PHILADELPHIA — Tens of thousands of horseshoe crabs from all over the East Coast climb like small army tanks from Delaware Bay and onto soft, sandy beaches each spring, ready to spawn with females capable of laying 90,000 eggs a season.

PHILADELPHIA — Tens of thousands of horseshoe crabs from all over the East Coast climb like small army tanks from Delaware Bay and onto soft, sandy beaches each spring, ready to spawn with females capable of laying 90,000 eggs a season.

They also carry within them a highly prized, copper-based, blue-coloured blood that’s used worldwide for testing vaccines and medical devices for toxins. As many as 750,000 horseshoe crabs were taken from waterbodies last year and transported to labs. There, up to 40 per cent of their blood was drawn by needles before they were released back into the wild.

Research has shown as much as 30 per cent of horseshoe crabs tested can die as a result of the blood extraction process, says the Horseshoe Crab Recovery Coalition, though specific numbers are hard to track. The need for a worldwide vaccine for COVID-19 has stoked fresh worries about the steady decline of horseshoe crabs as more of their blood might be needed for testing, leading to more deaths and an impact on spawning. Horseshoe crabs that have had blood taken have showed less movement, a necessity for breeding and spawning to keep populations thriving.

"In a technologically advanced society, there has to be a better way," said Eric Stiles, president and CEO of New Jersey Audubon, who has taken a lead role in the coalition, a group of 30 organizations that recently briefed congressional staff members on the issue.

"Fortunately a synthetic alternative exists that would conserve this iconic species without compromising human health," Stiles said.

Though horseshoe crabs are native to the Mid-Atlantic, they are closely identified with the Delaware Bay, the part of the Delaware River estuary that borders New Jersey and Delaware before emptying into the Atlantic Ocean. Their eggs provide food for 11 types of migrating birds such as the red knot, a federally threatened species.

They are not considered endangered, but the number of Atlantic horseshoe crabs has been declining since at least the 1990s, according to the National Oceanic and Atmospheric Administration, citing habitat loss and demand as commercial bait.

Horseshoe crabs are not really crabs but are distant cousins to spiders. They are not venomous or dangerous, and their ancestors date back 450 million years. Their blood contains Limulus Amoebocyte Lysate (LAL), which clots in the presence of bacteria and is used by researchers to detect toxins that could find their way into vaccines, needles, and medical equipment that go into human bodies.

That blood is valued at US$15,000 a quart.

The coalition is in favour of greater adoption of recombinant Factor C (rFC), a synthetic alternative to the blood. It is already being used in the manufacturing of two marketed medicines, according to the coalition, and is recognized as an alternative by the European Pharmacopoeia, which helps to establish standards and protocols in the E.U.

The U.S. Pharmacopeia has yet to follow that lead. It recognizes there might be alternatives to using horseshoe crabs, and has proposed qualifications needed for use of synthetic. A representative for U.S. Pharmacopeia could not be reached for comment.

But, the coalition calls the USP’s proposal "a lengthy and burdensome pathway."

"The COVID-19 pandemic is likely to lead to major increases in the use of horseshoe crab blood, as the nearly 200 vaccines and over 60 injectable therapies in development for COVID-19 will all need to be tested multiple times for fever-inducing contaminants," Elizabeth Baker, pharmaceutical policy program director of the Physicians Committee for Responsible Medicine, said in a statement. "As is often the case, policy is lagging behind the science. We must act now to remove unnecessary barriers to industry use of rFC."

The coalition is asking members of Congress to urge the U.S. Pharmacopeia to acknowledge that rFC is equivalent to the product derived from horseshoe crab blood. It is also urging the FDA to review existing regulations and guidance.

Stiles said horseshoe crabs are vital to the New Jersey economy. Tens of thousands of birders flock to Cape May starting in the spring to catch glimpses of migrating birds such as the red knots and ruddy terns that feast on the bay on their long journeys to the Antarctic.

"When you look at birding in Cape May," Stiles said. "It is a multi-hundred-million-dollar industry ... if you go to the Delaware Bay to watch these horseshoe crabs and shorebirds, and part of your soul doesn’t melt, you’re not human."

— The Philadelphia Inquirer