Multispecies Fish Passage Evaluation at a Rock‐Ramp Fishway in a Colorado Transition Zone Stream

Abstract

Stream habitat fragmentation caused by manmade structures is ubiquitous in Colorado, creating a need for passage solutions that accommodate multiple fish species. This study tested the effectiveness of a rock-ramp fishway to pass nine fish species with a range of swimming abilities. Target species for fishway design included Brassy Minnow Hybognathus hankinsoni (weakest swimming), Longnose Dace Rhinichthys cataractae, Longnose Sucker Catostomus catostomus, and Brown Trout Salmo trutta (strongest swimming). Testing included a 46-hour enclosure study and three-month extended study, during which fish passage was evaluated using PIT tags. All species exhibited successful passage through the fishway during the enclosure study, but movement

Evaluation of Low-Head Ramped Weirs for a Potamodromous Cyprinid: Effects of Substrate Addition and Discharge on Fish Passage Performance, Stress and Fatigue

“…Once more, this result highlights the importance that retrofitting low-head ramped weirs, especially by adding a natural substrate, such as cobbles, may have on the passage performance of fish, by promoting an effective energy dissipation along the ramp and immediately downstream of the weir. Moreover, with high discharges, the placement of cobbles, randomly distributed along the ramp, may provide important "flow refugia" [56], by creating areas and paths of reduced velocity and less turbulence that may be used by fish during the upstream negotiation of the ramp [21,57], especially when substrate dimensions are similar or larger than the body size of fish.…”

“…Thus, according to the European Water Framework Directive guidelines (WFD; [15]), field assessment is conducted to determine the possible removal of the barrier, which is in compliance with the new EU Biodiversity Strategy target of reconnecting at least 25,000 km of rivers in Europe by 2030 (Document 52020DC0380; [16]). However, when such removal is not possible, due to social, economic and/or historical significance, requalification measures are implemented to enhance fish passability, such as the addition of a natural substrate to the ramp (referred to as retrofitting) to mimic natural stream conditions and promote energy dissipation [17][18][19][20][21]. Despite some studies highlighting the usefulness of retrofitting for aiding fish passage through technical fishways [22,23], few studies are available on how this measure affects the negotiation of low-head ramped weirs, particularly by potamodromous cyprinid species, which are an important component of European fish assemblages [24][25][26].…”

“…The permeability of low-head ramped weirs to fish movements should be considered site-, season-and species-specific [19,21,27]. The effect that these instream obstacles have on fish migratory movements may not be linearly related to the number of small weirs that fish need to negotiate, but closely dependent on the physical characteristics of the weirs (e.g., ramp length, slope, substrate on ramp), on the hydrodynamic conditions present in the vicinity of the structure (i.e., velocity magnitude and turbulence, which are closely related to discharge), and on fish swimming abilities [19,28,29], which are directly associated with fish species' eco-morphological characteristics and individual body size [30][31][32].…”

Habitat associations of rainbow trout Oncorhynchus mykiss and brown trout Salmo trutta fry

“…The sensor was placed at an average depth at half the fry site width, and values were recorded once consistency in the readings was achieved. Depth measurements and depth‐average velocity, measured by setting a flow sensor to 0.6 of the measured depth from the water surface, were recorded at the same three locations using a Marsh‐McBirney flowmeter attached to a wading rod that measured depth in 0.03 m increments (Avila, 2016 ; Richer et al ., 2020 ). Fry site width was measured based on the farthest distance from shore a fry of either species was captured within the site and changed with each visit.…”

Design, construction, and preliminary hydraulic evaluation of a model rock ramp fishway

“…Early fishways were sometimes blasted out of bedrock to create primitive pool‐and‐weir structures to pass Atlantic Salmon Salmo salar over waterfalls (Berg 1973). Since then, multiple designs have been developed to accommodate a variety of fish species and project budgets (Katopodis and Williams 2012; Steffensen et al 2013; Richer et al 2020). These designs, including pool‐and‐weir, pool‐and‐weir‐with‐orifice, vertical slot, and rock ramp fishways, have been installed in waterways worldwide with widely varying degrees of fish passage success (Katopodis and Williams 2012; Silva et al 2018; Keefer et al 2021).…”