Effects of Surgical Outcomes and Fish Condition on in-River Survival Assessments

Operational parameters and structural configurations at hydroelectric facilities along with environmental conditions of the migration corridors are known to affect the survival of fish. Hydropower fish survival assessments at the individual- and population-level have progressed over the past decade with development of turbine simulation software, advances in turbine physical models, and improvements in telemetry systems, including, micro-transmitters, cabled and autonomous receivers, and advanced statistical designs that provide precise estimates of dam-passage and route specific passage survival. However, these approaches often ignore surgical effects and fish condition as a variable in passage and survival analyses. Careful physiological evaluations can augment survival model assumptions, resultant data, and predictive scenarios. Analyses indicted that surgeon observations of fish condition and surgical outcomes were related to 24 h holding mortalities and fish that were never detected after release. Short reach and long reach survival were related to surgical outcomes and fish condition, respectively. As the need for renewable energy sources increases, regional and site-specific behavioral and survival studies will benefit from the understanding of fish condition pre- and post-exposure. Systematic approaches like this can greatly improve the defensibility of compliance studies, and reduce costly after-installation modifications set to meet performance standards.