PORTLAND, Maine -- With summer crowds flocking to Maine's beaches, scientists are asking visitors not to disturb the horseshoe crabs, whose mating season begins this month.
"We don't really have a good idea of what the population numbers are," said Sue Schaller, who operates Bar Mills Ecological and helps coordinate an annual census of Maine's horseshoe crab population.
Teams of volunteers are scouting beaches from Casco Bay to Bar Harbor to count the large, slow-moving, salt-water crabs, which head to shore to find members of the opposite sex and spawn just below the high-tide line. At Thomas Point Beach in Brunswick, volunteers have found 700 horseshoe crabs in a single day this spring, Schaller said.
The Department of Marine Resources, the Maine Coastal Program, the Casco Bay Estuary Project, and Bar Mills Ecological are supporting the counts and the training of volunteers like Jed Wright of Falmouth.
Wright, a federal wildlife biologist, volunteered with his daughter to survey a small private beach in Cumberland nearly every day between May 20 and the end of June.
Ania Wright, 7, spotted a female horseshoe crab carrying a male on her back on the first day of their survey. The grown-ups had missed them, her father said.
"It really, for her, was pretty exciting," Wright said. "The educational component is just fantastic. It makes you feel like you're doing something to help."
The surveys, which began in 2001, cover 14 sandy sections of coastline, including beaches in Cumberland, Yarmouth, and Freeport that are being inspected for the first time.
Schaller said horseshoe crabs used to visit several York County beaches, but have disappeared for reasons that scientists do not yet understand.
"You have to wonder why they are not there now," she said.
The counts were instituted after oceanfront residents told scientists they no longer saw horseshoe crabs in areas where they had once been seen, said Pete Thayer of the Maine Department of Marine Resources.
The surveys are starting to produce data on the size of the horseshoe crab population and its vulnerability to pressure from the fishing industry. The data could also help scientists monitor changes in the environment caused by coastal development, pollution, or other factors.