Diet composition of an opportunistic predator from an upwelling area in the Southeastern Pacific

Abstract

The aim of this study was to use scat analysis to analyse the dietary composition of the South American sea lion (SASL, Otaria byronia) over a short temporal scale and in different but closely located colonies in the Humboldt Current System of northern Chile. Scat samples were collected at Arica (18°34 0 S), Iquique (20°48 0 S) and Mejillones (23°04 0 S) during the summer (January to March) and winter (July) of 2015. A total of 16 595 individual prey items from nine species were found in 194 of the 215 scat samples. In general, squat lobster (Pleuroncodes monodon) was the most important prey item for the sea lion diet, both by number and according to the index of relative importance (%IRI), followed by anchovy (Engraulis ringens), which was the most frequent prey item in the scats and the most important by weight. Patagonian squid (Loligo gahi) ranked third in importance in the sea lion diet. However, some spatiotemporal variations in the consumption of prey were found. Squat lobster was the most important prey for sea lions in Arica and Iquique, while anchovy was the dominant prey in Mejillones. Regarding seasonal variation, squat lobster was more important in winter than in summer in the three localities, while anchovy was also more important during winter, except in Mejillones where the levels of consumption of this prey were similar in both seasons. These results show that SASL adjust their dietary preferences, modifying the contribution of different prey both spatially and temporally. Spatiotemporal variations in the SASL diet can be explained by temporal changes in the distribution and abundance of their prey.

Resource partitioning as a mechanism for trophic segregation in sympatric otariids from the productive upwelling Peruvian Humboldt Current System

“…2002; Arias‐Schreiber 2003; Sarmiento‐Devia et al . 2020). This can be explained by the high proportions of 1–2 main prey items in each of the predator diets, in combination with the lower diversity of fish species found in our study, compared with previous studies.…”

“…2018; Sarmiento‐Devia et al . 2020). Trophic level values for other fish species were extracted from FishBase (http://www.fishbase.org; Froese & Pauly 2000).…”

“…1998; Paredes & Arias‐Schreiber 1999; Sarmiento‐Devia et al . 2020). However, some few studies have evaluated diet composition between SAFS and SASL concurrently in Peru in the 1980s and late 1990s.…”

Contrasting nursery habitats promote variations in the bioenergetic condition of juvenile female red squat lobsters (Pleuroncodes monodon) of the Southern Pacific Ocean

“…In the context of species interactions in the food web realm, hake ( Merluccius gayi ), the South American sea lion ( Otaria flavescens ), and squid ( Dosidicus gigas ) are described as the main predators of P . monodon ( Cubillos, Rebolledo & Hernandez, 2003 ; Sarmiento-Devia et al, 2020 ). Although these predators show a certain degree of mobility, their trophic habits and lifestyles are closely linked to specific feeding areas and/or locations ( Payá & Ehrhardt, 2005 ; Sarmiento-Devia et al, 2020 ; Sepúlveda, Carrasco & Quiñones, 2021 ), where they consume prey with a high energy content, such as the red squat lobster ( Sarmiento-Devia et al, 2020 ; Wehrtmann & Acuña, 2011 ).…”

“…monodon ( Cubillos, Rebolledo & Hernandez, 2003 ; Sarmiento-Devia et al, 2020 ). Although these predators show a certain degree of mobility, their trophic habits and lifestyles are closely linked to specific feeding areas and/or locations ( Payá & Ehrhardt, 2005 ; Sarmiento-Devia et al, 2020 ; Sepúlveda, Carrasco & Quiñones, 2021 ), where they consume prey with a high energy content, such as the red squat lobster ( Sarmiento-Devia et al, 2020 ; Wehrtmann & Acuña, 2011 ). Hence, the spatial variations in the bioenergetic condition of P. monodon may modify the energy transfer to higher trophic levels ( Lovrich & Thiel, 2011 ) and impact the nutritional status of these predators, which, in turn, are also important fishery resources ( M .…”