Poster Presentation International Conference on River Connectivity (Fish Passage 2018)

Exploring Chinook salmon passage through the world’s longest wooden fishway in the Upper Yukon River (#232)

William M Twardek 1 , Nicolas W. R Lapointe 2 , James C. C Sebes 1 , Steven J Cooke 1
  1. Carleton University, Ottawa, ON, Canada
  2. Canadian Wildlife Federation, Ottawa, ON, Canada

Upper Yukon River Chinook Salmon populations (Oncorhynchus tshawytscha) maintain some of the longest salmonid spawning migrations on earth (~3200 km) despite experiencing severe declines over the past century. To access the majority of spawning habitat, Upper Yukon River Chinook Salmon must pass the Whitehorse Hydro Plant (WHP) via the world’s longest wooden fishway (366 m). More than five decades of successful passage and subsequent spawning upstream provide clear evidence of individual passage success, although sub-lethal and population-level consequences of passage are unclear. Stakeholders have identified the movement of Chinook Salmon through the Whitehorse Rapids Fishladder as a priority research initiative in the recovery of Upper Yukon River Chinook Salmon populations. We evaluated the effectiveness of this fish ladder at facilitating fish passage including the attraction efficiency of the ladder and the ultimate fate of fish following successful passage. To address these objectives, acoustic transmitters were gastrically implanted into approximately 150 fish of wild and hatchery origin that were released either within or below the fish ladder in 2017 and 2018. An array consisting of twenty acoustic receivers was deployed providing coverage at the WHP and all major tributaries both up and downstream of the WHP. Behaviour below the fish ladder, proportion of fish entering the ladder, and the ultimate fate of each fish were quantified. This research will provide insight on the potential implications of fish ladder design and operations on the productivity of Upper Yukon River Chinook Salmon populations which may inform future management of ladder operations.