ANNAPOLIS, Md.— The Center for Biological Diversity sued the National Marine Fisheries Service today for failing to make a preliminary decision on whether to protect American horseshoe crabs under the Endangered Species Act. The Center and 25 additional organizations petitioned the agency in February 2024 to protect horseshoe crabs, who live along the Atlantic and Gulf coasts.

“Horseshoe crabs have saved so many people, and now it’s up to us to pay back that debt and save them,” said Will Harlan, a senior scientist at the Center. “We could lose these living fossils forever if they don’t get Endangered Species Act protections soon. It’s reckless to delay their obvious need for protection, so we’re going to court to force the government to do its job.”

Horseshoe crab populations have crashed by more than 70% in recent decades because of overharvesting and habitat loss. Biomedical companies drain the blood of horseshoe crabs for drug safety testing even though synthetic alternatives are available, approved and used widely in Europe and Asia. Biomedical harvests have doubled in the past seven years, with more than 1 million horseshoe crabs harvested in 2024.

Horseshoe crabs are also harvested for use as bait by the commercial whelk and eel fisheries. Even though horseshoe crab populations have fallen to historic lows, fishing regulators have increased the amount of horseshoe crabs that can be harvested.

In addition, development and sea-level rise are threatening horseshoe crabs and their spawning beaches across their entire range from Maine to Louisiana.

Nearly twice as old as the dinosaurs, horseshoe crabs have been crawling ashore for more than 450 million years. They are brown, body-armored arthropods with 10 eyes and a long, spiked tail. Each spring horseshoe crabs lay their eggs on beaches in massive spawning events.

As horseshoe crabs have declined, so have other species like endangered sea turtles, fish and birds. The rufa red knot, a shorebird species that feeds on horseshoe crab eggs during its 19,000-mile migration from South America to the Arctic, was listed as threatened under the Endangered Species Act in 2015. The listing decision cited horseshoe crab overharvesting as one of the contributing factors to the red knot’s decline.

An initial finding on whether the American horseshoe crab may warrant protection under the Endangered Species Act was due in May 2024.