The prehistoric-looking horseshoe crabs native to the Delmarva Peninsula are on the move for their annual migration down the Atlantic coastline back to Maryland.
According to the Maryland Department of Natural Resources, the peak of the horseshoe crab spawn depends on late spring and early summer high tides, culminating on or around each full and new moon in June.
“Dating back an estimated 350 million years, this yearly event along the Atlantic coast is thought to be the world’s oldest and largest wildlife migration,” said the department in a release about the arthropods. “On average, one spawning female horseshoe crab will deposit 20,000 eggs into the sand. Horseshoe crab eggs are a natural part of the diet for migratory shorebirds preparing to return to their summer nesting grounds in northern Canada.”
They also noted horseshoe crab larvae are an important food staple for juvenile Atlantic loggerhead turtles, as well as striped bass, American eel and flounder.
Biologists from the Maryland Department of Natural Resources monitor the returning horseshoe crab population for ecological and scientific research purposes.
The horseshoe crab’s blue, copper-based blood is critical for biomedical research. The animals are collected by specially permitted fishing operations, have blood drawn in a biomedical facility, then are released back into the water.
Conservation efforts
For its part, the Delaware Department of Natural Resources and Environmental Control has enacted conservation efforts to not only sustain healthy crab numbers in state waters but bolstered the future of migratory shorebirds that eat their larvae for sustenance on their journey.
The bellicose look of their armor and tail belies their gentle nature as they do not bite or sting, yet the department stresses people should give them ample space as to not injure them.
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“Shorebirds more than double their body weight during their brief stopover each spring along Delaware Bay, feasting on the abundant supply of horseshoe crab eggs from an increasing horseshoe crab population managed under the Atlantic States Marine Fisheries Commission’s Adaptive Resource Management framework,” Delaware’s department said.
It further noted the framework is an ecosystem-based approach that uses the best-available science to manage the Delaware Bay horseshoe crab population to ensure enough eggs to support the migratory red knot population during their annual spring stopover.
Under the management, the Delaware Bay horseshoe crab population has steadily increased over the last decade to an estimated 31.3 million crabs, made up of 21.9 million males and 9.4 million females.
Delaware allows a limited harvest of 162,136 only male horseshoe crabs, representing less than 1% of the scientifically estimated total Delaware Bay horseshoe crab population, with the harvested crabs used as bait for Delaware’s commercial conch fishery.
Horseshoe crab harvest in the state is not allowed until June 8 after migrating shorebirds have left to avoid disturbing the birds during their stopover.
The coastline itself has been the subject of conservation efforts by the department through beach nourishment projects designed to better handle storms and support native species.
“Both the Delaware Bay and Atlantic beaches and dunes also provide crucial habitat for migrating shorebirds, including several threatened species, and other wildlife, such as spawning horseshoe crabs — which, under ordinary circumstances, means beach nourishment projects must be completed by April 15 or by March 1 at some beaches, with beach nourishment not permitted again until Oct. 1,” it said in a statement following the recovery after the May nor’easter.
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The chance to witness the exodus to areas on the shore is possible under the supervision of the department.
