|Bay mussel on the beach of the Baltic Sea, Germany|
Mytilus trossulus is one of the three principal, closely related taxa in the Mytilus edulis complex of blue mussels, which collectively are widely distributed on the temperate to subarctic coasts the Northern Hemisphere, and often are dominant inhabitants on hard substrates of the intertidal and nearshore habitats.
Mytilus trossulus is the main native intertidal mussel in the Northern Pacific. In North America it is found from California to Alaska, and in Asia from Hokkaido northwards. At its southern limits, it hybridizes with Mytilus galloprovincialis (the Mediterranean mussel), which has been introduced to the Pacific by human activity.
In the North Atlantic, M. trossulus is found on the U.S. coast of Maine and northwards to Canada, as well as in scattered localities on North European coasts. In these regions it often coexists and hybridizes with Mytilus edulis. The entire Baltic Sea is inhabited by a peculiar population of Mytilus trossulus, which shows some genetic introgression from M. edulis and whose mitochondrial DNA has been replaced by M. edulis mtDNA.
In the Arctic, Mytilus trossulus is found in northwest Greenland where they are found scattered in the intertidal zone from 71°N to 77°N 
The species is the subject of long-term environmental monitoring in Prince William Sound, Alaska, to examine hydrocarbon signatures in order to develop a better understanding of the ecosystem's ongoing recovery from the Exxon Valdez oil spill which occurred there.
- McDonald JH, Seed R, Koehn RK (1991) Allozyme and morphometric characters of three species of Mytilus in the northern and southern hemispheres. Marine Biology 111:323–335.
- Vainola R, Strelkov P (2011) Mytilus trossulus in Northern Europe Marine Biology 158: 817-833.
- Mathiesen, Sofie Smedegaard; Thyrring, Jakob; Hemmer-Hansen, Jakob; Berge, Jørgen; Sukhotin, Alexey; Leopold, Peter; Bekaert, Michaël; Sejr, Mikael Kristian; Nielsen, Einar Eg (August 2016). "Genetic diversity and connectivity within spp. in the subarctic and Arctic". Evolutionary Applications. doi:10.1111/eva.12415.
- Payne, J.; Driskell, W.; Short, J.; Larsen, M. (2008). "Long term monitoring for oil in the Exxon Valdez spill region". Marine pollution bulletin. 56 (12): 2067–2081. doi:10.1016/j.marpolbul.2008.07.014. PMID 18835610.