Horseshow Crab Numbers Solid, Survey Finds

WEST OCEAN CITY – The local horseshoe crab population appears to be in good shape, according to the annual spawning survey conducted this summer.

“Locally it seems to be doing well, particularly at Skimmer Island,” said Maryland Coastal Bays Program (MCBP) technical coordinator Carol Cain. “It was just covered this year at certain times when they finally did show.”

MCBP enlisted volunteers to survey eight beach sites, which yielded 86 surveys, in the 7th Annual Spawning Horseshoe Crab Count.

Volunteers counted 10,690 horseshoe crabs in total, the most so far tallied in the annual survey.

The spawning season got off to a late start this year, with just one male horseshoe crab counted at the survey sites during May. The survey was extended through July to offset the delay.

Cain said the late spawning is a mystery for scientists.

“I don’t know what it was that delayed them this year. It’s a puzzle,” Cain said.

MCBP plans to begin future surveys in late May and continue counting through July, instead of early May through June.

One conclusion drawn from the survey is that the local horseshoe crab population should be genetically diverse, with three males counted for every female. Volunteers counted 8,391 males and 2,299 females this year.

Sites included three sections of Skimmer Island, which is located just north of the Route 50 bridge, the shore near the Oceanic Motel at the Inlet on the southwestern tip of Ocean City and Gudelsky Park in West Ocean City. Three sites on Assateague Island, with one on the Inlet and the other two on the bay side, were also surveyed.

Volunteers also found new spawning areas and saw more crabs than ever at less well-favored beaches. Wave energy, wind direction and temperature have some effect on where horseshoe crabs spawn, but the connection between those factors and the beaches selected by the reproducing crabs is not clear.

One unexpectedly well-used area was the southern tip of Skimmer Island, which had not been so popular with the horseshoe crabs in the past.

The survey also turned up 14 tagged horseshoe crabs at the Skimmer Island spawning sites. Thirteen of those animals had been tagged in 2007 or 2008, with one tagged in 2006. The crabs were tagged by either Salisbury’s Cambrex Labs or Virginia Tech University and were released off Ocean City and Tom’s Cove, Va., respectively.

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