CHATHAM, MASS. (WHDH) - A familiar sea creature that has helped save lives for decades may now need saving itself. 

Early each summer, horseshoe crabs crawl up on Massachusetts beaches to mate. 

“They are just lots of males here looking for some action,” one volunteer said. 

This time of year gives volunteers a chance to count just how many crabs remain. 

While horseshoe crabs outlived dinosaurs, their population along the East Coast drastically dipped in recent decades. 

One reason for the statistics is they are caught for fishing bait, another main other reason…they are captured for their blood. 

“You may not know it, but for the last 40 years we’ve been using purified horseshoe crab blood to ensure the safety of our medicine,” said Jay Bolden, senior director at Eli Lilly and Company.

The crab’s unique blue blood reacts to dangerous bacteria. That makes it a powerful tool when testing vaccines and other injectable medicines for contamination. 

“If you’ve had an injection, if you had an infusion, if you’ve had dialysis, if you’ve ever had a medical device, a vaccine, that [has] been tested for endotoxins using horseshoe crab blood,” Bolden explained.

Each year, around 200,000 crabs are caught for the biomedical purposes each year in Massachusetts. Nationwide, that number has tripled over the last 20 years, according to 2024 data from the Atlantic States Marine Fisheries Commission. 

While the crabs’ blood helps keep medicine safe, it also comes at a cost.

The Atlantic States Marine Fisheries Commission has historically estimated that about 15% of crabs die as a result of the biomedical process. 

“Without a doubt there is a negative impact on crabs through going through this process,” Bolden said. 

Horseshoe crabs don’t just help the biomedical industry, their eggs serve as a main source of food for other coastal wildlife. Scientists explain an impact to the horseshoe crab population creates a ripple effect throughout the environment. 

“You’re impacting migratory shore birds and sharks and turtles and spore fish, right? It’s all connected,” Bolden said. 

Scientists say there may be a better way to protect both people and horseshoe crabs. They have created a lab-made alternative to test medicines, so no crabs are needed.

“It is the exact same protein, it is just made through biotechnology,” Bolden said. 

Bolden said scientists at Eli Lilly tested thousands of samples on hundreds of different products and determined the alternative performs the same or better than purified horseshoe crab blood does. 

Starting in 2016, Eli Lilly started to switch its testing to the lab-made version. Now 80 percent of it is done using the alternative. 

The company plans to entirely eliminate the use of crab blood.

“When there is a suitable alternative that has been proven, that is scientifically valid, there really is no excuse to use a wild animal to do this test,” Bolden said. 

Bolden said it’s only fair to give back to the crustaceans that have given so much to science.

“We’re really grateful to horseshoe crabs really for protecting patient safety and protecting the supply of medicine, but this is our opportunity right now to positively benefit them,” he said.

“We’re seeing signs of hope,” said Mark Faherty, science coordinator at Mass Audubon’s Wellfleet Bay Wildlife Sanctuary. 

Part of that hope is due to changes Massachusetts has made in recent years. 

In 2023, Massachusetts put a limit on how many crabs the biomedical industry could catch annually. 

“Capping total horseshoe crab harvest and mortality is likely the single most important conservation measures the state can take this year,” said Dan McKiernan, division of marine fisheries director, in a 2023 press release announcing the cap. 

Then, in 2024, Massachusetts banned all horseshoe crab harvesting from April 15 through June 7, protecting about 90 percent of the spawning season. 

Faherty recalled just how bad the harvesting was when those protections were nonexistent.

“Before two years ago, someone could come to most beaches and just take female horseshoe crabs that were trying to spawn and then cut them up and use them for bait,” he said. 

With all types of harvesting now banned during those two crucial months for reproduction, Faherty is hopeful that the population will steadily increase. There are signs that the protections may be helping. 

Seventy-one percent of Massachusetts survey sites show an increasing population trend over the last 15 years. 

Last month, the Massachusetts Division of Marine Fisheries announced that horseshoe crab abundance continues to increase — but it could take another decade before the full benefit of the state’s newest protections becomes clear. The state attributed some of the population increase reported now to a 2010 decision to ban horseshoe crab harvest around new and full moons between April and June. 

However, in some areas of the state, the crabs have been protected for even longer, and the effects are noticeable. Faherty said the crabs were protected from bait harvesting for about 20 years.

“You clearly see in the data in and adjacent to these areas where there have been protections, longer term protections; they come back,” Faherty said.

While these protections seem to be taking a step towards changing the tides, Faherty said there is still work to do. 

“Things are looking up, but we need to accelerate that recovery, we need to eliminate unnecessary harvest,” Faherty said. 

Earlier this year, Massachusetts considered increasing the biomedical quota by 80,000 crabs. But after widespread opposition, the state withdrew the proposal. 

Other states are going further. Connecticut has banned harvesting of horseshoe crabs, while New York has passed legislation that will prohibit harvest beginning in 2029. 

Massachusetts lawmakers have proposed bills that would end harvesting the crabs for bait but they have not passed. 

In Massachusetts, harvesting is still allowed outside the two-month spawning season in most areas. 

“People are just rooting for them,” Faherty said. “There’s that resilience that 450 million years of success is built into them so if you just protect them a little bit they can come back.” 

Emma Martinez contributed to this report. 

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