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Decrease in Crabs Raises Concerns

May 27, 2002


For hundreds of millions of years, horseshoe crabs have spawned with relatively little fanfare. This spring, however, as they have hauled themselves up on the beaches of Delaware Bay, they have been counted, collected for bait, observed, and argued over.

Last fall, Jim Berkson of the Horseshoe Crab Research Center at Virginia Tech conducted one of the first extensive trawling surveys of horseshoe crab population.

This weekend, Berkson and his colleagues will be flying over the Delaware shoreline with digital video cameras to document the number of crabs on the beaches.

Environmentalists and birders are tracking the crab population as well, because a huge surge in the number of crabs collected for bait in the last decade, and a decrease in the number of the shorebirds that feed on them – red knots in particular – have caused alarm.

The issue is simple enough in its general outline, but one part is missing – how many horseshoe crabs there are, and exactly what is happening to the population.

There is no question that there has been an enormous assault on the population on the East Coast. In the 1990’s, the take of horseshoe crabs jumped from the thousands into the millions, because of a burgeoning fishery for whelk (also called conch, or, on the plate in an Italian restaurant, scungili) and eels.

Perry Plumart, the National Audubon Society’s director of government relations, wrote in 2000 on the proposed regulations to the Atlantic States Marine Fisheries Commission, “It is known that in the last five years alone between 15 and 20 million horseshoe crabs have been landed.”

Observers had noted fewer crabs on the beaches in the spring over time, and several surveys showed a drastic decline in the availability of eggs, a main food for red knots and other shorebirds that stop to feed on their long migration. For some of the birds, being able to fatten up in the Delaware Bay is a matter of life and death. The bay is the most important stop for migratory shorebirds in the lower 48 states.

Lobbying by environmental groups managed to bring about restrictions on the harvest of crabs and the establishment of a sanctuary in the bay, but the harvesting is still going on and one significant problem is that horseshoe crabs take about 10 years to mature sexually.

Current restrictions, put in place by the fisheries commission and the individual states, still allow females heavy with eggs to be taken. The restrictions may be insufficient to protect the crabs and birds, according to Plumart and others.

Berkson’s goal is to provide the solid numbers that will help the conflict to be resolved. He conducted a trawl survey off the Atlantic coast from Cape May, N.J., to Ocean City, Md., and said the estimate of the number of crabs in that area was a little over 11 million.

That did not include small crabs, he said, and, given the nature of the survey, the true number could be from 6 million to 17 million.

Given the harvesting rate in the past, that is not necessarily encouraging, but Berkson said there were horseshoe crab populations up and down the coast and at the moment, he said, the population was not endangered or threatened. What is not known, however, is how fast the population is declining and how fast reproduction is replacing crabs.

For Plumart, the lack of knowledge is a call to action, not only to research the numbers, which National Audubon strongly supports, but also to impose tougher restrictions. The numbers of crabs are declining, as are the birds, he says. And if we’re not sure what’s going on, that argues to play it safe, particularly since the birds need an abundance of eggs to survive their journey.

Dery Bennett, president of the American Littoral Society, agrees. “It seems to us as if the handwriting is there. We probably ought to lay off these animals completely.”

Berskon said, “My opinion is that we have enough crabs out there for the shorebirds, for the biomedical community and for some harvest.” What is not known, he said, is what level of harvest is tolerable to the crab population. “Nobody knows if measures taken so far are sufficient or overkill.”

The issue is not merely one of conservation; horseshoe crab blood is a basis for a required biomedical test of bacterial contamination to determine the safety of drugs, intravenous solutions and some medical devices. Estimates of the size of the industry vary but it is at least $50 million. Berkson is currently waiting for an assurance that he will get money for the next trawl survey, as well as a federal appropriations measure that would provide $700,000 a year for five years for monitoring the horseshoe crab population.

In the meantime, the fishing continues, and another organization, the nonprofit Ecological Research and Development Group in Lewes, Del., is looking for technical solutions.

“We’re an odd group within the environmental community,” said Glenn Gauvry, the group’s president. “We really are against regulation.”

Instead, Gauvry’s organization has been conducting research on alternative bait for whelk fishing, and on a very simple solution, that may be one of the only things everyone involved with the issue agrees on – bait bags.

The bait bag, first developed by a whelk fisherman, is simply an enclosure of rigid plastic mesh that protects the crab used as bait. Consequently, whelk fisherman can cut down on the amount of bait in traps because fewer creatures are able to eat it in bags, so it lasts longer.

The ecological research group now makes and gives the bags away free, and fishermen are starting to make their own. The bait bag, Gauvry says, could cut use of horseshoe crabs in half.

Plumart supports use of the bags. Bennett thinks they’re a good idea. Virginia has made them mandatory. If, as all evidence suggests, they allow roughly the same catch of whelk with less bait, they will save money for fishermen.

“The bait bags are an incredibly good idea,” Berkson said. “It looks like we have significantly reduced the number of horseshoe crabs needed for bait.” Gauvry, he said, “has probably done more for horseshoe crab conservation than anybody up and down the coast.”

But, Berkson said, the essential question, at the heart of all the discussion of horseshoe crabs, and on which there is not agreement, remains, “How many can we take?”

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Copyright 2002 The New York Times Company


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