Integrating fishing spatial patterns and strategies to improve high seas fisheries management

Fishing activity in waters beyond national jurisdiction generates multiple management issues, such as data poor fisheries, management of straddling fish stocks and lack of impact assessments on deep-sea Vulnerable Marine Ecosystems (VMEs). Fishing strategy is the key to understanding and managing high seas fisheries, targeting highly migratory resources that are widely distributed. An international fleet, including Spanish flag bottom trawlers, operates along the Patagonian shelf in Southwest Atlantic waters, which includes an unregulated strip of continental shelf beyond national jurisdiction. The Spanish fleet's fishing strategy was analyzed, and based on on-board observer data collected from 1989 to 2015, three main fishing seasons were identified: a first season mainly targeting Argentinean squid (Illex argentinus) from January to March, a second season targeting hake (Merluccius hubbsi) from April to August, and a third season from September to December showing an opportunistic and heterogeneous behavior. Findings were framed within current knowledge on resource distribution. A preliminary observation of the inter-annual CPUE rates of target species during their respective fishing seasons highlights the possible existence of species linkages and bioclimatic cycles which may affect species distribution and abundance in the area and might require future research. Even if current fishing activity from the Spanish fleet does not overlap deep-water VMEs, any slight change in the fishing strategy to deeper waters (i.e. the fleet targeting high density I. argentinus areas below 300 m, or a change in the target species) would be critical for the conservation of VMEs in these waters.