Local feeding patterns of the south american sea lion otaria byronia: Case of punta patache, Northern Chile

Abstract

-Food habits of the South American sea lion (Otaria byronia) (SASL) in the upwelling zone of Northern Chile were studied by means of scat analyses. The scat samples (n= 183) were collected at Punta Patache, south of Iquique (20°48’63”S) during two El Niño periods (1997/98 and 2009/10). A total of 10 pelagic neritic prey species were identified (including 4 fishes, 2 cephalopods and 3 crustaceans). The most important species in terms of abundance and frequency were anchovy (Engraulis ringens) (7.4%), prawn (Pleuroncodes monodon) (83.0%) and squid (Loligo gahi) (6.9%). In terms of biomass consumption, the most important items were squid (35.7%) and prawn (21.9%). In terms of energy inputs to the diet the most important were prawn (19.9-32.7%) and squid (24.9-40.5%), lipids contribution of anchovy (31.8-36.4%) and squid (20.9-41.0%), and prawn protein (22.5-29.9%). The comparison with results of previous studies under neutral/cold ENSO conditions (1996 and 2015) showed greater anchovy consumption (82.8% and 23.3-48.4%, respectively). On this basis it is concluded that in front of lack of anchovy during ENSO events, the SASL would adjust its diet to other resources, situation that determines a ‘nutritional stress’ derived from an inadequate nutrition, whose consequences are growth reduction, low birth rates, diseases, malnutrition and in many cases death, as has been reported for the strong ENSO 1982/83 and 1997/98.