We studied discard use and incidental mortality of seabirds attracted to high-sea trawl vessels operating in the Golfo San Jorge, Argentina, during the height of the fishing season in 2003 and 2004. Fourteen seabird species ate food made available by fishing operations. The most frequent and abundant seabirds (percent occurrence, mean number per haul) were the kelp gull Larus dominicanus (98.9%, 207.0), the black-browed albatross Thalassarche melanophrys (98.9%, 94.2) and the white-chinned petrel Procellaria aequinoctialis (91%, 8.4). Flock sizes for the 3 species varied from a few to a maximum of 1600 birds. Total seabird abundance varied significantly between stages of the fishing operation, being higher during discarding and haulback than during towing. Incidental capture of seabirds in nets was recorded in 37% of 89 hauls, with a mean capture rate of 1.2 birds per haul. Species incidentally caught were the great shearwater Puffinus gravis, the imperial cormorant Phalacrocorax atriceps and the Magellanic penguin Spheniscus magellanicus, with rates that varied between months and years. Considering the fishery's fishing effort, the estimated total numbers of birds killed during the study were 2254 great shearwaters (CV = 1.1), 1233 imperial cormorants (CV = 1.1) and 35 Magellanic penguins (CV = 2.4) in 2003, and 311 imperial cormorants (CV = 1.7) and 1516 Magellanic penguins (CV = 1.1) in 2004. Black-browed albatrosses and kelp gulls were also struck by the warp cable while feeding on discards from the surface, and drowned when they were dragged underwater. The results obtained in this study show that the hake trawl fishery operating in the Golfo San Jorge may have a significant effect on some seabird populations through the provision of fishing discards and incidental mortality.

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RESUMEN.En el golfo San Jorge se desarrollan varias actividades económicas de relevancia, entre ellas dos pesquerías industriales: la pesquería de merluza común (Merluccius hubbsi Marini, 1933) y la pesquería de langostino patagónico (Pleoticus muelleri Bate, 1888), ambas se solapan espacial y temporalmente. En la pesquería de merluza del golfo San Jorge opera una flota fresquera de altura, compuesta por unas 20 embarcaciones, y una flota costera, compuesta por unas 30 embarcaciones. En esta pesquería se pesca alrededor del 10% de lo capturado en el stock sur de merluza. En la pesquería de langostino del golfo San Jorge opera una flota congeladora tangonera compuesta por 80 embarcaciones, responsable de más del 75% de los desembarques de langostino realizados en la República Argentina. Ambas pesquerías tienen como principal problema la captura incidental de merluza, en una de sus principales áreas de cría. En el presente trabajo se describe el manejo actual en las pesquerías del golfo San Jorge, el cual consiste principalmente en cierres espaciales y temporales para la pesca de langostino, y zonificaciones por estrato de flota para la merluza. En ninguna de las dos pesquerías descriptas se han tomado medidas que reduzcan eficazmente la captura incidental. Palabras clave: pesquerías, merluza común, langostino patagónico, descarte, golfo San Jorge, Argentina. Characterization of the main fisheries in San Jorge Gulf, Patagonia, ArgentinaABSTRACT. In San Jorge Gulf, several important economic activities are developed, including two industrial fisheries: hake (Merluccius hubbsi Marini, 1933) and Argentine red shrimp (Pleoticus muelleri Bate, 1888). Both overlap spatially and temporally. The San Jorge Gulf hake fishery consists of a high-seas ice trawler fleet (n = 20 fishing vessels) and a coastal fleet (n = 30 fishing vessels). These fisheries capture about 10% of the catch of the southern hake stock. The Argentine red shrimp fishery consists of a double-beam trawler fleet with 80 freezer vessels, responsible for more than 75% of shrimp landings in Argentina. The main problem of both fisheries is the bycatch of hake in one of its principle nursery areas. The present work describes the current management of the fisheries of San Jorge Gulf, which consists primarily of spatial and temporal closures for the Argentine red shrimp and zoning by stratum of the fleet for hake. Neither of these two fisheries has taken measures that effectively reduce bycatch.

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...

Artículo Composición de las capturas y descartes generados en la pesca de merluza común Merluccius hubbsi y langostino patagónicoPleoticus muelleri: un caso de estudio en la flota fresquera de altura del Golfo San Jorge, Chubut, ArgentinaCatches composition and discards generated by hake Merluccius hubbsi and shrimp Pleoticus muelleri fisheries: a case of study in the high-sea ice trawlers of San Jorge Gulf, Chubut, Argentina Abstract.-The bottom trawling is the word most used fishing art generating large amounts of discards and incidental captures with a wide variety of species. In the San Jorge Gulf Argentine Patagonia, operates a fleet whose target specie is the hake Merluccius hubbsi, alternating with red shrimp Pleoticus muelleri. The information for this study covers a period of 10 years (2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012) and was collected by the On-board Observer Program of the Chubut Province (POBCh). Were identified a total of 90 taxa, 33 invertebrates, 34 osteichthyes and 22 chondrichthyes. Multivariate analysis indicated differences in the composition of the catch when the target species was shrimp or hake. When the target species was the hake catch composition varied by fishing areas, this pattern was not observed when the target species was the shrimp, with different numbers of taxa in the northern and central Gulf (north: hake 79 taxa, shrimp 71, center: hake 60 taxa, shrimp 50). The utilization of different species caught when the fleet operated on hake was integral, however when the fleet operated on shrimp most of the taxa were discarded. This study characterized the composition of the fleet catches at San Jorge Gulf, described the species caught when the fleet operates on hake or shrimp, analyzes the frequency of occurrence and abundance and describes the use of different taxa identified. Key words: Catches composition, Merluccius hubbsi, Pleoticus muelleri, ice-trawlers fleet, San Jorge GulfResumen.-La pesca de arrastre de fondo es el arte más utilizado a nivel mundial generando grandes cantidades de descarte por la captura incidental de una amplia variedad de especies. En el Golfo San Jorge en la Patagonia Argentina, opera una flota fresquera de altura cuya especie objetivo es la merluza Merluccius hubbsi, alternando con mareas a langostino Pleoticus muelleri. La información para el presente estudio abarca un periodo de 10 años (2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012) y fue obtenida por el Programa de Observadores a Bordo de la Provincia del Chubut (POBCh). Se identificaron un total de 90 taxones, 33 invertebrados, 34 peces óseos y 22 peces cartilaginosos. Los análisis multivariados describen 2 agrupamientos, el primero cuando la especie objetivo fue la merluza y el otro cuando la especie objetivo fue langostino. Cuando la especie objetivo fue la merluza la composición de las capturas varió según las áreas de pesca aunque no se observó este patrón cuando la especie objetivo fue el langostino, con distintos números de taxones el norte y el centro d...