Concurrent Sessions A: Passage Effectiveness Monitoring in Small Streams I - Alternatives to Direct Detection for Assessing the Effectiveness of Aquatic Organism Passage

Direct detection of individuals is often considered the most reliable indicator of the effectiveness of aquatic organism passage efforts, but given spatial and temporal variation in movement along with other logistical constraints this detection can be difficult and expensive to obtain, with a high probability of false negatives (concluding no passage when passage is possible). However, the ultimate goal of these projects is to restore population connectivity and increase population resilience. Therefore, we expect that effective aquatic organism passage should be manifest in predictable changes in abundance and genetic structure, which can at the same time serve as indicators of individual movement. Towards this goal we focused on two approaches. First, we used patterns of abundance and diversity above and below road crossings to test whether these patterns could be used to infer passage and connectivity. Second we took advantage of the discrete spawning location strategy used by most stream-dwelling species combined with new tools to assess local genetic structure (via parentage and sibling assignment) to determine whether relatedness structure was consistent with movement and successful dispersal across a potential barrier. For each of these approaches we employed two methods 1) simulation models which define sensitivity, power, and accuracy and 2) field applications which directly test performance. These approaches have been rigorously evaluated in simulations and successfully tested in the field in several locations in the northeastern US and these efforts have helped to define which species, which situations, and which sampling regimes where these techniques will and will not be effective. We are currently working to incorporating these models into assessment frameworks at both site and landscape scales