Delaware Bay
U Odyssey This
Horseshoe Crab Bait Subsitute
Horseshoe crabs first appeared on earth some 200 million years ago and haven’t changed much since then. They are a well-studied creature that is used to support human health, scientific research and the fisherman of Delaware Bay. Research on the horseshoe crab eye has revealed much information on how we see. The blood of the horseshoe crab is used by the pharmaceutical industry to manufacture a product called Lysate or LAL (Limulus Amoebocyte Lysate). LAL is used to test drugs to ensure they are bacteria free.
Horseshoe crabs are an important species to the millions of migrating shorebirds that visit Delaware Bay each spring. Each year starting in late May during the new and full moon hundreds of thousands of horseshoe crabs converge on the beaches to spawn and bury their eggs.
The horseshoe crab spawn coincides with millions of shorebirds stopping over from their long flight to their northern breeding to refuel for the journey. Delaware Bay has the largest population of horseshoe crabs in the world. Horseshoe crab eggs are rich in protein and easy to find. A shorebird can gorge on these eggs for a few short weeks and be ready to head north to nest and lay eggs.
The red knot is one of the most remarkable of these shorebirds. It begins its migration from the southern tip or Argentina and Chile. It will make only two stops on its way to the Artic -- once in Brazil and then again at Delaware Bay. When these birds arrive in Delaware Bay they can weigh somewhere around 112 grams. By the time they leave, depending on the abundance of crab eggs they can weigh 180 grams, a weight increase of approximately 40% in a two week period.
Horseshoe crabs are important to fisherman of Delaware Bay. They use the crab as bait for catching conch and eel. Because they are so easy to harvest the horseshoe crab has been subject to intense overfishing and has rapidly declined in numbers. This decline is particularly hard on the shorebirds that rely on the quick boost of energy and protein from the eggs so they can finish their migration.
The State of Delaware faced with declining numbers of horseshoe crabs and shorebirds and faced with intense public pressure has placed a moratorium on the collection of horseshoe crabs. This is very difficult for the fishermen that rely on the conch and eel fishery.
The State of Delaware asked the University of Delaware to assist with the development of an alternate bait. Dr. Nancy Targett and her team have isolated a mixture from the female horseshoe crab that makes them so attractive to eels and conch. The University of Delaware team has also developed a matrix to hold the attractant so it can slowly release the attractant.
DuPont is assisting the University of Delaware on a voluntary basis to accelerate their development of an alternate bait. DuPont Chemical Solutions Enterprise is bringing its analytical chemistry and formulation science to bear on this unique challenge as part of its global commitment to sustainability and, specifically, its ongoing support of the ecology of the Delaware estuary.