DURHAM, N.H. (AP) — Collecting and bleeding horseshoe crabs for biomedical purposes could be hastening a decline in their population in parts of the East Coast, according to researchers from Plymouth State University and the University of New Hampshire.

Horseshoe crab blood is used to make a life-saving product that ensures vaccines and medical equipment are free of bacterial contamination. The researchers captured crabs from Great Bay, collected some of their blood and strapped accelerometers to them to measure their speed and direction.

In a study published recently in The Biological Bulletin, they concluded that harvesting blood from horseshoe crabs for use in pharmaceuticals causes short-term changes in their behavior and physiology. For two weeks after the bleeding procedure, the crabs moved less frequently and in different directions, indicating they may have been disoriented. That is a concern because crabs are collected for bleeding during their breeding cycle, when it’s easiest to capture them on beaches. But if they are disoriented when they are returned, they may be less likely to breed, Chris Chabot, PSU professor of neurobiology. While the populations in New Hampshire are holding steady, the numbers of horseshoe crabs in Delaware and Cape Cod have declined.

“If the biomedical industry could delay the blood harvest, it would probably help these animals,” said Chabot.

Researchers say it’s unclear which is most detrimental to the crabs ”“ the bleeding, the transporting or simply keeping them out of their natural environment. But they say improvements in the process are critical to preserving the species which, in addition to its economic value, provides a critical food source for shorebirds that feed on crab eggs.