Behaviour and Energetics of Sturgeon Fishway Passage

Global reliance on water resource development has resulted in the disconnection of key migratory pathways for numerous fish species, leading to population declines. Fishways represent one solution for reinstating connectivity, although their biological effectiveness often remains unknown and the mechanisms contributing to successful passage for most species is poorly understood. This thesis applied an interdisciplinary approach to investigate fishway passage by lake sturgeon. Identification of key spawning habitats downstream of a dam equipped with a fishway revealed that attraction and passage efficiency of the fishway unlikely limit reproductive success in this population of lake sturgeon; nevertheless, lake sturgeon still locate and pass the fishway annually. Overall fishway passage efficiency was 36% and successful passage was unrelated to adult sturgeon size or water temperatures. Successful passage events were highly variable in duration, and turning basins within the fishway considerably delayed passage and increased failure rates, leading to speculation that variability in energy use resulting from path selection may be a possible mechanism for delayed or failed passage. New methods were developed for the field quantification of sturgeon swimming activity and energy use using animal-borne accelerometers. Calibrations demonstrated the utility of accelerometers as a direct measure of volitional swimming speed and identified that sturgeon are capable of swimming at speeds in excess of those previously observed. Field application identified that sturgeon rarely used high speed swimming to traverse the fishway and that energy use was not predictive of successful passage, although successful individuals exhibited a higher cost of transport. Successful fishway passage resulted in an energetic cost equivalent to individuals travelling 2.1–13.3 km in a lentic system. Other endogenous (i.e. internal state, navigational ability) or exogenous (i.e. fine scale hydraulics) factors possibly influence passage success, although these remain unknown and represent an area for future research on sturgeon and numerous other species. Fishways remain a promising solution for maintaining connectivity in fragmented systems and this thesis serves as a useful model for gaining insight into fishway effectiveness for a single species. It also highlights the challenges and necessary knowledge required to ensure optimal habitats are available to all species.