Evaluating Fish Passage and Tailrace Space Use at a Low‐Use Low‐Head Lock and Dam

Abstract

Impacts of low-head, run-of-the-river dams on migratory fish movements depend on the structure of the dam, river hydrology, and the ability of fish to navigate the tailrace environment. Here, we present results from a 3-year movement study in which telemetered Paddlefish Polyodon spathula and Smallmouth Buffalo Ictiobus bubalus were tracked as they approached and sometimes migrated past Claiborne Lock and Dam (CLD), a low-use low-head lock-and-dam structure on the Alabama River. A spillway portion of the dam is periodically inundated during early spring, dependent on precipitation and releases from the next upstream dam. Our goals were to (1) quantify dam passage rates for both species, (2) assess the importance of factors affecting passage success, and (3) quantify space use patterns in the tailrace. Both species exhibited annual upstream migrations during the study period. Correlation of daily average river position versus the CLD hydrograph showed that movements by both species appeared to be related to flow variation. Passage efficiency (range = 10.7-30.2%) varied between species and among years, with tailrace gauge height being the most important factor affecting passage success for both species. Using an acoustic positioning system in the tailrace, we quantified space use by individuals of both species. Time spent in the tailrace (mean = 3.9 continuous days; range = 0-94 continuous days) did not differ between individuals that passed and those that did not pass. Fine-scale position estimates showed that space use differed between species, across gauge heights, and between individuals that passed and those that did not pass. Differential space use may be due to the species' habitat preferences or swimming abilities. Our findings provide information to inform potential design of mitigation structures, and they also identify the need for additional work required to more fully understand the mechanisms of passage success versus failure for these and other native potamodromous species.

Using fish hard‐part microchemistry and genetics to quantify population impacts of low‐use lock‐and‐dam structures on the Alabama River

“…We quantified short-term (hard-part microchemistry) and long-term (genotype by sequencing) effects of three Alabama River lock-and-dam structures on the population structure of two fish species. Previous work has used tagging and tracking of individuals to show that individual fish movement was restricted to varying degrees by the dams (Simcox et al 2015;Hershey et al 2022), and…”

“…We quantified short‐term (hard‐part microchemistry) and long‐term (genotype by sequencing) effects of three Alabama River lock‐and‐dam structures on the population structure of two fish species. Previous work has used tagging and tracking of individuals to show that individual fish movement was restricted to varying degrees by the dams (Simcox et al 2015; Hershey et al 2022), and here we wanted to quantify potential effects at longer time scales (hard‐part microchemistry = within the life span of an organism, genetics = across generations); however, it appears that longer‐term genetic divergence was not manifesting in these long‐lived species, perhaps in part because the dams have been in place for a relatively short time relative to the lifespans and potential generation times of these species. Below we further consider and discuss these findings.…”

The effect of temperature and acute hypoxia/hyperoxia exposure on swimming performance and kinematics of Freshwater Drum

“…For migratory species in anthropogenically segmented rivers, increased swimming performance can increase the probability of passage at structures such as dams. In addition, tailwaters downstream of dams can be important staging habitat for fish before making a dam passage attempt (Hershey et al 2022). Combinations of temperature and DO levels that would allow for successful passage attempts can be determined by simulating tailwater conditions in a laboratory setting and quantifying sustained fish swimming performance via U crit (Tierney 2011).…”

Movement of Paddlefish once past a lock‐and‐dam structure on the Alabama River

“…gov/ monit oring -locat ion/ 02428 401/ ). Gauge heights for the tailrace are typically 7-8 m during non-high-water events in the spring migration period (Hershey et al 2022).…”

“…However, passage opportunities provided by these structures may be limited to only some fish species (Baumgartner et al 2006;Agostinho et al 2007;Schilt 2007). Navigational locks allow passage of some fish species (Young et al 2012) while showing limited effectiveness for others (Ramsey 1986;O'Neil 2004;Mettee et al 2005;Simcox et al 2015;Hershey et al 2022). In addition to locks, gated and crested spillways provide potential for passage, although these features typically are only found at low-head dams (Wilcox et al 2004;Simcox et al 2015;Kock et al 2021).…”