S. Reid Adams

Critical Swimming Speed and Behavior of Juvenile Shovelnose Sturgeon and Pallid Sturgeon

Abstract The swimming performance of hatchery-reared, juvenile shovelnose sturgeon Scaphirhynchus platorynchus and pallid sturgeon S. albus was studied in a laboratory swim tunnel at 20°C and 10°C. The mean 30-min critical swimming speed was not significantly different between species at either temperature (36.9 cm/s for shovelnose sturgeon and 35.9 cm/s for pallid sturgeon at 20°C, 19.4 cm/s for shovelnose sturgeon and 15.0 cm/s for pallid sturgeon at 10°C). Free swimming (swimming without contact with the substrate) was observed less than 18% of the time at speeds greater than 15 cm/s. As speed increased, pallid sturgeon swam significantly less in the water column at 20°C; however, speed had no effect on percent free swimming among shovelnose sturgeon at 20°C. The results of this study indicate that, over the temperature and size range tested, shovelnose sturgeon and pallid sturgeon probably do not segregate in rivers due to different swimming or station-holding abilities

Observations of Swimming Ability in Shovelnose Sturgeon (Scaphirhynchus platorynchus)

ABSTRACT Swimming performance and behavior of five adult (57—69 cm fork length) shovelnose sturgeon, Scaphirhynchus platorynchus, were studied in a 945-L swim tunnel at 16° C. Fifteen-minute critical swimming speeds ranged from 65 to 116 cm s−1. Sturgeon swam volitionally at low speeds (5—30 cm s−1), but at higher speeds (40—120 cm s−1) sturgeon alternated between active swimming and appressing themselves to the bottom of the tunnel. This second behavior is enhanced by sturgeon morphology—streamlined body shape, flat rostrum, and large pectoral fins. It allows shovelnose sturgeon to exploit river bottoms as a refugia from current and maintain position in high velocities.

Laboratory‐Based Measurements of Swimming Performance and Related Metabolic Rates of Field‐Sampled Smallmouth Buffalo (Ictiobus bubalus): A Study of Seasonal Changes

Numerous studies have demonstrated how the performance physiology of fish may change when they are acclimated to designated laboratory temperatures, but few researchers have examined naturally occurring seasonal effects on several physiological parameters associated with swimming performance. Using field‐acclimatized smallmouth buffalo (Ictiobus bubalus) collected each season, we report significant seasonal effects in the following variables: critical swimming speed (modified), metabolic rate (standard, active, and scope for activity), and swimming efficiency (total and net cost of transport). Underlying seasonal changes in performance was the reproductive cycle of buffalo, particularly the period of fall gonadal recrudescence. Compared with spring, fall buffalo had a significantly lower mean critical swimming speed (72%) and lower active metabolic rate (53%), even when tested at similar temperatures. During spring, buffalo had a high mean critical swimstandard ming speed and low net cost of transport in comparison with seaother seasons. Buffalo are known to participate in a spring migration and spawning that may require the increased performance and efficiency observed during that season. In addition, significant sex effects were detected in winter measurements of standard metabolic rate and net cost of transport, with females the more efficient swimmers,

Stranding Potential of Young Fishes Subjected to Simulated Vessel-Induced Drawdown

Abstract During early life stages, fish in the Mississippi River system may become stranded by shoreline drawdowns induced by the passage of commercial vessels. We examined the stranding of larval shovelnose sturgeon Scaphirhynchus platorynchus, paddlefish Polyodon spathula, and bigmouth buffalo Ictiobus cyprinellus and of juvenile blue catfish Ictalurus furcatus, largemouth bass Micropterus salmoides, and bluegill Lepomis macrochirus in a laboratory flume. Stranding was measured at three vertical drawdown rates (0.76, 0.46, and 0.21 cm/s) and two bank slopes (1:5 and 1:10). Blue catfish, shovelnose sturgeon, and paddlefish were not tested at both bank slopes. Susceptibility to stranding varied among species and was independent of drawdown rate. At a slope of 1:5, shovelnose sturgeons had the highest stranding percentage (66.7%), followed by paddlefish (38.0%), bluegills (20.0%), bigmouth buffalo (2.2%), and largemouth bass (0.0%). At 1:10, blue catfish had the highest stranding percentage (26.7%), follow...

Swimming Performance of the Topeka Shiner (Notropis topeka) an Endangered Midwestern Minnow

Abstract The Topeka shiner (Notropis topeka) is imperiled by extensive changes in stream hydrology. Responses of shiners to changes or variation in stream hydraulics, however, have not been quantified, hampering conservation efforts. We quantified swimming endurance and behavior for Topeka shiners in a laboratory swim tunnel. Sustained swimming (>200 min) was observed at water velocities of 30–40 cm/s. Prolonged and burst swimming (approximately 10 min to less than 0.1 min) was observed at water velocities of 40–75 cm/s and endurance was negatively correlated with water velocity. Larger individuals (4.4–5.5 cm standard length) exhibited greater sustained swimming ability than smaller individuals (3.0–4.2 cm standard length). Oral grasping of wire mesh within the swim tunnel was frequently employed at moderate water velocities (35–50 cm/s); this behavior may limit downstream displacement of shiners during freshets. Topeka shiners are capable of swimming speeds faster than water velocities which they typically inhabit. Fishways and culverts, therefore, may be employed to facilitate dispersal and recolonization. Swimming endurance data are used to determine optimal size and water velocities for such structures.

Oral Grasping: A Distinctive Behavior of Cyprinids for Maintaining Station in Flowing Water

Abstract We examined oral grasping behavior, a unique and relatively unknown method of maintaining station against flow, in nine species of North American cyprinids to determine whether oral grasping was used by a range of cyprinid species and to further investigate the relationship between oral grasping and water velocity. Fish were subjected to a stepwise increasing velocity test in a 100-liter laboratory swim tunnel that had wire mesh (0.6-mm diameter) attached to a flow filter serving as the grasping substrate. Frequency and duration of oral grasping events were noted for a particular fish during each velocity increment. We observed 608 grasping events, and oral grasping behavior was exhibited by all nine species examined. Mean number of grasping events was high (28.4/trial) for Cyprinella venusta, intermediate (approximately 18/trial) for Cyprinella camura, and Notropis longirostris, and low (< 5/trial) for Notropis texanus, Notropis maculatus, and Notropis wickliffi. Although critical swimming speed varied among species, the water velocity at which oral grasping behavior initially appeared (threshold grasping velocity), expressed as a percentage of critical swimming speed, was approximately 70–80% for most species tested. Oral grasping may be triggered by the onset of muscular fatigue, and is an attempt by minnows to maintain position in water velocities exceeding aerobic swimming ability. We speculate that minnows in lotic environments use oral grasping when high, energetically demanding water velocities are unavoidable, such as during a flood.

Two Catastrophic Floods: Similarities and Differences in Effects on an Ozark Stream Fish Community

In December 1982 a devastating flood occurred in Piney Creek, in the rural Ozark Mountains in Izard County, Arkansas, with vertical stage rises of 2–4 m in the headwaters, 11–12 m at downstream locations, and an estimated return time of 50–100 years. Physical effects in the watershed were catastrophic, with extreme scour and rearrangement of the stream bed, destruction of riparian forest, and deposition of huge amounts of sand from the creek in adjacent pastures or forest. In spite of the extreme nature of this winter flood, residual effects on the overall fish community of the watershed were minimal, and by eight months after the event, the community was virtually indistinguishable from that in the previous summer. In March–April 2008 flooding of equal or greater magnitude than the 1982 flood again occurred in Piney Creek. We followed effects of the spring 2008 flood on local fishes at five long-term fixed sites in the watershed, and on the fish community pooled across those sites, four months after the 2008 flood, and again in 2010 and 2012. In spite of the severity of the 2008 springtime flood, the community before and after was relatively similar qualitatively and quantitatively. But multivariate analyses of the fish community showed more change after the 2008 flood, and in a directional trajectory, than had occurred after the 1982 flood. At the five individual sites, changes in fishes after the 2008 flood were idiosyncratic, with two sites showing marked changes immediately after the flood, with only one subsequently returning toward its former structure. Fishes at all five sites showed more change in multivariate space after the 2008 than after the 1982 flood. In the summers after both floods some cyprinid and catostomid species showed sharp increases in numbers of young-of-year. Differences in the effects of the two floods on the fish community could relate to their timing, with springtime flooding having more effects on fish than the winter flood. Similarities between the two floods with respect to increased production of young-of-year could relate to the scouring of fines (silt and sand) by the floods, providing clean gravel and cobble with more interstitial spaces that could provide protection for fish eggs or larvae, and more microhabitat for food organisms used by young fishes such as micro- or macroinvertebrates. Regardless of mechanisms, much remains to be learned about the effects of extreme floods on stream fish communities, particularly in light of the potential for increased frequency of extreme events as global climate changes continue.

Fish Assemblage of a Cypress Wetland within an Urban Landscape

Abstract Fishes were sampled from Gillam Park Wetland, a small cypress swamp located within the city limits of Little Rock, AR during Fall 2005. The objectives of this research were to contribute to our knowledge of understudied wetland habitats in Arkansas, determine the status of the fish community in an urban wetland, and provide baseline data for future monitoring of this unique site. We collected 20 total species from three wetland sections (lower, middle, upper). Although fish community composition varied among the sections, species richness was similar across wetland sections. Fyke nets were more effective at capturing fish along the heavily vegetated and structured shorelines than either seines or funnel traps. The fish community residing in Gillam Park Wetland indicates that this “urban wetland” is functioning and seemingly healthy despite its proximity to anthropogenic impacts. Furthermore, Gillam Park Wetland is located along a major physiogeographic boundary that may play an important role in the distribution and conservation of several swamp specialist species in Arkansas.