Size-specific apparent survival rate estimates of white sharks using mark-recapture models

Journal of Applied Ecology
None
By: , and 

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Abstract

For species that exist at low abundance or are otherwise difficult to study, it is challenging to estimate vital rates such as survival and fecundity and common to assume that survival rates are constant across ages and sexes. Population assessments based on overly simplistic vital rates can lead to erroneous conclusions. We estimated sex and length-based annual apparent survival rates for white sharks (Carcharodon carcharias). We found evidence that annual apparent survival differed over ontogeny in a system with competitive foraging aggregations, from 0.63 (SE = 0.08) for newly recruiting sub-adults to 0.95 (SE = 0.02) for the largest sharks. Our results reveal a potential challenge to ontogenetic recruitment in a long-lived, highly mobile top marine predator, as survival rates for sub-adult white sharks may be lower than previously assumed. Alternatively, younger and competitively inferior individuals may be forced to permanently emigrate from primary foraging sites. This study provides new methodology for estimating apparent survival as a function of diverse covariates by capture-recapture study including when sex assignment is uncertain.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Size-specific apparent survival rate estimates of white sharks using mark-recapture models
Series title Journal of Applied Ecology
DOI 10.1139/cjfas-2018-0142
Volume 76
Issue 11
Year Published 2019
Language English
Publisher Canadian Science Publishing
Contributing office(s) Patuxent Wildlife Research Center
Description 8 p.
First page 2027
Last page 2034
Country United States
State California
Other Geospatial Ano Nuevo Island, SE Farallon Island, Tomales Point
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