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1 August 2008 Survival Rates of the California Sea Lion, Zalophus californianus, in Mexico
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Abstract

California sea lions (Zalophus californianus) in the Gulf of California have declined by 20% over the past 2 decades. The lack of data on life-history parameters for this species has limited the development of demographic models to assess the status of this population. We estimated age- and sex-specific annual survival probabilities for California sea lions using resighting data on 5 pup cohorts from 1981 to 2006. We modeled apparent survival and resighting probability using age-class, sex, and time as potential explanatory variables. Apparent survival rates varied for different age- and sex-classes. Only survival of pups varied by year (from 0.556 to 0.998). Survival was the same for immature males and females (0.90), but differed by sex for young (males = 0.90, females = 0.97) and old (males = 0.75, females = 0.91) adults. Resighting probabilities varied by time, age-class, and sex. Resighting probabilities were higher for females than for males, and lowest for juveniles. The survival estimates presented here provide practical insight into understanding age- and sex-specific survival rates for California sea lions.

Claudia J. Hernández-Camacho, David Aurioles-Gamboa, Jeffrey Laake, and Leah R. Gerber "Survival Rates of the California Sea Lion, Zalophus californianus, in Mexico," Journal of Mammalogy 89(4), (1 August 2008). https://doi.org/10.1644/07-MAMM-A-404.1
Accepted: 1 February 2008; Published: 1 August 2008
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