Surveys of Euphausia superba often target localised shelves and ice edges where their growth rates and predation losses are atypically high. Emphasis on these areas has led to the current view that krill require high food concentrations, with a distribution often linked to shelves. For a wider, circumpolar perspective we compiled all available net-based density data on postlarvae: 8137 mainly summer stations from 1926-2004. Unlike Antarctic zooplankton their distribution is highly uneven, with 70% of the total stock concentrated between 0o and 90oW. Within this Atlantic sector, krill are abundant over both shelf and ocean. At the Antarctic Peninsula, by contrast, they are found mainly over the inner shelf whereas in the Indian-Pacific sectors krill prevail in the ocean within 200-300 km of the shelf break. Overall, 87% of the total stock live over deep oceanic water (>2000 m) and krill occupy regions of moderate food (0.5-1.0 mg chl a m-3). Advection models suggest some loss northwards from these regions and into the low chlorophyll belts of the Antarctic Circumpolar Current (ACC). We found possible evidence for a compensating southwards migration, with an increasing proportion of krill found south of the ACC as the season progressed. The retention of krill in moderately productive oceanic habitats is a key factor in their high total production. While growth rates are lower than those over shelves, the ocean provides a refuge from shelf-based predators. The unusual circumpolar distribution of krill thus reflects a balance between advection, migration and top-down and bottom-up processes.
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Abstract:
El presente documento contiene información respecto a la administración pesquera que realiza el Estado de Chile para garantizar la conservación del recurso bacalao de profundidad y el desarrollo sustentable de la pesquería que se realiza en torno a este recurso en la zona económica exclusiva de Chile. Asimismo, se presentan los mecanismos mediante los cuales el Estado chileno asegura la participación responsable de sus naves en aguas sujetas a la jurisdicción de la CCAMLR y en aguas internacionales. Para estos efectos, el documento se divide en cuatro secciones. La primera trata la administración de la pesquería en el ámbito de la ZEE de Chile, distinguiendo la diferencia entre la pesquería que se realiza por naves industriales y las embarcaciones artesanales. La segunda sección, se refiere a la operación de las naves chilenas en el área de competencia de la CCRVMA y la tercera, a los mecanismos mediante los cuales se desarrolla la fiscalización y control de las normas pesqueras, dentro y fuera de la ZEE chilena. Finalmente, en la cuarta sección, se presentan las acciones que ha emprendido Chile para combatir la pesca Ilegal, No Declarada y No Regulada (INDNR).