A major problem in many fisheries is that too many immature fish are caught and discarded before they have the opportunity to reproduce or reach their optimal size in terms of future yield. Many of the worlds discarded fish are small juveniles of commercially-important species, which if left grow to mature size would produce significant yields. Major biological and economic losses occur as a result of bycatch, and reducing bycatch and discards has become one of the primary objectives of fishery management.
Technical measures, such as increased mesh sizes, are imposed in order to create conditions in which the capture of juvenile fish is minimized. The use of gear selectivity has a particular advantage because it provides a mechanism to reduce the mortality of younger fish while allowing the fleet to continue fishing. In recent years, there has been increasing interest in using various BRDs and gear modifications to improve the size- and species-selectivity of fishing gears. Many of these devices and modifications have reduced the levels of discarding. Traditionally, the fishing industry has been sceptical about the introduction of new and more selective gear modifications, but the deterioration of many important groundfish stocks has led to positive changes in attitudes towards the adoption of more conservative fishing methods. Real progress has been achieved in the reduction of bycatch and discards through gear modifications and operational improvements. Often, once the initial technical difficulties and resistance from fishers have been overcome, these new modifications are readily accepted.
In an ideal situation, when all escapees survive and selectivity and fishing effort are at optimal levels, the growth potential of the stock would be exploited efficiently and most fish would have a chance of growing to mature size and spawning. The spawning biomass would be high, resulting in larger and more stable catches. Fewer fish would be caught but the average size of the fish in the catch would be greater. Clearly, selective fishing has major potential for rational resource utilization. The ultimate success of selective gears, however, largely depends on fishers willingness to accept them. Measures and techniques that increase costs and reduce earnings are unattractive to fishers. Moreover, the fishing effectiveness and practicality of new designs are important; inefficient gears will not be used or will be manipulated. Individual fishers must not only understand the basic nature and magnitude of the problem, but must also believe that the resulting measures are effective and fair.
Fishing industries have played a crucial role in the development and implementation of most of the approaches that have been successful. Clearly, close cooperation among industries, scientists, managers and other stakeholders will be necessary throughout the development and introduction of environmentally-friendly fishing technologies. Factors that are critical to success have to be identified and determined together. A number of innovative technologies are already available, and further progress will be made. Innovative fisheries management plans offer positive incentives for the development and effective use of such fishing techniques. Proper management also stimulates the voluntary use of effective bycatch reduction practices by creating economic incentives.