Habitat use and population characteristics of potentially spawning shovelnose sturgeonScaphirhynchus platorynchus(Rafinesque, 1820), blue sucker (Cycleptus elongatus(Lesueur, 1817), and associated species in the lower Wisconsin River, USA

Abstract

Summary The goal of this study was to compare the possible locations, timing, and characteristics of potentially spawning shovelnose sturgeon (Scaphirhynchus platorynchus), blue sucker (Cycleptus elongatus), and associated species during the spring of 2007–2015 in the 149‐km‐long lower Wisconsin River, Wisconsin, USA, a large, shallow, sand‐dominated Mississippi River tributary. A 5‐km index station of two pairs of rocky shoals surrounded by sandy areas was electrofished for shovelnose sturgeon and blue sucker in a standardized fashion a total of 40 times from late March through mid‐June, the presumed spawning period. On one date in 2008 and two dates in 2012, all rocky shoals and adjacent sandy areas in the lowermost 149 km of the river were also electrofished for both species. Shovelnose sturgeon and blue sucker appeared to spawn in the limited rocky areas of the river along with at least four other species: mooneye (Hiodon tergisus), quillback (Carpiodes cyprinus), smallmouth buffalo (Ictiobus bubalus), and shorthead redhorse (Moxostoma macrolepidotum), usually at depths of 0.8–2.0 m and surface velocities of 0.4–1.0 m/s. However, apparently spawning shovelnose sturgeon were found only on mid‐channel cobble and coarse gravel shoals within a single 7‐km segment that included the 5‐km index station, whereas apparently spawning blue suckers were encountered on these same shoals but also more widely throughout the river on eroding bluff shorelines of bedrock and boulder and on artificial boulder wing dams and shoreline rip‐rap. Both species showed evidence of homing to the same mid‐channel shoal complexes across years. Blue sucker tended to concentrate on the shoals earlier in the spring than shovelnose sturgeon, usually from late April through mid‐May at water temperatures of 8.0–15.5°C along with quillback and shorthead redhorse. In comparison, shovelnose sturgeon usually concentrated on the shoals from mid‐May through early June at 13.5–21.8°C along with mooneye and smallmouth buffalo. Based on recaptures of tagged fish, at least some shovelnose sturgeon and blue sucker returned to the shoals at one‐year intervals, although there was evidence that female blue sucker may have been more likely to return at two‐year intervals. Most shovelnose sturgeon could not be reliably sexed based on external characteristics. Spawning shovelnose sturgeon ranged from 487 to 788 mm fork length, 500–2400 g weight, and 5–20 years of age, whereas spawning blue sucker ranged from 495 to 822 mm total length, 900–5100 g weight, and 5–34 years of age, although age estimates were uncertain. Females were significantly larger than males for both species although there was overlap. Growth in length was negligible for tagged and recaptured presumably spawning shovelnose sturgeon and low (3.5 mm/y) for blue sucker, suggesting that nearly all growth may have occurred prior to maturity and that fish may have matured at a wide range of sizes.

Habitat associations of shovelnose sturgeonScaphirhynchus platorynchus(Rafinesque, 1820) in the lower Platte River, Nebraska

“…Results from this study were similar to other studies where shovelnose sturgeon abundance increased during lower temperatures (Kappenman, Fraser, Toner, Dean, & Webb, ) and slower bottom velocities (Bramblett, ; Curtis, Ramsey, & Scarnecchia, ; Hofpar, ; Hurley, Hubert, & Nickum, ; Latka, ; Lyons, Walchak, Haglund, Kanehl, & Pracheil, ; Peters & Parham, ; Quist, Tillma, Burlingame, & Guy, ). Kappenman et al.…”

Seasonal movements and tributary‐specific fidelity of blue sucker Cycleptus elongatus in a Southern Plains riverscape

“…Wisconsin (Lyons et al, 2016). Conversely, a low probability of blue suckers was estimated in the RRT leaving during the non-spawning season, suggesting either mainstem movements or a non-migratory portion of the population.…”

“…Similarly, Lyons et al . (2016) observed ripe male blue suckers arriving at the spawning area earlier and remaining later than females in the Wisconsin River. Although males returned more frequently than females (1 year vs .…”

“…Blue sucker and southeastern blue sucker Cycleptus meridionalis (Burr & Mayden, 1999) are potamodromous species that may migrate >300 km within a year (Mettee et al ., 2015; Neely et al ., 2009) or remain within a 3 km river reach (Oliver et al ., 2017). Blue suckers are likely capable of homing, but little is known about specific migration strategies (Lyons et al ., 2016). The aim of this study was to determine coarse‐scale movement patterns by blue suckers during the spawning and non‐spawning seasons.…”

Ontogenetic structure and distribution patterns of ichthyoplankton in the confluence zone of two river systems in the Eastern Amazon

“…However, it is noteworthy that migratory species do not limit their reproductive strategy to mesotrophic waters. According to Barthem et al (2016) However, through a continuous drift process, eggs and larvae, even in the final stages of development, reach the confluence limit that acts as a strategic zone of aggregation and transport to the main river (Lyons et al, 2016;Pracheil et al, 2019). This dynamic allows the transport of organisms to flooded wetlands, with high productivity and complex habitats (e.g.…”