Part of an ongoing population study of the North American Horseshoe Crab, Limulus polyphemus, in Long Island Sound was completed during the 2003 – 2005 spawning seasons at Milford Point, in Milford, CT. Horseshoe crabs range more widely throughout Long Island Sound than expected and exhibit weak site fidelity. Animals originally tagged in Milford were found as far west as Stamford and as far east as Clinton, CT. during the 3 year study. Out of 522 female horseshoe crabs tagged in 2004 only 4 came back to spawn again at Milford Pt. in 2005. The sex ratios of tagged and recaptured horseshoe crabs are both skewed towards males (1:1.5 and 1:1.8, females to males, respectively). Only one percent of the horseshoe crabs that were observed to be mating at Milford Point were found in clusters consisting of one female and more than one male. In Delaware Bay, where horseshoe crab population density is higher, clustered mating behavior was reported to be 44% when counted in 1993 (Brockman, 1996). This difference in mating behavior may cause a decline in gene flow in the Long Island Sound population and could lead to the decline in health of the population. Harvest dates should be set for the last two weeks of June which would allow the majority of females to lay eggs before they are harvested and sanctuaries established, where no harvesting is allowed, in order to increase the Long Island Sound horseshoe crab population density.
Published in the Long Island Sound Research Conference Proceedings 2006.
Mattei, Jennifer Ph.D.; Goodell, Paul; DePierro, Christine; and Burke, Meghann, "A Switch from Polyandry to Serial Monogamy: Results from a Three Year Tagging Study of Horseshoe Crabs in Long Island Sound" (2006). Biology Faculty Publications. 6.