Artisanal fish fences pose broad and unexpected threats to the tropical coastal seascape

Dan A Exton,Leanne C Cullen-Unsworth,Paul W Simonin,Joel Rice,David J Smith,Duncan May,Richard K F Unsworth,Gabby N Ahmadia,Jamaluddin Jompa

doi:10.1038/s41467-019-10051-0

Abstract

Gear restrictions are an important management tool in small-scale tropical fisheries, improving sustainability and building resilience to climate change. Yet to identify the management challenges and complete footprint of individual gears, a broader systems approach is required that integrates ecological, economic and social sciences. Here we apply this approach to artisanal fish fences, intensively used across three oceans, to identify a previously underrecognized gear requiring urgent management attention. A longitudinal case study shows increased effort matched with large declines in catch success and corresponding reef fish abundance. We find fish fences to disrupt vital ecological connectivity, exploit > 500 species with high juvenile removal, and directly damage seagrass ecosystems with cascading impacts on connected coral reefs and mangroves. As semi-permanent structures in otherwise open-access fisheries, they create social conflict by assuming unofficial and unregulated property rights, while their unique high-investment-low-effort nature removes traditional economic and social barriers to overfishing.

Highlights

Gear restrictions are an important management tool in small-scale tropical fisheries, improving sustainability and building resilience to climate change
Coral reefs provide the majority of protein to over 400 million people[10], yet an estimated two-thirds of reef fish are already believed to have been lost[11]
Similar to management interventions[29], individual gear types express characteristics that span ecological, economic, and social sciences, and to fully understand their true impact they should be viewed beyond the narrow perspective of whether they are visibly destructive

Summary

Introduction

Gear restrictions are an important management tool in small-scale tropical fisheries, improving sustainability and building resilience to climate change. We show fish fences being used intensively across three ocean basins (Atlantic, Indian, Pacific), before presenting a unique 15-year case study incorporating ecological, fisheries catch and socioeconomic data to examine fish fence impacts across communities (natural and human) and ecosystems (seagrass, coral reef and mangrove), as well as exploring the social and economic drivers underpinning their use.

Results

Conclusion