Invasion
Invasion Description
1st record: Whidbey Island/WA/Penn Cove, Puget Sound (1994, Suchanek et al. 1997).
In this bioregion, local populations of Mytilus galloprovincialis have become locally established, especially near aquaculture areas and ports, in warmer and shallower inlets, hybridizing with the native M. trossulus. Mytilus galloprovincialis is being cultivated in commercial aquaculture operations (Anderson 2002; Wonham 2005). In a recent study of Mytilus in Puget Sound, Elliott et al. (2008) found that pure M. galloprovincialis comprised 0-14% of mussels sampled, while hybrids were 0-37%. 'Frequencies of M. galloprovincialis and M. galloprovincialis x M. trossulus were higher in subtidal habitats, such as docks, than on intertidal rocks, walls or pilings. Within intertidal habitats, M. galloprovincialis and M. galloprovincialis x M. trossulus were more frequent than M. trossulus in the lower reaches of the intertidal. At slightly more than half the sites the frequency of the three genotypes accorded with random mating expectations, suggesting no consistent barriers to gene flow between species' (Elliott et al. 2008). In a recent survey in British Columbia waters,, introgression of M. galloprovincialis genes was greatest near mussel farms, and greater at open-water sites than in estuaries (Crego-Prieto et al. 2015).
Geographic Extent
Sayward, Vancouver Island/British Columbia/Georgia Straits (Shields et al. 2010, 2%, M. galloprovincialis); Ladysmith, Vancouver Island/British Columbia/Georgia Straits (2005, 20% M. galloprovincialis, Shields et al. 2008; 10% M. galloprovincialis, Shields et al. 2010); Chemainus, Vancouver Island/British Columbia/Georgia Straits (2006, Shields et al. 2008; 8% M. galloprovincialis, Shields et al. 2010); Crofton, Vancouver Island/British Columbia/Georgia Straits (2006, Shields et al. 2008, 10% M. galloprovincialis, Shields et al. 2010); Union Bay, Vancouver Island/British Columbia/Georgia Straits (4% M. galloprovincialis, Heath et al. 1995, cited by Wonham et al. 2005; 3% M. galloprovincialis, 2005, Shields et al. 2010); Chemainus, Vancouver Island/British Columbia/Georgia Straits (14% M. galloprovincialis, Heath et al. 1995, cited by Wonham et al. 2005); Cates Tugs float, Vancouver/British Columbia/Burrard Inlet (M. trossulus X M. edulis hybrid, 2004, Heath et al. 1995, cited by Wonham et al. 2005); Bellingham/WA/Belllingham Bay (18% M. galloprovincialis, 9% hybrids, 1998, Wonham 2005, Richoux et al. 2006, genetic ID); Whidbey Island/WA/Penn Cove, Puget Sound (1994, 25% M. galloprovinicialis, 10% hybrids, Suchanek et al. 1997); Edmonds/WA/Puget Sound (19% M. galloprovincialis, 1998, Anderson 2002; Wonham 2005); Seahurst County Park/WA/Seattle (19% M. galloprovincialis, 1998, Anderson 2002; Wonham 2005); Silverdale/WA/Dyes Inlet (35% M. galloprovincialis 1998, Anderson 2002; Wonham 2005); Shelton/WA/Hammersley Inlet, Puget Sound (33-43% M. galloprovincialis, 1997- 1998, Anderson 2002; Wonham 2005); Taylor Shellfish Rafts/WA/Totten Inlet (75-100% M. galloprovincialis 1997- 1998, Anderson 2002; Wonham 2005); Sequim/WA/Sequim Bay, Strait of Juan de Fuca (18% hybrids, 1998, Wonham 2005); Port Angeles/WA/Strait of Juan de Fuca (23% M. galloprovinicialis, 31% hybrids, 1998, Wonham 2005); Sekiu/WA/Strait of Juan de Fuca (10% M. galloprovincialis, 1998, Wonham 2005); Makah Marina/WA/Neah Bay (8% hybrids, 1998, Wonham 2005)
Vectors
Level | Vector |
---|---|
Alternate | Hull Fouling |
Alternate | Ballast Water |
Alternate | Natural Dispersal |
Alternate | Fisheries Accidental (not Oyster) |
Regional Impacts
Economic Impact | Fisheries | |
Extensive aquaculture of M. galloprovincialis is conducted in waters of British Columbia and Puget Sound (Anderson et al. 2002; Wonham 2004; Elliott et al. 2008; BC Shellfishgrowers Association http://bcsga.ca/about/industry-encyclopedia/mussels/) | ||
Ecological Impact | Competition | |
In the Strait of Georgia and Puget Sound, where M. trossulus once was the sole species, the frequency of M. galloprovincialis is greatest in protected waters near marinas, shipping harbors, and aquaculture sites, sites of likely introduction, but also shallow, warmer waters favorable to the growth of the introduced mussel. At 4 of about 70 sites in this bioregion, purebred M. galloprovincialis exceeded 25% of sampled mussels (Wonham 2004). Elliott et al. (2008), sampling more selectively in Puget Sound found 6 of 29 sites in which frequencies of M. galloprovincialis comprised more than 25% of the sampled mussels. In most sites of the bioregion (Heath et al. 1995; Wonham 2004; Sheilds et al. 2010), the abundance of M. trossulus and its hybrid are so low than competitive impacts on M. trossulus are likely to be small. | ||
Ecological Impact | Hybridization | |
In the Strait of Georgia and Puget Sound, frequency of M. galloprovincialis X M. trossulus hybrids occasionally exceeds 10% near marinas, shipping harbors, and aquaculture sites (11 of ~70 BC-Puget Sound sites listed, Wonham et al. 2004; 15 of 29 Puget Sound sites listed by Elliott et al. 2008; 1 of 20 Strait of Georgia sites, sampled by Shields et al. 2010). Hybridization impacts of M. galloprovincialis are likely to be localized in shallow, protected, human-impacted embayment's. | ||