Sofía Copello

Spatio-temporal overlap between the at-sea distribution of Southern Giant Petrels and fisheries at the Patagonian Shelf

The interactions between seabirds and fisheries pose significant threats for the seabird species such as incidental capture. In contrast, several species of seabirds meet part of their energetic requirements through the use of fisheries discards. Knowledge about the relationship between at-sea distribution of Procellariiformes and fisheries is a key tool in marine ecosystem management. We analysed the spatio-temporal relationship between the areas used by 16 satellite-tracked breeding adults of the Southern Giant Petrel and fisheries distribution and catch at the Patagonian Shelf. We also determined the time spent by adults in different marine jurisdictions. Results indicated a marked spatio-temporal association between birds and fisheries, mainly trawlers. The Southern Giant Petrels concentrated their foraging effort over Argentinean waters. The use of an abundant and predictable food source provided by the fisheries discards may be one of the factors affecting the dynamics of the Southern Giant Petrel populations in Patagonia, Argentina.

Diet of Imperial Cormorants Phalacrocorax atriceps Breeding at Central Patagonia, Argentina

Abstract. Diets of breeding Imperial Cormorants Phalacrocorax atriceps were studied at two breeding colonies, Islas Blancas and Isla Arce, located approximately 30 km apart in an area subject to increasing fishing pressure off Central Patagonia, Argentina. The goal was to assess differences between locations and diet variation among stages of the breeding cycle. Pellet casts (403 and 358 pellets per colony, respectively) were collected from November 2002 to February 2003. Analyses of the pellets revealed that Imperial Cormorants at Islas Blancas and Isla Arce fed on at least 25 and 23 prey types, respectively. Fish showed the highest frequency of occurrence at both colonies (> 70%), followed by crustaceans and molluscs. Of the fish prey, Merluccius hubbsi (22–71%), Engranlis anchoita (16–51%) and Raneya brasiliensis (5–48%) showed the highest frequencies of occurrence, depending on the colony and breeding stage. At Islas Blancas, the consumption of fish and crustaceans was similar among breeding stages (incubation, young chicks and old chicks), while it was significantly different at Isla Arce. Overall contribution by frequency of occurrence showed that M. hubbsi was the most frequent prey at Islas Blancas (58%), and E. anchoita and Pleoticus muelleri were more frequent at Isla Arce (48 and 45%, respectively). Also, overall contribution by mass of the main fish prey indicated differences between colonies. Given the commercial value of the main prey species, cormorant feeding requirements and spatial ecological needs should be included as considerations in coastal fisheries management and future development.

Diversidad de Tetrápodos en un mosaico de ambientes del sudeste de la ecorregión Pampeana como herramienta para planificar en conservación

A pesar del avance en el conocimiento de la biodiversidad para ciertas regiones, este se encuentra en general disperso y no ha sido interpretado respecto a sus propiedades emergentes ni puesto en contextos que faciliten la toma de decisiones en conservacion. El sudeste de la ecorregion Pampas presenta una diversidad ambiental destacada en un area relativamente restringida, y existe ademas una importante cantidad de informacion sobre diversidad de Tetrapodos. Nuestro objetivo fue compilar y analizar este cumulo de informacion, a traves de una lista de especies con sus abundancias relativas por ambientes destacando aquellas endemicas y de interes para la conservacion. Evaluamos la complementariedad entre los taxa (anfibios, reptiles, aves y mamiferos) en terminos de composicion, numero de especies totales y amenazadas. La diversidad de Tetrapodos recopilada pone de manifiesto que esta pequena area presenta una importante riqueza de especies (12 especies de anfibios, 26 reptiles, 233 aves, 34 mamiferos; 41 estan amenazadas y tres son endemicas). Los ambientes representados (pastizales, dunas, sierras, humedales, estuarios, marino, agroecosistemas, urbanizaciones) contribuyen diferencialmente a la diversidad general de Tetrapodos. La distribucion desproporcionada de la riqueza de especies, de especies amenazadas y de la composicion entre ambientes dentro de cada taxon, entre taxa y entre diferentes unidades ambientales destacan la utilidad de este tipo de analisis en la interpretacion de la variacion espacial de la biodiversidad y deberian contribuir en la planificacion territorial en un marco que optimice la conservacion.