Trends in sympatric otariid populations suggest resource limitations in the Peruvian Humboldt Current System

Type Article
Date 2021-07
Language English
Author(s) Cárdenas-Alayza Susana1, 2, 4, Gutiérrez Dimitri2, 3, Tremblay Yann4
Affiliation(s) 1 : Centro para la Sostenibilidad Ambiental, Universidad Peruana Cayetano Heredia, Lima, 15074, Peru
2 : Laboratorio de Ciencias Del Mar, Universidad Peruana Cayetano Heredia, Lima, 15102, Peru
3 : Facultad de Ciencias y Filosofía, Programa Maestría en Ciencias Del Mar, Universidad Peruana Cayetano Heredia, Lima, 15102, Peru
4 : UMR 248 MARBEC: IRD – Univ. Montpellier – CNRS – Ifremer, Avenue Jean Monnet CS 30171, 34203, Sète Cedex, France
Source Marine Environmental Research (0141-1136) (Elsevier BV), 2021-07 , Vol. 169 , P. 105349 (11p.)
DOI 10.1016/j.marenvres.2021.105349
WOS© Times Cited 2
Keyword(s) Peru, Punta San Juan, Population decline, Competition, Fur seal, Sea lion, Otaria byronia, Arctocephalus australis

Sympatric species evolve mechanisms to avoid competition and coexist. In the Humboldt Current System (HCS), populations of South American sea lions (SASL, Otaria byronia) and South American fur seals (SAFS, Arctocephalus australis) fluctuate mostly due to ENSO events and prey availability. We evaluate population trajectories of Peruvian sympatric otariids and discuss mechanisms for competition and/or resource limitation. For this purpose, we analyzed population trajectories of SASL and SAFS in a sympatric breeding site in Punta San Juan, Peru between 2001 and 2019. Wavelet analysis was used to extract trends and derivatives to estimate rates and turning points. Age-class proportions and biomass times series were constructed from weekly counts and evaluated. Both populations show a growth phase and subsequent decline. SAFS started to decline ~2.25 years before and at a rate 1.5 times faster than SASL. Decrease in juvenile age-class suggests that resource limitation is the main contributing factor for current population decline.

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