Abstract
Use of surrogacy remains a useful method for prioritizing research on representatives of at-risk groups of fishes, yet quantifiable evidence in support of its use is generally not available. Blade strike impact represents one of the most traumatic stressors experienced by fish during non-volitional movements through hydropower turbines. Here, we use data generated from laboratory trials on blade strike impact experiments to directly test use of surrogacy for salmonid and clupeid fishes. Results of logistic regression indicated that a -taxonomic (genus) variable was not a significant predictor of mortality among large rainbow trout and brook trout. Similar results were found for young-of-the-year shad species, but genus-level taxonomy was a significant predictor of mortality while species was not. Multivariate analysis of morphometric data showed that shad clustered together based on similarities in fish shape which was also closely associated with genus. Logistic regression including size as a major covariate suggested total fish length was not a significant predictor of mortality, yet dose–response data suggest differential susceptibility to lower strike velocities. We suggest that use of surrogacy among species is justifiable but should be avoided within a species since the effects of size remain unclear.
Highlights
Downstream passage of fish through hydropower facilities represents a direct threat to migratory fishes worldwide
Results of the principal component analysis (PCA) were used to perform a hierarchical clustering on principal components (HCPC) analysis to test how shad may cluster or group according to similarities in body shape
Brook trout data should be a suitable representative to species like bull trout, Salvelinus confluentus, which is threatened throughout much of its native range in North America [32,33]
Summary
Downstream passage of fish through hydropower facilities represents a direct threat to migratory fishes worldwide. Fish passing through hydropower turbines are exposed to a suite of injurious or lethal stressors, including rapid decompression, cavitation, shear forces, and impact with structures such as turbine blades [2,3,4,5]. Field trials are often used to estimate morbidity and mortality rates of turbine-passed fish related to turbine characteristics or dam operation parameters; these trials are incapable of linking a specific stressor to risk of injury or death because exact exposure conditions are unknown. The risk and severity of injury is dependent on turbine type, design, and operations, which makes it difficult to apply inferences from one facility to another. Understanding how turbine type or associated characteristics impact survival of fishes is important, but rates of mortality are affected by how the fish interacts with the turbine
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