espanolEl crecimiento mantenido de la produccion de pescado, la mejora de los canales de distribu... more espanolEl crecimiento mantenido de la produccion de pescado, la mejora de los canales de distribucion y la falta de control y ordenamiento de los residuos generados a bordo han contribuido con la acumulacion de residuos provenientes de buques pesqueros en diferentes sitios de la costa patagonica. El presente estudio desarrolla un abordaje cuali-cuantitativo con enfasis en aspectos historico-ambientales de la flota de Rawson, Chubut, Argentina y su relevancia en la matriz socio-productiva local. La metodologia es de tipo descriptivo-exploratorio, siendo la unidad de analisis la flota pesquera y su entorno inmediato. En los ultimos anos esta flota ha ampliado el numero de embarcaciones y sus capacidades de bodega. La opinion del sector pesquero sostiene que el arrojo de residuos al mar por parte de las embarcaciones preocupa y deberia abordarse. La investigacion, de caracter diagnostico, realiza una revision historica y actualizacion de la situacion ambiental con enfasis en los residu...
En el golfo San Jorge se desarrollan varias actividades económicas de relevancia, entre ellas dos... more 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 J...
El consumo del descarte pesquero en el mar es actualmente un importante componente en la ecología... more El consumo del descarte pesquero en el mar es actualmente un importante componente en la ecología alimentaria de muchas especies de gaviotas. Los estudios de dieta son clave para evaluar la contribución relativa del descarte en su ecología trófica, así como empezar a comprender los potenciales efectos de la actividad pesquera sobre sus parámetros reproductivos y dinámica poblacional. El presente estudio analiza la composición dietaria de Gaviotas Cocineras (Larus dominicanus) que reproducen en la costa norte del Golfo San Jorge, Chubut, Argentina, durante la temporada de cría de 2007 en tres localidades de reproducción: Isla Vernacci Sudoeste (45°11’S, 66°31’O), Isla Felipe (45°04’S, 66°19’O) e Isla Laguna (45°02’S, 65°53’O). A su vez se seleccionaron tres períodos de muestreo: incubación, pichones pequeños y pichones grandes. Las muestras de dieta se obtuvieron mediante lavado estomacal. Los resultados obtenidos en las tres colonias analizadas confirman que en las costas del norte ...
Al menos unas 70 especies de aves marinas se alimentan en la plataforma continental argentina, qu... more Al menos unas 70 especies de aves marinas se alimentan en la plataforma continental argentina, que es posiblemente el area con mayor biomasa de albatros en el mundo. La distribucion de las aves en el mar generalmente coincide con la de las pesquerias comerciales en areas con elevada productividad marina, por lo que sus interacciones pueden ser frecuentes y diversas. El abordaje del Mar Argentino considerando a las aves como parte de un enfoque integrado representa un desafio. Algunos aspectos de la biologia de estas aves podrian actuar como indicadores ambientales permitiendo interpretar los sistemas, evaluar su estado de conservacion y analizar relaciones con procesos globales. Aunque las interacciones entre las aves y algunas flotas pesqueras que operan en la plataforma todavia no han sido estudiadas, el conocimiento sobre la ecologia, el comportamiento y la conservacion de estas aves ha crecido significativamente en la ultima decada. Incluir consideraciones ecosistemicas en el ma...
Resumen ∙ El consumo del descarte pesquero en el mar es actualmente un importante componente en l... more Resumen ∙ El consumo del descarte pesquero en el mar es actualmente un importante componente en la ecologia alimentaria de muchas especies de gaviotas. Los estudios de dieta son clave para evaluar la contribucion relativa del descarte en su ecologia trofica, asi como empezar a comprender los potenciales efectos de la actividad pesquera sobre sus parametros reproductivos y dinamica poblacional. El presente estudio analiza la composicion dietaria de Gaviotas Cocineras ( Larus dominicanus ) que reproducen en la costa norte del Golfo San Jorge, Chubut, Argentina, durante la temporada de cria de 2007 en tres localidades de reproduccion: Isla Vernacci Sudoeste (45°11’S, 66°31’O), Isla Felipe (45°04’S, 66°19’O) e Isla Laguna (45°02’S, 65°53’O). A su vez se seleccionaron tres periodos de muestreo: incubacion, pichones pequenos y pichones grandes. Las muestras de dieta se obtuvieron mediante lavado estomacal. Los resultados obtenidos en las tres colonias analizadas confirman que en las costa...
We quantified the trophic niche of Magellanic penguins (Spheniscus magellanicus) breeding and mou... more We quantified the trophic niche of Magellanic penguins (Spheniscus magellanicus) breeding and moulting in Golfo San Jorge, Argentina, through conventional stomach content and stable isotope analysis. A total of 112 adults were flushed during the early and late chick stages of 2011 and 2012 at Isla Vernacci Norte, and at least 15 prey taxa were found, including fishes, cephalopods, crustaceans and polychaetes. Overall, Argentine anchovy (Engraulis anchoita) showed the highest contribution in terms of importance by mass (68.1-85.3%, depending on chick stage and year), except for the old chick stage in 2011 when the shortfin squid (Illex argentinus) was the main prey consumed (56.0%). Based on carbon and nitrogen isotopic values from a total of 256 blood samples, corresponding to young and old chicks and to adults of both sexes sampled throughout the incubation, chick and moult stages at the above mentioned colony and years, Bayesian mixing model outputs showed that Argentine anchovy was always the main prey (48-86%). Bayesian mixing model outputs obtained from adults of both sexes and their chicks during the late chick stage of 2013 at Isla Vernacci Norte, Isla Tova and Isla Leones also showed that Argentine anchovy was the main prey consumed. This is the first comprehensive assessment of Magellanic penguin diet composition in northern Patagonia, quantifying the relative contribution of prey in the diet of adults and chicks at different stages of the annual cycle and years, and confirms the relevance of a forage fish such as the Argentine anchovy in its trophic ecology.
Many seabirds are attracted to trawl vessels to make use of fishery waste, and often this attract... more Many seabirds are attracted to trawl vessels to make use of fishery waste, and often this attraction results in increased incidental mortality. We assessed seabird attendance and associated incidental mortality at the Argentine red shrimp Pleoticus muelleri trawl fishery in Golfo San Jorge, Argentina. Information on seabird numbers was gathered in the autumn and winter 2006 and spring 2008, while information on seabird incidental captures was obtained for the period 2005-2007. Eighteen seabird species attended vessels, and the 2 most frequent and abundant seabirds (percent occurrence, median no. haul-1) were the kelp gull Larus dominicanus (> 94%, <100) and blackbrowed albatross Thalassarche melanophrys (> 94%, < 55). Seabird numbers were significantly lower in winter than the other 2 seasons and highest during discarding activities. Species incidentally killed in nets were the Magellanic penguin Spheniscus magellanicus and imperial cormorant Phalacrocorax atriceps, with a mean capture rate of 0.048 birds haul-1 , and for both species, mortality decreased with distance to the coast. Considering the fishery's fishing effort during each month, the estimated total mortality in the study period was 895 (95% CI: 572 to 1339) penguins and 172 (95% CI: 69 to 305) cormorants. Over 95% of the recorded mortality occurred in 2005, the year when the trawling moratorium generally implemented in the area was not enforced. No interactions with warp cables were recorded. Results highlight the relevance of complying with the current moratorium scheme, as adjusting it to the penguin and cormorant breeding seasons may by a potentially effective management tool. The proximity to the coast of the recorded incidental mortalities indicates the need to reevaluate the spatial design of the park and/or the definition of management actions beyond the boundaries of the Marine Protected Area.
We studied the interaction between seabirds and warp cables in the high-seas Argentine hake Merlu... more We studied the interaction between seabirds and warp cables in the high-seas Argentine hake Merluccius hubbsi trawl fishery operating in Golfo San Jorge, Argentina, and tested the efficacy of a simple mitigation measure designed to reduce mortality at warp cables. Observations ...
Nada más sencillo que conocer un lugar profundamente anhelado. Al mismo tiempo que desembarqué en... more Nada más sencillo que conocer un lugar profundamente anhelado. Al mismo tiempo que desembarqué en esta tierra helada y comencé mi labor científica, decidí redactar mí día a día. A medida que me introducía en la cotidianidad antártica la necesidad de indagar se profundizaba, transformando mis simples relatos antárticos en este libro que se animó humildemente a transitar por los caminos de la ciencia, la cultura, la sociedad y la filosofía antártica. Sin duda no fue solo conocer esta tierra lo que me agradó de sobremanera, sino también adquirir conocimiento acerca de su historia, su política y su manejo ambiental. Mi profundo desconocimiento respecto a las temáticas antes mencionadas activó los engranajes de la inquietud y la búsqueda del conocimiento. A excepción de los ANEXOS I,III y IV éste libro fue escrito en su totalidad en la Base Primavera, al mismo tiempo que desarrollaba mi labor científica como biólogo especializado en aves marinas durante la Campaña Antártica de Verano 201...
Wilson's Storm Petrels spend the austral winter and spring (May to October) at sea. Studies in th... more Wilson's Storm Petrels spend the austral winter and spring (May to October) at sea. Studies in the Golfo San Jorge, Patagonian Shelf, showed the presence of this petrel in seabird assemblages associated with commercial trawlers. A sailing superstition holds that the appearance of storm petrel foretells bad weather. By way of confirming this traditional belief, the aim of this study is to relate the appearance of the Wilson Storm Petrel with the weather conditions at sea and the feeding behaviour implications. Information about the presence and abundance was gathered on board from a total of 253 hauls during 2005, 2006 and 2008. A total of 65 individuals were recorded in 30 (11.86%) of fishing hauls. The number and presence of Wilson Storm Petrels be correlated with low atmospheric pressure. Given that they are among of the most abundant seabirds of the world, detailed data on interactions with fisheries and weather conditions at sea are not only interesting for analyze their association with fisheries or foretells bad weather, but may also be useful for monitoring the Southern Oceans.
Fil: Gonzalez Zevallos, Diego Ricardo. Consejo Nacional de Investigaciones Cientificas y Tecnicas... more Fil: Gonzalez Zevallos, Diego Ricardo. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Nacional Patagonico; Argentina
RESUMEN. En el golfo San Jorge se desarrollan varias actividades económicas de relevancia, entre ... more 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, Argentina ABSTRACT. 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.
Seabird abundances and breeding distribution have the potential to serve as ecological indicators... more Seabird abundances and breeding distribution have the potential to serve as ecological indicators. The western Antarctic Peninsula is one of the three sites in the world with the greatest increases in local temperature during the last 50 years. The aim of this study was to monitor the distribution and abundance of breeding populations of seabirds in the northern sector of the Danco Coast, northwest of the Antarctic Peninsula, during the breeding season 2010/11. The birds were the Wilson?s storm petrel (Oceanites oceanicus), South Polar skua (Stercorarius maccormicki), kelp gull (Larus dominicanus), Antarctic tern (Sterna vittata), snowy sheathbill (Chionis alba), chinstrap penguin (Pygoscelis antarctica), southern giant petrel (Macronectes giganteus), gentoo penguin (Pygoscelis papua), Cape petrel (Daption capense) and Antarctic shag (Phalacrocorax bransfieldensis). Annual breeding population growth increased in pygoscelids, southern giant petrel and sheathbill, and for the remaining species, breeding population trends were stable. Given that seabird populations can provide valuable information on the conditions of their feeding and nesting environments, this study highlights the need to maintain basics monitoring studies.
We studied discard use and incidental mortality of seabirds attracted to high-sea trawl vessels o... more 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.
We evaluated discard consumption by Kelp Gulls (Larus dominicanus) and Black-browed Albatrosses (... more We evaluated discard consumption by Kelp Gulls (Larus dominicanus) and Black-browed Albatrosses (Thalassarche melanophrys) associated with trawlers operating at Golfo San Jorge, Argentina, and assessed differences in their feeding behaviour, prey size preferences and foraging efficiency. Observations were made onboard hake (January 2007) and shrimp vessels (November 2008). The Kelp Gull and Black-browed Albatross were the most frequent and abundant
SummaryAssessing human activities and understanding their interaction with seabirds constitute im... more SummaryAssessing 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 par...
We evaluated discard consumption by Kelp Gulls (Larus dominicanus) and Black-browed Albatrosses (... more We evaluated discard consumption by Kelp Gulls (Larus dominicanus) and Black-browed Albatrosses (Thalassarche melanophrys) associated with trawlers operating at Golfo San Jorge, Argentina, and assessed differences in their feeding behaviour, prey size preferences and foraging efficiency. Observations were made onboard hake (January 2007) and shrimp vessels (November 2008). The Kelp Gull and Black-browed Albatross were the most frequent and abundant seabirds at both fisheries, while Argentine Hake (Merluccius hubbsi) dominated the composition of discards. Kelp Gulls and Black-browed Albatrosses consumed 91% of experimentally discarded hake (n = 1236). Mean sizes of prey consumed by gulls were 22.4 and 23.7 cm in the hake and shrimp fisheries, respectively, while those of prey consumed by albatrosses were 28.5 and 31.3 cm, respectively. In both fisheries, gulls selected the smaller prey available (<25 and < 30 cm in hake and shrimp fisheries, respectively) while Black-browed Alb...
Assessing human activities and understanding their interaction with seabirds constitute important... more 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. Resumen La 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 significativa de su tiempo en el mar dentro de áreas utilizadas por ambas pesquerías (pingü inos: 17,9-66,2%; cormoranes: 46,0-89,0 %). En ambos añ os, las áreas de alimentació n de pingü inos y cormoranes mostraron una clara superposición con las zonas de operació n de ambas pesquerías. Los patrones de forrajeo observados para los pingü inos y cormoranes sugieren una alta probabilidad de conflicto espacial con las flotas pesqueras. Es más, se registró mortalidad incidental de aves en ambas pesquerías, con valores que oscilaron entre 0,02 y 0,34 individuos por lance dependiendo de la especie y la pesquería. Aunque uno de los objetivos del nuevo parque marino es la protecció n de las poblaciones del Pingü ino de Magallanes y del Cormorán Imperial, los límites definidos del área protegida no parecerían ser adecuados para su protecció n efectiva. Los resultados sugieren la necesidad de re evaluar el diseñ o espacial del parque y/o definir acciones de manejo en aguas por fuera del parque para minimizar los efectos negativos sobre pingü inos y cormoranes.
We studied discard use and incidental mortality of seabirds attracted to high-sea trawl vessels o... more 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.
espanolEl crecimiento mantenido de la produccion de pescado, la mejora de los canales de distribu... more espanolEl crecimiento mantenido de la produccion de pescado, la mejora de los canales de distribucion y la falta de control y ordenamiento de los residuos generados a bordo han contribuido con la acumulacion de residuos provenientes de buques pesqueros en diferentes sitios de la costa patagonica. El presente estudio desarrolla un abordaje cuali-cuantitativo con enfasis en aspectos historico-ambientales de la flota de Rawson, Chubut, Argentina y su relevancia en la matriz socio-productiva local. La metodologia es de tipo descriptivo-exploratorio, siendo la unidad de analisis la flota pesquera y su entorno inmediato. En los ultimos anos esta flota ha ampliado el numero de embarcaciones y sus capacidades de bodega. La opinion del sector pesquero sostiene que el arrojo de residuos al mar por parte de las embarcaciones preocupa y deberia abordarse. La investigacion, de caracter diagnostico, realiza una revision historica y actualizacion de la situacion ambiental con enfasis en los residu...
En el golfo San Jorge se desarrollan varias actividades económicas de relevancia, entre ellas dos... more 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 J...
El consumo del descarte pesquero en el mar es actualmente un importante componente en la ecología... more El consumo del descarte pesquero en el mar es actualmente un importante componente en la ecología alimentaria de muchas especies de gaviotas. Los estudios de dieta son clave para evaluar la contribución relativa del descarte en su ecología trófica, así como empezar a comprender los potenciales efectos de la actividad pesquera sobre sus parámetros reproductivos y dinámica poblacional. El presente estudio analiza la composición dietaria de Gaviotas Cocineras (Larus dominicanus) que reproducen en la costa norte del Golfo San Jorge, Chubut, Argentina, durante la temporada de cría de 2007 en tres localidades de reproducción: Isla Vernacci Sudoeste (45°11’S, 66°31’O), Isla Felipe (45°04’S, 66°19’O) e Isla Laguna (45°02’S, 65°53’O). A su vez se seleccionaron tres períodos de muestreo: incubación, pichones pequeños y pichones grandes. Las muestras de dieta se obtuvieron mediante lavado estomacal. Los resultados obtenidos en las tres colonias analizadas confirman que en las costas del norte ...
Al menos unas 70 especies de aves marinas se alimentan en la plataforma continental argentina, qu... more Al menos unas 70 especies de aves marinas se alimentan en la plataforma continental argentina, que es posiblemente el area con mayor biomasa de albatros en el mundo. La distribucion de las aves en el mar generalmente coincide con la de las pesquerias comerciales en areas con elevada productividad marina, por lo que sus interacciones pueden ser frecuentes y diversas. El abordaje del Mar Argentino considerando a las aves como parte de un enfoque integrado representa un desafio. Algunos aspectos de la biologia de estas aves podrian actuar como indicadores ambientales permitiendo interpretar los sistemas, evaluar su estado de conservacion y analizar relaciones con procesos globales. Aunque las interacciones entre las aves y algunas flotas pesqueras que operan en la plataforma todavia no han sido estudiadas, el conocimiento sobre la ecologia, el comportamiento y la conservacion de estas aves ha crecido significativamente en la ultima decada. Incluir consideraciones ecosistemicas en el ma...
Resumen ∙ El consumo del descarte pesquero en el mar es actualmente un importante componente en l... more Resumen ∙ El consumo del descarte pesquero en el mar es actualmente un importante componente en la ecologia alimentaria de muchas especies de gaviotas. Los estudios de dieta son clave para evaluar la contribucion relativa del descarte en su ecologia trofica, asi como empezar a comprender los potenciales efectos de la actividad pesquera sobre sus parametros reproductivos y dinamica poblacional. El presente estudio analiza la composicion dietaria de Gaviotas Cocineras ( Larus dominicanus ) que reproducen en la costa norte del Golfo San Jorge, Chubut, Argentina, durante la temporada de cria de 2007 en tres localidades de reproduccion: Isla Vernacci Sudoeste (45°11’S, 66°31’O), Isla Felipe (45°04’S, 66°19’O) e Isla Laguna (45°02’S, 65°53’O). A su vez se seleccionaron tres periodos de muestreo: incubacion, pichones pequenos y pichones grandes. Las muestras de dieta se obtuvieron mediante lavado estomacal. Los resultados obtenidos en las tres colonias analizadas confirman que en las costa...
We quantified the trophic niche of Magellanic penguins (Spheniscus magellanicus) breeding and mou... more We quantified the trophic niche of Magellanic penguins (Spheniscus magellanicus) breeding and moulting in Golfo San Jorge, Argentina, through conventional stomach content and stable isotope analysis. A total of 112 adults were flushed during the early and late chick stages of 2011 and 2012 at Isla Vernacci Norte, and at least 15 prey taxa were found, including fishes, cephalopods, crustaceans and polychaetes. Overall, Argentine anchovy (Engraulis anchoita) showed the highest contribution in terms of importance by mass (68.1-85.3%, depending on chick stage and year), except for the old chick stage in 2011 when the shortfin squid (Illex argentinus) was the main prey consumed (56.0%). Based on carbon and nitrogen isotopic values from a total of 256 blood samples, corresponding to young and old chicks and to adults of both sexes sampled throughout the incubation, chick and moult stages at the above mentioned colony and years, Bayesian mixing model outputs showed that Argentine anchovy was always the main prey (48-86%). Bayesian mixing model outputs obtained from adults of both sexes and their chicks during the late chick stage of 2013 at Isla Vernacci Norte, Isla Tova and Isla Leones also showed that Argentine anchovy was the main prey consumed. This is the first comprehensive assessment of Magellanic penguin diet composition in northern Patagonia, quantifying the relative contribution of prey in the diet of adults and chicks at different stages of the annual cycle and years, and confirms the relevance of a forage fish such as the Argentine anchovy in its trophic ecology.
Many seabirds are attracted to trawl vessels to make use of fishery waste, and often this attract... more Many seabirds are attracted to trawl vessels to make use of fishery waste, and often this attraction results in increased incidental mortality. We assessed seabird attendance and associated incidental mortality at the Argentine red shrimp Pleoticus muelleri trawl fishery in Golfo San Jorge, Argentina. Information on seabird numbers was gathered in the autumn and winter 2006 and spring 2008, while information on seabird incidental captures was obtained for the period 2005-2007. Eighteen seabird species attended vessels, and the 2 most frequent and abundant seabirds (percent occurrence, median no. haul-1) were the kelp gull Larus dominicanus (> 94%, <100) and blackbrowed albatross Thalassarche melanophrys (> 94%, < 55). Seabird numbers were significantly lower in winter than the other 2 seasons and highest during discarding activities. Species incidentally killed in nets were the Magellanic penguin Spheniscus magellanicus and imperial cormorant Phalacrocorax atriceps, with a mean capture rate of 0.048 birds haul-1 , and for both species, mortality decreased with distance to the coast. Considering the fishery's fishing effort during each month, the estimated total mortality in the study period was 895 (95% CI: 572 to 1339) penguins and 172 (95% CI: 69 to 305) cormorants. Over 95% of the recorded mortality occurred in 2005, the year when the trawling moratorium generally implemented in the area was not enforced. No interactions with warp cables were recorded. Results highlight the relevance of complying with the current moratorium scheme, as adjusting it to the penguin and cormorant breeding seasons may by a potentially effective management tool. The proximity to the coast of the recorded incidental mortalities indicates the need to reevaluate the spatial design of the park and/or the definition of management actions beyond the boundaries of the Marine Protected Area.
We studied the interaction between seabirds and warp cables in the high-seas Argentine hake Merlu... more We studied the interaction between seabirds and warp cables in the high-seas Argentine hake Merluccius hubbsi trawl fishery operating in Golfo San Jorge, Argentina, and tested the efficacy of a simple mitigation measure designed to reduce mortality at warp cables. Observations ...
Nada más sencillo que conocer un lugar profundamente anhelado. Al mismo tiempo que desembarqué en... more Nada más sencillo que conocer un lugar profundamente anhelado. Al mismo tiempo que desembarqué en esta tierra helada y comencé mi labor científica, decidí redactar mí día a día. A medida que me introducía en la cotidianidad antártica la necesidad de indagar se profundizaba, transformando mis simples relatos antárticos en este libro que se animó humildemente a transitar por los caminos de la ciencia, la cultura, la sociedad y la filosofía antártica. Sin duda no fue solo conocer esta tierra lo que me agradó de sobremanera, sino también adquirir conocimiento acerca de su historia, su política y su manejo ambiental. Mi profundo desconocimiento respecto a las temáticas antes mencionadas activó los engranajes de la inquietud y la búsqueda del conocimiento. A excepción de los ANEXOS I,III y IV éste libro fue escrito en su totalidad en la Base Primavera, al mismo tiempo que desarrollaba mi labor científica como biólogo especializado en aves marinas durante la Campaña Antártica de Verano 201...
Wilson's Storm Petrels spend the austral winter and spring (May to October) at sea. Studies in th... more Wilson's Storm Petrels spend the austral winter and spring (May to October) at sea. Studies in the Golfo San Jorge, Patagonian Shelf, showed the presence of this petrel in seabird assemblages associated with commercial trawlers. A sailing superstition holds that the appearance of storm petrel foretells bad weather. By way of confirming this traditional belief, the aim of this study is to relate the appearance of the Wilson Storm Petrel with the weather conditions at sea and the feeding behaviour implications. Information about the presence and abundance was gathered on board from a total of 253 hauls during 2005, 2006 and 2008. A total of 65 individuals were recorded in 30 (11.86%) of fishing hauls. The number and presence of Wilson Storm Petrels be correlated with low atmospheric pressure. Given that they are among of the most abundant seabirds of the world, detailed data on interactions with fisheries and weather conditions at sea are not only interesting for analyze their association with fisheries or foretells bad weather, but may also be useful for monitoring the Southern Oceans.
Fil: Gonzalez Zevallos, Diego Ricardo. Consejo Nacional de Investigaciones Cientificas y Tecnicas... more Fil: Gonzalez Zevallos, Diego Ricardo. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Nacional Patagonico; Argentina
RESUMEN. En el golfo San Jorge se desarrollan varias actividades económicas de relevancia, entre ... more 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, Argentina ABSTRACT. 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.
Seabird abundances and breeding distribution have the potential to serve as ecological indicators... more Seabird abundances and breeding distribution have the potential to serve as ecological indicators. The western Antarctic Peninsula is one of the three sites in the world with the greatest increases in local temperature during the last 50 years. The aim of this study was to monitor the distribution and abundance of breeding populations of seabirds in the northern sector of the Danco Coast, northwest of the Antarctic Peninsula, during the breeding season 2010/11. The birds were the Wilson?s storm petrel (Oceanites oceanicus), South Polar skua (Stercorarius maccormicki), kelp gull (Larus dominicanus), Antarctic tern (Sterna vittata), snowy sheathbill (Chionis alba), chinstrap penguin (Pygoscelis antarctica), southern giant petrel (Macronectes giganteus), gentoo penguin (Pygoscelis papua), Cape petrel (Daption capense) and Antarctic shag (Phalacrocorax bransfieldensis). Annual breeding population growth increased in pygoscelids, southern giant petrel and sheathbill, and for the remaining species, breeding population trends were stable. Given that seabird populations can provide valuable information on the conditions of their feeding and nesting environments, this study highlights the need to maintain basics monitoring studies.
We studied discard use and incidental mortality of seabirds attracted to high-sea trawl vessels o... more 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.
We evaluated discard consumption by Kelp Gulls (Larus dominicanus) and Black-browed Albatrosses (... more We evaluated discard consumption by Kelp Gulls (Larus dominicanus) and Black-browed Albatrosses (Thalassarche melanophrys) associated with trawlers operating at Golfo San Jorge, Argentina, and assessed differences in their feeding behaviour, prey size preferences and foraging efficiency. Observations were made onboard hake (January 2007) and shrimp vessels (November 2008). The Kelp Gull and Black-browed Albatross were the most frequent and abundant
SummaryAssessing human activities and understanding their interaction with seabirds constitute im... more SummaryAssessing 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 par...
We evaluated discard consumption by Kelp Gulls (Larus dominicanus) and Black-browed Albatrosses (... more We evaluated discard consumption by Kelp Gulls (Larus dominicanus) and Black-browed Albatrosses (Thalassarche melanophrys) associated with trawlers operating at Golfo San Jorge, Argentina, and assessed differences in their feeding behaviour, prey size preferences and foraging efficiency. Observations were made onboard hake (January 2007) and shrimp vessels (November 2008). The Kelp Gull and Black-browed Albatross were the most frequent and abundant seabirds at both fisheries, while Argentine Hake (Merluccius hubbsi) dominated the composition of discards. Kelp Gulls and Black-browed Albatrosses consumed 91% of experimentally discarded hake (n = 1236). Mean sizes of prey consumed by gulls were 22.4 and 23.7 cm in the hake and shrimp fisheries, respectively, while those of prey consumed by albatrosses were 28.5 and 31.3 cm, respectively. In both fisheries, gulls selected the smaller prey available (<25 and < 30 cm in hake and shrimp fisheries, respectively) while Black-browed Alb...
Assessing human activities and understanding their interaction with seabirds constitute important... more 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. Resumen La 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 significativa de su tiempo en el mar dentro de áreas utilizadas por ambas pesquerías (pingü inos: 17,9-66,2%; cormoranes: 46,0-89,0 %). En ambos añ os, las áreas de alimentació n de pingü inos y cormoranes mostraron una clara superposición con las zonas de operació n de ambas pesquerías. Los patrones de forrajeo observados para los pingü inos y cormoranes sugieren una alta probabilidad de conflicto espacial con las flotas pesqueras. Es más, se registró mortalidad incidental de aves en ambas pesquerías, con valores que oscilaron entre 0,02 y 0,34 individuos por lance dependiendo de la especie y la pesquería. Aunque uno de los objetivos del nuevo parque marino es la protecció n de las poblaciones del Pingü ino de Magallanes y del Cormorán Imperial, los límites definidos del área protegida no parecerían ser adecuados para su protecció n efectiva. Los resultados sugieren la necesidad de re evaluar el diseñ o espacial del parque y/o definir acciones de manejo en aguas por fuera del parque para minimizar los efectos negativos sobre pingü inos y cormoranes.
We studied discard use and incidental mortality of seabirds attracted to high-sea trawl vessels o... more 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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