For the Birds Radio Program: Horseshoe Crabs

Original Air Date: June 26, 2002

Laura heard from a first-hand witness to how horseshoe crabs are disappearing.

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One of the genuinely frightening and tragic population losses the US has suffered during the past decade is the decline of horseshoe crabs of the east coast. The Delaware Estuary on the New Jersey coast is the largest staging area for shorebirds in the Atlantic Flyway, with an estimated 425,000 to 1,000,000 migratory shorebirds of 11 species converging in one small area to feed and rebuild their energy reserves before completing their northward migration. These shorebirds breed in the far north, where the harsh climate and short growing season make their breeding season uniquely intense, and most of them winter thousands of miles away in South America. Fattening on horseshoe crabs during migration is essential to give them the energy, fat and protein they need to produce babies.

Female crabs lay eggs in May and June during the new and full moons when the tides are greatest; the churning water facilitates fertilization. Shorebirds swarm the beaches during that time, pigging out on crab eggs. Birds mostly feed on sites that have been disrupted by waves and storms, so the feeding of the shorebirds does not have an adverse affect on the breeding success of the crabs.

But human crab harvesting has such an extreme effect that major newspapers have been publicizing the crab population crisis on the east coast since the late 90s. Horseshoe crabs are used as bait for commercial eel and conch fishing and, to a small degree, for biomedical research. An enzyme in the crabs’ blood is used to create a product tests for lethal impurities in intravenous drugs. Although a nonlethal level of blood is drawn from each crab and they are returned to the water within 72 hours, about 10 percent die during the process according to the National Marine Fisheries Service, the federal agency that manages the nation’s marine resources. More horseshoe crabs may die after being returned to the water, but no one currently tracks this.

A few weeks ago, on the Internet BIRDCHAT, a woman named Cary] Baron posted an account of her trip to New Jersey this Memorial Day weekend. She described some lovely things she’d seen, like Clapper Rails, Marsh Wrens, a hummingbird, and many nesting warblers. She writes:

It was a wonderful weekend, and also a sad and frightening one.

Although we did see Ruddy Turnstones, a few Red Knots, some Dunlin and Black­ bellied Plovers, and countless Laughing Gulls, the number of Horseshoe Crabs laying eggs on the beaches in the high tides of the fulI moon were less than 10% of the incredible numbers we witnessed 15 years ago—maybe as few as 1%. There has been so much harvesting (that’s a euphemism) of the crabs that their decimation is frightening. The Passenger Pigeon comes to mind.

And what of the birds? Fifteen years ago w could not drive to the beaches because the roads were covered with Horseshoe Crabs. We saw beaches carpeted with horseshoe crab caviar, and covered with the Red Knots and Ruddy Turnstones and other shorebirds busily consuming the fatty calorics that would get them to the arctic. Today, there is a raucous congregation of Laughing Gulls, but even these are not evident in numbers approaching those of a decade and a half ago. And a smattering of turnstones, and an occasional knot So these populations must be equally decimated.

Caryl Baron continues:

What is it about Man that makes us so destructive, so devastating, such a scourge upon the earth? I am ashamed to belong to the human species, the species that wreaks such havoc upon nature.

That was Caryl Baron, and I’m Laura Erickson, speaking for the birds.