2007 SOUTHEASTERN NATURALIST 6(2):305–320 Catostomid Fishes of the Wateree River, South Carolina David J. Coughlan1,*, B. Kim Baker1, D. Hugh Barwick1, A. Brad Garner2,3, and W. Robert Doby2,1 Abstract - Fish surveys throughout the Wateree River in 2004–2005 documented the presence of 8 catostomid species—Carpiodes sp. cf. Cyprinus (quillback), Erimyzon oblongus (creek chubsucker), Ictiobus bubalus (smallmouth buffalo), Minytrema melanops (spotted sucker), Moxostoma collapsum (notchlip redhorse), M. macrolepidotum (shorthead redhorse), Scartomyzon rupiscartes (striped jumprock), and Scartomyzon sp. undescribed species (brassy jumprock)—but failed to document C. sp. cf. velifer (highfin carpsucker), Moxostoma sp. cf. Erythrurum (Carolina redhorse), or M. robustum (robust redhorse). Four native (quillback, spotted sucker, notchlip redhorse, and shorthead redhorse) and the nonnative smallmouth buffalo were collected in sufficient numbers to allow observations of unique aggregations. Based on time of year, expression of milt, presence of tubercles, and published thermal preferenda during spawning, we believe these aggregations were associated with spawning, although direct observations of spawning behavior were not made. Spotted suckers used Piedmont and transitional-zone habitats early in the year and also aggregated in larger numbers in the mouths of blackwater Coastal Plain tributaries. Low catches of spotted sucker in riffle habitat in the Wateree River at temperatures exceeding 14 °C appears anomalous and merits further investigation. All other suckers were collected predominantly in areas of gravel, cobble, and bedrock in the Piedmont and transitional zone; aggregations of quillback, shorthead redhorse, and then notchlip redhorse successively followed high spotted sucker catches. The nonnative smallmouth buffalo appeared to use these same habitats during the entire time when quillback, shorthead redhorse, and notchlip redhorse were present, although smallmouth buffalo were collected at low catch rates. The elevated temperatures at which notchlip redhorse aggregated appeared anomalous and merits further investigation. Introduction Limited knowledge of the occurrence, abundance, and natural history of many catostomid species has been an impediment to status assessment and the determination of need for conservation measures within this family. Exotic species, environmental contaminants, habitat degradation due to agricultural and urban development, hydropower projects, migration barriers, water diversions, eutrophication, and exploitation by commercial, recreational, and subsistence fishers are some of the numerous threats that may 1Duke Energy-Carolinas, Biological Services, 13339 Hagers Ferry Road, Huntersville, NC 28078. 2GeoSyntec Consultants, 1100 Lake Hearn Drive, Suite 200, Atlanta, GA 30342-1523. 3Current address - North Carolina Cooperative Fish and Wildlife Research Unit, Campus Box 7617, North Carolina State University, Raleigh, NC 27695-7617. *Corresponding author - djcoughl@duke-energy.com. 306 Southeastern Naturalist Vol. 6, No. 2 face the 76+ sucker species in North America (Cooke et al. 2005). Assessment of the significance of each of these threats is sometimes further compounded by limited ability of biologists to differentiate various catostomid species, limited knowledge of sucker natural history or exploitation, perception of suckers as trash fish tolerant of poor water quality, and limited or non-existent research funding (Cooke et al. 2005). Research efforts directed at a particular catostomid species or entire assemblages in a river are critical to assess the current status of sucker populations and suggest avenues for future research. The catostomid fauna of southeastern United States Atlantic slope drainages is in particular need of study. Species with uncertain taxonomy, such as Carpiodes sp. cf. cyprinus (quillback) and C. sp. cf. velifer (highfin carpsucker); species lacking formal description, such as Moxostoma sp. cf. erythrurum (Carolina redhorse) and Scartomyzon sp. (brassy jumprock) (formerly known as the smallfin redhorse); and the recently rediscovered M. robustum (Cope) (robust redhorse) exist here. Although suckers can be readily observed and studied when they congregate in shallow riffles during spawning (Curry and Spacie 1984, Hackney et al. 1971, Kwak and Skelly 1992, McSwain and Gennings 1972), there are few catostomid spawning studies directed at southeastern Atlantic slope rivers with the exception of those occurring on the Savannah River, GA–SC. Grabowski and Isely (2007) observed a consistent sequence of use of main channel gravel bars with limited temporal and spatial overlap by spawning catostomids, including robust redhorse. Grabowski and Isely (2006) found robust redhorse to occupy main-channel gravel bars only during spring and then abandon these areas in favor of limited home ranges in downstream reaches for the remainder of the year. Excepting the above-mentioned studies, sucker migrations preceding spawning events and subsequent residence times in spawning areas are relatively unknown in the southeastern United States. We expect that movement and catch-rate information systematically collected throughout a large river during spring will benefit researchers trying to assess or conserve southeastern United States catostomid assemblages. We sampled for rare catostomids (highfin carpsucker, Carolina redhorse, and robust redhorse) throughout the Wateree River, SC, by boat electrofishing from late winter to early summer of 2004–2005, including their presumed period of congregating to spawn. At the same time, we collected and documented the presence of other catostomid species in the Wateree River, and these are discussed in relation to river kilometer, substrate, and temperature. Study Site The confluence of the Catawba River with the Big and Little Wateree creeks forms the Wateree River, which flows through the Piedmont and 2007 D.J. Coughlan, B.K. Baker, D.H. Barwick, A.B. Garner, and W.R. Doby 307 Coastal Plain physiographic provinces of central South Carolina. After completion of the Wateree Dam in 1920, the upper 28 km of the Wateree River were inundated by Wateree Lake. The lotic portion of the Wateree River now originates at the tailrace of the Wateree Dam and terminates at its confluence with the Congaree River, where the conjoined rivers are known as the Santee River (Fig. 1). Flows in this 124-km long portion of the Wateree River are regulated primarily by operation of the Wateree Hydroelectric Facility. Figure 1. Map of Wateree River fish-sampling locations, listed by river kilometers upstream from the confluence of the Wateree and Congaree rivers, and relation of map to the state of South Carolina (inset). 308 Southeastern Naturalist Vol. 6, No. 2 The Wateree Hydroelectric Facility (5 generating units) has a combined generation capacity of 82 megawatts, a maximum generation flow of 383 cubic meters per second (cms), and generally operates as a load-following facility (Duke Power 2003). From March 15 through May of each year, the facility continuously operates a minimum of 1 hydroelectric unit (approximately 76.5 cms) to facilitate Morone saxatilis Walbaum (striped bass) spawning migrations from downstream reservoirs. The upper 12 km of the Wateree River lie in the Piedmont province, and the substrate is generally composed of bedrock, boulder, cobble, and gravel (Fig. 2). A transitional area with substrate composed largely of gravel and approximately 7 km in length occurs near the city of Camden, SC. The Wateree River then meanders for approximately 105 km through Coastal Plain swampland before joining the Congaree River. The riverine substrate in the Coastal Plain is predominantly organic detritus, sand, and gravel, with the gravel component diminishing downstream in percent contribution and size. Methods Boat-mounted electrofishing was repeatedly conducted at specific locations along the Wateree River during 2004 and 2005. Sampling locations, listed by river kilometer (rkm) upstream from the confluence of the Wateree and Congaree rivers (Table 1 and Fig. 1), were chosen based on field surveys, aerial videography of the entire river at low-flow conditions, and Figure 2. Dominant substrate component identified during instream flow measurements in the Wateree River, SC (Duke Energy, unpubl. data collected in 2004–2005). Substrate type was determined by visual and tactile methods at numerous points across representative transects in the vicinity of each of the 6 fish-sampling locations. The total percentage of each substrate type was determined per transect, and the average for all transects at a location appears in the figure. Substrate data from a single transect at rkm 123.4 coincided with the area where fish collections occurred. 2007 D.J. Coughlan, B.K. Baker, D.H. Barwick, A.B. Garner, and W.R. Doby 309 possible use by both diadromous and freshwater fish communities. Coastal Plain sampling was directed towards tributary stream confluences (Little River, Colonels Creek, and Swift Creek at rkms 2.6, 40.7, and 62.4, respectively), whereas gravel and rock shoals were selected at more upstream locations (rkms 108.0 and 119.3). The tailrace of the Wateree Hydroelectric Facility (rkm 123.4) was also sampled, and this location was typified by variable flows and bedrock, boulder, cobble, and gravel substrate. Sampling typically involved use of 2 Smith-Root 5.5-m electrofishing boats equipped with 5.0 GPP control units and operated at a setting sufficient to draw 5–6 amps of 120-pulses-per-second DC current. Two netters per boat were always employed to collect stunned fish. Each boat crew sampled a variety of habitats at each location, and catches were pooled after each crew had expended about 1800 seconds of electrofishing pedal time. In 2004, we documented catostomid catch rates weekly at rkms 108.0 and 119.3 at specified water temperatures (18–24 ºC) thought to bracket the range of spawning temperatures for the robust redhorse (Robust Redhorse Conservation Committee 2002). Our objective was to concentrate fish collection efforts on gravel bars where aggregations of spawning catostomids could conceivably include rare catostomid species. Gravel and rock shoals at rkms 108.0 and 119.3 were surmised to be some of the best available sucker spawning habitat in the river. Assessment of our 2004 data indicated that not all sucker species used these 2 locations and that high catch rates could occur outside the 18–24 ºC water temperature range. In 2005, we quantified catch rates of all catostomids encountered at all 6 locations during the mid- February-to-early-June sampling period (13 sampling trips), and that data, along with some supporting data from 2004, are described here. Water temperature (ºC) and dissolved oxygen concentration (mg/L) were measured at each location during each sampling event with a calibrated thermistor and dissolved oxygen probe, respectively. Specific conductance was measured at all 6 sampling locations and in the Coastal Plain tributary streams by a calibrated Hydrolab Datasonde 3 during the May 2–3, 2005 trip. Table 1. Description of sampling locations in the Wateree River, SC. RKM = Distance in kilometers upstream from the confluence of the Wateree and Congaree rivers. RKM Description Province Latitude (N) Longitude (W) 2.6 In the vicinity of the Little R. confluence Coastal Plain 33º45.759' 80º36.188' 40.7 In the vicinity of the Hwy 76 and 378 Coastal Plain 33º56.886' 80º37.697' Landing and the Colonels Creek confluence 62.4 In the vicinity of the Swift Creek Coastal Plain 34º02.465' 80º36.201' confluence 108.0 In the vicinity of the Interstate 20 bridge Transition 34º13.336' 80º37.719' 119.3 In the vicinity of the Mickle Island shoal Piedmont 34º18.172' 80º40.997' upstream from Hwy 1 123.4 Wateree Hydroelectric facility tailrace Piedmont 34º20.009' 80º41.960' 310 Southeastern Naturalist Vol. 6, No. 2 All catostomids were netted, identified in the field by at least 2 qualified taxonomists, and released alive, although some individuals were retained for vouchers in the Duke Energy Fish Museum. Fish identification followed Etnier and Starnes (1993), Jenkins and Burkhead (1994), Marcy et al. (2005), and Menhinick (1991). Taxonomy followed Nelson et al. (2004), except we continue to use the generic name Scartomyzon for the striped and brassy jumprocks. The determination of the native or nonnative origin of each species followed Lee et al. (1980). Results Water temperatures at the 6 locations sampled in 2005 ranged from 8.4 to 25.4 ºC, while dissolved oxygen concentrations ranged from 6.2 to 11.7 mg/L. Specific conductance ranged from 96 to 114 and from 14 to 114 􀂗S/ cm in the main channel and Coastal Plain tributaries of the Wateree River, respectively. Water-quality values and trends measured during our fishsampling activities in 2004 and 2005 appeared generally similar. Spring 2005 was particularly cool with sporadic high-rainfall events (March 28 and 29; April 5, 14, 15, and 18; and June 6). Fish distributions and collection efficiency were undoubtedly affected by cooler water temperatures and occasional high water levels in the river. During 2 years of boat-electrofishing in the Wateree River, we expended over 133 hours of pedal time and collected 62 fish species representing 15 families (Duke Energy, Huntersville, NC, unpubl. data). Eight of those 62 species were catostomids and included quillback, Erimyzon oblongus Mitchill (creek chubsucker), Ictiobus bubalus Rafinesque (smallmouth buffalo), Minytrema melanops Rafinesque (spotted sucker), Moxostoma collapsum Cope (notchlip redhorse), M. macrolepidotum Lesueur (shorthead redhorse), Scartomyzon rupiscartes Jordan & Jenkins (striped jumprock), and the undescribed brassy jumprock. Five catostomid species comprised the majority of the catches, although catch rates varied considerably, and will be discussed in further detail. Three species made negligible contributions to the catostomid assemblage sampled by boat electrofishing and included: 15 creek chubsuckers collected infrequently at rkms 2.6, 40.7, 62.4, and 123.4 during the 2 years of sampling; 5 brassy jumprocks collected only at rkm 119.3 from May 11 to June 30, 2004 (water temperature ranged from 20.4 to 28.6 ºC); and a single striped jumprock collected at rkm 123.4. We did not collect or observe any highfin carpsucker, Carolina redhorse, or robust redhorse. Quillback were collected in low numbers early in 2005 at various locations in the river, but mainly at rkm 108.0 (Fig. 3). From late April to late May, quillback appeared to concentrate at the transitional zone and 2 Piedmont sampling locations (rkms 108.0, 119.3, and 123.4). Some fish exhibited tuberculation on the cheek and operculum. Water temperature during the time of increased catch rates (April 14–May 24) ranged from 2007 D.J. Coughlan, B.K. Baker, D.H. Barwick, A.B. Garner, and W.R. Doby 311 16.5 to 21.8 ºC, and the peak catch rate occurred about May 3 at temperatures ranging from 17.6 to 18.7 ºC. Smallmouth buffalo were collected in low numbers early in 2005 at various locations in the river, but catch rates increased at the transitional zone and 2 Piedmont locations around March 29 (temperatures ranged from 13.3 to 13.7 ºC) and remained elevated during our sampling trips. Temperatures during the time of increased catch rates (March 29–June 7) ranged Figure 3. Catostomid catch rates (numbers per hour of electrofishing) at rkms 2.6, 40.7, 62.4, 108.0, 119.3, and 123.4 on the Wateree River throughout spring 2005. 312 Southeastern Naturalist Vol. 6, No. 2 from 13.3 to 22.5 ºC, and the peak catch rate occurred from March 29 to April 28 at temperatures ranging from 13.3 to 18.0 ºC. Smallmouth buffalo catch rates were generally low at the 3 Coastal Plain locations. Spotted sucker were collected at high rates early in the year (February 15–March 15) in Piedmont, transitional zone, and Coastal Plain locations. While some spotted sucker appeared to prefer the boulder, cobble, and gravel substrates at rkm 119.3, higher catch rates were observed from the lower reaches of the blackwater tributary streams at rkms 40.7 and 62.4 in the Coastal Plain. Temperatures during the time of increased catch rates (February 15–March 15) ranged from 8.7 to 13.6 ºC, and tuberculate males were abundant. Thereafter, low catch rates of spotted sucker occurred primarily from rkm 40.7 to 119.3. The total number of spotted suckers collected in 2005 (883) was the highest of any catostomid species observed in the Wateree River. Notchlip redhorse were only collected in the Piedmont and primarily at rkm 119.3 in the Wateree River during both 2004 and 2005. Catch rates at rkm 119.3 in 2004 varied from 1 to 9 fish per hour through May 17 and then rose to 22.3 fish per hour on May 25 (temperature = 23.4 ºC) and remained elevated as water temperatures increased. Similarly in 2005, notchlip redhorse catch rates ranged from 0–4 fish per hour until June 7, when the catch rate rose to 22.9 fish per hour at a water temperature of 22.4 ºC. Catch rates of shorthead redhorse were generally low throughout the river through April 19 (except on February 16 at rkm 108.0) and then increased on April 28 as water temperatures began to exceed 17 ºC. Shorthead redhorse catch rates steadily increased at rkm 119.3 and peaked at 80 fish per hour on May 24 (water temperature = 21.6 ºC), while catch rates at rkm 108.0 remained fairly steady at about 23 fish per hour throughout this period. The total number of shorthead redhorse collected in 2005 (572) was the second highest of all catostomid species. The observed pattern of catch for shorthead redhorse in 2004 differed from 2005 and was higher at rkm 108.0 than at rkm 119.3. Discussion Eight catostomid species were collected from the Wateree River during our surveys, and these same species have been varyingly observed in one or more neighboring river systems (Table 2). Species differences among river systems were generally most noticeable in regard to the three rare catostomid species (i.e., highfin carpsucker, Carolina redhorse, and robust redhorse) that were the initial focus of this investigation. Failure to collect any of the 3 species is discussed in greater detail; however, we can currently say that each species is extremely rare should it occur in the Wateree River. Highfin carpsuckers were not collected during 2 years of effort in the Wateree River; however, we did collect several catostomid species including highfin carpsucker and Hypentelium nigricans Lesueur (northern 2007 D.J. Coughlan, B.K. Baker, D.H. Barwick, A.B. Garner, and W.R. Doby 313 hog sucker) during similar sampling forays in the Congaree River. Collections were made near the Old Granby Lock and Dam in Columbia, SC (an area of bedrock, boulder, cobble, and gravel substrate 83.4 km upstream from the confluence of the Wateree and Congaree rivers) in 2004. Highfin carpsuckers were collected on a single trip to the Congaree River at a rate of 19 fish per hour (water temperature of 20.3 ºC) on April 26 in association with many quillback. Tuberculate individuals of both species were collected; highfin carpsuckers exhibited diagnostic nuptial tuberculation on the snout and top of the head. Highfin carpsuckers ranged in total length from 305–368 mm, averaged 335 mm, and were smaller than most of the mature quillback collected at the same time. We can provide no definitive reason for the absence of highfin carpsucker from the neighboring Wateree River. We saw no evidence of Carolina redhorse in the Wateree River, although we have collected a specimen in the Pee Dee River during cooperative forays there in search of robust redhorse. Formal description of the species is being pursued by R.E. Jenkins, Roanoke College, and W.C. Starnes, North Carolina State Museum (Wayne Starnes, North Carolina State Museum,Raleigh, NC, pers. comm.). To date, the species has only been collected in the Pee Dee, NC–SC, and Cape Fear, NC, drainages. No robust redhorse were observed during our 2 years of Wateree River sampling. South Carolina Department of Natural Resources (SCDNR) surveys of the Wateree River have also been unsuccessful in collecting robust Table 2. Catostomidae in lower Piedmont and upper Coastal Plain reaches of selected southeastern US rivers. S = Savannah; C = Congaree; W = Wateree; and P = Pee Dee. Scientific name Common name SA CB,E,F WB PC,D Carpiodes sp. cf. cyprinus Quillback X X X X Carpiodes sp. cf. velifer Highfin carpsucker X X X Catostomus commersoni White sucker X Erimyzon oblongus Creek chubsucker X X X X Erimyzon sucetta Lake chubsucker X X Hypentelium nigricans Northern hog sucker X X Ictiobus bubalus Smallmouth buffalo X X Ictiobius cyprinellus Bigmouth buffalo X Minytrema melanops Spotted sucker X X X X Moxostoma collapsum Notchlip redhorse X X X X Moxostoma sp. cf. erythrurum Carolina Redhorse X Moxostoma macrolepidotum Shorthead redhorse X X X Moxostoma robustum Robust redhorse X X Scartomyzon rupiscartes Striped jumprock X X Scartomyzon sp. Brassy jumprock X X X X AMarcy et al. (2005). BCoughlan et al. (2005). CProgress Energy (2003). DRohde et al. (in press). ERose (2004). FSCE&G (1998). 314 Southeastern Naturalist Vol. 6, No. 2 redhorse (Ross Self, SCDNR, Columbia, SC, pers. comm.). These findings are interesting as the geographic location of the Wateree River (straddling the Piedmont–Coastal Plain boundary of the Atlantic slope in the southeastern United States) coincides with that of the Pee Dee, Savannah, and Oconee (GA) rivers where remnant populations of the robust redhorse occur (Robust Redhorse Conservation Committee 2002). For unknown reasons, it appears the robust redhorse did not persist in the Catawba and Wateree rivers of the Santee drainage. It is noted that, unlike the Santee River into which these rivers flow, all reaches of the three Atlantic slope rivers wherein robust redhorse persist offer unrestricted access from the lower Piedmont to their estuaries. However, we do anticipate the collection of this species in the future as the SCDNR has initiated a multi-year program to stock robust redhorse in the Wateree River. Approximately > 100 phase-I and-II robust redhorse juveniles were released into the Wateree River in November and December 2005. Additional stockings will take place in future years with the goal of establishing a genetically diverse, self-sustaining population (Forrest Sessions, SCDNR, Bonneau, pers. comm.). Despite our inability to collect any of the targeted rare catostomid species in the Wateree River, we did observe what we presumed to be spawning aggregations of quillback, smallmouth buffalo, spotted sucker, notchlip redhorse, and shorthead redhorse. While we did not attempt to observe spawning acts, the changing pattern of fish abundance within the river, the presence of tuberculate individuals, the expression of milt upon gentle abdominal pressure to male fish, and occurrence at water temperatures similar to those noted for these species spawning in other river systems all strongly suggest these fish were either actively spawning or preparing to do so. For example, quillback in the Wateree River exhibited a protracted spawning season typified by increased catch rates from April 14–May 24 and coinciding with the presence of tuberculate individuals (we did not quantify the prevalence of tubercles). This is consistent with observations of a quillback spawning migration up the North Platte River from Lake McConaughy, NE, between April 26 and May 29, 1969 (Madsen 1971). Male and female quillback both exhibited tubercles (at times reaching 100% of all captured individuals) during this Nebraska spawning migration, although water temperatures were not given. Quillback in Virginia generally reside in warm reservoirs and low- to moderate-gradient rivers except during the spawning period, when they enter medium-sized rivers (Jenkins and Burkhead 1994). We recorded low catch rates of quillback at times (prior to mid-April) and locations (in the Coastal Plain throughout our study) that were presumably unsuitable for spawning. Increased catches of quillback at rkms 108.0, 119.3, and 123.4 in April and May appear indicative of migratory behavior. A prolonged migration may precede quillback spawning in 2007 D.J. Coughlan, B.K. Baker, D.H. Barwick, A.B. Garner, and W.R. Doby 315 the Wateree River, depending on the locations where fish reside for the majority of the year (whether in downstream reservoirs or Coastal Plain portions of the Wateree or upper Santee rivers). The suggested movements of quillback in the Wateree River prior to spawning appear similar to those observed in Nebraska and Virginia. Beecher (1980) found highfin carpsucker in Florida in close proximity to quillback during periods of high flow, but segregated at other times between areas of relatively higher flow in midchannel areas (quillback) and areas of low flow over silt, clay, and sand substrates (highfin carpsucker). We have collected highfin carpsuckers and quillback together during higher spring flows in the Congaree River, but were never able to capture a highfin carpsucker in the Wateree River, despite collection of quillbacks over a wide range of flows. Etnier and Starnes (1993) and Rohde et al. (1994) speculate that highfin carpsucker are sensitive to pollution, siltation, and impoundment, and we hypothesize that one or a combination of these factors might detrimentally affect the abundance and distribution of highfin carpsucker in the Wateree River. Smallmouth buffalo are native to the Mississippi River and western Gulf Coast drainages and have been introduced into the Wateree River and other Atlantic slope drainages (Table 2). They were collected at elevated catch rates in the transitional area and Piedmont over an extended period from late-March through early-June. Smallmouth buffalo in Wheeler Reservoir, AL, also spawned over an extended time period from March 28–May 25 at water temperatures ranging from 13.9–21.1 ºC (Wrenn 1969). Water temperatures measured during the period of our increased catches on the Wateree River were 13.3–22.5 ºC and coincided with those for spawning smallmouth buffalo in Alabama. Etnier and Starnes (1993) and Mettee et al. (1996) observed upstream spawning migrations by smallmouth buffalo in Tennessee and Alabama rivers. The low catch rates of smallmouth buffalo early in the year and at Coastal Plain locations throughout the year might indicate the occurrence of a similar spawning migration in the Wateree River. We recorded high catch rates of mature spotted sucker in the lower reaches of 2 blackwater tributaries with abundant sunken timber (rkms 40.7 and 62.4) from mid-February to mid-March. At the same time, Wateree River spotted suckers were collected at upstream locations in the Piedmont, but at considerably lower catch rates. Based on the preferred spawning substrates described by Grabowski and Isely (2007), Marcy et al. (2005), and Mettee et al. (1996), we might speculate that spotted suckers were spawning in upstream reaches of the Wateree River and possibly staging in blackwater tributary streams. This appears consistent with observations indicating spotted suckers in the Savannah River and Alabama rivers thrive in low- or no-current situations over silt, sand, mud, clay, or gravel substrates and typically spawn in riffles (Marcy et al. 2005, Mettee et al. 1996). 316 Southeastern Naturalist Vol. 6, No. 2 We are unaware of spawning activity or riffle habitat in upstream reaches of the blackwater tributary streams. The early aggregation of spotted suckers in Wateree River tributaries was consistent with observations from the Flint River, GA. McSwain and Gennings (1972) noted blocked spawning migrations of spotted suckers below 2 dams on the Flint River as early as January 21, 1971; however, running-ripe females were not observed until March 11 (12.2 ºC) and were last observed on May 4 (19.4 ºC). The range of spawning temperatures recorded for Flint River fish was similar to that observed (14.4–19.7 ºC) for spotted suckers spawning on Savannah River gravel bars (Grabowski and Isely, 2007). While the early aggregations of spotted suckers on the Wateree and Flint rivers correspond, the extended spawning period on the Flint River (into May) and the elevated spawning temperatures observed (in excess of 19 ºC on both the Flint and Savannah rivers) greatly exceeds the period and temperatures where increased catches of spotted sucker occurred on the Wateree River. In contrast, Wateree River spotted sucker aggregations had dispersed by mid- to late-March when water temperatures exceeded 14.0 ºC. The aggregations and movements of Wateree River spotted suckers appear anomalous and merit further investigation. At this time, we do not know if fish made spawning runs into small tributary streams possessing riffle habitat, as has been observed in Alabama (Mettee et al. 1996). We suggest that collections of spotted suckers occurring from April through June from rkm 40.7 to rkm 119.3 likely represent catch rates typical for year-round resident populations. The notchlip redhorse is the recently re-elevated sister species of Moxostoma anisurum (Rafinesque) (silver redhorse) and typically inhabits rivers, large streams, and reservoirs on the southeastern Atlantic slope (Marcy et al. 2005). We observed very few notchlip redhorse throughout the Wateree River early in the year and then a definite aggregation at rkm 119.3 during both 2004 and 2005. Notchlip redhorse initiated the congregating process from late-May to early-June when water temperatures reached 22–23 ºC. Jenkins and Burkhead (1994) found notchlip redhorse in Virginia to move upstream and spawn in April. Grabowski and Isely (2007) found notchlip redhorse in the Savannah River to spawn between 12.7–19.7 ºC, a temperature range that generally included the month of April at a minimum. They observed notchlip redhorse on mid-channel gravel bars for a longer duration than all other suckers except the northern hog sucker. Migration to and aggregation of Wateree River notchlip redhorses in areas of gravel and rocky substrates are similar to those observed in other rivers. However, these aggregations occur in the Wateree River at water temperatures well in excess of those observed elsewhere. This anomalous distribution of Wateree River notchlip redhorse was observed in both 2004 and 2005 and leads us to believe that further investigation is merited. We might speculate that either spawning occurred earlier in the 2007 D.J. Coughlan, B.K. Baker, D.H. Barwick, A.B. Garner, and W.R. Doby 317 year at some unmonitored location, spawning may actually happen at temperatures and dates outside the range typically observed, or spawning may take place in smaller tributary streams. The Santee drainage represents the southern limit of shorthead redhorse on the Atlantic slope (Jenkins and Burkhead 1994). Catch rates of shorthead redhorse in the Wateree River began to increase and peak at water temperatures of 17 and 21.6 ºC, respectively, and coincided with the temperature range (17 to 21.5 ºC) observed for spawning fish in Virginia (Jenkins and Burkhead 1994). Shorthead redhorse spawning in Virginia occurred in areas of slow to moderate runs and the tails of pools with large-gravel substrate, not dissimilar to locations where high catch rates occurred in the Wateree River. The observation of Jenkins and Burkhead (1994) that shorthead redhorse breeding areas were not utilized during non-spawning periods appears to be corroborated by our observations, as few fish used these locations early in the year; however, we do acknowledge a lack of observations from late-summer through early-winter. Thus, it appears that native catostomids in the Wateree River exhibit an annual progression of varying abundances that begins with spotted suckers and proceeds successively to quillback, shorthead redhorse, and notchlip redhorse as water temperatures increase. Aggregations of catostomids occur in the transitional area and Piedmont (with spotted sucker also congregating in blackwater Coastal Plain streams) of the Wateree River and demonstrate temporal segregation, although some overlap occurs. For example, spotted sucker used rkm 119.3 through mid-March, quillback used this same location from late March through early May and, as their numbers declined in early May, shorthead redhorse catches increased and peaked in late May (Fig. 3). Notchlip redhorse catches increased in early June at rkm 119.3 just as shorthead redhorse catches started to decline. Temporal segregation patterns by spawning catostomids have also been observed by Curry and Spacie (1984), Grabowski and Isely (2007), and Kwak and Skelly (1992). Our sampling efforts were too coarse to provide information on spatial segregation during periods of temporal overlap. However, others have observed spatial segregation among spawning catostomids. Grabowski and Isely (2007) have noted spawning catostomids on a single mid-channel Savannah River gravel bar to segregate based on flow, depth, and substrate slope and size. The syntopic Moxostoma erythrurum Rafinesque (golden redhorse) and M. duquesnei Lesueur (black redhorse) segregate between different microhabitats during spawning, and further isolate by exhibiting differential spawning behavior (territorial vs. communal) and the occurrence of dissimilar morphological structures such as large head tubercles (Kwak and Skelly 1992). Suckers in Deer Creek, IN, segregate by size, time of spawning, and habitat to reduce competition for spawning sites (Curry and Spacie 1984). 318 Southeastern Naturalist Vol. 6, No. 2 The nonnative smallmouth buffalo appears to congregate in the same area and at the same time as quillback, shorthead redhorse, and notchlip redhorse, although their numbers appear to wane as notchlip redhorse catches increase. The effects of this nonnative species on the spawning ecology of the native catostomid assemblage may merit further investigation. Suckers in southeastern United States rivers, including the Wateree River, continue to face potential threats posed by numerous factors, including exotic species introductions, environmental contaminants, agricultural and urban habitat degradation, hydropower projects, migration barriers, water diversions, eutrophication, and exploitation (Cooke et al. 2005). Here we have described results of a faunal survey demonstrating a diverse catostomid assemblage in the Wateree River that varies temporally and spatially in spring and which appears to function similarly to those in other river systems where suckers have been studied. However, our findings have indicated that further investigation into the biology of several of these catostomids (i.e., smallmouth buffalo, spotted sucker, and notchlip redhorse) could answer questions relating to anomalous distributions or potential species interactions. Flow and dissolved-oxygen issues downstream of the Wateree Dam have been major concerns during the Federal Energy Regulatory Commission hydroelectric relicensing process. Upon issuance of the new license, we anticipate a future of continuous water releases with more favorable dissolved-oxygen regimes during summer. This catostomid survey, while providing catch data related to the abundance of suckers throughout a spring season, will also serve as a reference point upon which to compare future population responses to changes in water quantity and quality in the Wateree River. Acknowledgments We are indebted to the following individuals who either assisted in the field, maintained boats and trailers, provided safety and logistical oversight, provided references, coordinated safe water flows, provided financial and administrative support, or reviewed drafts of this manuscript: John Alexander, Steve Arnold, Jason Bettinger, Jim Bulak, Mark Cantrell, John Crane, the staff at Duke Energy Hydro Central, John Dulude, Scott Fletcher, Tim Grabowski, M.K. Green, James Hall, Jeremy Hall, Duane Harrell, Steve Johnson, Amanda Hill, Robert Jenkins, Tim Leonard, Jeff Lineberger, Glenn Long, Todd Lynn, Matt McKinney, Mark Oakley, Mark Rash, Garry Rice, Drew Robb, Wayne Starnes, Steve Summer, Gene Vaughan, Jay Wylie, Ty Ziegler, and 2 anonymous reviewers. This manuscript was the result of Federal Energy Regulatory Commission (FERC) relicensing studies conducted for the Catawba-Wateree Hydroelectric Development (FERC No. 2232). Literature Cited Beecher, H.A. 1980. 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