The at-sea discarding of fish harvested from the ocean and its associated mortalities have been recognized and noted by fisheries scientists as inherent problems in the management of world fisheries since early in this century. Indeed, references pertaining to bycatch that date back to biblical times can be found (Matthew 13:47–48):
Again, the Kingdom of Heaven can be illustrated by a fisherman, he casts a net into the water and gathers in fish of ever kind valuable and worthless. When the net is full he drags it up onto the beach and sits down and sorts the eatable ones into crates and throws the others away.
Programs and techniques that try to reduce bycatch are not new, either. Introduction of mesh regulations to reduce the catch of undersized target species constitutes a long-accepted management technique introduced into Western European (ICES 1 1971, 1975; Jermyn and Robb 1981; Commission of European Communities 1991; Caddy 1989) and North American (Freeberg 1992) fisheries early in this century. Voluntary actions were probably taken much earlier by fishermen attempting to reduce sorting of bycatch. For many years, countries have set minimum mesh sizes for nets and, at times, for pots, traps, and other gear to minimize catches of juveniles. Such regulations were frequently coupled with minimum size and time/area restrictions (Commission of the European Communities 1991). Further, many states have also introduced or passed legislation limiting harvest methods and operational modes for selected waters and regions. Thus, bycatch and associated discards, as well as programs attempting to resolve them, are not new phenomena.
What is new, however, is the almost explosive interest taken over the past decade in the documentation and search for solutions to bycatch problems. To a considerable degree, this sudden interest has followed the phenomenal growth of world conservation and environmental groups and their early interest in the consequences of fishing activities on populations of marine mammals, birds, and turtles (Alverson 1992a; Bricklemyer 1989/1990; Murray et al. 1992; Northridge 1991a, 1991b).
1Full names for all acronyms used in this report are presented in the glossary.
In the early 1980s numerous bycatch papers surfaced regarding levels of discards in world shrimp fisheries (Allsopp 1982; Caddy 1982; Campos 1981; Grantham 1980; Sheridan et al. 1981; Slavin 1982; Sternin and Allsopp 1982). Saila (1983), noting that anticipated demand for edible fish would double between 1979 and the year 2000, prepared a detailed report on world bycatch and discard levels for the Food and Agriculture Organization of the United Nations (FAO). In the report, Saila estimated a minimum world discard of fish and shellfish of about 6.72 million metric tons (14.8 billion pounds). It is clear from Saila's report, however, that only minimal or partial data were available on many marine species groups, and no information is summarized on bycatch of higher trophic level forms (marine mammals, birds, and turtles). Nevertheless, Saila's work was the first comprehensive examination of bycatch and was an “eye-opener” in terms of the potential losses (mortalities) occurring as the result of discards in world fisheries.
Since the publication of Saila's work and particularly at the onset of this decade, the documentation of bycatch levels, search for solutions to reduce discard levels, and evolution of management strategies to deal with bycatch has increased rapidly and become a focal point of world fishery management. An in-depth review of bycatch problems covering Northeast Pacific trawl fisheries was published in 1984 by Natural Resources Consultants, Inc. (NRC 1984). This review was followed by a comprehensive documentation of the “Nature and Scope of Fisheries-Dependent Mortalities” for a variety of Northeast Pacific fisheries (NRC 1990). Bricklemyer et al. (1989/1990), in the Audubon Wildlife Report, discussed the broader aspects of discarded catch in U.S. commercial fisheries, and more recently Andrew and Pepperell (1992) estimated a global bycatch in world shrimp fisheries as high as 16.7 million mt. The growing importance of bycatch in world fishery management is further reflected in the increased attention paid to this topic by international ocean-oriented bodies, such as ICES, IPHC, INPFC, FAO, IWC, and IATTC, throughout the 1980s and continuing into this decade.
By the early 1990s, bycatch had become a topic of global attention at various international forums, such as the World Fisheries Congress in Athens, Greece, May 1992; the Symposium on Fish Behavior in Relation to Fishing Operations Workshop in Bergen, Norway, June 1992; the International Conference on Responsible Fishing in Cancun, Mexico, May 1992; the NAFO Symposium on Gear Selectivity, Dartmouth, Nova Scotia, Canada, 1993, and later at the Brazil UNCED meetings. During this period, bycatch and discards also became the subject of discussion at a variety of national workshops and conferences in North America, Europe, Asia, Australia, and elsewhere (Schoning et al. 1992; International Conference on Shrimp Bycatch 1992; Sissenwine and Daan 1991; Commission of the European Communities 1991). The increasing importance of bycatch issues did not escape the world press, of course, and a rash of articles concerned with biological damage and waste in fisheries added momentum to U.S. and United Nations efforts to eliminate high seas driftnetting (gillnetting) from the North and South Pacific (Northridge 1991a; Burke et al. 1993). The media's recent characterization of waste in world fisheries has helped create the image of fishing as a “dirty” industry. Robin Alden (1992), publisher and editor of Commercial Fishing News (Stonington, Maine, U.S.A.), noted:
The tide of public opinion has turned against commercial fishing. Whereas before, the industry was either invisible and ignored, or seen as something desirable, it is now being seen as an extractive industry. We have become “industry” instead of a proud, renewable, and thus environmentally sound, way of making a living.
… the barrage of negative publicity focuses the choice before us. Are we going to be an extractive industry paying for the power in Washington and state capitols to try to continue to operate unfettered? Or are we going to grapple with the dirty side of the business, clean up our act, and then be able to defend with pride our right to exist at whatever scale is appropriate for a given fishery?
Murawski (1992), reflecting on the growing bycatch problem, states:
Bycatch interactions have been and remain almost the most frustrating, difficult, and time-consuming problems faced in fisheries management areas throughout the world (Hobson and Lenarz 1977; Mercer 1982; Pikitch 1988). Although bycatch has always been an integral part of fishing with non-discriminative gear, efforts to manage bycatch effectively have intensified (Dewees and Ueber 1990; Murawski 1991; Daan and Sissenwine 1991).
Given changing public perceptions of fishing and the complexity of the bycatch discard issue, better information is needed if we are to address the management problems introduced by bycatch. In recent years greater efforts have occurred to document the body of scientific data concerning quantities of bycatch, levels of discards, survival of discards, and impacts of losses resulting from discards on target and non-target marine populations. Nevertheless, we are still at an early state of understanding the regional and international biological/ecological and economic consequences of discarding, its impact on ecological communities, and the means to reduce discard levels in order to maintain the productivity of the world's ocean fisheries. Not surprisingly, individuals, fishery and environmental organizations, and national and international government perspectives differ significantly in terms of the need for bycatch management and how best to go about it.
It is the purpose of this study to summarize current knowledge concerning the quality and quantity of bycatch and discards in world fisheries, the biological, ecological, and economic consequences of discarding, and the scientific, socio-economic, and political bases of current national and international bycatch management strategies and to evaluate alternative solutions. The paper first reviews terminology used in the scientific literature and establishes operational definitions for terms used in this study. The subsequent aspects of this major chapter examine the database available regarding world bycatch and discard levels, make provisional estimates of discard ratios by gear type and region, and conclude with a global estimate of world discards. Subsequent chapters of the paper examine the potential impacts of discards as they relate to biological/ecological, economic, and sociological factors, and regional overviews for the Northeast Pacific, Northwest Atlantic, and the Northeast Atlantic. The final chapters examine the evolution of bycatch policy and solutions designed to reduce bycatch levels and present a general discussion of the paper's key findings and recommendations.