Jackie Galvez

UC Berkeley

“Morphological consequences of artificial barriers in riverine steelhead trout”

Artificial damming of freshwater rivers influences many aspects of stream ecology. Human-made dams can create barriers to upstream breeding and rearing habitats of anadromous fishes and can limit gene flow between populations. Studying fish impacted by damming provides a unique opportunity to study the downstream effects of these dispersal limitations, with potential to reveal how damming influences the evolutionary trajectory of populations and how endangered fishes cope with anthropogenic environmental change. In this study, we conducted a morphological comparison of anadromous steelhead trout, Oncorhynchus mykiss, along the South Fork Eel River. We used 2D geometric morphometrics to analyze differences in lateral body shape spatially (above versus below) and temporally (before versus during) across a human-made barrier, Benbow Dam. Results indicate differences in morphological dispersion both spatially and temporally. Furthermore, Procrustes ANOVA and pairwise comparisons also indicate differences in lateral body shape for all groups. These results lead us to propose functional hypotheses for how muscle mass and movement may differ in trout populations separated by a dam barrier, with particular emphasis on differing trends among freshwater resident and migratory fish.


I study the impacts of human infrastructure upon native salmonid anatomy on the West Coast. Specifically, my research investigates how artificial dam barriers impact body shape in endangered steelhead trout, and the anatomical features that allow hatchery rainbow trout to survive in new environments.

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