Most bycatch studies focus on technical changes and compare a modified gear or fishing method to the traditional gear and method under experimental conditions. Relatively few studies have been able to track the actual reduction achieved if there is fleetwide implementation of the change. Modifications to fishing gear and methods emerges as by far the most effective for ETP species, with observed reductions from 40% to nearly 100% in actual fishery case studies. However, with some exceptions, gear modification has not been widely implemented in fishing fleets and evaluated estimates of their effectiveness are based on what is not caught, usually without accounting for post-release mortality resulting from gear-related injuries. In addition, to evaluate fleetwide effectiveness, a very high rate of observer or electronic monitoring would be required and there are relatively few fisheries in the world where such conditions are met.
Gear and fishing method changes, followed by dynamic area management, are the most effective approaches for bycatch reduction and probably the most well accepted by fishers. They are already implemented in many parts of the world and managers can learn from those case studies on how to implement and enforce these mitigation measures. Permanently closed areas appear to be less effective than closed areas that move with changing fish distribution but do require either intensive real-time monitoring or reliable predictive monitoring. However, if the dominant bycatch concern is a single species, then closed areas targeting the areas of high bycatch can be effective.