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Conservation groups urge Delaware to set its own ban on harvesting female horseshoe crabs

Horseshoe Crabs on Pickering Beach
Delaware Public Media
Horseshoe Crabs on Pickering Beach

A regional fisheries regulator appears poised to allow people to catch female horseshoe crabs in the Delaware Bay for the first time in a decade.

But that has some conservation groups up in arms and worried the move could put the red knot and other migratory shorebirds that feed on the horseshoe crab eggs at increased risk.

Contributor Jon Hurdle explains why the Atlantic States Marine Fisheries Commission is considering the change and the opposition to it.

Contributor Jon Hurdle explains why conservation groups are urging Delaware to set its own ban on harvesting female horseshoe crabs

Critics of a plan to catch female horseshoe crabs in the Delaware Bay for the first time in 10 years urged Delaware to ban the crab harvest altogether in its waters, saying a resumption of the female harvest would mean a new threat to the survival of the threatened red knot and other migratory shorebirds.

As a fisheries regulator moved closer to allowing the female catch to resume next year, Delaware Audubon and other conservationists assailed the plan which they said would further cut the supply of crab eggs, making it harder for the red knot’s rufa subspecies to find the food it needs to complete a long-distance migration via the bay beaches each spring en route to breeding grounds in the Canadian Arctic.

The Atlantic States Marine Fisheries Commission held hearings in Delaware and other mid-Atlantic states in early September to gather public comment on a plan that, if finally approved in November, would allow the annual harvest of about 150,000 female crabs for bait starting in 2023, as well as a catch of 500,000 male crabs, which is already permitted.

Commission officials say the number of female crabs in the bay has increased to about 9 million, and that the number of red knots passing through the bay on migration every spring is estimated by modeling rather than observation to be stable at about 45,000. It says that a bay-wide harvest of 150,000 female crabs would be less than 2 percent of the population, and so would not damage the species or its ability to feed the birds.

But conservationists dispute the commission’s count of the birds, saying the actual number is much lower, and that the population isn’t large enough to withstand threats such as the bigger storms that are coming with climate change. Naturalists fear that a portion of the red knots’ population that migrates from southern South America to Arctic Canada via the Delaware Bay each spring – the so-called long-distance birds -- may already be headed for extinction.

“Based on actual observations rather than controversial computer model estimates, extinction of the rufa subspecies is now an imminent possibility unless responsible and resolute action is taken by Delaware public officials,” said Steve Cottrell, president of the Delaware Audubon Society, in a statement.

A Red Knot birg
Delaware Public Media
A Red Knot bird

Because of the birds’ dependence on crab eggs to regain weight after flying thousands of miles, Delaware should have banned the harvest in 2014 when the federal government listed the species as threatened, Cottrell said. If it had acted then, it would have matched the standard set by New Jersey which banned the harvest of all horseshoe crabs in its waters with a state law in 2008.

New Jersey’s moratorium may have helped to stabilize the population of knots, albeit at lower levels, in the 2010s but the numbers appear more recently to have resumed their decline. In 2021, the number of red knots counted by observation bay-wide dropped to a record-low 6,880. That measure edged back up to about 12,000 this year but is still a fraction of the 90,000 or so that visited annually until the late 1990s, drawing scientists and birders to one of the world’s great natural spectacles.

Pressure on the crab population is increased by the biomedical industry that catches an unpublished number of crabs for their blood which is used to detect bacteria in medical products including vaccines. So-called bleeding companies extract about a third of the animals’ blood and then return them to the ocean where some die and others are unable to breed, conservationists say.

Even though there’s an effective synthetic alternative to the crab-based product, the new substance hasn’t yet been officially endorsed by USP, a trade group that sets professional standards, and so demand for crab blood remains high among U.S. biomedical companies.

Now, naturalists say Delaware could help preserve the crucial food source for the birds by imposing its own ban on the crab harvest, which it can do even if the commission finalizes its plan to restart the harvest of females.

“The horseshoe crab bait harvest moratorium must be a priority issue for the 2023 Delaware legislative session,” Cottrell said. “Delaware officials will be recognized worldwide as environmental champions if they have the courage to take the necessary action to prevent the iconic red knot from sliding to extinction. They must also keep in mind that if inaction results in the demise of the red knot, there is no reset button.”

Cottrell told Delaware Public Media lawmakers have not responded to his latest letter but he has over the last year urged all members of the legislature to support his call and has received a positive response from some of them.

“We are in the early stages of our legislative effort, but as we get closer to 2023 we will be reaching out again to all the legislators to see where they stand on this issue,” he said.

State Sen. Stephanie Hansen (D-10), chair of the Environment and Energy Committee, called the proposal to restart the female crab harvest “unwise”. She said the policy would increase pressure on horseshoe crabs after they were harvested in increased numbers during the Covid-19 pandemic because their blood is used in the production of vaccines.

Hansen also argued that the commission’s model hasn’t included all climate-change impacts, including warmer water temperatures, when projecting crab numbers.

And she accused the commission of proposing a policy that would promote fishing industry interests while doing no more than preventing a further drop in the numbers of crabs and knots. Rather, she said, the commission should be seeking to protect the whole ecosystem.

“There are many other species, some threatened or endangered like our new state sea turtle, the loggerhead, that depend upon horseshoe crab eggs for their survival,” she said. “We need to take a more holistic view of what any increase in horseshoe crab harvesting, particularly for females, means to the entire ecosystem.”

Possible solutions could be a revision to the commission’s plan that would allow more scope for crab recovery; an executive decision by the Department of Natural Resources and Environmental Control to opt-out of the female crab harvest, or a new law to ban the female catch in Delaware waters, she said.

But Hansen said she wants to wait for the commission’s final decision in November before deciding whether a bill is needed. She also raised the prospect that DNREC could impose its own ban on the female harvest before the legislature returns in January.

Michael Globetti, a spokesman for DNREC, declined to say whether Delaware would impose its own ban on the female crab harvest if the commission adopts the plan.

When the commission completes its process, “the state will consider public input and the best available science for horseshoe crab and related red knot management,” he said. “Delaware’s allowable horseshoe crab harvest is required to be at least as restrictive as the upcoming harvest measures approved by the ASMFC.”

Globetti said DNREC has currently issued 63 conch pot licenses and 55 eel pot licenses, both of which use horseshoe crabs as their primary bait. He said every licensee is an individual business because Delaware does not have large commercial fishing companies.

For its part, the commission wants to update its Adaptive Resource Management framework that’s designed to maximize the harvest of horseshoe crabs while providing adequate stopover habitat for migrating shorebirds. The program is also designed to ensure that the crab population is not limiting the number of birds stopping over on bay beaches such as those at Sussex County’s Mispillion Harbor, or impeding the recovery of the species overall.

The Virginia-based regulator has gathered 10 years’ worth of data for the Delaware Bay region since the model was adopted in 2012, and now says it needs new software that can incorporate data on crabs and birds – factors that the old software was not capable of handling.

If the proposed framework revision had been in effect in 2019, the most recent year for which data are available, it would have assumed a female crab population in the bay of about 9.4 million, a male crab population of 21.9 million, and red knot numbers of 45,100, according to an online presentation by commission officials. That scenario would allow a bay-wide female crab harvest of 144,800 and a male harvest of 500,000. Under the revised framework, the commission would not recommend a maximum female harvest of more than 210,000 in any year.

A Horseshoe Crab survey being conducted
Delaware Public Media
A Horseshoe Crab survey being conducted

“The Commission’s Revised ARM Framework was peer-reviewed and endorsed as the best available science for managing the bait fishery of Delaware Bay-origin horseshoe crabs to ensure that horseshoe crab management does not affect the recovery of the red knot population,” the regulator said in a statement.

Critics of the commission’s plan argue that the density of horseshoe crab eggs on the bay beaches has dropped to about a fifth of what it was when the shorebird population was much larger, and that’s a crucial sign that the female crab harvest should not be restarted.

But the commission said egg data were not included in its model because the numbers gathered on both sides of the bay have been too variable, and that the data and its methodology was not provided to the commission when it was developing the model. “These inconsistencies and the variability made the datasets a poor choice for the model and there were better inputs for the model,” it said.

It acknowledged the need for more research on egg density but argued that even if more was known about the relationship between egg density and red knot survival, it would probably not influence the model because it has already established a link between female crab abundance and survival of the bird.

Asked to explain the difference between its modeled estimate of the red knot population and the much lower numbers reported by some scientists from observation, the commission said the low physical counts of the Covid years 2020 and 2021 may reflect a reduction in the number of observers available to watch sites where the birds gather.

“The commission determined it is more accurate to model the population using physical count numbers as an input to the model,” it said.

The plans were endorsed in January by the U.S. Fish and Wildlife Service, which said the proposed harvest of female crabs would represent a “negligible risk” to the recovery of red knots. The federal agency compared the revised model to a scenario where there would be a full ban on the harvest of horseshoe crabs in the Delaware Bay region, and found there was almost no difference between the two scenarios.

“We found that there is less than a 1 percent chance that bait-harvest levels guided by the revised ARM framework will result in a lower abundance of rufa red knots, relative to the moratorium scenario,” said Bridget Macdonald, a spokeswoman for the agency.

Conservationists argue that any resumption of the female crab harvest now would increase the threat to the knots and other species such as the semipalmated sandpiper – which has also declined sharply in the last two decades – from which they may not recover.

Matthew Sarver, conservation chair of the Delaware Ornithological Society, said the project lacks reliable data on the number of crabs and knots in the bay before the populations plunged in the early 2000s in response to over-harvesting of crabs.

“The fact that we don’t have good baseline historical data prior to this large crash that we all know occurred, combined with the fact that there’s no attempt to estimate ecological carrying capacity to inform the model is really of great concern to me about the appropriateness of this model in managing this system moving forward,” he said, during the public hearing for Delaware.

Sarver said the model uses only one input related to climate change – snow cover in the knots’ Arctic breeding grounds – whereas accelerating climate change has many effects that could influence the number of crabs and birds. He said the proposal should also include effects on other birds and marine species, and is based on recent bird counts that may not be reliable because of personnel restrictions during the Covid-19 pandemic.

“So this is really, really bad timing for making quota changes with the fact that we are coming off several years of unreliable population estimates for red knot,” he said.

Chris Bason, former executive director of the Center for the Inland Bays, a Sussex County nonprofit, also opposed restarting the female crab harvest, arguing that their eggs are an important ecological resource,

He called on the commission to delay the female crab harvest for the 10 years that the model covers. “That would allow those projections to be evaluated so that we can understand better the ecological carrying capacity for the crab,” he said.

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Jon has been reporting on environmental and other topics for Delaware Public Media since 2011. Stories range from sea-level rise and commercial composting to the rebuilding program at Prime Hook National Wildlife Refuge and the University of Delaware’s aborted data center plan.