Life, death, and resurrection: accounting for state uncertainty in survival estimation from tagged grass carp

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Authors Daniel S. Stich, Yan Jiao, Brian R. Murphy
Journal/Conference Name North American Journal of Fisheries Management
Paper Category
Paper Abstract Information about Grass Carp Ctenopharyngodon idella survival would be useful for improving the management of fish used for aquatic weed control. Reliable methods for estimating annual poststocking survival of Grass Carp from radiotelemetry data do not exist because the fish remain sedentary for prolonged periods between movements, giving the false impression of death, only to be observed alive (i.e., “resurrected”) at a later date. We constructed a state-space, multistate mark–recapture survival model accounting for uncertainty in the live/dead states of tagged Grass Carp in a large (8,500 ha) reservoir, and we estimated monthly and annual survival. Model results were compared with life history-based methods for estimating survival, and survival estimates that were corrected for state misclassification were compared with uncorrected estimates. Corrected estimates of annual survival (mean = 0.23; 95% credible interval [CRI] = 0.15–0.41) contained less bias than uncorrected estimates (0.12; 95% CRI = 0.08–0.18). However, both corrected and uncorrected estimates were substantially lower than the survival expected based on life history theory (mean = 0.69; 95% confidence interval = 0.52–0.78), suggesting that mark–recapture survival estimates for Grass Carp might be negatively biased due to tag shedding, tag-related mortality, or both. Our model effectively reduced bias in monthly and annual survival estimates due to state misclassification, illustrating the potential for application of existing mark–recapture frameworks to estimate Grass Carp survival with telemetry data, despite the behavioral idiosyncrasies of the species. Furthermore, these methods may have application for studies of other animals that undergo periodic quiescence between movements, such as salmonids, ictalurids, and reef fishes. To account for bias resulting from tag loss, future mark–recapture studies of Grass Carp could incorporate tag shedding rates within the framework developed here.
Date of publication 2015
Code Programming Language R

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