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The horseshoe crab enhancement project at the Aquaculture Innovation Center (AIC) focuses on increasing survival of the horseshoe crab’s early life history stages. Aquaculture provides a means to give the young horseshoe crabs a jump-start on life.
This project was featured in NJ.com: “How Rutgers is ensuring horseshoe crabs’ survival in N.J. waters.”
Background
The Delaware Bay is one of the largest horseshoe crab (Limulus polyphemus) spawning areas in the world. Limulus is a key species in the estuary’s ecosystem because of its importance as food for migrating shore birds, in medical research and as bait for commercial fisheries.
The abundance of horseshoe crabs in the Bay declined considerably in the later half of the 20th century, largely due to overharvesting. New Jersey has imposed a moratorium on their harvest since 2008 and the Atlantic States Marine Fisheries Commission has curtailed harvest along the Mid-Atlantic. As such, there is strong interest to conserve and revitalize populations of this globally significant species.
Culture and Release of Horseshoe Crabs
The AIC is piloting research to evaluate the feasibility of large-scale aquaculture of horseshoe crab eggs harvested from suboptimal Delaware Bay beaches. The AIC is ideally suited for this effort having both seawater pumping capacity and base infrastructure to support a culture system using the same Delaware Bay water that hosts the natural population.
An aquaculture setting will provide early life stage horseshoe crabs protection from predation and enhance survivorship. Young horseshoe crabs will be released in the wild at 4-12 months of age.
The project also aims to develop a mark-recapture program that can be used to assess the success of a hatchery program for stock enhancement. The tagging effort will use an intramuscular tag that has been successfully used for tagging other molting crustaceans, such as blue crabs and spiny lobster. The tags will be inserted at the second juvenile tailed stage or later, when the crab is at least 6 mm in width. Trials will be conducted with horseshoe crabs maintained in the hatchery, so the success of the tag can be evaluated before the horseshoe crabs are released into the wild.
Research and Restoration Strategy
- Collect eggs from natural nests
- Culture at the AIC, enabling horseshoe crabs to grow in predation-free controlled environment
- Tag cultured horseshoe crabs
- Release older, bigger stronger horseshoe crabs back into Delaware Bay
- Assess recovery and survival of tagged horseshoe crabs post-release