Fish aggregating devices could enhance the effectiveness of blue water marine protected areas

In the past two decades, drifting fish aggregation devices (FADs) have revolutionized pelagic fisheries, and are now responsible for the majority of tuna purse seine catches. Here, we argue that by taking advantage of the same proven aggregative properties, FADs could be used to enhance the benefits provided by blue water marine protected areas (MPAs). Using models of commercially targeted fish populations, we explore the potential benefits that could be achieved if unfished conservation FADs-designed as self-powered devices capable of remaining semi-stationary-were deployed within blue water MPAs. By increasing the residence time of exploited species in MPAs, conservation FADs will reduce average mortality rates. By increasing the local density of exploited species, they may also improve the function of ecosystems in blue water MPAs. Conservation FADs could, therefore, amplify the benefits of blue water MPAs. We find this amplification is largest in those contexts where blue water MPAs have attracted the most criticism-when their area is small compared to both the open ocean and the distribution of fish stocks that move through them.

Automated summary

Drifting fish aggregation devices (FADs) have had a revolutionary impact on pelagic fisheries and are now the main method for tuna purse seine catches. This article discusses the potential benefits of using FADs to enhance blue water marine protected areas (MPAs) and finds that deploying conservation FADs can reduce mortality rates and improve ecosystem functioning. The amplification of benefits is most significant in blue water MPAs with smaller areas compared to the open ocean and fish stocks distribution.