July 31, 2026 — Horseshoe crab populations in Massachusetts waters are reaching record highs, a sustained rebound that marine biologists attribute to decades of strict harvesting limits and expansive spawning protections.
According to July report from the Massachusetts Division of Marine Fisheries (DMF), data from three distinct surveying methods show significant increases in the species’ abundance, reversing a downward trend that persisted until roughly 2010.
The decline that preceded the recovery alarmed wildlife managers because horseshoe crabs play a critical role in both the coastal ecosystem and modern medicine. According to Cape Cod National Seashore, the animals are harvested for bait in eel and whelk fisheries, while their blue blood is used to produce Limulus amebocyte lysate, a substance used to detect bacterial contamination in injectable drugs, vaccines and implantable medical devices.