Sustainable fisheries are directed fisheries, catching target species and little else; waste and by-catch are minimal. They are generally passive fisheries, not active. The catch is always fresh. Sustainable fisheries are such because fish are removed at an age and volume that does not affect the stocks' ability to reproduce at a replicative rate.
Fishing technique is one of the most important factors when judging the sustainability of a fishery. While all fishing methods have an effect on fish habitat, some have far less impact than others. Different fishing methods have greater impact at different times and in different areas for each species. A nondiscriminating longline fishery during the 1970's was responsible for the crash of Atlantic Swordfish populations. Today, halibut longlining in Alaska is a well-managed, sustainable fishery that successfully addresses all management issues. Sustainable fishery methods may include encircling seine nets, long lines, hook and lines, jigging, weirs, traps, dipnets, harpooning, gillnetting, diving, and trolling.
Broad-based consumer boycotts, which advocate the boycott of an entire species, irrespective of fishing method or area of capture, only harm proponents of conservation; namely, the small-scale sustainable fishermen. Species-specific consumer boycotts put the sustainable fishermen, who have an interest in the stewardship of ocean resources, out of business. They do not prevent industrialized fishing vessels from moving on to other species and waters.
Sustainable fisheries management is complicated; myriad factors are in constant flux. When trying to make responsible decisions we must be well informed to judge each fishery on its own merits, and be aware of the effect these decisions have on the lives of the people involved in fisheries.