Spatial use of multiple jurisdictions by Magellanic penguins and assessment of potential conflicts in the face of changing trawl fisheries scenarios

Abstract

Seabirds often have wide distribution ranges and may travel relatively long distances to breeding grounds, often crossing jurisdictional boundaries. When engaged in foraging behaviour, seabirds are prone to interact with different fisheries and suffer incidental mortality. We assessed the spatial use of foraging Magellanic penguins Spheniscus magellanicus breeding at 3 colonies within the Patagonia Austral Marine Park (San Jorge Gulf, Argentina) in relation to different jurisdictions. We also quantified their spatial overlap with 3 trawl fisheries and bycatch (incidental mortality), an interaction previously reported in the region. Breeding Magellanic penguins mainly used waters under provincial jurisdiction within the gulf, with some use of federal waters depending on the breeding season and colony location. Spatial use by breeding penguins resulted in a variable but relatively low overlap with the operations of the 3 fishing fleets in 2014-2016 (1.1-26.3%). Changes in the spatial distribution of fishing operations in recent years resulted in a lower overlap than in 2005-2007 (12.1-60.8%). Incidental mortality during 2008-2014 was also variable and relatively low (0.0-0.363 birds per haul). Breeding Magellanic penguins foraged outside protected area boundaries where they can spatially overlap with and face potential threats from different fishing fleets that operate in waters of provincial and/or federal jurisdiction. Despite the current low spatial overlap, the relatively fast changes in fishing patterns in the recent past draw attention to the need for continuous monitoring. Data obtained in this study may prove valuable in case the implementation of spatial and temporal closures of fishing operations is needed.