Saturday, January 26, 2013

Horseshoe Crabs, Red Knots and Hurricane Sandy


Hurricane Sandy tore up much of New Jersey's coastline and the boardwalks and homes have gotten a lot of attention. But it also tore up natural areas in bays that are important to fish and wildlife.

One of those effects will probably be felt by our horseshoe crabs and the Red Knot sandpipers who depend on them and visit us each spring.

The Red Knot is one of the well-traveled shore birds that migrate in spring. Their trip is from a winter home in Tierra del Fuego (at the southern tip of South America) all the way to summer breeding grounds in the North American Arctic. Midway on that incredible journey, is a very important stopover in New Jersey.

Our Delaware Bayshore is a critical feeding place where the birds rely on eggs laid by horseshoe crabs. Red Knots can almost double their body weight in a few weeks of feeding.

Two unfortunate things are limiting their chances this year.

1) The superstorm damaged important horseshoe crab nesting beaches. The high water pushed sand higher into the dunes on salt marshes. It also exposed some mudflats, marsh plant roots, and debris.

2) Our state Senate and Assembly introduced bills to lift the moratorium on the harvest of horseshoe crabs for bait.

The NJ Endangered and Non-Game Species Program scientists have shown in great detail for several decades the importance of the horseshoe crabs to the migratory birds having sufficient energy stores to complete the journey to their Arctic breeding grounds.



The crabs will still go to the beaches to lay eggs. The birds will still arrive. Neither species follows the news about Hurricane Sandy.

But there may not be enough eggs to feed the birds AND to propagate sufficient numbers of crabs. The birds actually eat excess and dying eggs that will not become crabs. The viable eggs are buried and generally birds would not go after them.

In the past 30 years, we have gone from horseshoe crabs on top of each other battling for nesting space to far fewer egg-laying females on the beaches.

Part of the problems has been the harvesting of the crabs for the bait industry. Horseshoe crabs are also bled for lysate which is important to pharmaceutical uses. In both cases, the crabs used, even if returned to the water usually die.

NJ created a harvest moratorium starting in 2006 to help in the recovery of the crabs and to help prevent problems with the red knots.


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