The use of artisanal fish fences can damage ecosystems, remove traditional barriers to overfishing, and create social conflict by assuming unofficial and unregulated property rights, according to a case study in Nature Communications.
Artisanal fish fences are used extensively along tropical coastlines to capture fish by using fences to funnel them into a holding structure as the water recedes at low tide. The impacts of these fences and other artisanal fishing equipment are assumed to be lower than industrialised techniques, but they have received little scrutiny.
Dan Exton and colleagues report a 15-year (2002-2016) case study of the ecological and socioeconomic effects of artisanal fish fences on Kaledupa Island, Indonesia. The authors show that during this time, artisanal fish fence use increased substantially, with the number of fences increasing approximately 400% and the cumulative total length of fences in use increasing by almost 300%. Yet, the number of individual fish caught each day per fence decreased by about 90% from the peak and fish abundances on surrounding coral reefs almost halved. They found that fish fences trapped more than 500 species of fish and the number of juvenile fish caught increased by 400%. Fences also caused direct damage to seagrass ecosystems with impacts on coral reefs and mangroves. Meanwhile, interviews with the local community revealed increasing social conflict over fishing space and fence ownership.
The authors argue that the use of artisanal fishing gears are in urgent need of assessment and updated management practices.