shorebird ecology, wildlife conservation

new season on Delaware Bay

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Curlew Sandpipers have been the great attraction of the Heislerville Impoundments but they are of great value to marsh shorebirds as a roosting area at high tide. Photo by D WelchThe red knots of Delaware Bay have returned and with them the NJ shorebird banding team.  Over the last few days, we and the DE team have counted about 3,500 knot, mostly in Delaware’s Mispillion Harbor, but about 500 in the Reeds Beach area.   We estimate only a small number of ruddy turnstones and sanderlings in the bay but NJ Audubon’s David Mizrahi reports nearly 25,000 semipalmated sandpipers and semipalmated plovers, short billed dowitchers and other species in the Heislerville impoundments.    We are still in the beginning of the season.

Two issues tower above all this season.  The first is the number of birds in the bay.   There is solid evidence of population declines in the wintering areas and the big question for our team is whether  declines will be reflected in the Delaware Bay counts.  I’ve written on the declines before, but its safe to say for a number of species, red knots, ruddy turnstone and semipalmated sandpipers the future is by no means secure.

Location

2004/5

2005/6

2006/7

2007/8

2008/9

2009/10

2010/11

Tierra del Fuego

17,653

17,211

17,316

14,800

17,800

16,260

9,850

Florida west coast

NC

2,500

1,200

550

1,532

1,378

NC

Texas, Mustang Is.

120

 

117

121

26

55

13

SE United States *

4,543

NC

NC

NC

NC

NC

3,552

 

 

The second big question is what to do about the harvest of crabs.  All of the crab surveys of the previous year point to no improvement in the number of crabs or the density of eggs.  The reasons are at first obvious, the crab harvest has remained unchanged despite a moratorium in NJ and severe reductions in harvest in DE.  Why?  Because more crabs were taken by adjacent states. 

 

So the question of the harvest of crabs in other states is central to the recovery of the bays crabs.  Agency biologists are tossing around the question of whether crabs taken outside the Delaware Bay are actually Delaware bay breeders.   For example, the technical team of the ASMFC is now suggesting crabs harvested just off the tiny coast of MD and only a 20 miles south of the mouth of the bay are from another unknown breeding area. The first estimate based on a tortured data set was that only 13% of Maryland’s crabs were of Delaware Bay origin.  After acknowledging the difficulty of making an estimate the agency team switched over to the use of genetics information from only a handful of harvest trawls to arrive at an estimate of 50%.    The truth is MD harvest is likely all Delaware Bay crabs, but typical of ASMFC decision making, this will have to be proved.  In any other harvest — waterfowl, deer, bears — hunting agencies have to proof the harvest will have no impact on the population.  In the crazy world of marine fish harvests those hoping to conserve a species will have to prove the damaging effects before a harvest can be reduced or stopped. Most of MD horseshoe crab harvest is landed at Ocean City MD, only 30 miles from Delaware Bay and within the known non-breeding distribution of Delaware Bay crabs. Inexplicably the ASMFC technical team first suggested only 12% of the MD crab harvest is from Delaware Bay and the rest from some unknown breeding area.

But the prevarications of the ASMFC are amateur compared to the drug companies exploiting horseshoe crabs for their blue blood.   The agencies have been accepting, without serous scrutiny, industry estimates of 15% mortality from the bleeding of crabs for the essential chemical limulus amoebocyte lysate (LAL) used to detect bacterial contamination in everything from injectable drugs to surgical instruments and implants.  LAL is a life-saving extract from the blood of the crab that safe-guards the world’s supply of injectable drugs.  The companies drain crabs of their blood until it stops then release them to back to the wild.  Until last week, agencies accepted industry estimates of  15% mortality, but the first independent estimate found mortality of at least 30%.  But it could be worse.  The companies have been accused of dumping crabs from the  Delaware Bay into other locations and giving the crabs to the fishermen to release on their own word.

No one would  argue that bleeding shouldn’t take place — it is the most important use of horseshoe crabs.  But we shouldn’t be killing hundreds of thousands of crabs unnecessarily.    It’s time for a change.   Why not let crabbers catch crabs, sell the blood to the drug companies, then use the dead for bait.  Brutal as this sounds, it will limit the kill to 500,000 males instead of ~500,000 crabs bled and >500,000 crabs taken for bait  —  a more effective way start a recovery.

horseshoe crabs being bled.