Help them finish the journey

Diminishing supplies of horseshoe crab eggs on the shores of the Delaware Bay - in part because of Maryland watermen - imperil migratory red knots

August 05, 2008|By Charles D. Duncan

With the Summer Olympics almost upon us, it seems appropriate to take special note of an ultra-marathon champion that seldom gets the attention it deserves. The event is seemingly impossible: a journey from Tierra del Fuego to the Canadian Arctic and back, 9,300 miles each way, in nonstop stages that last days without food or water. And like some nightmare of Roman gladiators, if you fail, you die.

But there's a catch: The participants can fly. These ultra-marathoners are migratory red knots, shorebirds not much more than half the weight of a pigeon. They use a handful of stopover sites in Argentina, Uruguay, Brazil and the U.S. to rest and refuel between the migratory stages,

One of the crucial links in the chain is the Delaware Bay, where northbound red knots put on fat as fuel for the next stage of the migration by feeding on the eggs of horseshoe crabs. The knots gain as much as 10 percent of their body weight per day. In human terms, this is the equivalent of needing 54,000 calories daily (25 times what your doctor recommends).

But the population of these Olympians is dropping precipitously. Aerial surveys in 1985 and 2000 in Tierra del Fuego found more than 50,000 knots. At the start of this year, the count was under 15,000, a drop of more than 70 percent in eight years. Scientists have searched other areas in South America, and it's not that birds have moved - they're gone.

This population crash is linked to a similar decline in horseshoe crabs along the east coast of the U.S. Fewer crabs means fewer eggs, and that means fewer knots gain enough weight to fuel the last 1,800-mile leg to the Arctic ready to begin breeding. Knots that fail to make the threshold weight of 180 grams are unlikely to survive, and we know that the percentage of underweight birds has been increasing since 1999. This year, barely half the red knots made the threshold. Extinction of red knots in our hemisphere is a real possibility.

What is causing the decline of the crabs? Since the mid-1990s, horseshoe crabs have been caught as bait for whelk and American eels. The crab catch has skyrocketed, and the eggs on the beach available to red knots have plummeted. Watermen in Maryland's offshore waters catch horseshoe crabs, those that are Maryland's and those that would have gone to the bayside beaches of New Jersey and Delaware to spawn.

The fishery is regulated by the Atlantic States Marine Fisheries Commission, but despite recent regulatory actions, there has been no evidence of significantly increased crab egg density on the beaches or in recovery of the crabs' breeding population. In March, the New Jersey legislature exercised its authority and overwhelmingly passed a moratorium on the harvest of crabs in state waters until the populations of red knots and horseshoe crabs can be demonstrated to have recovered. Then, a sustainable, regulated harvest of horseshoe crabs can be instituted.

Maryland is considering its own crab harvest regulations. In a recent letter to group of schoolchildren called the Friends of the Red Knot, John R. Griffin, secretary of the Department of Natural Resources, affirmed that "Maryland will continue to take a leadership role in promoting the protection of horseshoe crabs for their ecological role." For the survival of red knots and for the crab fishery, this is very welcome news

The Western Hemisphere Shorebird Reserve Network is a voluntary coalition of hundreds of agencies, corporations, nonprofit groups and individuals in 10 nations protecting over 20 million acres of shorebird habitat. As director of WHSRN's executive office, I work with national governments throughout the range of the red knot. In all these nations, WHSRN's partners are working to ensure that knots will find havens throughout the rest of their annual cycle if only we in the U.S. will address the crab egg issue. Careful science shows that no threat to knots elsewhere compares to the loss of horseshoe crab eggs at Delaware Bay.

Not long ago, flocks of tens of thousands of red knots could be seen wheeling in unison. Those flocks are terribly reduced, as is the potential for economic growth from bird watching-associated tourism in key sites. I urge Maryland's regulators to take prompt and decisive steps to rebuild horseshoe crab stocks, create a sustainable fishery for people and protect this Olympian migrant.

Charles D. Duncan is director of the shorebird recovery project of the Western Hemisphere Shorebird Reserve Network.

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