Lowcountry outdoors: 2023 Horseshoe Crab Awareness / Strandings

Thursday, May 4, 2023

2023 Horseshoe Crab Awareness / Strandings

Stranded horseshoe crab on Edisto Beach.
Broken tail prevents it from flipping itself over.

Horseshoe crabs will be coming onto the beach to lay their eggs during the full moon high tides, and beachgoers may witness them. Horseshoe crabs are vitally important to the ecosystem, since their eggs are eaten by migratory shorebirds, and the crabs themselves are eaten by sea turtles and sharks. When the horseshoe crabs come ashore, they are focused on mating and laying eggs, and can become flipped over and stranded when the tide goes out. Some horseshoe crab mortality is normal, but it is OK to carefully pick up a stranded horseshoe crab and place it back in the ocean.

Dr. Al Segars at Edisto on May 6

Dr. Al Segars is a retired SCDNR biologist and veterinarian. “About 10-percent of horseshoe crab mortality each year is beach strandings,” said Segars. “They prefer the habitat on the edges of barrier islands, because crawling up a flat beach is easiest for them. Edisto Beach from Access 30 to 37 and Otter Island are known to have concentrations of horseshoe crabs. Younger horseshoe crabs can turn themselves over using their tail, but older horseshoe crabs mostly cannot due to broken off or worn down tail length. Horseshoe crab eggs are vitally important to shorebirds like the Red Knot that must eat the eggs and store up enough energy to fly to the Arctic nesting grounds.” Segars comes to Edisto on May 6 to look for horseshoe crabs with the Edisto Land Trust.

Horseshoe crabs are in decline, and the S.C. Department of Natural Resources is asking for members of the public to report any sightings of horseshoe crabs to them using an online form. “We need your help, as the new moon and full moon approach, horseshoe crabs will be scuttling ashore to lay eggs. Why? Because tides are highest then and eggs have the best chance of surviving when buried at the high tideline.” Of course, the tide action uncovers some of the eggs and that’s when shorebirds swoop in to feast, highlighting Mother Nature’s balancing act between these species.