Credit: (Steph Yin/WHYY)

If fisheries officials approve a plan to resume harvesting female horseshoe crabs for bait next year, the population of these ancient crustaceans and other wildlife in the Delaware Bay ecosystem could drop again, naturalists warn.

The proposal to allow the fishing industry to catch female crabs for the first time in a decade was first floated a year ago but then dropped by the Atlantic States Marine Fisheries Commission, a federal regulator, because of public concern over the fate of the creatures that date back hundreds of millions of years.

Now, the commission’s Horseshoe Crab Management Board is due to consider the idea again at a meeting next week on Oct. 16. This time it would allow more females to be harvested than was planned last year.

Sustaining Migrating Shorebirds

Naturalists urged the board to reject the latest plan, arguing it would mean a new cut to the food supply for migrating shorebirds. That’s especially true for  the federally protected red knot, which depends on horseshoe crab eggs on Delaware Bay beaches to complete a long-distance migration from South America to the Arctic Circle each spring.

“We urge the management board to retain the moratorium on the harvest of female Delaware bay origin horseshoe crabs,” said the Horseshoe Crab Recovery Coalition, a conservation group, in a statement.

Although New Jersey banned the harvest of all horseshoe crabs in its waters starting in 2008, the other three bay states — Delaware, Maryland and Virginia — still have annual quotas for the catch, set by the commission. The crabs are commercially valuable as fishing bait.

Conservationists argue that female crabs are essential to the survival of migratory birds and other creatures in the bay’s ecosystem. They say the population of both crabs and knots is still recovering from a drastic overharvest of crabs in the early 2000s which led to a crash in the red knot population, prompting predictions it was headed for extinction.

Partial recovery

Although the bird’s numbers have recently begun to recover, they are still well below the levels seen in the 1980s and early ‘90s. Unless their essential food source continues to be protected, the latest progress could be set back, naturalists warn.

The board’s previous decision not to reopen the female harvest was “widely applauded” by the conservation community at last year’s meeting, when some 30,000 public comment letters urging the board to drop the plan were sent to commission ahead of the meeting.

Since then, conservationists have welcomed a number of other steps toward protecting crabs and birds at various places along the Atlantic coast migratory route. They include a new law in Connecticut banning the hand harvest of horseshoe crabs; a federal court order banning the crab catch on about 30 island beaches off South Carolina during the red knot migration season; and a plan by the pharmaceutical industry to move away from using a crab-based product to test for bacteria in medical products.

But they now say the revived plan to catch female crabs would offset recent gains by making it harder for migrating birds to find food, and so reducing the chances that they will breed successfully.

Despite naturalists’ attacks, a link between horseshoe crabs and red knots underlies the commission’s ban on female harvesting, which has stood since 2013. The agency now estimates that the bay’s female crab population has grown to about 16 million from a recent low of 3.7 million in 2006, and that a proposed female harvest of up to 175,000 would not damage the population. The new catch would be 50,000 females more than planned a year ago.

By contrast, the proposed harvest of male horseshoe crabs in the bay would be 500,000 next year, the same as this year, in a population of about 40 million, the commission said.

The latest population estimates exclude removals by the biomedical industry, whose data are shielded from public disclosure by a confidentiality requirement, said Caitlin Starks of the commission.

Ecosystem integrity

The policy’s objective is to “manage harvest of horseshoe crabs in the Delaware Bay to maximize harvest but also to maintain ecosystem integrity, provide adequate stopover habitat for migrating shorebirds and ensure that the abundance of horseshoe crabs is not limiting the red knot stopover population or slowing recovery,” the commission said in its recommendation and briefing materials for the Oct. 16 meeting. .

But critics say the policy fails to protect either crabs or red knots because it is based on a flawed model, the Adaptive Resource Mechanism (ARM), that overestimates both populations. They say the model erroneously ignores the volume of crab eggs on the beaches as the crucial indicator of the crabs’ ability to feed the birds.

“They cannot sensibly resume a female harvest based on the outputs of this model,” said Ben Levitan, an attorney with Earthjustice, an environmental law firm that represents New Jersey Audubon and Defenders of Wildlife before the board. “This model continues to provide a veneer of safety and stability that masks the tremendous instability of the ecosystem.”

Levitan said public opposition to the proposed female harvest is just as strong as it was a year ago when the commission left the ban in place. At that time, it was about 7,000 public comments against to just one in favor, he said.

An earlier study by Kevin Shoemaker, a University of Reno professor, shows a strong correlation between the birds’ survival and the availability of horseshoe crab eggs, contrasting with the ASMFC’s model that ignores the relationship, Levitan said. Opponents of the commission’s policy don’t have their own estimate of the bay’s crab population but argue that the commission’s version is too high because it reflects the flawed model.

The two sides also differ sharply on the red knot population migrating through Delaware Bay each year; the commission’s estimate of about 40,000, based on modeling rather than observation, is about twice as high as the latest counts by observers on land, sea and air.

On the Delaware side of the bay, red knot numbers continue to decline because of a shortage of horseshoe crab eggs, said Steve Cottrell, president of Delaware Audubon. Although the annual catch is nominally male-only, it is not fully enforced by state fishery officials, and there are “disturbing reports” of poaching, he said.

“The necessary action for reversing the downward trajectory of the red knot is a total ban of the horseshoe crab harvest, with stiff penalties for violations,” Cottrell said.