Small-scale variation in the diet of the South American Sea lion (Otaria flavescens) in northern Patagonia (Argentina)

JARMA, DAYANA; ROMERO, MARÍA ALEJANDRA; GARCÍA, NÉSTOR A.; SVENDSEN, GUILLERMO; GONZÁLEZ, RAÚL; DANS, SILVANA LAURA; CRESPO, ENRIQUE ALBERTO

Regional Studies in Marine Science

ELSEVIER

Lugar: LONDRES; Año: 2019 vol. 28 p. 1 - 11

2352-4855

An understanding of the mechanisms that shape animal-population dynamics is a fundamentalconsideration in conservation biology and ecology. Populations of the species of South-Americansea lions (SASLs) Otaria flavescens reveal different growth rates, which variations could be linked tochanges in the accessibility of nutritional resources in any given location. The available information ondifferences in the SASL diet on a local scale, however, is relatively scarce. We therefore searched forevidence of geographical variations in the diet of the SASLs in Northern Patagonia?namely, in the GolfoSan Matías (GSM) and the Golfo Nuevo (GN), both of which bays are quite different regarding theirphysiography, oceanography, and anthropic pressures. From 2005?2013, stomach samples ( nGSM = 39;nGN = 31) were collected from animals found dead on the coast or accidentally caught in fishing nets.The dietary composition differed between the two gulfs with respect to the most common species, thezoological groups, and the sizes of the primary prey. In the GSM, the SASLs fed on demersal?pelagicfish, while in the GN the diet exhibited a high contribution of benthic species. Differences in theitems and sizes of prey consumed at each area are discussed in terms of differential prey availabilityalong with the opportunistic feeding behavior of this predator. These differences, in addition to thespecies?s main prey as targets for major fisheries, must be taken into account in order to understandthe different population dynamics of this apex predator and thus ensure its conservation.