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Ecological connectivity of invasive and native fishes in a historic navigation waterway
(Canadian Science Publishing, 2024-01-29) Bergman, Jordanna Nicole; Bennett, Joseph R.; Minelga, Valerie; Vis, Chantal; Fisk, Aaron T; Cooke, Steven J.
Regulated waterways, interconnected by navigation barriers (locks, dams), are uniquely difficult to manage given interest in enabling native species connectivity while minimizing invasions. Canada’s historic Rideau Canal Waterway, a 202-km navigable route located in eastern Ontario and connected by 23 lockstations, embodies this challenge. The lock(s) and water-control dam that compose each lockstation may respectively offer a connectivity pathway, though to what extent is unclear. We used acoustic telemetry (native largemouth bass [Micropterus nigricans], northern pike [Esox lucius]; invasive common carp [Cyprinus carpio]; n=224) to evaluate fish connectivity relative to lock operations and environmental data over three years (2019-2021). Thirty-five passages by 23 native fishes were recorded, with 49% of passages through locks. No common carp passages were detected; movements indicate they favour higher-flow areas downstream of dams, regions with no pathway upstream. Most passages were downstream and, of concern to obligate upstream migrators, we found that multi-flight and higher-lift locks appear impassable to upstream movements. Our results suggest these lockstations limit, but not entirely restrict, connectivity.