By Scott Fallon
Perhaps the most remarkable creature to call the waters off New Jersey home is older than the dinosaurs, helps balance the state’s ecosystem and looks like it crept out of the Aliens movie franchise.
Now the horseshoe crab is playing a vital role in the development of a COVID-19 vaccine, with billions of doses expected to be produced worldwide over the next several years.
The crab’s distinctive blue blood has been used in the development and production of nearly all injectable medicines and vaccines along with medical devices in the U.S. and much of the world for four decades.
Its blood is hyper-sensitive to endotoxin, a bacteria that can enter the bloodstream through injections. Scientists developed a test in the 1960s using horseshoe crab blood that slowly became the industry standard to ensure that injectable substances won’t harm people.
And as pharmaceutical companies begin to role out COVID-19 vaccines, some of those vials will be deemed to be safe thanks to a creature that was sitting off the southern tip of New Jersey in the dark waters at the bottom of Delaware Bay — home to the largest population of horseshoe crabs in the world, at 25 million to 30 million.
But the 450-million-year-old crab that is often referred to as a “living fossil” is also a key cog in New Jersey’s often-battered ecosystem. The millions of eggs they lay each spring on New Jersey’s beaches are a vital food source for endangered birds such as red knots making their way along the East Coast during peak migration season.
Laboratories that bleed the crabs say they will be able to supply enough crab blood for what is anticipated to be the largest inoculation campaign in decades without significantly increasing the number of crabs they take from the ocean. Once bled, the crabs are returned to the ocean alive.
Conservation groups say they will keep a close eye on whether there is an impact to the crab population, whose dwindling numbers a decade ago led to a drop in the bird population and prompted a ban on commercial fishing for the crab.
“It’s absolutely worthwhile for horseshoe crabs to be used in the development of a vaccine,” said David Wheeler, executive director of the Conserve Wildlife Foundation of New Jersey. “They play an extraordinary role in public health. But they are irreplaceable in New Jersey and Delaware for how they keep the bird population alive.”
Every May, beaches in New Jersey, Delaware and Maryland are teeming with horseshoe crabs as they spawn. Each female will lay up to 90,000 eggs, which serve two ecological purposes: to ensure the survival of the species and to provide bountiful food for migratory birds.
Birds such as red knots and ruddy turnstones depend on the eggs for enough energy to complete their epic 9,300-mile journey each spring from South America to their own breeding grounds in the Arctic.
“There is no other way they can get the energy they need for the second leg of their journey,” Wheeler said. “Take the horseshoe crabs away and you take the shorebirds away.”
That apparently happened a little more than a decade ago. While it is difficult to get a census of a creature that lives at the bottom of the sea, wildlife biologists were able to see a precipitous decline in red knots on Delaware Bay beaches, dropping from 90,000 in the 1980s to 45,000 in the late 1990s, and to a low of 13,000 in 2007.
That prompted Gov. Jon Corzine to sign a law that banned harvesting horseshoe crabs, which were in demand as bait for eel and conch fishermen. But the law made an exception for taking horseshoe crabs to extract their blood for biomedical purposes so long as the crabs are released back into the ocean.
And so from Massachusetts to the waters off Cape May and on down to South Carolina, boats head out regularly to collect the crabs, where they are transported in refrigerated vans to laboratories. About a third of their blood is taken out of their bodies to develop the LAL test or limulus amebocyte lysate — the substance that reacts to the endotoxins. Industry guidelines call for them to be returned to the ocean within 36 hours.
But what happens to the crabs after that?
One study used by the Atlantic States Marine Fisheries Commission, which regulates commercial fishing of horseshoe crabs, estimates that 15% of the bled crabs die. The industry says it’s closer to 3% to 5%.
“The problem is no one really knows how many recover and make it to the next reproductive cycle,” said Barbara Brummer, state director of The Nature Conservancy in New Jersey. “The industry is not transparent and there hasn’t been a lot of independent study into this.”
The fisheries commission has designated the horseshoe crab population in Delaware Bay as “neutral,” meaning they’re neither endangered nor thriving.
“Delaware Bay is holding its own,” said Tina Berger, a spokeswoman for the commission.
The commission, which oversees fishing from Florida to Maine, has imposed a 500,000 annual quota for horseshoe crabs in the Delaware Bay. But that’s only for commercial fishing. The commission has no regulatory authority over biomedical firms, Berger said.
Allen Burgenson, an executive at the biomedical firm Lonza, which bleeds crabs, said his industry’s impact on the crab population in Delaware Bay is minimal.
“We are seeing many more crabs being taken from places like Charleston, South Carolina and Cape Cod,” said Burgenson, chair of the commission’s advisory panel on horseshoe crabs.
Burgenson has calculated that it would take less than a week’s worth of blood production from his industry to meet the demands of the global vaccine initiative for five billion doses given over a two-year period.
“This is no different from any other drug or vaccine that’s being developed,” he said. “Our product is used in nearly every injectable substance or medical device so we’re constantly meeting those demands.”
Conservationists have been pushing for the U.S. to allow synthetic alternatives to crab blood that would limit or even eliminate the need to take crabs out of the ocean.
“Why take a live animal out of its habitat when you could have a synthetic substitute?” Brummer said. “When you think of it, it’s unbelievable that we depend on such a primitive animal for so many of our health needs.”
Scott Fallon covers the environment for NorthJersey.com.
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