Under the light of the summer full moon, College of Southern Maryland students have been wading into the shallows of local beaches with a decidedly ancient research subject: horseshoe crabs, animals that have crawled onto Atlantic beaches to spawn for hundreds of millions of years, long before dinosaurs existed.
The effort is led by CSM biology professor Dr. Tracey Stuller, who has spent the spawning season — roughly mid-May through early July — bringing student volunteers to local beaches to tag the crabs as part of the U.S. Fish and Wildlife Service’s Cooperative Horseshoe Crab Tagging Program. “The tags… help track where they’re going and learn more about the scope of the local population,” Stuller said.
Stuller’s tagging effort grew out of a longer-running relationship with horseshoe crab research. Since 2023, she has led student trips to Cape May, New Jersey, on the Delaware Bay, which hosts the largest horseshoe crab spawning population in the Western Hemisphere and has become the epicenter of decades of tagging and conservation work tied to the species. Southern Maryland’s own stretch of Chesapeake Bay shoreline supports a smaller but ecologically significant breeding population, and Stuller and her students eventually launched a parallel tagging effort closer to home in Calvert County, applying techniques they learned in New Jersey to local beaches. “Many of our volunteers don’t know much about horseshoe crabs, and hosting these events closer to home gives them an opportunity to learn about them and grow an appreciation for our regional ecosystem,” Stuller said.
The USFWS tagging program Stuller’s students contribute to has operated since the late 1990s and represents the longest continuous dataset on horseshoe crab movement along the Atlantic coast, with well over 165,000 crabs tagged and roughly 17,000 recaptures recorded in past program assessments. During tagging events, volunteers walk the shoreline searching for crabs and their eggs, learn about the species’ biology and history in the region, record data including size and sex, and drill a small hole in the edge of a crab’s shell to attach a numbered tag before releasing the animal back into the water.
Horseshoe crab populations have declined sharply from historic levels along the Atlantic coast, a trend scientists attribute to decades of harvesting for bait and, more recently, for the biomedical industry, which relies on a compound in the animals’ blue blood to test medical equipment and vaccines for bacterial contamination. That decline carries consequences well beyond the crabs themselves: horseshoe crab eggs are a critical food source for migratory shorebirds, most notably the red knot, a long-distance migrant that stops at Delaware Bay each spring to gorge on the fat-rich eggs before continuing to its Arctic breeding grounds. The U.S. Fish and Wildlife Service listed the red knot as a threatened species in 2014, citing the bird’s dependence on a healthy horseshoe crab population among other pressures. Data gathered through tagging programs like the one CSM students participate in helps regional fisheries managers estimate whether local crab populations can sustain both the species itself and the shorebirds that depend on it.
For CSM students, the appeal has been as much personal as scientific. Hannah Aud, a human services major who joined this spring’s Cape May trip before continuing with tagging events in Calvert County, said the experience reshaped how she thinks about the region’s wildlife. “It made me more aware of horseshoe crabs and what interesting creatures they are,” Aud said. “It sparked something in me that I wanted to learn more about and do my part.” Kloie Austin, an environmental science student who plans to pursue a career in animal science and conservation, described a similar shift after her first season of tagging. “So many people think they look scary, even though they are so helpful for our environment,” Austin said. “I want to do my part in conserving the bay and helping our ecosystem in Maryland.”
The tagging program fits within CSM’s broader recognition as a “bird campus” by the Maryland Bird Conservation Partnership, a designation tied to the college’s conservation programming, including its horseshoe crab work given the species’ role in supporting migratory bird populations.
CSM is now recruiting volunteers for next year’s spawning season tagging events, with interested students and community members able to sign up through a volunteer form available through the college.
