Harvesting of horseshoe crabs will end on more than 30 islands along the South Carolina coast under a new deal conservation groups struck with Charles River Laboratories.

The deal comes in the wake of a federal lawsuit challenging the Charleston-based lab’s controversial collection of the crabs for its lucrative blood extraction business. The company has long collected the crabs for their bluish blood, which is used to make an extract that can detect deadly toxins, a life-saving substance used in vaccines and medical equipment. A gallon can fetch $60,000.

But conservationists also have fought the practice for years, arguing that the harvest harms the crabs and threatens vulnerable birds such as the red knot, a species that feeds on the crabs’ eggs.

The agreement, which was filed Aug. 23 in the federal court in Charleston, lasts for five years and involves Charles River Labs, the S.C. Department of Natural Resources, Gault Seafood and Marsh Point Farm. The Southern Environmental Law Center represented the Defenders of Wildlife and the Coastal Conservation League.

It comes in the wake of investigative reports by The Post and Courier Uncovered project in 2022, “Monkeys and Blood,” and The State newspaper that exposed the secretive nature of Charles River Labs monkey-breeding and horseshoe crab businesses in South Carolina.

Horseshoe crab collection, according to the deal, would be restricted on more than 30 island beaches that are established feeding grounds for red knots. Charles River Labs agreed not to collect crabs from Cape Romain National Wildlife Refuge.

Federal wildlife officials determined this month that horseshoe crab harvesting was not compatible with Cape Romain’s mission of protecting nature and recommended it should be halted during the spawning season.

Catherine Wannamaker, senior attorney for the Southern Environmental Law Center, called the settlement a landmark in conservation in the Palmetto State that “represents a huge milestone for South Carolina wildlife and the citizens who care about it.”

She hailed the settlement as “rather incredible” in the protections it will offer red knot birds, which have seen a dramatic decline in the last decade. In 2014, they were listed as threatened under the federal Endangered Species Act.

Gregory Marshall, Charles River Labs vice president and general manager, said the agreement would allow for the conservation of both red knots and horseshoe crabs, which “play a vital role in ensuring patient safety.”

The deal also would prohibit the temporary placement of female horseshoe crabs in holding ponds so they continue to spawn on South Carolina beaches. It requires DNR to gather more data.

Charles River will also cover the financial cost of an independent monitor, who will report to federal court officials.

Robert Boyles, DNR’s executive director, said stewardship of South Carolina’s natural resources is a “team sport,” and that the agency would continue to collaborate with all parties.

Ben Prater of Defenders of Wildlife said the deal will help maintain the integrity of horseshoe crab populations.

And Faith Rivers James, executive director of the Coastal Conservation League, said the deal allows for “smart, focused restrictions on horseshoe crab harvesting.”

If after five years all of the parties wish to extend the deal, they can do so under the terms of the agreement.

Ema Schumer contributed reporting to this story.