Horseshoe Crabs
By John L. Turner
The horseshoe crabs that emerged during this Spring’s spawning season don’t know it, but their future and the future of their progeny is brighter than it has been for many decades.
The crabs can thank a convergence of actions for this outcome, one that will result in many fewer crabs being killed for some human use in the years ahead. This is because of a New York State harvest ban, research to develop effective alternative baits not involving horseshoe crabs that will prevent any attempts in the future to overturn the harvest ban in the future, increasing use of an alternative to the use of LAL only gotten by bleeding female crabs, and a petition by the Center for Biological Diversity to have the American horseshoe crab protected under the federal Endangered Species Act.
The most notable and directly beneficial of these actions was Governor Kathy Hochul’s signing legislation in December 2025 implementing a ban on the harvest of horseshoe crabs, which will be phased in over three years. For more than a decade the New York State Department of Environmental Conservation set an annual harvest quota of 150,000 crabs, harvested as bait for the whelk and eel fisheries. With the passage of the ban, 112,500 crabs can be harvested this year, 75,000 in 2027, 37,500 in 2028 and none from 2029 on.
This law is a huge step toward replenishing horseshoe crab populations from many decades of highly suppressed abundance. Conservationists were somewhat surprised by the Governor’s approval given the fact she vetoed legislation implementing a ban the year before; apparently adding the three year phase-out provision was enough to change her mind and the legislative outcome. And another great factor to help ensure accountability — it’s an election year!
Recognizing, though, that almost all conservation policy ties back to politics and therefore runs the risk of being reversed if, in this case, baymen convince enough politicians they have no effective alternative to horseshoe crabs, the Seatuck Environmental Association, NYS Department of Environmental Conservation, and Four Harbors Audubon Society are funding a study to determine the effectiveness of other bait formulations that can be used to catch whelk.
Being conducted by staff in the Marine Resources division at Cornell Cooperative Extension, the trials are taking place at the Lawrence Swanson Marine Lab at Flax Pond in Old Field.
In the trial, the bait formula is placed into a canister which water first flows through before emptying into a flume where whelk resides. An overview camera will record their movement toward the water scented with bait. Software will analyze the videos to determine if there’s a statistically significant movement of the whelk toward the water stream infused with the scent of the bait. (In a similar study conducted in a New Hampshire lab, a bait made up of pulverized green crabs — an invasive species — and clam bellies was more effective than a bait of horseshoe crabs in attracting whelk). The goal is to develop an alternative bait that is effective both as to cost and in field use; if this can be achieved, future pressure to reverse the harvest ban should disappear.
In several states, but not New York, female horseshoe crabs are captured to be “bled” to secure a chemical known as limulus amebocyte lysate (LAL) found in their blue-colored blood (horseshoe crab blood is copper based, while ours is iron based). LAL is used to detect certain types of bacterial contamination and is used to make sure that vaccines, other injectables, and joint replacement hardware are safe and free of contamination.
The bad news about this bleeding is that approximately 15% of the bled crabs die, resulting in tens of thousands of crabs succumbing annually. The good news is that scientists have successfully synthesized in the laboratory another compound called recombinant Factor C or rFC, which in many ways is even more effective than LAL in detecting bacterial contamination. In May of 2025 rFC was approved for use in the United States and was previously approved for use in Asia and Europe. As time goes on, crabs being “bled to death” should become a thing of the past.
Throughout their entire range horseshoe crabs will benefit from a successful petition by the Center for Biological Diversity to list the species under the Endangered Species Act. The Center recently brought the suit against the National Marine Fisheries Service (NMFS), contending that NMFS has not decided on the organization’s 2024 petition to list the species. If the courts agree, NMFS will have to make a determination if the petition has merit. And if it determines the petition has merit and lists the species, horseshoe crabs everywhere will benefit from the protective provisions afforded by this important federal law.
The “living fossil,” as horseshoe crabs are known, due to their ancient lineage going back in the fossil record approximately 400 million years, has drastically declined in abundance over the past century on Long Island. With the advances underway involving harvesting prohibitions and alternatives to bleeding, the future for horseshoe crabs in New York waters is brighter than it has been for many decades.