Sponsor: Great Lakes Fishery Commission Increasing connectivity into and within rivers can benefit fishes by providing access to important habitats. Deliberate fragmentation of rivers can protect fishes by limiting the spread of invasive species. This symposium first addressed the geographic scope of interest in, and need for, selective bidirectional fish passage. It then explored the science needed to achieve it, including use of seasonal and velocity barriers, electrical guidance, and inclined ramps to selectively sort fishes. The final talk synthesized advances developed for sorting materials in the recycling industry. A facilitated discussion among ~50 attendees identified key challenges and research needs for selective fish passage. Passage and blocking success can be context-specific. The same structure may work well in one river, but not in another. Greater flexibility and fine-tuning are needed. Background information required for engineering design is often lacking, as is the will to improve success post-construction by fine tuning the design and its operation. Balancing policy objectives and passage/blocking success can be difficult. Passage and blocking devices are rarely 100% effective, but they could be less effective and still meet management targets. Sorting methods for recyclable waste could offer novel research directions to achieve the sorting of desirable fishes and blocking of invasive species required for selective fish passage. — Rob McLaughlin, University of Guelph, [email protected] Read the symposium abstracts here.