The Horseshoe Crab An Ecological Keystone in Delaware Bay

1. The Horseshoe CrabAn Ecological Keystone in Delaware Bay

2. Outline • Life history • Ecological significance of the species • Uses throughout history • From Native American to big industry • Current uses and issues surrounding the species • Ongoing research to alleviate pressures on the species

3. In the beginning… • Lineage pre-dates the dinosaur era • Pre-dates flying insects • Pre-dates flowering plants

4. Eggs and trilobite stage • 14 day development-hatching time • Extremely vulnerable to predation

5. Juvenile stage • Maturing to adulthood takes about 10 years and 14 molts! • Ages 1-10 live in Delaware bay or on the continental shelf

6. Adulthood

7. The Horseshoe Crab Spawn • Occurring primarily in Spring and Summer • Activity peaks in June • Around full and new moons • Each female may lay up to 88,000 eggs annually • Egg predation - the base of the food web

8. Ecology • Native range from Maine • to the Yucatan • Population centered • around Delaware Bay • Spawn in estuaries • Need well oxygenated sandy beaches • Low energy waves

9. Biological Importance of the Horseshoe Crab • Horseshoe crab eggs are important to migratory birds • Red knot • Uses eggs to refuel on their journey to the arctic • 95,000 visited the Delaware bay in 1989 • Only 16,000 in 2003

12. Early uses of the Horseshoe Crab • Native Americans • Ate muscle tissue • Used telsons as spear tips • First to use horseshoe crabs as fertilizer • Early Americans • 1800’s - collection for farm use as fertilizer or hog or poultry feed

13. The first over-harvest • Between 1920’s to the 1950’s harvest exploded as the fertilizer business went big

14. Current uses • Population rebounded from the 50’s to the 80’s • LAL and the medical industry • With horseshoe crabs abundant again… • Use as bait in the eel and whelk industries in the late 1980’s

16. Biomedical uses • Limulus amebocyte lysate (LAL) • A suite of proteins that aggressively gel in the presence of bacterial endotoxins • Ensures the sterility of intravenous drugs and medical devices to be placed in the body The biomedical industry is required to release the horseshoe crabs back into the wild after bleeding. Studies show only 10% mortality.

17. http://www.dnrec.state.de.us/fw/hcrabs/larry%20niles%20presentation.pdfhttp://www.dnrec.state.de.us/fw/hcrabs/larry%20niles%20presentation.pdf Declining crab populations

18. Inconsistent data collection ASFMC -Horseshoe Crab 2004 Stock Assessment Report

19. Why the rapid decline? • While the biomedical industry catches and releases, the eel and whelk fisheries are a 100% mortality harvest. • 1 female crab per eel pot • 1-2 male crab per whelk pot

20. Managing the horseshoe crab • 1998 ASMFC multi-state management plan • No harvest limits recommended (lack of data) • DE and NJ voluntarily reduced limits • Addendums I-III • Established a horseshoe crab sanctuary at the mouth of the Delaware bay • Created a quota transfers between states • Created a closed season during peak spawning Current harvest moratorium for both Delaware and New Jersey waters

21. Ongoing research • Artificial bait for both eel and whelk • Find out why horseshoe crabs are so effective at catching both eel and whelk • Core questions • Are the attractants the same for both species? • If not, isolation of the attractant from the horseshoe crab becomes even more difficult.

22. Laboratory bioassays • Whelk • Modified trap design • Eel • Flume tank design Drain Water input Eel traps

23. The road ahead • Hope to have a preliminary bait in the water by April/May 2007 • Field trials during this time to refine bait • Attractant • Delivery matrix

24. Questions?