A Planned Restart of a Crab Harvest Pits Conservation Against Industry

https://www.nytimes.com/2022/11/08/science/crab-harvest-horseshoe-conservation.html

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For the first time in 10 years, a fisheries regulator is poised to restart the harvest of female horseshoe crabs in the Delaware Bay, a policy change that conservationists say will threaten the survival of the Atlantic species of the red knot, an imperiled shorebird.

On Nov. 10, the Atlantic States Marine Fisheries Commission will vote on whether to move toward lifting a ban on the female crab catch that had been imposed after overharvesting led to a severe decline in the populations of knots and other migratory shorebirds dependent on crab eggs as a critical food source.

Between 2003 and 2012, the population of female horseshoe crabs in the Delaware Bay was estimated at 3 million to 6 million, according to the commission. Since the ban took effect in 2013, the commission said, the bay’s female horseshoe crab population has rebounded to about 11.2 million.

Under the new proposal, the fishing industry across four bay states — New Jersey, Delaware, Maryland and Virginia — would be allowed to catch a total of about 150,000 female crabs for bait next year. The fisheries commission contends that the quotas set would not threaten the crab population or the birds that feed on crab eggs. Quotas for the harvesting of 500,000 male crabs would stay the same next year.

In a new peer-reviewed paper, Larry Niles, a co-author and wildlife biologist who has monitored shorebird migration on the New Jersey side of the Delaware Bay for 26 years, reported that the density of horseshoe crab eggs on the bay’s beaches is only about one-tenth of what it was in the 1980s.

“A lack of recovery of horseshoe crab egg and shorebird abundance suggests that horseshoe crab harvest management has functioned to stabilize populations but has been inadequate to promote the recovery of horseshoe crab and shorebird populations, including the endangered red knot, to levels that existed prior to a wave of unregulated harvest,” the paper said.

Conservationists like Dr. Niles, who is a critic of the commission’s policies, argue that allowing any catch of female crabs would further reduce the supply of eggs, which is already sharply lower than it was before the knot population plummeted in the early 2000s.

Lifting the ban would put more pressure on a bird species that some believe is nearing extinction, they have argued. In 2015, the U.S. Fish and Wildlife Service listed the knot as threatened, and in 2021, the number of birds migrating via the Delaware Bay beaches dropped to a record low of 6,880, according to a count by Dr. Niles and others.

Conservationists who patrol the beaches during the brief migratory stopover each May say the number of birds has declined to a critical level because they can’t find enough food. The knots depend on crab eggs to regain weight after a long-distance migration that, for some, begins in southern Argentina. Without an adequate supply of horseshoe crab eggs, conservationists say, many birds will not be able to breed or will die en route to their breeding grounds in Arctic Canada.

Horseshoe crabs are also used by the biomedical industry for L.A.L., an extract of crab blood is put toward the detection of bacteria in medical products. The number of crabs taken by the so-called bleeding companies is not published for competitive reasons and is not part of the commission’s proposal.

Opponents of the commission’s plan argue that it is using inaccurate models that overestimate populations of crabs and knots, and that earlier declines in knots alongside higher crab harvests prove how reliant the birds are on this particular food source.

“Despite that history and the fact that both remain depleted, they are now assuming there is very little relationship between the two,” said Timothy Preso, managing attorney of the biodiversity defense program at Earthjustice, a nonprofit law firm that is representing the conservation groups. “We hope that A.S.M.F.C. will pause and take a reset on this because there are some big questions they have to answer.”

Mr. Preso also said the public had not been able to examine the commission’s plan because the U.S. Geological Survey has not released specific details of the model. A spokesman for the Geological Survey, Jason Burton, said the agency was reviewing requests for more information from Earthjustice.

Mr. Preso added that the commission’s plan to lift the harvesting restrictions could be a violation of the Endangered Species Act.

The commission defended its proposals, saying they were not the result of pressure from the fishing industry and were based on improved modeling and new data on crab and knot populations. The commission declined to comment on whether lifting the ban would not comply with the Endangered Species Act.

“The conceptual model of horseshoe crab abundance influencing red knot survival and reproduction remains intact with the intent of ensuring that the abundance of horseshoe crabs does not become a factor limiting the population growth of red knots,” said Tina Berger, a spokeswoman for the commission.

The commission also pointed to other factors threatening the knot population, Berger said, including loss of habitat due to rising sea levels and coastal development; disruption by natural predators such as peregrine falcons in breeding grounds; and an increasing mismatch between migratory patterns and the availability of food.

The population of knots passing through the bay each spring had been stable at around 45,000 in recent years, Berger said, although conservationists contended that count was based on modeling rather than actual counts.

The plan to update quotas has been endorsed by the U.S. Fish and Wildlife Service, which, in its own analysis, concluded there was a negligible chance that restarting the female harvest would reduce the knot population.

The federal agency acknowledged that the over-harvest of crabs on the bay in the late 1990s and early 2000s was the key reason for the birds’ decline. But the agency argued that that the crab population had become large enough to survive a resumed female harvest.

If approved, the fisheries’ recommended female catch would be less than 2 percent of the estimated population, said Bridget Macdonald, a spokeswoman for the Fish and Wildlife Service. By comparison, the natural mortality rate of female crabs is 26 percent to 28 percent a year, she said.

“The impact of directed harvest on the female horseshoe crab population is at such a conservative level that it would be indistinguishable from the effects of natural mortality that would occur even in the absence of harvest,” Ms. Macdonald said. “Thus, we conclude that this low level of female harvest will not reduce the availability of eggs for red knots or other shorebirds.”