Rutgers lab churning out baby horseshoe crabs

LOWER TWP. – Six thousand baby horseshoe crabs made their way in the waters near Cape May this weekend, thanks to a Rutgers University center that grows and releases them into the wild.

The New Jersey Aquaculture Innovation Center released the hatchlings, each tinier than a child’s fingernail, into the Cape May Canal on Friday.

The center has released 250,000 of the young crabs over the past two years.

“I like to consider this a Head Start program for horseshoe crabs,” said Mike DeLuca, senior associate director of the Rutgers Institute of Marine and Coastal Sciences. “There is a 90 percent mortality rate for these crabs once they get into the wild. The crabs lay millions of eggs, but not many survive to become adult crabs.”

Enter the aquaculture center, which grows not only horseshoe crabs, but oysters and mummichog, a bait fish.

It’s part of an effort to replenish the population of horseshoe crabs, which is under pressure from habitat loss, commercial fishing that uses them as bait for whelk and eels (New Jersey prohibits harvesting them but neighboring Delaware does not), pollution and poachers.

But it’s also intended to spur economic development in southern New Jersey, where Delaware Bay is home to the largest horseshoe crab population in the world.

A property in the crabs’ blood called limulus amoebocyte lysate is coveted by the pharmaceutical industry, which uses it to test for contamination in drugs and medical devices. DeLuca said five groups have permits to harvest horseshoe crabs in New jersey for medicinal purposes.

The crabs are placed on racks and 30 percent of their blood is drawn before they are released. The pharmaceutical industry pays $15,000 per quart, which it uses to test for adulteration of drugs and medical devices to be implanted into patients, DeLuca said.

The process usually kills about 10 to 15 percent of the crabs, so it is important to keep replenishing their numbers in the wild.

The crabs are also a crucial food source for several species of endangered or threatened shore birds. Because the crabs lay their eggs in the sandy beaches of Delaware Bay, the area is the main stopover for red knots, a shorebird listed as endangered in New Jersey and proposed for listing as such with the federal government. The birds gorge themselves on horseshoe crab eggs to refuel themselves for the second half of their 10,000-mile annual migration from South America to Canada.

The red knot’s numbers have declined by 80 percent since 2000; there are about 35,000 left in the world. Other species that depend on the crab eggs include the ruddy turnstone and the short-billed dowitcher.

DeLuca estimated the horseshoe crab population in the mid-Atlantic region at 2.5 to 4 million, a number he said is slowly rebounding from years of decline.

Gene Slowinski, director of open innovation research at Rutgers Business School, said a team of six Rutgers MBA students is working on a marketing plan for the marine life the center produces.

“The fun part of all this is the marine guys got together with the business guys who got together with the students,” he said.

The center collects crab eggs from Delaware Bay beaches for three months of the year, when the crabs are most vulnerable to being eaten by other species. Housed and nurtured in large rectangular tanks in a warehouse not far from the Cape May ferry, the crab hatchlings can be studied in a way they can’t be in the wild at this early stage in their lives, giving insight into their habitat and feeding preferences, DeLuca said.

They require little specialized care through their first four years, when they grow old enough to try to make it on their own. The 600 or so crabs expected to survive from the 6,000 that were released into the canal may one day be seen dragging their helmet-shaped shells through the sands of southern New Jersey’s beaches — or lying upside and down and gutted after become lunch for an exhausted and famished shore bird.

It’s the circle of life, with a little assist from Rutgers.