Evaluation of passage and sorting of adult Pacific salmonids through a novel fish passage technology

Abstract Throughout their life cycle, salmonids migrate between different habitats. During their journey, they often encounter barriers, such as hydropower dams, which may impede their migration and therefore decrease habitat connectivity. Fish passage systems have been developed to enable the migration of fish around barriers but their design is rarely adaptable to a wide range of species and hydraulic conditions. The Whooshh Fish Transport System (WFTS) is a fish passage technology that was designed to move fish around barriers through a flexible tube using differential air pressure. In this study, we evaluated the combination of the WFTS with the Whooshh Ellips Scanning Sorting system (WESS). This combined system allows autonomous and volitional entry, and subsequent selective upstream passage for fish of different sizes. The sorting by size and the passage efficiency of Chinook salmon ( Oncorhynchus tshawytscha ) and steelhead ( O. mykiss ) through the WESS-WFTS was assessed. We found that the WESS-WFTS was able to sort the fish by size, few fish had external injuries, and few unexpected events (e.g. backward transport, discontinuous transport) occurred. Our results support the use of the WESS-WFTS as an effective transport system for adult salmonids when used in conjunction with a volitional fishway entrance.