Comparison of Methods to Verify Fish Passage through Remediated Culverts: Everything Including the Kitchen Sink

Resource agencies managing aquatic habitats and organisms have invested substantial resources restoring physical connectivity of systems affected by stream road crossings.  Remediation activities such as culvert removal or replacement with passage-friendly structures are expected to result in movement past the former barrier and utilization of the re-connected habitat.  Relative to the cost of remediation, much less money has been spent on demonstrating biological effectiveness even though that is the ultimate goal.  Here we report on efforts to identify an efficient, cost-effective monitoring scheme to detect movement of native trout past remediated culverts that biologists could use to demonstrate ‘success’.    We conducted a capture-mark-recapture study with native cutthroat trout adjacent to remediated culverts in four streams in the northern Rocky Mountains of Idaho and Montana.  We tagged trout above and below culverts, then monitored their subsequent movements by:  ‘traditional’ recapture using electrofishing, passive detection at antennas located inside the culverts, and active detection with mobile antennas.   Accuracy of each method was assessed relative to associated costs of the necessary equipment and labor, and results were contrasted with those of a companion study investigating genetic methods to detect passage (Neville and Peterson, this symposium).