Crab's Migration

In: Science

Submitted By kotaro87
Words 984
Pages 4
Crab Migrations
Many species, including crabs, undergo long-distance migrations in order to release offspring in areas favorable for proper early development. The risks associated with migrating can be costly, including acquiring and allocating energy for both migration and oogenesis (egg development) and increased predatory risk. Two of the most spectacular migrations of crabs are blue crab migration at Chesapeake Bay and red crab migration Chrismas Island. However, blue and red crabs choose different strategies (e.g. timing, route, mechanisms) in order to successfully complete migration and maximize survival of offspring.
At Chesapeake Bay, blue crab mating typically occurs from May to October in lower salinity areas of the Chesapeake Bay. After mating, males remain in these lower salinity areas. However, because blue crab larvae require high salinities for proper development, females will begin moving south to the spawning grounds near the mouth of the Chesapeake Bay and near-shore coastal areas. Periods of peak spawning (larval release) along the Mid-Atlantic Bight have typically been documented from late July through August. After spawning, many females use flood tides to return to the lower estuary, where they may produce subsequent broods, but do not move back into lower salinity zones. Some mature females may also move into near-shore and offshore coastal waters after spawning.
The Chesapeake Bay is a large estuary and for many crabs the distance between mating areas the spawning grounds can be considerable (> 100 km). Peak spawning typically occurs in the late summer; therefore, crabs beginning to migrate in the early fall may not be able to spawn that year. According to a study, in which, blue crab were tagged, released and recaptured, it appears that most female blue crabs in the upper Chesapeake Bay appear to begin the spawning migration in the…...

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