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Movements and location at sea of South American sea lions ( Otaria flavescens )
Author(s) -
Campagna Claudio,
Werner Rodolpho,
Karesh William,
Marín María Rosa,
Koontz Fred,
Cook Robert,
Koontz Charles
Publication year - 2001
Publication title -
journal of zoology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.915
H-Index - 96
eISSN - 1469-7998
pISSN - 0952-8369
DOI - 10.1017/s0952836901001285
Subject(s) - rookery , continental shelf , pelagic zone , range (aeronautics) , foraging , fishery , geography , biology , oceanography , seasonal breeder , ecology , geology , population , demography , materials science , sociology , composite material
This study examined the foraging locations of lactating female and pre‐breeding adult male South American sea lions Otaria flavescens in the Patagonian continental shelf, south‐west Atlantic ocean. Research on females included the diving pattern, and was conducted during the 1994–98 breeding seasons in five northern and central Patagonian rookeries. Twenty females were satellite‐tracked using the Argos system and yielded 1558 locations at sea. Satellite transmitters were also deployed on two adult males tracked for a total of 94 days ( n = 364 locations) before the onset of the 1999 breeding season. Foraging trips for both sexes were confined to the temperate waters of the Patagonian continental shelf although males travelled greater distances than females, and arrived close ( c. 80 km) to the edge of the shelf. Females from the same rookery dispersed widely and locations at sea often overlapped. Individual differences were apparent between coastal and pelagic animals. Trips lasted a mean of 3.4 days ( sd = 1.3, n = 115 trips). Mean travel distance per trip was 206 km ( sd = 117 km, maximum 864 km, n = 115 trips). Females reached further distances by travelling faster rather than by extending the duration of trips. Consistent with the shallow continental shelf, 65% of 75 087 dives recorded for nine animals were in the range of 2–30 m. Males alternated periods on the coast with trips to sea lasting a mean of 5.7 days ( sd = 3.0, n = 8 trips). Mean travel distance exceeded 591 km (1 sd = 301 km, n = 8 trips). Results are consistent with sex differences reported from diet studies. Locations overlap with the summer operation of shelf fisheries targeting species that are also part of the sea lion diet.