Predation on cephalopods by Weddell seals, Leptonychotes weddellii, at Hope Bay, Antarctic Peninsula

Abstract

Cephalopods play a key role in marine environments as food resources for top predators such as marine mammals and seabirds. However, detailed information on their trophic relationships with Antarctic seals is scarce. The aim of the present study was to examine the cephalopod portion of the diet of adult and subadult Weddell seals, Leptonychotes weddellii, at Hope Bay, Antarctic Peninsula, through the analysis of scats collected during three consecutive summers (2003, 2004 and 2005). Cephalopods occurred in almost 45% of the 217 samples collected during the whole period of study. A total of 662 beaks (358 upper and 304 lower) were removed from scats containing cephalopod remains (n = 93). Octopods were largely dominant in comparison with teuthoids constituting in numerical abundance over 95% of the cephalopod prey. The octopod Pareledone turqueti was the most frequent and dominant prey species representing, respectively, 57.9 and 71.1% in numbers and biomass of cephalopods consumed. Species belonging to the group of papillated Pareledone were second in importance. The results were compared with information from previous dietary studies of L. weddellii at other localities of Antarctica. Based on the examination of the cephalopod prey taxa identiWed in this study, it is suggested that during the study period Weddell seal individuals foraged mainly on benthic prey resources close to the coast, in inshore waters where octopods were dominant in comparison with pelagic squid.

Cephalopod remains in scats of Weddell seals (Leptonychotes weddellii) at Cape Shirreff, South Shetland Islands, Antarctica

“…The octopods, Pareledone charcoti, P. turqueti and Megaleledone setebos (=M. senoi), were previously reported in the diet of Weddell seals in the Scotia Arc and Antarctic Peninsula, with P. charcoti and P. turqueti as the main prey species (Lipinski and Woyciechowski 1981;Clarke and MacLeod 1982;Cassaux et al 1997;Casaux et al 2006Casaux et al , 2009Daneri et al 2012). The genus Pareledone also occurred in the diet of Weddell seals in East Antarctica (Lake et al 2003).…”

“…In all three previous studies conducted in the Scotia Arc and in the present study, squid in the diet was negligible or absent. Conversely, Clarke and MacLeod (1982) found cephalopod remains in the stomach contents of eight Weddell seals killed at Deception Island, (Casaux et al 2006), while in seals from Hope Bay, octopods were the principal prey item (Daneri et al 2012). The octopods, Pareledone charcoti, P. turqueti and Megaleledone setebos (=M.…”

“…Lipinski and David 1990;Imber 1992;Rodhouse et al 1992;Cherel et al 1996;Clarke 1996;Klages 1996;Santos and Haimovici 1998). However, information on the cephalopod component of the diet of Weddell seals is scarce in the region of the Scotia Arc, with only three studies (Lipinski and Woyciechowski 1981;Clarke and MacLeod 1982;Daneri et al 2012). The aims of the present study were to investigate the cephalopod component of the diet and to assess the contribution, estimated size and wet mass of this prey taxon ingested by Weddell seals at Cape Shirreff in the South Shetland Islands.…”

“…The ability to dive below 700 m allows Weddell seals to forage in both benthic and pelagic habitats over the Antarctic continental shelf (Testa 1994;Lake et al 2003). The diet of Weddell seals has been studied in East Antarctica (Green and Burton 1987;Green et al 1995;Lake et al 2003), the Antarctic Peninsula (Casaux et al 2006;Daneri et al 2012), the Weddell Sea (Plötz 1986;Plötz et al 1991), the Ross Sea (Dearborn 1965;Calhaem and Christoffel 1969;Davis et al 1982;Castellini et al 1984;Testa et al 1985;Green and Burton 1987;Burns et al 1998) and the South Shetland Islands (Lipinski and Woyciechowski 1981;Clarke and MacLeod 1982;Cassaux et al 1997). The diet has been reported to consist of nototheniid fishes, cephalopods, prawns and other small invertebrates.…”

“…They occupy a wide range of habitats (Clarke 1996, Daneri et al 2012) and constitute an important food resource for top predators (e.g. Lipinski and David 1990;Imber 1992;Rodhouse et al 1992;Cherel et al 1996;Clarke 1996;Klages 1996;Santos and Haimovici 1998).…”