Managing the Fisheries
Crab Fisheries Management Plan Stimulates Research
to concerns from scientists, environmentalists, and the
biomedical industry over the status of the horseshoe crab
population, the Atlantic
States Marine Fisheries Commission (ASMFC) adopted
Fisheries Management Plan (FMP) in 1998. Besides harvesting
controls, the plan developed a research and monitoring
strategy to produce data for future management decisions.
Partnerships were formed between state, federal and private
organizations and volunteers to initiate and coordinate
activities included in the plan. A few examples of research
undertaken include in the first year of the plan include:
|1. Statistically robust spawning and egg count surveys were designed and implemented in the Delaware Bay.
|2. The U.S. Fish and Wildlife Service agreed to coordinate the coastwide horseshoe crab tagging program.
|3. A horseshoe crab benthic survey design workshop was conducted in July 1999.
|4. The U.S. Geological Survey-Biological Resources Division initiated a genetics project to evaluate whether or not regional horseshoe crab populations exist along the Atlantic coast.
|5. Several migratory
shorebird research and monitoring activities were conducted
in the Delaware Bay, Arctic breeding grounds, and South
American wintering areas.
Since then other research projects were begun, including a
pilot trawl survey study, a horseshoe crab stock identification/delineation
project, the development of criteria for identifying new recruits,
and a feasibility study to use videography to monitor horseshoe
crab spawning. On-going spawning surveys, egg studies, and
tagging studies also were continued. These research
areas are summarized in the 2002 Review of the Fishery Management
Plan for Horseshoe Crab.
Addendum III of the FMP, passed in spring
2004, has reorganized, modified, and expanded the original
monitoring program set forth in the 1998 FMP. Several new research
needs have been identified and included. The first is to "develop
an effective and efficient field protocol to identify critical
life history stages of the horseshoe crab. The protocol should
identify horseshoe crabs that have spawned previously, those
that are within one year of spawning for the first time, and
those that are more than one year from spawning for the first
time." The second is to research the feasibility of alternative
trap design (i.e., traps with bait bags). A third research
addition is "to identify important juvenile habitat and
its extent of use."
Alternative Bait and Trap Design
Another area of fisheries research is focused on alternative bait and trap design for the eel and whelk fisheries. Combining sensible fishery management practices with the use of alternative baits could further reduce fishery demand for horseshoe crabs. If an economically feasible, sustainable alternative to live horseshoe crab bait can be identified, this natural resource will be offered greater long-term protection.
There are two primary criteria for developing
alternative baits. The first is cost. Presently, fishermen
pay $0.50 to $1.00 for each horseshoe crab they buy for bait
use. One crab provides bait for one to four eel or whelk pots.
Fishermen also have associated bait storage costs for freezing
or refrigeration. The second critera has to do with the life
of bait, or how long it can be used effectively. Horseshoe
crab bait can be used for three to five tidal cycles depending
upon water temperature.
A feasible alternative to horseshoe crab bait must be comparable in cost and bait life, as well as pounds of harvest. Within these parameters, some flexibility is possible. A slight increase in cost may be acceptable if the bait lasts longer or requires less storage. Currently, scientists and fishermen are investigating four methods for reducing or replacing horseshoe crab bait.
#1: Alternative Live Bait: Commercial
fishermen have experimented with alternate live baits such
as herring, crushed blue mussels, blue crabs, shrimp heads, and surf
clams. However, eel and whelk bait preferences are regionally dependent;
horseshoe crab bait is still the most effective eel and conch bait
across the region.
| Dr. Nancy Targett is developing an
artificial bait to reduce the use of horseshoe crabs
as bait for eels and conch.
#2: Artificial Bait: Eel
fishermen refer to egg-laden females as a "superior bait," even
though eels prefer other types of food in the wild. Why are horseshoe
crabs such an excellent bait for eel and whelk? Is it possible
that a specific odor or chemical cue attracts eel to female
horseshoe crabs? Dr. Nancy Targett and Dr. Pamela Green
of the University of Delaware College of Earth, Ocean, and Environment are
collaborating to develop an artificial
bait based on the attractant in horseshoe crab eggs. Preliminary
laboratory testing suggests the synthetic bait may provide
eel fishermen with a sustainable alternative to live horseshoe
#3: Bait Extenders: Incorporation
of ground horseshoe crab into a binder matrix increases the
amount of bait a fisherman can obtain from one crab. Dr.
Bob Fisher, a fisheries scientist at the Virginia Institute
of Marine Science, is testing the efficacy of whelk
baits made from ground horseshoe crab and surf clam byproducts.
Bait bag with
horseshoe crab bait
#4: Bait Extensions or Bait Bags: Developed
by Frank Eicherly, a commercial waterman from Bowers Beach, Delaware,
and now 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 25–50% when
bait bags are used. In 2000, Virginia fishermen adopted the
bait bags for their pots.