Fishway passage bottleneck identification and prioritization: a case study of Pacific lamprey at Bonneville Dam

Abstract

26Fishways designed for salmonids often restrict passage by non-salmonids and effective tools are 27 needed both to identify passage problems for non-target species and to inform remediation 28 planning. In this case study, we used migration histories from 2170 radio-tagged adult Pacific 29 lamprey (Entosphenus tridentatus) to identify locations of poor passage ("bottlenecks") at a 30 large, multi-fishway dam. Over ten years, 49% of tagged lamprey that entered fishways failed to 31 pass the dam. Models accounting for repeated attempts by individual lamprey indicated 32 successful passage strongly depended on attempted passage route. Success also varied with time 33 of fishway entry, water temperature, and lamprey body size. Most failed passage attempts 34 terminated in lower fishway segments, but extensive seasonal shifts in bottleneck locations were 35 detected. Ranking metrics helped prioritize bottlenecks and identified sites where structural or 36 operational modifications should improve lamprey passage. Our integration of spatially-37 intensive monitoring with novel analytical techniques was critical to understanding the complex 38 relationships between fishway features, environmental variation, and lamprey behavior. The 39 prioritization framework can be applied to a wide range of fish passage assessments. 40 41 42

Network analyses reveal intra‐ and interspecific differences in behaviour when passing a complex migration obstacle

“…The lack of a body size effect in network metrics suggests while size selection occurs at the dam‐wide scale, size‐selectivity is weak at local scales (this study; Keefer et al . ). It may also be that these size‐selective processes are associated with genotype (Hess et al .…”

“…burst‐swimming speed), structural impediments and environmental factors may explain the low passage rates observed for Pacific lamprey at Columbia River dams compared to salmon (Keefer et al . , ; Johnson et al . ; Kirk et al .…”

“…; Keefer et al . ), most of the fitness‐related consequences have been evaluated using time‐based metrics (i.e. passage time).…”

Quantification of emigration and habitat use inform stocking rates of lake sturgeon (Acipenser fulvescens , Rafinesque, 1817) in the Cumberland River, Tennessee, USA

“…Depending on the type and function of specific dams, migration pathways of fish (e.g. potamodromous and anadromous species) are impacted at different levels (Haxton & Findley, ; Keefer et al., ; Nilsson, Reidy, Dynesius, & Revenga, ). Quantifying emigration rates with a goal to maintain/establish a MVP are essential components in a recovery plan when evaluating stocking strategies.…”

Lampreys: Biology, Conservation and Control

“…In western North America, studies have shown that fewer than 50 % of adult Pacific lamprey encountering the lower Columbia River hydroelectric dams were able to negotiate the fishways (Moser et al 2002a, b;Keefer et al 2013), and dams in some tributaries (e.g., the Umatilla and Snake rivers) and the upper Columbia River are largely impassable to lampreys (see Ward et al 2012). In the Yakima River subbasin in south-central Oregon, for example, an average of only 20 adult lamprey are now observed returning per year (Patrick Luke, Yakama Nation, Toppenish, WA, personal communication, 2013).…”