Quantification of anthropogenic debris from small-scale fisheries and community-based aquaculture in marine and coastal ecosystems of Southwestern Madagascar

Abstract

Most coastal populations in Southwestern Madagascar live on the resources provided by small-scale fishery (SSF), and over the past twenty years, sea cucumber and seaweed farming has grown significantly. This study analyzes the importance of these fisheries and community-based aquaculture (CBA) activities in the contribution of anthropogenic marine debris (AMD) to coastal ecosystems in Southwestern Madagascar. Sampling was conducted in the rainy and dry seasons in three sites with contrasted fishing and farming activities. We have investigated two important coastal ecosystems in these sites, the mangroves and the beaches. At all, about 16,000 AMD items, were collected predominantly plastics. A lower amount of AMD was observed in the rainy season compared to the dry season. The contribution of SSF and CBA activities to the AMD pollution is very important representing 40 % of all AMD in the initial survey. On beaches, 4003 items were found with an average density of 0.17 items m−2. In mangroves, 1039 items were found with an average density of 0.04 items m−2. The most polluted site by SSF and CBA items is Toliara with 3218 debris, Toliara being the one with the highest number of fishermen. The pollution brought by fishing is much more important than that brought by farming. The pollution concerns much more the beaches, where the fishermen start their activities.