Trying to weigh the needs of migrating birds, the demands of fishermen and the well-being of an ancient sea creature, the Atlantic States Marine Fisheries Commission has decided to slash the coastal harvest of horseshoe crabs 25 percent.

The Feb. 9 action had split the Bay states, with Maryland calling for a 50 percent cut and Virginia calling for no harvest reduction.

A number of states, including Maryland, Delaware and New Jersey, had already imposed sharper reductions. ASMFC, a panel of East Coast states that manages coastal fisheries, encouraged them to maintain their lower catch limits.

The ASMFC’s Horseshoe Crab Management Board action stems from rising concern by some biologists that the species, which has been around almost 360 million years, is on the verge of being overfished.

That would not only put the horseshoe crab in peril, but also migrating shorebirds, which depend on crab eggs for food during stopovers; their numbers have fallen as has the crab population.

But no one knows the status of the horseshoe crab stock for certain, fisheries officials say, because of a lack of monitoring. “By far, the greatest challenge we face in the conservation and management of horseshoe crabs is the lack of sufficient data to accurately assess the status of the population,” said Bruce Freeman, chair of the ASMFC Horseshoe Crab Management Board.

He welcomed a pledge by New Jersey Gov. Christine Todd Whitman to contribute $50,000 toward data collection activities to determine the status of the horseshoe crab population and its potential impact on migratory shorebirds.

She challenged Delaware, Maryland and Virginia to donate similar amounts. The Department of the Interior would then match the money to establish a monitoring program that Freeman said would “bring us much closer to our goal of generating a statistically sound stock assessment for this important species.”

In addition to shorebirds, adult horseshoe crabs are a significant part of the diet of juvenile Atlantic loggerhead turtles, a threatened species that uses the Chesapeake Bay as a summer nursery area. A variety of other species also consume the horseshoe crab at various stages of their life.

Humans, too, rely on the horseshoe crab. Scientists have used them in eye research, surgical sutures and wound dressing development. Their blood is used to detect bacteria in drugs, a test that must be done on every manufactured pharmaceutical. After withdrawing the blood, the crabs are returned to the water, though some still die.

Horseshoe crabs are also the primary bait source for the commercial conch and eel fisheries along the East Coast. Demand is so high for the crabs that a single, egg-filled female can fetch from 75 cents to a $1 on the bait market.

The ASMFC action hits Virginia the hardest because as other mid-Atlantic states had cut back on horseshoe crab catches in recent years, its landings soared from around 20,000 in the mid-1990s to a half-million crabs last year. Because the catch is measured from a three-year old baseline, when Virginia’s catch was lower than it is today — 203,000 crabs — its new limit of 150,000 is actually greater than a 25 percent cut from the present harvest.

Jack Travelstead, Virginia’s fisheries director, worried that the new cap would hurt his state’s $14 million-a-year conch fishery, the wealthiest on the East Coast. “I don’t know how they can get by with 25 percent of their bait needs suddenly gone,” Travelstead said.

The 25 percent coastwide reduction was a compromise between the 50 percent cut sought by conservation groups and the biomedical community and a smaller reduction sought by the commercial fishing industry.

Maryland officials had supported a 50 percent reduction saying it would be more “risk averse” for the crabs and shorebirds. In 1998, Maryland slashed its horseshoe crab harvest by two-thirds.

Overall, the new coastwide catch limit will be 25 percent below the nearly 3 million average crab harvest from the years 1995–97. Individual horseshoe crab fisheries will be closed once the cap for each state is reached. States have to implement the limits beginning May 1.

The ASMFC also called on the National Marine Fisheries Service to establish a crab sanctuary within a 30-mile radius off the mouth of Delaware Bay, the most important stopover for shorebirds that migrate from South America to the Arctic in late spring. No horseshoe crab catches would be allowed within the sanctuary.

The issue is another example of growing regional concern over “multispecies management” — trying to take into account how fishing actions directed at one species may adversely affect another.

Similar questions about species interactions have swirled around striped bass, menhaden and blue crabs in recent years.

To deal with such issues in the Bay, the Bay Program’s draft Chesapeake 2000 Agreement calls for incorporating multispecies issues in Baywide fishery management plans by 2007. Although the Bay Program has a horseshoe crab plan now, it sets no catch limits.

Despite its name, the horseshoe crab isn't a true crab at all. In fact, it’s more closely related to the spider and the mite.