title: Using Satellite Tracking and Isotopic Information to Characterize the Impact of South American Sea Lions on Salmonid Aquaculture in Southern Chile.
abstract: Apex marine predators alter their foraging behavior in response to spatial and/or seasonal changes in natural prey distribution and abundance. However, few studies have identified the impacts of aquaculture that represents a spatially and temporally predictable and abundant resource on their foraging behavior. Using satellite telemetry and stable isotope analysis we examined the degree of spatial overlap between the South American sea lion (SASL) and salmon farms, and quantify the amount of native prey versus farmed salmonids in SASL diets. We instrumented eight SASL individuals with SRDL-GPS tags. Vibrissae, hair and skin samples were collected for δ13C and δ15N analyses from five of the tagged individuals and from four males captured in a haul-out located adjacent to salmon farms. Tracking results showed that almost all the foraging areas of SASL are within close proximity to salmon farms. The most important prey for the individuals analyzed was farmed salmonids, with an estimated median (±SD) contribution of 19.7 ± 13.5‰ and 15.3 ± 9.6‰ for hair and skin, respectively. Using vibrissae as a temporal record of diet for each individual, we observed a remarkable switch in diet composition in two SASL, from farmed salmonids to pelagic fishes, which coincided with the decrease of salmon production due to the infectious salmon anemia virus that affected salmon farms in Chile at the end of 2008. Our study demonstrates the usefulness of integrating stable isotope derived dietary data with movement patterns to characterize the impacts of a non-native prey on the foraging ecology of an apex marine predator, providing important applied implications in situations where interactions between aquaculture and wildlife are common.
authors: Centro de Investigación y Gestión de Recursos Naturales (CIGREN), Instituto de Biología, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile.
authors: Maritza
authors: M
authors: Sepúlveda
authors: Biology Department, University of New Mexico, Albuquerque, United States of America.
authors: Seth D
authors: SD
authors: Newsome
authors: Centro de Investigación y Gestión de Recursos Naturales (CIGREN), Instituto de Biología, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile.
authors: Guido
authors: G
authors: Pavez
authors: Centro de Investigación y Gestión de Recursos Naturales (CIGREN), Instituto de Biología, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile.
authors: Doris
authors: D
authors: Oliva
authors: University of California Santa Cruz, Ecology and Evolutionary Biology, Santa Cruz, California, United States of America.
authors: Daniel P
authors: DP
authors: Costa
authors: University of California Santa Cruz, Ecology and Evolutionary Biology, Santa Cruz, California, United States of America.
authors: Luis A
authors: LA
authors: Hückstädt
mesh_terms: D000818:Animals; D017756:Aquaculture; D002247:Carbon Isotopes / Q000032:analysis; D002677:Chile; D004032:Diet; D017753:Ecosystem; D005260:Female; D008297:Male; D009587:Nitrogen Isotopes / Q000032:analysis; D009928:Organ Specificity; D011235:Predatory Behavior; D012474:Salmon / Q000254:growth & development*; D046070:Sea Lions / Q000254:growth & development*; D018531:Spacecraft; D062206:Spatial Analysis
chemical_list: D002247:Carbon Isotopes; D009587:Nitrogen Isotopes