Managing the Fisheries

Fisheries Research

Horseshoe Crab Fisheries Management Plan Stimulates Research Efforts. Responding 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 an Interstate 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:

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 crabs.

#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.