This Week’s Creature Feature ... Counting Horseshoe Crabs at Herring Bay
Ancient sea creatures provide food for birds, medicine for us
On the beaches of the Chesapeake, you can consort with creatures that predate the dinosaurs and whose existence you’ve benefited from if you’ve been to the doctor in the past 30 years.
Especially if you get up very early in the morning.
A full moon between mid-May and June signals the mating period for horseshoe crabs, limulus polyphemus. Females emerge from the water to lay eggs that are then inseminated by eager males. The worldwide epicenter of horseshoe crab reproduction is Delaware Bay. The swath of the Chesapeake between Annapolis and North Beach also attracts droves. Herring Bay sees a lot of horseshoe crab action.
This week, Advocates for Herring Bay are combing the beaches in the early hours of the morning, doing a headcount. Mark McCaig counted 125 on Fairhaven’s beach in the morning of June 4.
The Advocates hope to gauge this year’s population. Numbers across the crabs’ range are in decline. Among the reasons are loss of habitat to beach development and overfishing. The crab is used as bait by fishermen fishing for whelks and eels.
Fewer crabs means fewer eggs, which in turn means fewer birds like the red knot, which rely on the extra eggs for food in their northward migration.
Horseshoe crabs help people as well as birds. The study of their eyes has led us to understand more about our own. Their blood contains a protein that helps to sterilize medical equipment.
For the Advocates of Herring Bay, horseshoe crab counting is worth rising early: “Being outside at four in the morning under a full moon is an interesting experience,” says McCaig.
The data collected will be sent to the Maryland Department of Natural Resources, which is keeping tabs on the crabs’ habitats and population.