Mytilus trossulus (blue mussel)

Found in area labeled mussel beds and from areas 6 to 7 to 8.

The blue mussel is a species found world-wide, but interestingly enough even though the blue mussels look alike, there are different species. Prior to 1980 there were thought to be 3 blue mussels: Mytilus edulis (Linnaeus, 1758), Mytilus galloprovincialis (Lamarck, 1819), and Mytilus californianus (Conrad, 1937). Mytilus edulis was thought to occur worldwide. You can still find un-updataed references to it on sites on the internet. In the 1980s, a genetic study was done comparing blue mussels from New York to blue mussels from Oregon. The New York blue mussel (found in Europe, Iceland, the east coasts of the US, and in parts of eastern Canada) was a different species from the Oregon blue mussel (found in Oregon, Washington, Alaska, eastern Canada, and the Baltic Sea). That they are separate species was confirmed by the fact that the co-located colonies in eastern Canada have remained distinct species. It should be noted that Mytilus galloprovincialis has been introduced to the eastern Pacific. It lives in areas warmer than Mytilus trossulus.

You cannot just name a species. You have to research to find if anyone has ever named that species and, if so, that older name is chosen. After searching there was a reference to a blue mussel in Killimook, Oregon, named Mytilus trossulus by Gould in 1850. Actually “Killimook” is Tillamook, Oregon. That scientific name had not come into use and Pacific northwestern blue mussels were called Mytilus edulis until the 1980’s. An article entitled “The mussels Mytilus galloprovincialis and M. trossulus on the Pacific coast of North America” by J.H. McDonald and R. K. Koehn appeared in Marine Biology 99: 111-118, in 1988. That is the first effective use of the term Mytilus trossulus in classification of Pacific northwest blue mussels since Gould identified it and wrote about it in 1850.

Blue mussels anchor themselves to rocks with a thread-like structure called a byssus.