|By Kathleen Castro
and Erik Williams
What is it?
Bycatch describes living creatures that are caught unintentionally by fishing gear. Unlike target speciesanimals specifically targeted for capturebycatch is unwanted and often unused. Sometimes bycatch may be kept or sold; for example, and angler who catches a legal-sized bluefish while fishing for striped bass may keep the catch to eat at home or to sell, if he has a proper license. Other times, bycatch cannot be usedfor example, if it is undersized or a protected speciesand must be thrown back. This returned bycatch is called discard.
Everyone who fishes, whether for a living or recreation, catches bycatch. Unwanted bycatch is usually thrown back into the water; however, handling and exposure sometimes injure the bycatch, which may die after being discarded. Although this discard may serve as food for other species when it is thrown back, it is not recruited into, and does not become a part of, the reproducing population. As a result, discard not only affects the current population, but influences the species' opportunity to replenish itself.
The National Marine Fisheries Service (NMFS), the government agency that manages fisheries, has called bycatch "the problem of the 1990s." Although the extent of the problem has not been satisfactorily determined, three areas of particular concern have been identified by NMFS:
Bycatch in the Northeast
One of the main reasons bycatch is a problem in many fisheries is that different species of animals are found together: this is called a multispecies fishery. It is possible to catch any mix of whiting, flounders, hake, squid, cod, butterfish, or other species on a given day in a given place. Since these fishes attain different sizes when fully grown, it is hard to target only one of them in their shared habitat. However, efforts to adapt fishing gear to specific target species have resulted in more selective fishing. Appropriately, such gear is termed "selective."
Hook and line, and long-line:
Fishermen and scientists have been working for many years to resolve the inefficiency and wastefulness of bycatch. One early response to the problem was the inclusion of escape vents and variably spaced laths, or slats, in traps to allow escape of nontarget species. More recently, educational programs for recreational anglers in catch-and-release fishing have helped minimize harm to fish. And the introduction of the Turtle Excluder Device (TED) in the southern shrimp fishery, and the similarly designed Fish Excluder devicethe Nordmore Gratein the Gulf of Maine fishery, has helped assure the release of nontarget animals from shrimp trawls. Other promising areas of research include the use of sound devices attached to gill nets to ward off dolphins and whales, and new designs of bottom trawls that take into account fish behavior.
As these examples attest, much progress has been made in reducing bycatch. With continued interest and concern, progress will continue, particularly in the following avenues:
Research and Development:
Petruny-Parker, M.E., K.M. Castro, M.L. Schwartz, L.G. Skrobe, and B. Somers (eds.) 2003. Proceedings of the new England Bycatch Workshops. Rhode Island Sea Grant, Narragansett, R.I. 52pp. pdf.