East Coast Biologists Puzzled By Horseshoe Crab Decline

[hatrack]

"Before dinosaurs roamed the land, horseshoe crabs crawled the ocean floor, always emerging on the beach this time of year to reproduce. Few things have changed over the eons for the living fossil with the distinctive armor-like shell, but recently, researchers have notice a decline in their numbers that is worrisome. "They're really hard to kill," said Jennifer Mattei, a professor and biology department chairman at Sacred Heart University in Fairfield. "They're in decline and we don't know why. That tells people something is wrong."

The decline had been noticed anecdotally, but first got the attention of researchers in the late 1990s in Delaware Bay. One of the crabs' predators, red knot shorebirds, weren't visiting the bay to gorge on horseshoe crab eggs as often as they had in the past. The bay had been an annual feeding ground for the red knots, which double in size to prepare for their long flight back north for the summer.

"One hypothesis is the birds are going to other places for food," said Brad Spear of the Atlantic States Marine Fisheries Commission, a quasi-governmental group that gets funding from the federal government and from 15 participating states to help manage marine resources in the region. That's when researchers noticed that the absence of red knots seemed to be linked to the dwindling horseshoe crab population. In 1998, marine officials developed the first management plan for horseshoe crabs, said Spear, who helped coordinate the interstate plan. "Population declines in one area may have an effect in other areas," Spear said.

In addition to asking states to monitor the horseshoe crab population, the plan further limited the number of horseshoe crabs that people could harvest. Crabs are harvested for use as bait in conch and eel fishing and for the pharmaceutical industry, which extracts the blood from the crab and use it to test for bacterial contamination in drugs. The crab's blood can be made to clot in the presence of bacteria and is the fastest and most reliable way to ensure intravenous drugs are bacteria-free.

In Connecticut, which also is a breeding ground for the crabs, harvesting isn't as popular as in other states, but there is evidence the state has fewer horseshoe crabs than it once did. Researchers said many people who live on the Connecticut coast have stories about horseshoe crabs piled up on beaches in years past. Although most people agree there are fewer crabs on the beaches now than in past decades, researchers have little data beyond one or two population surveys that catalog a broad swath of species along the ocean floor. Horseshoe crabs aren't researched much, probably because they are so abundant and don't have the economic value that seafood, such as lobsters, do."

EDIT

http://www.greenwichtime.com/news/local/scn-gt-crabs4jun19,0,3376927.story?coll=green-news-local-headlines

[Withywindle]

1. That's disturbing

When I was a kid in the 70s we'd go to the beach in MD every year (Dad's from Baltimore) and they'd be EVERYWHERE. It was actually a little traumatic for me; I was terrified of them when I was little.

I never ever thought they could be rare, and it's not like they're overharvested....