Spatial overlap between foraging seabirds and trawl fisheries: implications for the effectiveness of a marine protected area at Golfo San Jorge, Argentina

Abstract

Assessing human activities and understanding their interaction with seabirds constitute important steps in the development of adequate conservation planning schemes. We evaluated the spatial use of the marine environment by foraging Magellanic Penguins Spheniscus magellanicus and Imperial Cormorants Phalacrocorax atriceps breeding at a newly designated marine park in Golfo San Jorge, Argentina, to assess the potential spatial conflict between these seabirds and commercial hake and shrimp trawl fisheries. GPS loggers were deployed on 45 adults of both species during the 2006 and 2007 breeding seasons. Distribution of hauls made by hake and shrimp trawlers was obtained from the On-board Observer Program of Chubut Province. Penguin foraging range varied between 25.8 and 120.1 km while cormorant foraging range varied between 1.5 and 68.2 km. Distances travelled to fishing grounds were short for both species (, 4.43 km) and, depending on the season, they spent a significant part of their time at sea within waters used by both fisheries (penguins: 17.9-66.2%; cormorants: 46.0-89.0%). In both years, foraging Magellanic Penguins and Imperial Cormorants showed a clear overlap with operating vessels. The observed foraging patterns of penguins and cormorants suggest a high probability of spatial conflict. Moreover, incidental mortality was regularly recorded in both fisheries, at rates that varied between 0.02 and 0.34 individuals per haul depending on species and fishery. Although one of the goals of the new marine park is the protection of Magellanic Penguin and Imperial Cormorant populations, the defined boundaries do not appear to be adequate for their effective protection. Results suggest the need to re-evaluate the spatial design of the park and/or the definition of management actions in waters outside the park to minimise negative effects on penguins and cormorants. ResumenLa evaluació n de las actividades humanas y la comprensió n de su interacció n con las aves marinas son importantes para la elaboració n adecuada de esquemas de planificació n para la conservación. Se analizó el uso espacial del ambiente marino por parte de Pingü inos de Magallanes Spheniscus magellanicus y Cormoranes Imperiales Phalacrocorax atriceps reproduciendo en un parque marino recientemente creado en el Golfo San Jorge, Argentina. El objetivo fue evaluar el potencial conflicto espacial entre estas especies y las flotas arrastreras comerciales que operan sobre merluza y langostino. Se colocaron dispositivos GPS en 45 adultos de ambas especies durante las temporadas reproductivas 2006 y 2007. La distribució n de lances efectuados por los arrastreros merluceros y langostineros se obtuvo del Programa de Observadores a Bordo de la Provincia de Chubut. El rango de forrajeo de los pingü inos varió entre 25,8 y 120,1 km mientras que el de los cormoranes varió entre 1,5 y 68,2 km. En ambas especies, las distancias recorridas desde las colonias a las áreas de pesca fueron cortas (, 4,43 km) y, dependiendo del añ o, las aves pasaron una parte signific...

Behavioural mapping of a pelagic seabird: combining multiple sensors and a hidden Markov model reveals the distribution of at-sea behaviour

“…Advances in miniature telemetry and data-logging systems continue to revolutionize the remote observation of long-distance movements in these and other elusive species [2][3][4][5][6][7], but such systems can be expensive as well as impactful (especially on smaller species), and the resulting data are often under-used. Many tracking studies use recorded locations to examine movement and habitat use only in broad terms [3][4][5][6], leaving key questions about where and when animals engage in specific behaviours unanswered. However, behaviour may be inferred by characterizing patterns of movement based solely on the geometry or complexity of an animal's path using techniques such as tortuosity [8,9], positional entropy [10,11] or first-passage time [12].…”

Natural and anthropogenic factors affecting the feeding ecology of a top marine predator, the Magellanic penguin

“…In addition, the abundance and distribution of conspecifics and fishing vessels were expected to influence the diet and foraging distribution of penguins through a density-dependent depletion of optimal (i.e., high-protein) prey types (Tella et al 2001, Forero et al 2002a). We used remote sensing and geographic information systems (GIS) to derive several explanatory variables likely informing marine productivity patterns (Acha et al 2004), fishing pressure (Skewgar et al 2007, Yorio et al 2010, and intra-specific competition (Tella et al 2001, Forero et al 2002a. A species distribution model was used to quantitatively infer the role of different environmental features in explaining the at-sea distribution of penguins and general linear models were used to evaluate the effect of food availability on different dietary metrics (inferred from penguin blood d 13 C and d 15 N values).…”

“…v www.esajournals.org conspecifics (Tella et al 2001, Forero et al 2002a and fishing pressure (see Skewgar et al 2007, Yorio et al 2010. Indeed, increasing densities of conspecifics may increase competition for common resources among penguins and deplete more optimal prey types such as anchovy (Tella et al 2001, Forero et al 2002a.…”

“…In particular, remote sensing data on oceanographic features for the last decades are now available (e.g., Acha et al 2004, Boersma et al 2009, Louzao et al 2012, thus providing valuable information on marine productivity patterns at large spatial and temporal scales. In addition, spatially explicit information derived from monitoring programs of fishing vessels provides a unique opportunity to investigate the interaction between marine predators and fishing activities (Yorio et al 2010, Bertrand et al 2012. Furthermore, the recent development and widespread application of bio-logging techniques have revolutionized our knowledge on the movement ecology and spatial distribution of marine predators (Weimerskirch et al 2009, Masello et al 2010, Louzao et al 2012.…”

“…iucnredlist.org; accessed on December 2012), and interacts with humans through fisheries and ecotourism (Yorio et al 2001, Villanueva et al 2012. Magellanic penguins have been the subject of several studies aimed at investi-gating the link between prey availability and diet (e.g., Forero et al 2002a, Wilson et al 2005, spatial distribution of conspecifics (e.g., Wilson et al 2005, Boersma et al 2009, Yorio et al 2010 and reproductive performance (e.g., Tella et al 2001, Forero et al 2002a). However, most previous studies have not addressed large-scale ecological mechanisms in an integrative way.…”