Lock operations influence upstream passages of invasive and native fishes at a Mississippi River high-head dam

Numeric Simulation Demonstrates That the Upstream Movement of Invasive Bigheaded Carp Can Be Blocked at Sets of Mississippi River Locks-and-Dams Using a Combination of Optimized Spillway Gate Operations, Lock Deterrents, and Carp Removal

“…exceedance values, known gate settings, velocities, fish passage routes and swimming abilities) and a validated fish passage model that was designed to provide conservative overestimates of actual passage [28]. It is also promising that silver carp telemetry data suggest this species does not challenge LDs repeatedly [31,32]. The recent documented movement of significant numbers of adult bigheaded carp through both LD 19 [52] and LD 8 [53] attests to an urgent need to reduce bigheaded carp passage rates below the conditions currently existing at LD 8.…”

“…A 50% reduction in passage rates seems possible using a single control option, while a 90% or greater reduction to an overall rate of just 2% appears attainable if both a deterrent and carp removal is used, even during times of high flow and need only be moderately effective (25%). Previous suppositions that carp can only be stopped at systems that lack operating gates [32] appear overly simplistic, which is important because only 2 of the 29 LDs in the UMR do not have bottom mounted spillway gates.…”

“…Adjusting spillway gate openings is a good option to reduce carp passage. Its potential has been shown by both modeling [28] and descriptions of fish passage from fish tracking studies [26,[31][32][33], the latter showing a strong correlation between spillway gate opening, water velocity, and passage. Numerical modeling at two relatively typical Mississippi River LDs, LD 2 and LD 8, has shown that fish passage through their gated spillways is dependent on hydraulic conditions that include velocities that exceed 5 m/s at lower gate openings through which very few fish can pass [26,28,34].…”

Prioritizing native migratory fish passage restoration while limiting the spread of invasive species: A case study in the Upper Mississippi River

“…In particular, Mississippi Lock and Dam 3, 18, and 19 were identified in the 'invasive' scenario runs as being locations with potential for selective habitat connectivity gains for the native migratory species despite higher economic costs and lower passabilities compared to traditional fishways. Since Lock and Dam 19 is a high-head dam with low baseline passability rates (Tripp et al, 2014), it has been viewed as a "pinch point" in limiting bigheaded carp dispersal in the UMR (Fritts et al, 2020) and may also provide an opportunity to selectively pass native species as indicated by results in this study. Aside from lift-and-sort structures, the need to restore connectivity for desirable species while restricting bigheaded carps has spurred various strategies within the UMR, including a combination of deterrence strategies (e.g., electric currents, bubbles, and noise) and modifications to gate and lock operation.…”

“…For lock and dam structures, annual average length of time gates were open was used as a surrogate for baseline pre-passability values, however gate operation (i.e., degree of openness) can vary both annually and seasonally with discharge conditions (Tripp et al, 2014;Bouska et al, 2019), leading to differing potential passabilities based on these factors. Further, fish passage can occur through locks during their operation (Fritts et al, 2020), including low levels of fish movement during closed gate conditions (Finger et al, 2020). We recognize that passability at dams can vary depending upon a number of factors, such as species-specific swimming capabilities, life stage, direction of movement (i.e., upstream or downstream) and physical characteristics of individual dams (Ioannidou and O'Hanley, 2019).…”