Collaboration on technical innovation towards the reduction of seabird bycatch in purse seine fisheries

Purse seine fisheries are widely common in the seas of the world. However, this is one of the least attended in bycatch of non-target species such as seabirds, in contrast to international attention focused in longline, trawl and gillnet fisheries. During characterization of bycatch in small-scale purse seine fisheries (length ≤15m) for Anchoveta in the north (~18° S) and Sardine in south-central Chile (~37° S), we identified from complete sets (n=73), different net’s hotspots of negative interaction with seabirds. These affected plunge divers such as boobies and pelicans (north) and pursuit as shearwaters (south-central). As sources of bycatch, we identified a high hanging ratio of net (>45%), resulting in: i) drowning of divers due the presence of ceiling of the drifting body and cod of net during setting, and ii) entanglement and trauma of divers with net folds by this excess of net during hauling. We also identified entangled birds on zippers (connectors between net and buoys) and ropes of the buoy line during hauling. In south-central Chile, we recorded 12 seabird species associated to setting and 6 species during hauling. Among these, the recently listed ACAP species Pink-footed and Sooty shearwaters (81% and 19%, respectively) reached a maximum combined bycatch of 3.58 birds/setting, 7.62 birds/trip. Since 2014, we have begun a collaborative initiative with fishermen and net industry to carrying out experimental trials of a modified net with reduced hanging ratio, zipper and size of rope sinus attached to the buoy line. When compared in a first stage of simultaneous sets (n=39) with control nets (hanging ratio >40% and zippers between 2½ - 3½ inches of mesh size), treatment (modified) net has presented no mortality associated with the modified gear hotspots versus 0.55 birds/setting, 1.11 birds/trip as recorded for sets with control (unmodified) nets.