| The effects of in-stream barriers, used to control of sea lamprey in the Great Lakes basin on the diversity of non-target fishes, is an important concern for fishery managers. Upstream loss of fish species observed in 24 barrier streams (relative to paired reference streams) was variable across the basin. We examined three hypotheses for this variation: sampling design, variation attributed to environmental differences between barrier and reference streams within pairs, and variation attributed to environmental differences among barrier streams. Simulation modeling demonstrated that a large variance in effect size is expected for our sampling design, and individual stream estimates are imprecise. Regression models and an information-theoretic method of model selection provided no support for the ecologically-based hypotheses. Therefore, the mean effect size is the most reliable and unbiased estimate of the non-target effects of sea lamprey barriers. This study will inform decisions pertaining to the placement and operation of new barriers. |
