Mussels
Mussels are a bivalve mollusk related to clams and oysters. Various species of mussels are found around the world, but they are most abundant in cold temperate waters. They’re native to the Pacific Northwest and common along the coast, where they form large colonies in intertidal zones.
Four species of mussels are found in the Pacific Northwest. Of these, two are native species: the surf mussel (Mytilus californianus) and the Pacific blue mussel (Mytilus trossolus).
The two non-native species, the blue mussel (Mytilus edulis) and the Mediterranean blue mussel (Mytilus galloprovincialis), were introduced for cultivation purposes. They’re closely related to the Pacific blue mussel.
Together, these three species are part of the Mytilus edulis species complex, which includes several different species of mussels that are closely related, to the point that they are difficult to distinguish from each other and they will often hybridize if found in the same waters. Collectively, these species are known as blue mussels.
Freshwater mussels
There are several species of freshwater mussels that inhabit the rivers of the Pacific Northwest. Although edible and once fished by indigenous people, they’re illegal to harvest in Washington and Oregon. Freshwater mussels are threatened species and highly sensitive to pollution so they should not be harvested in the Pacific Northwest for environmental reasons.
Species
Mussels
Surf mussel (Mytilus californianus)
Blue mussels
Pacific blue mussel (Mytilus trossulus)
European blue mussel (Mytilus edulis)
Mediterranean blue mussel (Mytilus galloprovincialis)
Surf mussels
The surf mussel (Mytilus californianus), also known as the California mussel, is native from Alaska to northern Mexico.
Surf mussels are distinct from the M. edulis species. They grow to about 7 inches long and have brown or black shells. They’re abundant in exposed rocky areas along the Pacific Northwest coastline. They aren’t farmed currently, but research has indicated that they would be successful in aquaculture systems, so there’s a possibility they might be one day.
Blue mussels
Blue mussels grow to about three inches in length and have blue and black shells. In the wild, they’re mainly found in bays and other sheltered areas protected from stronger waves.
Blue mussels are the species farmed in aquaculture systems. In the Pacific Northwest, Puget Sound is an important center for mussel cultivation. Mussel farming, however, is a more recent development in our region. The oldest commercial mussel farm in North America, Penn Cove Shellfish, has only been in operation since 1975.
In the Pacific Northwest, the Mytilus edulis species complex is represented by the native Pacific blue mussel (Mytilus trossulus), also known as the bay mussel. Its habitat ranges from Alaska down to California. It’s more abundant in northern California than southern California, where it is competing with the non-native Mediterranean blue mussel.
The namesake of the species complex, Mytilus edulis was introduced to our region via aquaculture throughout the 20th century. Atlantic blue mussels don’t appear to found in the wild in significant numbers on the Pacific coast, but have hybridized to some extent in native populations of Mytilus trossulus.
The Mediterranean blue mussel (Mytilus galloprovincialis), which has a higher tolerance to warm ocean temperatures, was introduced to the Pacific coast in the early 1900s. They have since naturalized in central and southern California, where they hybridize with the native blue mussel, Mytilus trossulus. Mediterranean blue mussels are also raised commercially in the Salish Sea region.
Cooking with mussels
As is the case with most shellfish, mussels are best harvested and eaten in cold months. Meat yields from the mussels are higher in winter and there’s a lower risk of shellfish poisoning.
Unlike oysters, mussels are not often eaten raw. They can be cooked like clams and are often steamed, simmered, or smoked. They should always be live when they are cooked. To check, press on any open shells. If they’re alive, the shell will close. Mussels also require debearding before cooking, which means removing the byssal threads that mussels use to attach themselves to rocks. Mussel shells, especially wild ones, often have barnacles growing on them.
