The Mismanagement of Limulus polyphemus in Long Island Sound, U.S.A.: What Are the Characteristics of a Population in Decline?
Over the past 15 years, horseshoe crabs in Connecticut have gone from being considered a nuisance species to a species of Greatest Conservation Need in 2015. This has happened through first, its discovery as an economically important species, second through research of its ecological role in coastal estuaries, and third, through education of the public concerning its role in the environment and their own health. To manage horseshoe crab populations successfully requires long term monitoring, research and education. The use of annual or biannual trawl data trends to assess the success of management decisions is limited due to the high variance of counts by location, season, and year, and is prone to misinterpretation. Trawling also damages the very habitat that the target species needs to survive. What is required to reach the goal of a sustainably managed population is the determination of local population dynamics and then modifying management practices to maximize reproductive success of the species. In Long Island Sound (LIS), these basic requirements for sustainable management have not been available until recently. The two states that manage horseshoe crabs in Long Island Sound (Connecticut and New York) have drastically different harvest regulations and management plans that are clearly not working. The LIS horseshoe crab population has declined and remains low as shown by both the long term trawl data and our long term mark-recapture data. After 13 years of a classic ecological study we found the Long Island Sound horseshoe crab population to be one discrete management unit where at least 3 % of the recaptures were found to cross the Sound. The LIS population is aging with low recruitment of newly molted adults and is reproducing well below its maximum rate. We observed very low spawning densities, increasing numbers of single females on the beach, and less than 6 % of polyandrous mating behavior. These basic population trends over the length of this study indicate the current harvest quotas and management techniques are not sustainable. We recommend at the very least the implementation of a unified management plan for Long Island Sound with one shared harvest quota for the entire LIS population. Second, we suggest that the number of no-harvest zones should be increased on both sides of the Sound and a ban of the harvest of spawning females should be added to existing harvest regulations. Ultimately, we would recommend the establishment of multiple Marine Protected Areas (MPAs) within LIS where the entire MPA is off limits to commercial or recreational fishing of any type.
Beekey, M. & Mattei, J. (2016). The mismanagement of Limulus polyphemus in Long Island Sound, U.S.A.: what are the characteristics of a population in decline? In R.H. Carmichael, M.L. Botton, P.K.S. Shin, & S.G. Cheung (Eds.), Changing global perspectives on horseshoe crab biology, conservation and management. New York, Springer, 2015.