Associate Editor, Hedley Grantham discusses our August Editor’s Choice article, Optimized fishing through periodically harvested closures by Carvalho et al.

Fisheries management, and sustainable marine management more broadly, require an assembly of management strategies to be effective. Two primary fisheries management tools are catch and effort restrictions, which are often not very spatially-specific. In contrast, spatially-explicit permanent fishing closures like no-take marine reserves are an increasingly popular fisheries management tool. They are also perceived to be particularly effective when catch and effort restrictions are difficult to enforce, such as in the case of many small-scale, open-access fisheries.

Installing the marker for the newly declared Daveda Tabu MPA
Fijians marking tabu area (periodic closure) with tree branch. © Keith Ellenbogen

Within the Asia-Pacific region, periodic closures have been used for centuries by local communities as key fisheries management tools, particularly in places that have traditional marine tenure. These are fishing grounds that are normally open, and occasionally closed, or rotational harvests where the area open to fishing rotates on a cycle.  For example, in Fiji they are used by local communities regularly, and this has led to some fisheries benefits, such as, the ability to harvest fish more easily around cultural events. It is likely that one of the reasons periodic closures can provide these benefits is that it gives time for fish stocks to recover before harvesting again. Another is the differences in wariness of fish to fishing gear in periodic closures. This ‘catchability’ behaviour has not been the focus of many studies until more recently, and research is now revealing the differences in behaviour around periodic closures.

How effective are periodic closures compared with other fisheries management strategies? This Editor’s Choice study by Carvalho et al. integrates emerging data on catchability into bio-economic fisheries models to demonstrate how to design periodic closures to maximise fisheries benefits in terms of yield, harvest efficiency, and stock abundance. They show that, theoretically, periodic closures can have the same, or higher, benefits than non-spatial management or spatial management with permanent closures. This is due to the changes in fish wariness that occur when areas are temporarily closed then opened again. Given the potential benefits of periodic closures, and the difficulty in implementing permanent closures in some regions, they are likely going to be a progressively popular tool in the future. However, while they might lead to fisheries benefits, they might not lead to the same level of biodiversity benefits, with some evidence suggesting that they do not necessarily achieve biodiversity objectives effectively. Therefore, other strategies like no-take marine reserves are still going to be required as part of the mix for sustainable marine management.

The full Editor’s Choice article, Optimized fishing through periodically harvested closures is free to read for a limited time in issue 56:8 of Journal of Applied Ecology.