Reducing bycatch in the South African pelagic longline fishery: the utility of different approaches to fisheries closures

Seabirds, turtles and sharks are often of conservation concern because they are frequently bycatch in fisheries. Fisheries managers shifting from a target species focus to an ecosystem-based approach are being required to consider the impact of fisheries on non-target species. There are a range of complementary management tools that help reduce bycatch, such as gear restrictions, temporal restrictions, and bycatch reduction devices. One management approach that is increasingly being considered is fisheries closures. We tested the utility of 3 closure approaches for the improved protection of bycatch species in the South African pelagic longline fishery. As there was some variation where and when different groups of bycatch species were caught, we found that temporary spatial closures were the most effective strategy for both protecting bycatch and minimizing the cost to fishers. This is logical because having mobile closures in space and time provides more flexibility than permanent spatial closures or seasonal closures. However these benefits need to be traded off against the costs and problems of implementing temporary spatial closures. Of the 2 sub-optimal
strategies, we discovered that seasonal closures are significantly less effective than spatial closures.