Horseshoe Crabs and Shorebirds

The ancient horseshoe crab is at the heart of one of nature's most amazing wildlife spectacles. During high tides towards the end of May each year, hundreds of thousands come ashore in Delaware Bay to spawn. Though this breeding ritual began long before Delaware Bay even formed and the very first birds evolved, millions of shorebirds have since become dependent on the crabs' eggs to fuel their migration to the Arctic to breed.

Delaware Bay developed its current shape approximately 10,000 years ago as sea levels rose and the Delaware and Susquehanna River valleys became inundated following the last Ice Age. The Bay's extensive sheltered beaches provided ideal habitat for both spawning horseshoe crabs and staging shorebirds. Red Knots, Ruddy Turnstones, Semipalmated Sandpipers, and other shorebirds timed their migration to arrive as the crabs spawned, so the abundance of eggs could fuel their last leap to the Arctic.

By the mid-1960s, humans had found other uses for the horseshoe crab. In 1967, Americans H. Keffer Hartline and George Wald won the Nobel Prize for Medicine for a study of the horseshoe crab's eye. Four years later it was proven that chemicals isolated from the crab's immune system could help test the purity of medicines. Today, limulus amebocyte lysate, sustainably harvested from the copper-based blood of live crabs, is marketed worldwide in an industry valued at $50 million per year.

A new market for the crabs opened up in the 1980s, when it was discovered that they make excellent conch and eel bait. Conch (channeled whelk) are trapped off the Atlantic coast of the United States, freeze-dried and exported to Asia, or shipped to the growing New York market. Soon, beach and aerial surveys started to show major declines in crab and shorebird numbers. These declines continued throughout the 1980s and 90s.

Collaborative studies by several institutions published in 2004-2005 showed a large reduction in the availability of crab eggs from 1990 levels, and a 50% decline in eastern ( rufa ) Red Knots on their breeding grounds. Another study showed that a decrease in crab eggs was likely responsible for similar declines in Red Knots on their wintering grounds in South America.

ABC has worked steadily since 1997 to ensure horseshoe crabs are adequately protected to guarantee a plentiful food supply for the birds that rely on them. Thanks to these efforts and those of its partners, and despite significant resistance from crab fishermen and the state of Virginia in particular, crab harvest quotas have now been cut dramatically, and a 1,500 square mile horseshoe crab sanctuary established in the mouth of Delaware Bay.

The Atlantic States Marine Fisheries Commission elected in May 2006 to enact a rule that allowed only male horseshoe crabs to be taken in New Jersey and Delaware for two years (though ABC and others had fought for a total ban on all crab take). Take and landings of crabs are now prohibited altogether between January 1 through June 7, and take is capped at 100,000 males each per year. Horseshoe crab take and landings have also been prohibited in Maryland for two years between January 1 and June 7, but there are no restrictions on the take of females, and the cap for the state remains at 170,000 crabs.

In spring 2006, New Jersey showed its concern for the plight of the Red Knot and horseshoe crab and displayed leadership among the Atlantic states by acting independently to impose its own statewide full moratorium, meaning no crabs will be taken in the state. In November 2006, Delaware followed suit with its own 2-year moratorium. Both of these moratoriums now face challenges from watermen.

Virginia is now prohibited from landing crabs caught in federal waters for two years between January 1 and June 7. No more than 40% of Virginia's quota may be landed from federal waters, and those landings must be comprised of at least twice as many males as females.

Concurrent with efforts to reduce landing quotas, ABC has also promoted the use of bait bags among conch fishermen. These reusable nylon mesh bags reduce the demand for horseshoe crab bait by up to half. In 2001, ABC sent sample bags to hundreds of East Coast conch fishermen. The program was a success, with many fishermen taking up the offer of a free bait bag, based on a return voucher.

Despite recent successes, however, the battle is not over. The last 20 years have taken their toll, and the rufa Red Knot remains at critically low levels. Historically, more than 100,000 Red Knots stopped at Delaware Bay. By 2004, this number had dropped to 13,315 birds.

To ensure its continued survival, ABC and other groups petitioned for the rufa Red Knot to be listed under the Endangered Species Act (ESA). In January 2006, the U.S. Fish and Wildlife Service denied the petition, instead opting to place the species on the ESA Candidate List. There is no mandatory timeline for moving a species from the Candidate List to the Endangered List, and so, rather than this being a positive step, it is in fact a potentially never-ending limbo for a bird in need of immediate protection. Following this decision, a coalition of conservation groups, including ABC, filed suit to have the rufa Red Knot listed under the ESA. We hope that this action will soon result in the federal protection that the species so urgently needs.