European+green+crab+sam+zrillo



GENERAL INFORMATION

The European Green crab's specific name is the carcinus maenas. This species has a harmful effect on the economy. They came from Europe and were first seen in 1989 at the San Fransisco bay. Soon after in 1996, they were seen at Coos Bay, Oregon.They were about 2-3 inches in shell width. The shell can be a dark red, green, orange, or molted. It has five spines on both sides of their eyes. (2) The underside can be green to orange to red. Their last pair of walking legs are flat. There are also three lobes or bumps by their eyes.

DETAILED DESCRIPTION In the North Sea, mating takes place from April to November. In the Baltic Sea it takes place between May and June. Most of the time, the European Green Crabs will lay their eggs during the spring. Healthy embryonic development occurs when the temperature is between 11 and 25 degrees celcius. The larvae come together in surface waters during the ebb tide because that is when the currents are strongest. European Green Crabs that live along the central coast of Maine mate between July and October. (2) It eats mussels, oysters, other crabs, small fish, insects, mostly whatever is available at the time. The organism is so successful because it is highly adaptable and can stand a various different temperatures and salinities. Another reason is because they grow very quickly and give birth to many at once. The green crab feed on several different things, but nothing really eats them because they do not have a lot of meat. Therefore, nothing really wants to waste their time eating the green crab. However, they can not withstand a wave off the open coast so they are only around bays. (1) (explain in detail how they compete or out compete native species)

HABITAT AND DISTRIBUTION The crabs are originally from Europe and now live along the west coast along California, Oregon, California, and are spreading elsewhere like all along the East Coast in Maine and Maryland. It also lives in many different countries such as South Africa, Australia, Japan, and will start spreading to others. (2)

IMPACTS They have a negative impact on local commercial and recreational fisheries because they eat the young of valuable species such as oysters and Dungeness. They also compete with their resources. (1) They are blamed for the collapse of soft shell clams in Maine. In California, the green crab have also been impacting the Malia clams, resulting in a 40% drop in population. There are mesh nets around the places that the green crab already live to protect the clams from being eaten.(2)

HISTORY Although we don't have a good idea as to how these green crabs came from Europe, there is a pretty good chance it was the ballast water that came from the ships that carry larvae. The reason the water is spreading it northward is probably because the larvae in the water was mixing with the ocean currents. What where the enviormental conditions there- (1)

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CONTROL MEASURES Bounty hunter programs are actually paying waterman for catching and removing the green crabs from our waterways. They are also providing coastal boundaries and actually prohibiting transportation and possession of live green crabs. When studying the green crabs, they have to be kept in isolation or quarantine, they are not allowed to be placed in local marine waters. (2)

Economic Value of West Coast Fisheries Resources That Could Potentially Be Affected by Green Crabs

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). (3)

WORKS CITED (three different sources/ all resources must be cited/ format to follow)