Hydropower Development, Riverine Connectivity, and Non-sport Fish Species: criteria for Hydraulic Design of Fishways

Abstract

Hydropower barriers are among the most conspicuous anthropogenic alterations to natural riverine connectivity, resulting in species-specific effects linked to dispersal abilities, especially swimming performance. They may present a particular problem for small-bodied 'non-sport fish', such as those that characterize the freshwater communities of temperate regions in the Southern Hemisphere. Recent studies have suggested that nature-like fishways could ensure passage of diverse fish assemblages through hydropower barriers. Through experiments performed in a swim tunnel, we present, for the first time, fishway design criteria for two non-sport species endemic to Chile, a country experiencing rapid hydropower development. In`cremental velocity tests showed that Cheirodon galusdae and juveniles of Basilichthys microlepidotus were capable of very similar standardized critical swimming speeds of 69.7 and 69.6 cm s À1 , respectively. When expressed in units of body lengths, C. galusdae was capable of very high critical speeds of 16.2 bl s À1, whereas for B. microlepidotus, this was 7.6 bl s À1 . However, fixed velocity tests revealed that the swimming endurance of the latter species was slightly higher. Dimensionless analysis showed a clear relationship between fatigue time and fish Froude number, similar to that already described for subcarangiforms. Based on these results, we present fishway design curves indicating a transition from sustained to prolonged swimming at a fishway length of 15 m. Our results show that the swimming capacity of these species is well-suited to the mean flow velocity field described for nature-like fishways. However, more work is required to understand the effects of turbulence on the passage of non-sport species.

Swimming behavior of crucian carp in an open channel with sudden expansion

“…The critical swimming velocity ( U crit ) is the maximum sustainable swimming speed at which a fish can no longer maintain its position in the water column, which is also widely used to evaluate steady swimming performance (Laborde et al, ; Link et al, ; Plaut, ) and typically is correlated with fish length. With reference to similar external environment (temperature, dissolved oxygen), crucian carp were capable of a critical swimming velocity of 5.08–5.49 BL s −1 (Yan et al, ; Yan et al, ; Yang et al, ), which means that a lower U crit can be tolerated by smaller fish compared with that of larger fish.…”

“…Hydraulic structures used for flood control, electricity generation, navigation, and irrigation may affect the hydrological environment and sediment exchange of fish habitats. The migratory routes of fish can be blocked by these hydraulic structures (Godinho & Kynard, ; Williams, Armstrong, Katopodis, Larinier, & Travade, ), and remediation strategies such as fish passages (Laborde et al, ; Link et al, ) are commonly employed in such circumstances. The impacts of habitat heterogeneity to fish habitats and stocks are well known, given that the flow regime strongly influences the swimming behavior (Das et al, ).…”

Fragmentation of Chilean Andean rivers: expected effects of hydropower development

“…Furthermore, probability to pass different barriers is not necessarily independent. We are not able to make quantification, but based on small body size and low swimming capacity of most of the fish species in our study area we assumed passability of all these barriers is very low or null [41].…”

Fish‐Net: Probabilistic models for fishway planning, design and monitoring to support environmentally sustainable hydropower

“…It has sometimes been assumed that passage of resident fish can be mitigated using technical fishways to a degree sufficient to maintain connectivity between subpopulations (e.g. Laborde et al, 2016;Link et al, 2017). The empirical evidence for these assumptions is scarce, and metapopulation theory suggests that high dispersal rates may be necessary to avoid local extinctions, support healthy subpopulations and maintain high patch occupancy (Schnell, Harris, Pimm, & Russell, 2013;Villard & Metzger, 2014).…”

“…This is especially true of small‐bodied, non‐recreational species (e.g. adults <150 mm TL; Link & Habit, ), whose relatively weak swimming abilities are consistent with their diminutive stature (Bestgen, Mefford, Bundy, Walford, & Compton, ; Ficke, Myrick, & Jud, ; Laborde et al., ; Leavy & Bonner, ; Nelson, Gotwalt, Simonetti, & Snodgrass, ; Nikora, Aberle, Biggs, Jowett, & Sykes, ). Several of these species support culturally and economically important capture fisheries (e.g.…”