East coast horseshoe crabs poised for recovery
By Jon Hurdle
PHILADELPHIA (Reuters) - Restrictions by U.S. east coast states on harvesting horseshoe crabs, whose eggs provide food for endangered migrating shore birds, have boosted the animal's population after years of over-fishing, experts say.
Some experts have linked a decline in migratory shore birds to the over-fishing of horseshoe crabs, which come ashore every spring to lay their eggs, so Delaware, New Jersey and other nearby states turned their attention to boosting crab numbers.
Until the last few years, the crabs were harvested in their millions by commercial fishermen who used them as bait for conch and eel. But with ornithologists warning that the red knot, a robin-sized shore bird, was in imminent danger of extinction because of the lack of crab eggs, the states where the crabs spawn have banned or restricted the harvest.
New Jersey imposed a two-year moratorium on the crab harvest and then banned it altogether earlier this year, while Delaware allows only males to be harvested, and restricts those numbers.
The population of male crabs on Delaware beaches has now risen to 4.22 per square meter (11 square feet) from 2.50 in 1999, while female numbers have risen to 0.89 from 0.77, said Stewart Michels, a fisheries scientist at the Delaware Division of Fish and Wildlife.
"We are very optimistic that the significant increase is a good sign of things to come," Michels said.
Delaware's crab harvest declined to around 77,000 in 2007 from 487,000 in 1995, while the numbers taken on the East Coast as a whole, dropped to 817,000 in 2007 from around 3 million in 1995, Michels said.
The crabs are also used by biomedical companies that use their blood to extract a substance used to detect fever-causing bacteria in humans.
The number of red knot stopping over on Delaware Bay beaches during their 10,000-mile (16,000-km) migration from south America to Arctic Canada each spring has dropped in recent years to around 15,000, a number that scientists say is below that needed to sustain the species.
Scientists hope that if they can save the red knot, they will also be able to help other species such as ruddy turnstone and semi-palmated sandpiper, whose numbers have also declined because of the dwindling number of crab eggs.
(Editing by Michelle Nichols and Sandra Maler)