The use of behavioural metrics to evaluate fishway efficiency

Abstract

Fishways are installed worldwide to facilitate accessibility to functional habitats and to increase the ecological continuity of rivers. Their evaluations are increasing, but complete studies in the field with wild individuals are still scarce. In the lower Bocq River (Belgium), a pool type fishway was installed in 2011. A combined passive-integrated-transponder-tag and radio-telemetry system was designed and installed downstream of the dam and in the fishway to analyse fine-scale individual fish behaviour. Three fish species (brown trout, European grayling, and barbel) were captured in the river; n = 125 fish were tagged and released downstream of the fishway. Behavioural metrics were proposed and used in order to attain a comprehensive view on the efficiency of the fishway, including attraction and entrance efficiency, searching and passage delays, and overall and adjusted passage efficiency. The results indicate a major problem in terms of attraction efficiency (48.9% for the trout, 20.5% for the grayling, and 41.2% for the barbel) and time to find the entrance of the fishway (mean 65.1 hr for the trout and 538.9 hr for the grayling).For fish that succeed to approach the entrance of the fishway, the passage efficiency was 86.9% for the trout, 55.5% for the grayling, and 7.1% for the barbel. The time taken to cross the structure was reasonable for the salmonids (mean < 1.5 hr for trout and grayling) but very long (21 hr) for the barbel. Our results underline the necessity of a holistic approach to evaluate fishway efficiency using precise comprehensive metrics and hydraulic characterization.

Evaluation of the performance of successive multispecies improved fishways to reconnect a rehabilitated river

“…Other authors used the technique of capturing fish at the top of fishways and subsequently evaluating reascension (Pont et al 2009;Thiem et al 2013;Harty et al 2016). Our intra-and inter-river translocation method did not affect their spawning migration behaviour, as was already observed with the rheophilic cyprinid nase (Ovidio et al 2016), the trout, and the grayling (Ovidio et al 2017). It also has the advantage of avoiding habituation behaviour due to the recurrence of the passage and the associated possibility of learning, which may influence the ability of individuals to find the entrance of the fishway more rapidly.…”

“…Finally, a total of five fish (n = 4 barbel, n = 1 chub) were single-tagged with an RFID transponder (Table 2). The fish were surgically tagged following the procedure described by Ovidio et al (2017) and Benitez et al (2018).…”

“…These multispecies and multistage characteristics imply that the fishways must be efficient throughout the seasons for species with various swimming and leaping capacities, as well as different motivational states for migration. However, it is thus critical to improve the design of the fishway and to collect standardized performance data from a wide range of structure type, in a wide variety of rivers and regions to find successful and more integrative solutions for the future (Ovidio et al 2017).…”

“…The use of individual tagging and further detection by telemetry devices (e.g. Radio Frequency Identification [RFID], radio telemetry) make it possible to measure individual behaviour of fishes (Lucas and Baras 2001;Lennox et al 2017) and the passage performance associated to fishways (Ovidio et al 2017). Studies on the successive uses and performance of fishways are scarce, mainly monospecific, and have essentially focused on diadromous species (Gowans et al 2003;Calles and Greenberg 2005;Lucas et al 2009;Castro-Santos et al 2017) and rarely on potamodromous species (but see : De Leeuw and Winter 2008;Tummers et al 2016;Benitez et al 2018).…”

Updating the consensus on fishway efficiency: A meta‐analysis

“…Raabe et al (2019) adjusted their passage efficiency metric to reflect that imperfect detection efficiency probably led to underestimated passage efficiency. Ovidio et al (2017) reported “overall passage efficiency” as the number of successfully passed fish divided by the total number released, and the “adjusted passage efficiency” as the number of successfully passed fish divided by the number that was attracted, which is actually how passage efficiency is defined for this meta‐analysis. Only unadjusted metrics and data were used for this analysis.…”