Spatial Association Between Hotspots of Baleen Whales and Demographic Patterns of Antarctic Krill Euphausia Superba Suggests Size-Dependent Predation
Vol. 405: 255–269, 2010 MARINE ECOLOGY PROGRESS SERIES Published April 29 doi: 10.3354/meps08513 Mar Ecol Prog Ser Spatial association between hotspots of baleen whales and demographic patterns of Antarctic krill Euphausia superba suggests size-dependent predation Jarrod A. Santora1, 2,*, Christian S. Reiss2, Valerie J. Loeb3, Richard R. Veit4 1Farallon Institute for Advanced Ecosystem Research, PO Box 750756, Petaluma, California 94952, USA 2Antarctic Ecosystem Research Division, Southwest Fisheries Science Center, 3333 Torrey Pines Ct., La Jolla, California 92037, USA 3Moss Landing Marine Laboratories, 8272 Moss Landing Road, Moss Landing, California 95039, USA 4Biology Department, College of Staten Island, City University of New York, 2800 Victory Boulevard, Staten Island, New York 10314, USA ABSTRACT: We examined the spatial association between baleen whales and their principal prey, Antarctic krill Euphausia superba near the South Shetland Islands (Antarctic Peninsula) using data collected by the US Antarctic Marine Living Resources (AMLR) program during January surveys from 2003 through 2007. Whale distributions were determined using ship-based visual surveys, while data on krill distribution, abundance, and demographic characteristics were derived from net hauls. Approximately 25 000 km of transects and 500 net hauls were sampled over 5 yr. We defined hotspots based on statistical criteria to describe persistent areas of occurrence of both whales and krill. Hotspots were identified, and whales and krill length-maturity classes exhibited distinct spatial seg- regation in their distribution patterns. We found that baleen whales aggregated to krill hotspots that differed in size structure. Humpback whales Megaptera novaeangliae were associated with small (<35 mm) juvenile krill in Bransfield Strait, whereas fin whales Balaenoptera physalus were associ- ated with large (>45 mm) mature krill located offshore.
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