No abstract

A mark–recapture field study was conducted to determine fish passage at 5 concrete box culverts and 5 low‐water crossings (concrete slabs vented by culverts) as well as 10 control sites (below a natural riffle) in Flint Hills streams of northeastern Kansas. Additionally, we tested the upstream passage of four fish species native to Great Plains streams (Topeka shiner Notropis topeka, green sunfish Lepomis cyanellus, red shiner Cyprinella lutrensis, and southern redbelly dace Phoxinus erythrogaster) through three simulated crossing designs (box culverts, round corrugated culverts, and natural rock riffles) at water velocities of 0.1 to 1.1 m/s in an experimental stream. The field study indicated that cyprinids were twice as likely to move upstream of box culverts than low‐water crossings and 1.4 times as likely to move upstream of control reaches than any crossing type. The best models indicated that the proportion of cyprinids that moved upstream increased with decreased culvert slope and length, perching, and increased culvert width. Our controlled experiment indicated that fish can move through velocities up to 1.1 m/s in a 1.86‐m simulated stream and that the proportion of fish that moved upstream did not differ among crossing designs for southern redbelly dace, green sunfish, or Topeka shiner; however, natural rock riffles had lower proportional movements (mean = 0.19) than the box (0.38) or corrugated culvert designs (0.43) for red shiners. Water velocity did not affect the proportional upstream movement of any species except that of Topeka shiners, which increased with water velocity. Crossing design alone may not determine fish passage, and water velocities up to 1.1 m/s may not affect the passage of many Great Plains fishes. Barriers to fish movement may be the result of other factors (e.g., perching, slope, and crossing length). The use of properly designed and installed crossings has promise in conserving Great Plains stream fishes.

Despite the hypothesized benefits to age-0 Scaphirhynchus sturgeon, the role that slow, shallow water plays during early life history remains uncertain. Although several studies have reported the depths and velocities observed at age-0 sturgeon capture sites, conditions at larger spatial scales beyond the immediate capture location may also be important. Therefore, the specific objectives of this study were to (a) compare catch among large reaches (26-37 km in length) that varied in the availability of water <1.5 m deep and (b) identify the local habitats that best promote use by age-0 sturgeon within each reach. Results from the reach-scale analysis suggested that increased availability of water <1.5 m did not yield increased age-0 sturgeon catch. At the local-scale, age-0 sturgeon were routinely captured from a wide variety of depths, velocities, and microhabitats (L-dike, wing-dike, rootless-dike, and channel sandbar); these results coupled with previous research suggest that age-0 sturgeon may not require specific depth and velocity criteria but further study is needed to test this hypothesis. Although the prevalence of water <1.5 m had little effect on catch rates, this habitat may still be important to age-0 sturgeon.Additional research should investigate the potential effects of shallow water, at local and broad scales, on prey consumption and condition of age-0 sturgeon. KEYWORDS pallid sturgeon, river restoration, shallow water habitat, shovelnose sturgeon

Detecting nuisance species at low abundance or in newly established areas is critical to developing pest management strategies. Due to their sensitivity to disturbance and erratic jumping behavior, Silver Carp Hypophthalmichthys molitrix can be difficult to collect with traditional sampling methods. We compared catch per unit effort (CPUE) of all species from a Long Term Resource Monitoring (LTRM) electrofishing protocol to an experimental electrofishing technique designed to minimize Silver Carp evasion through tactical boat maneuvering and selective application of power. Differences in CPUE between electrofishing methods were detected for 2 of 41 species collected across 2 years of sampling at 20 sites along the Illinois River. The mean catch rate of Silver Carp using the experimental technique was 2.2 times the mean catch rate of the LTRM electrofishing technique; the increased capture efficiency at low relative abundance emphasizes the utility of this method for early detection. The experimental electrofishing also collected slightly larger Silver Carp (mean: 510.7 mm TL versus 495.2 mm TL), and nearly four times as many Silver Carp independently jumped into the boat during experimental transects. Novel sampling approaches, such as the experimental electrofishing technique used in this study, should be considered to increase probability of detection for aquatic nuisance species.