|Status & Synopsis||Economic Value of Potentially Affected Fisheries||Geographic Distribution||PSMFC Funded Projects|
In 1998, the European green crab (Carcinus maenas) was formally recognized as an Aquatic Nuisance Species (ANS) by the Federal ANS Task Force (a national coordinating body). That same year Washington State made it illegal to possess or transport European green crabs. It is a prohibited species in Oregon and California. In Alaska, there are no fish and game laws barring importing live green or mitten crab into the state for the live food market.
Background: The European green crab was first discovered on the east coast of North America in the early 1800’s (Say 1817). They are native to Europe and northern Africa and were introduced into North America via shipping. Green crabs arrived in California prior to 1990. By 2000, the green crab had dispersed as far north as Port Eliza on the northern coast of Vancouver Island, British Columbia. The potential range of green crabs includes southeast Alaska (Behrens Behrens-Yamada 2001, Carlton 2003).
Dungeness crab (Cancer magister) 2005 Oregon fishery ex-vessel value (through 2/9/05): $50 Million (Oregon Dungeness Crab Commission 2005).
Annual value in sales of farmed oysters, mussels, clams, and geoducks in Washington state: $77 million (PCSGA 2003).
Scientists, managers and shellfish growers are concerned that increases in the abundance and distribution of this efficient predator and competitor could permanently alter native communities. They are also concerned that the green crab will threaten commercial species such as juvenile Dungeness crab, juvenile flatfish, and bivalves (Lafferty and Kuris 1996, Jamieson et al. 1998). Green crabs have been shown to compete with native juvenile Dungeness crabs and shore crabs (McDonald et al. 2001, Jensen et al. 2002), as well as many types of organisms, including commercially valuable bivalve mollusks (e.g., clams, oysters, and mussels), polychaetes, and small crustaceans (Cohen et al. 1995).
On the east coast of North America, green crabs have been associated with the decline in soft shell clam (Mya arenaria) landings (Glude 1955, Ropes 1968). Research and observations on the west coast have not indicated similar impacts to shellfish. However, green crabs are a relatively new arrival to the west coast, so future effects on native species have yet to be determined.
Research conducted by Dr. Ted Grosholz (University of California, Davis) in California (see PSMFC Funded Projects) has shown that in recent years, green crab population densities are highest in Tomales Bay and Elkhorn Slough. There is no evidence that green crabs have established populations south of Elkhorn Slough and there are no records of any green crab presence south of Point Conception. Therefore, the populations in central California continue to represent the majority of green crabs found along the west coast. These may be the key source of recruits for populations farther north, although this remains to be demonstrated.
Circumstantial evidence from research conducted by Dr. Sylvia Behrens-Yamada (see PSMFC Funded Projects) suggests that Coos, Yaquina, Netarts, and Tillamook estuaries in Oregon and Willapa Bay in Washington, harbor small self-sustaining populations of green crabs that do not depend on a larval source from California.
Source: National Introduced Marine Pest Information System (NIMPIS), Australia
- Global Invasive Species Database Green Crab Page
- CSIRO Marine and Atmospheric Research Green Crab Page
- USGS – Nonindigenous Aquatic Species Green Crab Page
- Smithsonian Environmental Research Center Marine Invasions Research Lab
Behrens Yamada, S. 2001. Global Invader: The European Green Crab. 123 pages. Oregon Sea Grant, Washington Sea Grant.
Behrens Yamada, S., B.D. Dumbauldt, A. Kailin, C. Hunt, R. Figlar-Barnes and A. Randall. 2005. Growth and persistence of the recent invader Carcinus maenas in Pacific Northwest estuaries. Biological Invasions, 7(2): 309-321.
Carlton, J.T. and A.N. Cohen. 2003. Episodic global dispersal in shallow water marine organisms: the case history of the European shore crabs Carcinus maenas and C. aestuarii. Journal of Biogeography, 30: 1809-1820.
Cohen, A.N., J.T. Carlton and M.C. Fountain. 1995. Introduction, dispersal and potential impacts of the green crab Carcinus maenas in San Francisco Bay, California. Marine Biology, 122: 225-237.
Glude, J. B. 1955. The effects of temperature and predators on the abundance of the soft- shell clam, Mya arenaria, in New England. Trans. Am. Fish. Soc., 84: 13-26.
Oregon Dungeness Crab Commission. 2005. Oregon Dungeness Crab Landings (through 4/8/05). Coos Bay Oregon. www.oregondungeness.org/index.shtml
Jamieson, G.S., E.D. Grosholz, D.A. Armstrong and R.W. Elner. 1998. Potential ecological implications for the introduction of the European green crab, Carcinus maenas, (Linnaeus), to British Columbia, Canada and Washington, USA. Journal of Natural History, 32: 1587-1598.
Jensen, G.C., P.S. McDonald and D.A. Armstrong. 2002. East meets west: Competitiveinteractions between green crab, Carcinus maenas, and native and introduced shore crab Hemigrapsus spp. Marine Ecology Progress Series, 225: 251-262.
Lafferty, K. and A. Kuris. 1996. Biological control of marine pests. Ecology, 77: 1989-2000.
McDonald, P.S., G.C. Jensen and D.A. Armstrong. 2001. The competitive an predatory impacts of the nonindigenous crab Carcinus maenas (L.) on early benthic phase Dungeness crab Cancer magister Dana. Journal of Experimental Marine Biology and Ecology, 258(1): 38-54.
Oregon Dungeness Crab Commission. 2005. Crab harvest off the Charts. Press release of August 15, 2005. Coos Bay, Oregon. www.oregondungeness.org
PCSGA (Pacific Coast Shellfish Growers Association). 2003. Shellfish Economy: Treasure of the tidelands. Olympia, WA. www.pcsga.org
Ropes, J. W. 1968. The feeding habits of the green crab, Carcinus maenas. Fish. Bull., 67: 183-203.
Say, T. 1817. An account of the crustacean of the United States. Journal of the Academy of Natural Sciences of Philadelphia, 1: 57-63.