcium, are rich in minerals such as iron and zinc, and contain good levels of vitamin B. They also contain high levels of natural DHA omega-3 fatty acids that are essential for human functions and important in reducing the risk of heart disease and other human diseases.