Effects of whitewater parks on fish passage: a spatially explicit hydraulic analysis

Abstract

EFFECTS OF WHITEWATER PARKS ON FISH PASSAGE:A SPATIALLY EXPLICIT HYDRAULIC ANALYSIS Whitewater parks (WWPs) provide a valuable recreational and economic resource that is rapidly growing in popularity throughout the United States. WWPs were originally thought to enhance aquatic habitat; however, recent studies have shown that the hydraulic conditions required to meet recreational needs can act as a partial barrier to upstream migrating trout and that WWP pools may contain lower densities of fish compared to natural pools. There is limited knowledge of the direct effects of WWPs on fish passage. Managers and policy makers are forced to review WWP designs and make permit decisions without sound scientific evidence. It is also difficult to make design recommendations for future WWPs and possibly retrofitting existing WWPs to allow for successful fish passage without improved understanding of the factors contributing to suppression of movement in WWPs. We describe novel approaches combining fish movement data and hydraulic results from a three-dimensional computational fluid dynamics model to examine the physical processes that limit upstream movement of trout in an actual WWP in Lyons, Colorado. These methods provide a continuous and spatially explicit description of velocity, depth, vorticity, and turbulent kinetic energy (TKE) along potential fish swimming paths in the flow field. Variation in the magnitude and distribution of velocity and depth relative to fish swimming ability is reflective of variation in passage success among WWP structures and size classes of fish. Logistic regression analyses indicate a significant influence of velocity and depth on limiting passage success and accurately predict > 86 percent observed fish movements. Relationships emerge at individual WWP structures that iii highlight unique hydraulic characteristics and their effect on passage success. The methods described in this study provide a powerful approach to quantify hydraulic conditions at a scale meaningful to a fish and mechanistically evaluate the effects of hydraulic structures on fish passage. The results of these analyses can be used for management and design guidance, have implications for fishes with lesser swimming abilities, and demonstrate the need to assess additional WWPs of various sizes.iv ACKNOWLEDGMENTS

Mutually promoting or constraining? Disentangling the superimposed effect of velocity and illuminance on fish motion in low‐velocity flows with a novel metric

“…Fish movement is associated with many hydraulic elements like flow velocity, turbulence intensity, and Reynolds shear stress (Hockley et al, 2014; Silva et al, 2011). Velocity, for example, is perceived as an exhaustive swimming barrier where fish cannot maintain positive ground speed over a certain distance (Stephens et al, 2015). Usually, fish swimming can be categorised into sustained, burst, and prolonged speeds (Beamish, 1978) according to the relationship between time to exhaustion and flow velocity.…”

“…To accurately assess the traversability of fish passage, the rapids that fish migrants need to wrestle with have attracted widespread attention (Leng et al, 2019; Stephens et al, 2015). Compared to the well‐studied fish responses to high‐velocity flow, which affects fish swimmers by fatiguing them to some extent, fish behaviour in low‐velocity flow is not well understood.…”

“…Fish movement is associated with many hydraulic elements like flow velocity, turbulence intensity, and Reynolds shear stress (Hockley et al, 2014;Silva et al, 2011). Velocity, for example, is perceived as an exhaustive swimming barrier where fish cannot maintain positive ground speed over a certain distance (Stephens et al, 2015).…”

Experimental Investigation of the Reynolds Shear Stress Exceedance Rate for the Injury and Disorientation Biocriteria Boundary in the Pool-Orifice and Vertical Slot Type Fishways

“…In order to improve the design of new fishways and optimize the existing ones, hydraulic environment needs to be described by relevant variables and its dependency on the fishway geometry needs to be quantified. Fishways are often found to be ineffective for species with different morphological and ecological characteristics [31], and data acquired from hydraulic environment can be used in studies focusing on flow-fish interactions to evaluate fish behavior in response to hydraulic conditions and define turbulence at a scale relative to fish size [47]. River fragmentation analyses are mostly focused on the larger structures, such as hydropower dams [48], often overlooking smaller structures that make up the majority of barriers in the European rivers-68% out of more than 1.2 million barriers are structures less than 2 m high [49].…”

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

“…Instream structures with the potential to create fish migration barriers include dams and water diversions (Malmqvist and Rundle 2002; Sheer and Steel 2006; Fencl et al 2015), road crossings (Warren and Pardew 1998), grade control structures (Ficke and Myrick 2009), and whitewater parks (Stephens et al 2015; Fox et al 2016). Barriers to fish movement can be attributed to dry‐up points, inadequate water depth, elevated water velocity, and/or vertical obstacles.…”