Delaware Bay, Science, shorebird ecology

A Case for Restoring the Horseshoe Crabs of Delaware Bay


In 1991 Mark Botton and Bob Loveland conducted a survey of horseshoe crab eggs lying on the surface of the beaches along the lower Delaware Bay.  At the time horseshoe crabs spawned throughout the Bayshore, in great numbers in all tides.  Botton and Loveland measured egg densities as high as 100,000 eggs/square meter. One could find windrows of eggs washed in piles on beaches like Reeds Beach.   Now barely a then of that remains

In 1990 Botton and Loveland measured egg densities of  100,000 eggs/square meter – now barely of tenth of that remain

Large portions of 6 Arctic nesting shorebird species died as a result of this catastrophic mismanagement of a public resource.  Without eggs, in abundance, the birds couldn’t build fat reserves needed to survive the flight to the Arctic or to breed.  Shorebird numbers on Delaware Bay fell by 70 %.  One species, the red knot, had to be federally listed as threatened.   Horseshoe crab eggs anchored the whole thing.

With the collapse of horseshoe crab eggs shorebird numbers fell by 70 %, the once iconic weakfish population crashed

But crab eggs anchored more.  The collapse of weakfish, the iconic bread-and-butter fish of Fortescue and other bayside communities, coincided with the decline of crabs.  Studies done in the 1950’s showed the stomachs of baitfish like shiners and killifish filled with eggs and the hatched young that followed.  The crab produced a platform of high protein food that supported the bay fishery.  Once the crab platform collapsed so did the fisheries.

Fortunately, nothing stands in the way of restoring the Delaware Bay ecosystem back to its full potential.  The restoration begins with bringing the horseshoe crabs back to full carrying capacity, the maximum number the bay can support,  three times the number that currently exists.

Fortunately, nothing stands in the way of restoring the Delaware Bay ecosystem back to its full potential.  Restoration starts with horseshoe crabs

Below is a case for action to do this.  I’ve prepared it in the form of a slide doc,  a modified powerpoint that is meant to be read as well as presented.   It was written for all the people who love the bay, the crabs the fish and the birds to convince them to take action.  It contains science but for everyone.

The action? To make sure every crab that is taken for whatever purpose must have a known origin and the user abides by the rules of that area.  In Delaware Bay, it is a male only harvest of 500,000 crabs.  Period.

To view press the first slide