Northeast
Photo: Gregory Breese/USFWS

USA - New Hope for Horseshoe Crabs — and the Shorebirds That Depend on Them

A globetrotting bird, a crab that’s not a crab, a marine snail and a fish whose reproduction is so mysterious it fascinated Freud — they all walk into a sandbar. Unbeknownst to them, their future — no joke — hung in the balance of a decision made this November by the Atlantic States Marine Fisheries Commission.

For the past decade the commission has maintained a strict ban on fishing female horseshoe crabs in Delaware Bay — not because it’s full of diehard feminists, but because horseshoe crab eggs are a hot commodity. Fish and shorebirds hurry to gobble up these fat-rich, blueish-green gifts from the sea.

None of these diners are hungrier than the red knot. This robin-sized bird flies from the southernmost tip of South America all the way up to the Arctic to breed. Thousands of endangered red knots stop in Delaware Bay to bulk up to prepare for the remainder of their migration. How much weight they gain is the difference between a successful brood or a total reproductive bust.

Red Knots Horseshoe Ctabs

In the late 1990s, the red knot population began to plummet. Biologists thought that the unregulated harvesting of horseshoe crabs in the region left too few eggs for knots to gain the necessary weight to finish their migration.

As a result, in 2012 the fisheries commission developed a framework to limit the number of horseshoe crabs fished so there would be enough eggs for the birds. Unlike most fisheries limits, this method considered not just the species being fished but the species that rely on them as well.

A lot can change in ten years. The fisheries commission met this November to vote on a revised version of the model that outputs horseshoe crab harvest quotas, which suggested that females could be fished without hurting the red knot population. The proposal generated immediate concern in the conservation community, as the model was not scheduled to be published until after the vote Nov. 10.  This concern over lack of transparency turned to action, and the fisheries commission received more than 30,000 letters in defense of females.

That’s right. More than 30,000 letters standing up for a crab who’s not a crab — an un-crustacean.

And it wasn’t just tenderheartedness driving that concern. Some biologists worried the new model wouldn’t incorporate enough information. Larry Niles, a prominent biologist who studies the interaction between red knots and horseshoe crabs, believes the model should incorporate egg densities.

These densities have not increased since the early 2000s and remain pathetically low compared to past counts. In 1880 4 million horseshoe crabs were taken from the bay, their bodies stacked along the beach. They were so plentiful they were used as fertilizer until a synthetic product replaced it.

Still Exploited

Now horseshoe crabs are used as bait in the eel and whelk fisheries. In 2021 fishers landed 365 tons of channeled and knobbed whelk, two species of marine snails, in the Middle Atlantic and New England, generating $8,229,963, while 184 tons of American eel generated $18,664,377. Eels, whose strange sexual development cause Freud to dissect 4,000 of them, are considered endangered by the IUCN, but not by the U.S. Endangered Species Act. Though eels can be eaten, they are also often used as bait in the recreational striped bass fishery, elongating the food chain beyond its natural limits. Whelk, marine snails with beautiful whorled shells, can take up to 10 years to reach sexual maturity, putting them at higher risk of exploitation than faster-growing species.

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