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Estimating and predicting collection probability of fish at dams using multistate modeling

Transactions of the American Fisheries Society

By:
, , , , ,
DOI: 10.1080/00028487.2012.694828

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Abstract

Dams can be equipped with a bypass that routes a portion of the fish that enter the turbine intakes away from the powerhouse into flumes, where they can be counted. Daily passage abundance can be estimated by dividing the number of fish counted in the bypass by the sampling rate and then dividing the resulting quotient by the collection probability (i.e., the proportion of the fish population passing the dam that is bypassed). We used multistate mark–recapture modeling to evaluate six candidate models for predicting the collection probabilities of radio-tagged subyearling fall Chinook salmon (n = 3,852) as a function of 1–2-d time periods (general model), four different combinations of outflow (i.e., the total volume of water passing the dam) and turbine allocation (i.e., the proportion of outflow directed through the turbines), and a null (intercept only) model. The best-fit model was the additive combination of turbine allocation and outflow, which explained 71% of the null deviance. Cross validation of the best-fit model accounted for the variation that may arise from different data sets and the ensuing parameter values on the collection probability estimates and yielded a standard error of 0.613 that can be used to construct approximate 95% prediction intervals in nonstudy years. Such estimates have been unavailable and will be useful anywhere estimates of daily passage abundance at dams with bypasses are needed to manage migratory fishes.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Estimating and predicting collection probability of fish at dams using multistate modeling
Series title:
Transactions of the American Fisheries Society
DOI:
10.1080/00028487.2012.694828
Volume
141
Issue:
5
Year Published:
2012
Language:
English
Publisher:
Taylor & Francis
Contributing office(s):
Idaho Cooperative Fish and Wildlife Research Unit
Description:
10 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
1364
Last page:
1373