Horseshoe crab population in Long Island Sound is in 'severe decline,' study finds

Loss of habitat, overharvesting and a degrading environment have contributed to the persistent "severe decline" of horseshoe crabs in and around Long Island Sound over more than two decades, according to a report in the journal Nature that reviewed a half-dozen field studies.

There’s a need for more data collection to monitor the species, which has survived 450 million years, according to the study. But one of Long Island’s longest-running surveys of horseshoe crabs ended in June with the closure of Molloy University’s Center for Environmental Research and Coast Oceans Monitoring field station in West Sayville for financial reasons.

The study in Nature’s Scientific Reports catalog horseshoe crabs’ "severe population decline in multiple locations for over 20 years," with declines averaging from 2.8% to 9.3% per year in "all six Long Island Sound region datasets." The researchers looked at data from Long Island and Connecticut sites, as well as one in the center of Long Island Sound, where they found the declines less consistent and one brief period of increase.

"The data presented here are suggestive of alarming trends in the abundance of L. polyphemus [the crab’s Latin name] in Long Island Sound, alongside demographic changes that may hamper population recovery," according to the report. "Given these concerning trends, urgent action is needed to prevent loss of local populations in this important species."

Release of the study comes as Gov. Kathy Hochul is once again mulling a bill passed by the State Legislature that would ban the harvest of horseshoe crabs for bait and biomedical purposes. Her spokesman, Ken Lovett, on Wednesday said only that Hochul "will review the legislation."

In her veto message last year she said her Department of Environmental Conservation had implemented countermeasures to keep the species’ decline at bay, saying management of the species is "better left to the experts."

The Atlantic States Marine Fisheries Commission, an interstate fisheries management body, in a 2024 assessment found the New York population of horseshoe crabs were in "poor" shape.

Conservation groups, collectively incensed by Hochul’s December veto, are urging her anew to sign the bill this year. While Hochul’s DEC "maintains that they can manage the horseshoe crab population, it is clear their strategy has shown little, if any, improvement in the overall population," said Group for the East End, an environmental organization. "We do not need more data; we need action!"

John Tanacredi, a Molloy University professor of earth and biological sciences whose research is cited in the study, said continued field studies and a ban on bait harvesting are crucial to the survival of the species locally. Closure of CERCOM, which he directed, came because the center "reached the end of its funding cycle" by Molloy. He said he continues to do research, but "lab facilities are not available for the foreseeable future."

For 22 years, Tanacredi and a team of research assistants conducted beach surveys of 115 locations across the region during the horseshoe crab spawn in spring and summer. The report called continued monitoring of the population "essential" to determine whether the declines were part of a longer downward trend. Tanacredi cited the state’s continued allowance of the harvest of up to 150,000 horseshoe crabs a year for bait as the main culprit in population declines.

"It goes right back to the collection for bait," he said. Most "are not even getting onto the shore in New York. If they had a chance to get onto the breeding beaches before they were removed" the decline could be offset, he said.

Connecticut and New Jersey, among other states, already restrict the harvesting of horseshoe crabs.

Will Caldwell, a Hampton Bays fisherman who has worked with regulators on possible alternatives to horseshoe crabs for bait, said none have worked and he opposes a ban because it isn’t needed.

"I’ve never seen as many horseshoe crabs on the beaches as I have in the last two years," he said. "Last year was insane. I was tripping over them."

During the harvest season, fishermen can take up to 200 horseshoe crabs per day, and are restricted from harvest around high-spawn full-moon days.

Caldwell noted that a relative collapse of the overseas food market for whelk, a large snaillike creature known locally as conch, has translated into a lower horseshoe crab harvest in the past two years. Horseshoe crabs are the primary bait for use in whelk traps.

But the report cited other factors in horseshoe crabs’ decline, including coastal "armoring" against sea level rise, pollution and "infrastructure development," all of which are "reshaping coastlines and diminishing the extent of natural areas ideal for horseshoe crab spawning." The study also cites "a potentially concerning trend" — a change in the sex ratio in two of the population studies showing a larger percentage of females.

"The long-term trends are alarming and clearly indicative of a population in decline, especially for the Peconic Estuary," according to Christopher Gobler, a professor at Stony Brook University’s School of Marine and Atmospheric Sciences. "While there are regional, mid-Atlantic regulations, the trends suggest tighter regulations at the state level, at least for the Peconics, might be helpful/needed," he wrote in an email.

By Mark Harrington

mark.harrington@newsday.comMHarringtonNews

Mark Harrington, a Newsday reporter since 1999, covers energy, wineries, Indian affairs and fisheries.