A new study (Essington, 2009) supports the results of other studies showing the benefits of catch share management in fisheries (Costello et al., 2008; Heal and Schlenker 2008). The paper looks for a response in biomass, exploitation rate, discards, effort, compliance with catch targets and landings in 15 North American catch share fisheries. The paper did not find that these catch share fisheries, on average, reduced overall landings or that they increased biomass. That seems to be because most of these fisheries were not overfished–so the overall catch would not be expected to go down, and biomass would not be expected to increase, because these were not management goals. To test the hypothesis that catch shares can rebuild depleted populations, it will be important to analyze depleted fisheries, over rebuilding time frames. In this study, only one of the 8 fisheries that had explicit overfishing targets was substantially overfished.
The author used a rigorous methodology to examine these fisheries (before-and-after comparisons were complemented by comparisons within fisheries with non-catch share and catch share sectors, and with a meta-analysis). As more catch shares are implemented and a greater diversity of fisheries under catch shares are studied with such methods, I anticipate that the author’s observation that variance in management metrics is reduced by catch share management will be borne out. This will translate into improved rebuilding of depleted stocks, prevention of overfishing, reduction in bycatch and discard, and even a reduction in the effects of fishing on habitats – if the management targets themselves are robust.
EDF's position on the conservation benefits of catch shares is available here.