Updating the consensus on fishway efficiency: A meta‐analysis

Abstract

To update the consensus on the effectiveness of fish passage mitigation structures or “fishways,” I conducted a meta‐analysis on the fish passage literature and synthesized attraction and passage efficiency estimates from 60 peer‐reviewed articles. One hundred unique species were studied at 75 unique fishways of various designs and sizes yielding 210 and 252 estimates of attraction and passage efficiency, respectively. Following Bunt et al. (River Research and Applications, 28, 2012, 457), the fishways were grouped into five types: nature‐like, denil, pool‐and‐weir, vertical slot or locks and lifts that were operated automatically. Generalized linear mixed effects models showed that fishway type was not a significant predictor of passage efficiency, although nature‐like fishways had significantly lower attraction efficiency than other types. Neither fishway slope, nor elevation change was significant predictors of attraction or passage efficiency. Models comparing efficiency between ecological guilds of fishes (pelagic or benthic and rheophilic or limnophilic) showed that attraction and passage efficiency were highest for pelagic rheophiles and lowest for limnophiles. Models comparing migratory guilds of fishes (diadromous, potamodromous, facultative or non‐migratory) showed that diadromous species outperformed other guilds, as expected. Fish that were captured inside or above fishways had significantly higher passage performance than fish that were naive to the fishway. Inconsistency in fishway evaluation methods was pervasive in the surveyed literature and made this meta‐analysis challenging. When designing studies of fishway evaluations, researchers should conform to best practices so that their results are more generalizable and their conclusions of wider scope.

Attraction, Entrance, and Passage Efficiency of Arctic Grayling, Trout, and Suckers at Denil Fishways in the Big Hole River Basin, Montana

“…Forty et al (2016) used "proportion of displaced fish attempting passage" as a metric of motivation but combined approach, attraction, and entrance into a single efficiency component. Such inconsistent methodology and terminology have prevented comparisons among studies and limited our understanding of the distinct components of overall fishway efficiency (Bunt et al 2012(Bunt et al , 2016Kemp 2016;Williams and Katopodis 2016;Hershey 2021).…”

“…Such inconsistent methodology and terminology have prevented comparisons among studies and limited our understanding of the distinct components of overall fishway efficiency (Bunt et al. 2012, 2016; Kemp 2016; Williams and Katopodis 2016; Hershey 2021).…”

Impacts and Risks of Hydropower

“…Correspondingly, comprehensive guidelines exist to facilitate operational upstream migration facilities under varying environmental, technical and biotic conditions e.g., the DWA guidance M 509 (DWA 2014). However, upstream migration facilities show highly varying passage rates between 0 and 100% (Bunt et al 2012;Gowans et al 2003;Hershey 2021;Kemp et al 2011), mostly due to the unique and highly complex interaction between the species' internal state and motivation to migrate, their anatomy and swimming ability, ambient hydraulic conditions and type and design of the passage facility (Banks 1969, Castro-Santos et al, 2009, Crisp 2000, USFWS (U.S. Fish and Wildlife Service) 2019).…”

“…In Europe the implementation of the WFD stipulated the re-establishment of the longitudinal connectivity (Schletterer et al 2016) and various technical as well as natural fishways were developed or species-specifically improved (Clay 2017; Hershey 2021; Jungwirth et al 1998;Katopodis 1992;Santos et al 2014). Factors determining passage success of an upstream fishpass include attraction efficiency mediated by position of entrance and attraction flow and passability mediated by slope, flow velocity in the migration corridor, height differences and physical dimensions (Banks 1969;Bunt et al 2012;DWA 2014;Hershey 2021, USFWS 2019. Failing upstream passage success of fish result in excessive energy expenditure and migration delays (Noonan et al 2012;Silva et al 2019;Thorstad et al 2008) and thus, delayed arrival at spawning events (Silva et al 2019), and increased predation (Agostinho et al 2012).…”

Conservation behaviour in action: using fish behaviour to understand and mitigate the impacts of hydropower development

“…However, it has become clear over the last few decades that management regimes targeted solely to anadromous species are not resulting in the desired freshwater fisheries conservation outcomes (Dettmers et al 2012;Katopodis and Williams 2012). Upstream fish passage via fishways remains problematic for most species and fishway designs (Hershey 2021). Mallen-Cooper and Brand (2007) reviewed 50 years of monitoring data for a salmonid-designed fishway intended to pass non-salmonid fishes.…”