Invasion
Invasion Description
1st record: Skagit County/WA/Samish Bay (1924, Kincaid 1947, cited by Carlton 1979)
Geographic Extent
Princess Royal Island/Britsh Columbia/southern Queen Charlotte Sound (2006, Gillespie et al. 2007, approximate northern limit); Spider Island/British Columbia/Hecate Strait (1972, Carlton 1979); Vancouver Island/British Columbia/Quatsino Sound (1971, Quayle and Bourne 1972, cited by Carlton 1979); Vancouver Island/British Columbia/Esperanza Inlet (1950s, Quayle and Bourne 1972, cited by Carlton 1979); Vancouver Island/British Columbia/Desolation Sound (Whiteley and Bendell-Young 2007, clam farm); Vancouver Island/British Columbia/Barkley Sound (1950s, Carl and Giguet 1958, cited by Carlton 1979; Whiteley and Bendell-Young 2007, clam farm); Vancouver Island/British Columbia/Baynes Sound (Carswell et al. 2006; Lewis et al. 2007, 49.5°N, 124.8°W; Whiteley and Bendell-Young 2007, clam farm); Vancouver Island/British Columbia/Mud Bay (2007, Mach et al. 2017); Campbell River, Vancouver Island/British Columbia/Strait of Georgia (2008, Choi et al. 2016); Nanaimo, Vancouver Island/British Columbia/Nanaimo estuary (2007, Mach et al. 2017); Ladysmith (Vancouver Island)/British Columbia/Strait of Georgia (1932, Quayle 1938, cited by Carlton 1979); Vancouver Island, British Columbia/Cowichan Bay (2008, Choi et al. 2016); Esquimalt, Vancouver Island/British Columbia/Strait of Juan de Fuca (2008, Choi et al. 2016); Port Alberni, Vancouver Island/British Columbia/Alberni Inlet (2008, Choi et al. 2016); San Juan Island/WA/Argyle Lagoon, Juan de Fuca Straits (1958, Academy of Natural Sciences of Philadelphia 2004); San Juan Islands/WA/Juan de Fuca Straits (1975, Carlton 1979); Whatcom County/WA/Birch Bay (1963, Carlton 1979); WA-British Columbia/Boundary Bay (1977, Carlton 1979); Chuckanut Island, Whatcom County/WA/Bellingham Bay (1963, Carlton 1979); Skagit County/WA/Samish Bay (1924, Kincaid 1947, cited by Carlton 1979); Skagit County/WA/Padilla Bay (Riggs 2011; WA/Puget Sound (1943, Eyerdam 1943, cited by Carlton 1979; Cohen et al. 1998); Kamilche Point/WA/Totten Inlet, Puget Sound (2000, Cohen et al. 2001); Taylor Shellfish Rafts/WA/Totten Inlet, Puget Sound (2000, Cohen et al. 2001); Evergreen State College Beach, Olympia/WA/Eld Inlet (2000, Cohen et al. 2001); Seattle/WA/Elliott Bay Puget Sound (2000, Cohen et al. 2001); Dosewallips/WA/Hood Canal (1983, USNM 820014, US National Museum of Natural History 2007); WA/Neah Bay, Strait of Juan de Fuca (2002, deRivera et al. 2005)
Vectors
| Level | Vector |
|---|---|
| Probable | Oyster Accidental |
Regional Impacts
| Economic Impact | Fisheries | |
| Ruditapes philippinarum is intensively farmed on the southern coast of British Columbia. These farms are planted with a high density of clam seed in leased sections of beaches, and often covered by netting to restrict predators (Carswell et al. 2006; Munroe et al. 2007; Whiteley and Bendell-Young 2007; Bendell et al. 2010). In Baynes Sound, these farms occupied about 20% of the shoreline, with 3% covered by netting (Carswell et al. 2006). Japanese littlenecks are also frequently harvested by recreational shellfishers in British Columbia and Washington (Fisheries and Oceans Canada 2009; Washington Department of Fish and Wildlife 2013) | ||
| Ecological Impact | Habitat Change | |
| Sites in which farming of R. philippinarum took place had 'significantly greater amounts of ammonium, phosphorus and manganese in bulk and organic matter, and ammonium, iron, manganese and silt in surficial sediments' (Bendell et al. 2010). Antipredator nets at these sites may increase the deposition of silt and sediments (Bendell et al. 2010). However, farming activity did not affect the abundance of other bivalve species at the sites (Whiteley and Bendell-Young 2007). | ||
| Ecological Impact | Food/Prey | |
| Ruditapes philippinarum may be more vulnerable to predators than the native Leukoma staminea (Pacific Littleneck) because of its shorter siphon. Simulated sublethal predation (cropping the siphon) caused R. philippinarum to bury at shallower Repths, making it more vulnerable to predators, while L. staminea, even after losing 40% of its siphon, remained at the same depth (Meyer and Byers 2005). Sea ducks (Surf Scoter- Melanitta perspicillata; White-Winged Scoter- M. fusca) fed primarily on R. philippinarum and Nuttallia obscurata (Purple Varnish Clam) in Britsh Columbia waters. Scoter predation appeared to be the primary cause for winter decline in these bivalves (Lewis et al. 2007). | ||
| Ecological Impact | Competition | |
| Ruditapes philippinarum appears to be replacing the native Leukoma staminea (Pacific Littleneck) in farmed areas and reference sites, despite its greater vulnerablity to predators, partly because of the intensity of seeding in farmed areas (Bendell 2014). | ||