Fisheries
Bait Extensions or Bait Bags
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Bait bag with horseshoe
crab bait |
Developed by Frank Eicherly, a commercial waterman
from Bowers Beach, Delaware, and formerly marketed by the Ecological
Research and Development Group (ERDG), this polyethylene
mesh bag protects horseshoe crab bait from scavengers, extending
the number of tidal cycles that the horseshoe crab bait can
be fished. In a Sea Grant study with Virginia conch fishermen,
researchers found that overall bait needs can be reduced by
50% when bait bags are used. In 2000, Virginia fishermen
adopted the bait bags for their pots.
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Dr.
Nancy Targett is leading a Sea Grant research
project to reduce the use of the horseshoe crab as
eel and conch bait by developing an artificial bait
based on the chemical attractant found in the crab. |
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Artificial Bait
Why are horseshoe crabs
such an excellent bait for eels and whelk? Eel fishermen refer
to egg-laden females as a "superior bait," even though
eels prefer other types of food in the wild. Is it possible
that a specific odor or chemical cue attracts eels to female
horseshoe crabs? A few years ago, Dr. Nancy Targett and her
research team at the University of Delaware College of Earth, Ocean, and Environment isolated the active compound in female horseshoe crabs
that makes them so attractive to eels and conch. The scientists
originally thought the compound was in the tissue of female
crabs, but they found that the attractant, a protein, is concentrated
in the eggs. Dr. Targett now is collaborating with colleague
Dr. Pam Green at the Delaware Biotechnology Institute to produce
a protein that can be incorporated into an artificial bait.
To find out more, Click
Here.
Population
Estimates
For decades, the horseshoe crab was not considered an important
enough fishery issue to warrant population studies of any kind.
Records of catch years go back to the mid-1800s, but overall
catch data is sporadic, with many years of data missing or
incomplete over the last 150 years. Shell middens confirm that
horseshoe crabs were fished by the American Indian, and coast-wide,
farmers and watermen used horseshoe crabs for fertilizer, eel
bait, and chicken and hog food for at least 150 years. Records
from the mid- to late 1800s in the Delaware Bay estimate harvests
of up to 2 million or more horseshoe crabs for use in the local
fertilizer industry. Farmers and watermen harvested the animals
by hand from the beaches or from fishing pounds. These harvests
for fertilizer ended by 1970, but pressure was renewed by the
late 1970s and continues today by the bait industry.
 Studies
confirm that the Delaware Bay and the adjoining coastal waters
hold the largest population of horseshoe crabs. Population
estimates by Dr. James Berkson from Virginia Polytechnic Institute
and State University in 2002 estimate the Mid-Atlantic population
to be at least 13 million juvenile and adult animals. The census
population of spawning adults on Delaware Bay beaches peaked
in about 1990 with over 900,000 but has been declining ever
since. During the recent five-year period from 1999–2003,
estimates of spawning adults in the Delaware Bay indicate a
stable or slight decline (for more information, please see Horseshoe
Crab Census Data). Because of this documented population
decline within the Delaware Bay, the states of New Jersey,
Delaware, and Maryland, have a harvest limit of 150,000 horseshoe
crabs for 2004.
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