https://cpw.cvlcollections.org/files/original/1e21a8a880e1c18df484881a2da9921a.pdf b27baf4ef565ac5105bb05e1f71860dc PDF Text Text The research in this publication was partially or fully funded by Colorado Parks and Wildlife. Dan Prenzlow, Director, Colorado Parks and Wildlife • Parks and Wildlife Commission: Marvin McDaniel, Chair • Carrie Besnette Hauser, Vice-Chair Marie Haskett, Secretary • Taishya Adams • Betsy Blecha • Charles Garcia • Dallas May • Duke Phillips, IV • Luke B. Schafer • James Jay Tutchton • Eden Vardy �North American Journal of Fisheries Management © 2021 The Authors. North American Journal of Fisheries Management published by Wiley Periodicals LLC on behalf of American Fisheries Society. ISSN: 0275-5947 print / 1548-8675 online DOI: 10.1002/nafm.10623 MANAGEMENT BRIEF Razorback Sucker Spawning in an Intermittent Colorado Tributary Zachary E. Hooley-Underwood* and Kevin G. Thompson Colorado Parks and Wildlife, 2300 South Townsend Avenue, Montrose, Colorado 81401, USA Kevin R. Bestgen Larval Fish Laboratory, Department of Fish, Wildlife, and Conservation Biology, Colorado State University, 1474 Campus Delivery, Fort Collins, Colorado 80523, USA Abstract Endangered and endemic Razorback Suckers Xyrauchen texanus of the Colorado River basin largely spawn in main-stem rivers and reservoirs. While documenting other native ﬁsh use of two intermittent tributaries of the Gunnison River, Colorado, USA, we detected PIT-tagged Razorback Suckers during the 2015–2019 spawning seasons (April–June) and captured reproductively ready individuals. Because the species is rarely documented in small tributaries, we highlight this occurrence. Prior to 2019, up to 30 individual Razorback Suckers were detected annually in Roubideau Creek, a tributary to the Gunnison River near Delta, Colorado. In 2019, use increased as we detected 110 individual Razorback Suckers in Roubideau Creek, and, for the ﬁrst time, we handled or detected seven in Cottonwood Creek. These ﬁsh represented multiple age-classes of hatchery-reared ﬁsh repatriated to the Gunnison River to aid recovery. We collected and identiﬁed 1,171 larval catostomids from Cottonwood Creek, but none were Razorback Suckers, and even though ripe adults were collected, it remains unclear if reproduction occurred. We suspect that high runoff in 2019 drove increased use of the system. Presence of Razorback Suckers in ﬁve consecutive years indicated that intermittent tributaries might be of greater importance than previously thought for this species, and these streams warrant further investigation and protection. Intermittent streams make up a substantial proportion of waterways in the western United States and provide important habitats and resources to ﬁshes (Laub et al. 2018; Colvin et al. 2019). However, these streams and the ecological services they provide have historically been afforded limited protections (Downing et al. 2003), and recently, federal protections have been reduced (USEPA 2019). Hooley-Underwood et al. (2019) previously reported spawning by up to nearly 11,000 individual imperiled Bluehead Suckers Catostomus discobolus, Flannelmouth Suckers C. latipinnis, and Roundtail Chub Gila robusta annually in Cottonwood Creek—a small, intermittent stream—during 2014–2017. In 2019, through continued work in Cottonwood Creek, we identiﬁed the presence of Razorback Suckers Xyrauchen texanus, a species federally listed as endangered (USFWS 1991). Additionally, in Roubideau Creek, another, larger intermittent stream, we detected Razorback Suckers during the April–June spawning period in 2015–2019. These observations, along with those of Cathcart et al. (2015, 2018), document the rare occurrence of Razorback Suckers using small, naturally intermittent (unaffected by water use) tributaries in recent decades. Further, these ﬁndings add more evidence supporting the importance of small and intermittent tributaries for sucker species in the western United States (Weiss et al. 1998; Bottcher et al. 2013; Webber et al. 2013; Cathcart et al. 2015; Fraser et al. 2017, 2019). The Razorback Sucker is a large-bodied, long-lived, endemic species of the Colorado River basin (CRB) that has declined substantially in distribution and abundance as a result of anthropogenic inﬂuences. Razorback Suckers were scarce by the 1930s in the lower CRB (below the present site of Glen Canyon Dam, erected in 1963) and by *Corresponding author: zachary.hooley-underwood@state.co.us Received November 13, 2020; accepted March 24, 2021 This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modiﬁcations or adaptations are made. 1 �2 HOOLEY-UNDERWOOD ET AL. 1950 in the upper CRB (above Glen Canyon Dam; Mueller and Marsh 2002). In 1991, the species was listed as endangered, and portions of main-stem rivers throughout the basin, as well as several large impoundments, were designated as critical habitat for Razorback Suckers (USFWS 1994). The U.S. Fish and Wildlife Service and their partners have prioritized the research, stabilization, and recovery of Razorback Suckers since the late 1980s, and research on the species indicates that they primarily use main-stem rivers and reservoirs for the majority, if not the entirety, of their life history. For instance, of the 1,011 surveys in which Razorback Suckers were documented in the Colorado Parks and Wildlife’s Aquatic Data Management System database (an annually updated database containing all known aquatic sampling efforts conducted by agency personnel, historic naturalists, and investigators holding scientiﬁc collection permits), only six were not in mainstem habitats and were instead in off-channel ponds or impoundments directly fed by main-stem waters (Colorado Parks and Wildlife, unpublished data). Razorback Suckers are known to spawn nearly exclusively in main-stem habitats, with almost all known spawning occurring in several speciﬁc river reaches and main-stem impoundments (Tyus 1987; Modde and Irving 1998; Modde et al. 2005; Mueller et al. 2005; Bestgen et al. 2020). While evidence is strong that main-stem habitats are of primary importance to the species, tributaries may be important as well. Razorback Sucker larvae and adults in spawning condition have been found near mouths of tributaries (Minckley 1983), and Bottcher et al. (2013) documented frequent use of smaller rivers by PIT-tagged Razorback Suckers and other endangered ﬁshes. Webber et al. (2013) documented production of larval Razorback Suckers in the White River, a midsized tributary to the Green River, which is a major tributary to the Colorado River. Cathcart et al. (2018) detected Razorback Sucker in a small San Juan River tributary when main-stem ﬂows were high. Additionally, there is historical evidence of more widespread use of smaller systems. Minckley (1983) presented multiple accounts of archeological remains of Razorback Suckers in smaller systems, and Quartarone (1995) presented ﬁrst-hand accounts from interviews with elderly farmers, ranchers, and anglers who reported numerous Razorback Suckers present in small tributaries including Kannah Creek (Gunnison River tributary), the Price and Duchesne rivers (Green River tributaries in Utah), and the Black’s Fork River (Green River tributary in Wyoming). We speculate that small tributary use may be diminished presently compared to use before the species underwent rangewide declines. Razorback Suckers are stocked in the dam-regulated Gunnison River at several locations to aid recovery of the species, but little reproduction has been documented there (Osmundson and Seal 2009; Bestgen et al. 2020). All stocked ﬁsh are PIT-tagged, and sampling evidence has indicated that wild ﬁsh are rare or nonexistent (e.g., only 1 of 195 Razorback Suckers sampled in the Gunnison River in 2018 did not have a detectable tag; Colorado Parks and Wildlife, unpublished data). Because we have handled and detected over 35,000 catostomid ﬁshes in our prior work on two Gunnison River tributaries (Roubideau and Cottonwood creeks) with few detections of Razorback Suckers, their presence in ﬁve consecutive years and increased abundance in 2019 is noteworthy. Our objective is to highlight Razorback Sucker use of the partially intermittent Roubideau Creek over 5 years of observation and the ﬁrst detected presence of the species in Cottonwood Creek (an intermittent, third-order stream) in 2019. We also examined catostomid larvae hatched in Cottonwood Creek to determine if presumptive spawning by the ripe Razorback Suckers we observed resulted in detectable larvae production. METHODS Study area.—Our observations were made in Cottonwood and Roubideau creeks near Delta, Colorado, USA. Roubideau Creek is a moderate-sized (mean bankfull width near mouth is 9.7 m) tributary to the Gunnison River; the upper elevation reach (>40 km upstream of mouth) and the lower 9.5 km sustain perennial ﬂows, but the intermediate reach is intermittent. Cottonwood Creek is an intermittent tributary of Roubideau Creek, whose conﬂuence is approximately 4.5 km upstream from the Gunnison River. Cottonwood Creek is higher in gradient than Roubideau Creek near the two streams’ conﬂuence and has substrates dominated by clean gravel and cobble, whereas Roubideau Creek is dominated by silt, sand, and embedded cobbles in the perennial reach. In the intermittent reaches of Roubideau Creek upstream, the habitat is similar to Cottonwood Creek. The Gunnison River substrate in the area around the conﬂuence with Roubideau Creek is mostly cemented, large cobble in higher-velocity areas, with an abundance of silt in slower-velocity areas. A detailed physical description of Cottonwood Creek is in Hooley-Underwood et al. (2019). Roubideau Creek receives snowmelt runoff in April, May, and June, but the intermediate-elevation reach usually dries from July until the following spring snowmelt; monsoonal rain in July and August sometimes delays drying. The lower 9.5-km perennial segment receives supplemental water associated with irrigation returns from midMarch until early November. Cottonwood Creek ﬂows only in years with near-average or greater snowpack, and even in high snowpack years, Cottonwood Creek generally has discharge sufﬁcient to allow access of ﬁsh only in April and May; discharge nearly always ceases in early �MANAGEMENT BRIEF June. Annual snowpack (as the % of long-term median snow-water equivalent averaged over the ﬁrst 7 days of April; https://www.cbrfc.noaa.gov/station/sweplot/swe plot.cgi?cpsc2) was exceptionally low in 2015 (7.9%) and 2018 (27.8%), normal in 2016 (99.1%), and high in 2017 (98.8%, but 150% through the ﬁrst 7 days of March resulting in an early and long runoff) and 2019 (168.5%). Under average snowpack conditions, Roubideau Creek discharge (500 m from the mouth) ranges from approximately 0.3 to 11 m3/s (annual minimum to maximum), and Cottonwood Creek discharge (200 m from the mouth) ranges from 0 to 3 m3/s (Hooley-Underwood et al. 2019). The high snowpack in 2019 resulted in runoff that was high and extended, with measured discharge >25.5 m3/s in Roubideau Creek, though maximum discharge was estimated at over 42.5 m3/s. In Cottonwood Creek, discharge >11 m3/s was measured in 2019. The highest discharge measurements in both streams were obtained with an acoustic doppler current proﬁler (Colorado Water Conservation Board, unpublished data). Roubideau Creek Razorback Sucker detection.—In the spring of 2015, we installed a passive interrogation array (PIA) in Roubideau Creek about 500 m upstream from the Gunnison River to detect PIT-tagged ﬁsh. The array consisted of two sets of paired antennae (6.1 × 0.9 m each) that, in combination, spanned the entire channel in two locations separated by approximately 30 m, which allowed assessment of directional movement of individual ﬁsh. Detections on all four antennas are recorded and stored by an IS1001 Master Controller (Biomark, Boise, Idaho), and continuous power is provided via a solar bank and battery storage. Our target species were Flannelmouth Sucker, Bluehead Sucker, and Roundtail Chub, of which we PIT-tagged nearly 10,400 in the Gunnison River basin since 2014. Others have released hatchery-reared, translocated, and wild PIT-tagged ﬁshes in the region, mainly the main-stem Gunnison River, including Razorback Suckers. The PIA was powered and operational year-round since its installation. Individual antenna function was tested hourly with virtual test tags and automated diagnostics. While individual antennas occasionally miss test tags, no antenna has experienced prolonged failure. Additionally, temporal distributions of the numerous detections of our target species (e.g., 26,560 total spawning season detections in 2019) indicated no interruptions of PIA operation during any spawning season. Array detections were downloaded weekly or every other week during the spawning period (March–June) and less frequently during the rest of the year. Data were downloaded using Biomark Tag Manager software (Biomark), and analyses were conducted in Microsoft Excel. For 2019 detections, detection histories were created for each individual tagged ﬁsh, and directional movements were identiﬁed. For detection sequences to qualify as an 3 immigrant or emigrant movement, a tag had to be detected on at least one antenna in each channel-spanning pair, with the detection order determining direction. Additional directional movements were identiﬁed when an uninformative detection sequence was followed by an informative sequence later in the season (e.g., a detection sequence on the lower antenna pair only was identiﬁed as an immigrant movement, when followed by a deﬁnitive emigrant sequence later in the season). We disregarded individual ﬁsh immigration events that lasted less than 4 h, assuming these were unlikely to represent attempts to spawn. To identify whether the increased use of Roubideau Creek by Razorback Suckers was driven by recent stocking of the Gunnison River in close proximity to Roubideau Creek’s mouth, we ascertained the stocking date, stocking location, and year-class of each detected individual in the Species Tagging, Research and Monitoring System database, a repository for all PIT tag data collected by or relating to the Upper Colorado and San Juan River Endangered Fish Recovery Programs partners (STReaMS, 2019). Cottonwood Creek Razorback Sucker sampling and detection.—Three gear types were used to sample or detect ﬁshes in Cottonwood Creek in 2015–2017: an upright picket weir with trap boxes, submersible PIT readers (SPRs; 0.9-m rigid submersible antenna, Biomark), and electroﬁshing. The use of the picket weir and SPRs during 2015–2017 are explained in detail in Hooley-Underwood et al. (2017, 2019). In brief, we constructed a picket weir and trap boxes designed to separately capture and hold upstream- and downstream-bound mature catostomids in Cottonwood Creek 130 m above its mouth. Elevated discharge and debris loads rendered the weir inoperable (i.e., the picket fence was partially or fully removed to prevent damage and bank erosion) for at least some of each spawning season. We placed one (2016) or two (2017) SPRs in Cottonwood Creek 65 m upstream from the mouth of the creek, anchored to the substrate in the thalweg, in a narrow portion of channel. In 2017, the second antenna was deployed approximately 5 m downstream from the ﬁrst. In 2018, Cottonwood Creek received no discharge due to the low snowpack. In 2019, two SPRs were placed and operated as in 2017. High ﬂows fully disabled SPRs during most of May because we were unable to access the readers to replace depleted batteries. In 2015–2017 and 2019, Cottonwood Creek was also sampled with backpack or bank electroﬁshers (SmithRoot, Vancouver, Washington; LR24 backpack, GPP 5.0). Electroﬁshing surveys covered 90 to 400 m of stream and occurred between three and ﬁve times per year during April and May. The objective of these surveys was to assess mature sucker species composition, so single pass surveys were usually conducted, though several two-pass �4 HOOLEY-UNDERWOOD ET AL. surveys were also conducted. One to three backpacks, or four anode poles (bank shocking) were used, and electroﬁsher output was set based on measured conductivity and adjusted based on ﬁsh response. Cottonwood Creek larval catostomid collection and identiﬁcation.— We collected larval ﬁsh annually in Cottonwood Creek, including in 2019, as part of our research on our target species. Larvae were collected with twilight or early morning drift net sets and visually targeted dip net sweeps as described in Hooley-Underwood et al. (2019). The 2019 larvae were collected (a subset of which were identiﬁed to species) on June 4 (n = 73), 10 (n = 27), 12 (n = 321), and 27 (n = 416) and July 2 (n = 776). Larvae were identiﬁed at the Larval Fish Laboratory (Colorado State University, Fort Collins, USA). RESULTS Razorback Sucker Use of Roubideau Creek The PIA detected Razorback Suckers every year since 2015 (Table 1). Detections occurred in March–September, but the vast majority were in May and June. Individual ﬁsh detections were highest in 2019 (n = 110) followed by 2017 (n = 28). All individuals detected throughout the year in 2019 were also detected within the April–June spawning period. In 2019, immigration and emigration movements peaked the week of June 27 (Figure 1). Based on detections that were much lower than normal for our target species in 2019 compared to previous years, we believe PIA detection efﬁciency was reduced as a result of high ﬂows (e.g., Aymes and Rives 2009). Thus, we suspect that many PIT-tagged ﬁsh, including Razorback Suckers, immigrated undetected in April and May during elevated discharge. This is further conﬁrmed by numerous detections of ﬁshes in Cottonwood Creek during this same time period, indicating ﬁsh were entering and dispersing throughout the system in April and May. Razorback Sucker records downloaded from the Species Tagging, Research and Monitoring System database TABLE 1. Razorback Sucker PIT tag detections from Roubideau Creek, just upstream of the Gunnison River, Colorado from 2015 to 2019. Date ranges denote when the ﬁrst and last Razorback Sucker was detected each year. Year n Date range 2015 2016 2017 2018 2019 4 11 28 8 110 Mar 30 to Jun 5 Apr 8 to Jun 6 Apr 28 to Jun 4 Apr 8 to May 12 Apr 8 to Sep 30 indicated that ﬁsh were stocked over 11 different years, and represented at least eight different year-classes, indicating contributions from many stocking events (Table 2). Nearly 75% were one- and two-year-old Razorback Suckers stocked in 2015 and 2016. Razorback Sucker Use of Cottonwood Creek Of the >35,000 catostomids we handled in Cottonwood Creek prior to 2019, none were Razorback Suckers. In 2019, we captured ﬁve individuals and SPRs detected two more (Table 3). Of the Razorback Suckers we captured, four were PIT-tagged (we captured one such individual on two sampling occasions) and one was not. All Razorback Suckers handled were in reproductive condition and included both gravid females and tuberculate males that produced milt. On one electroﬁshing occasion, a female producing ova and a tuberculate male were captured in a relatively short 91 m electroﬁshing reach. The Cottonwood Creek SPRs detected 536 to 2,162 individual PIT-tagged ﬁsh in each year, but Razorback Suckers were only detected in 2019. Between SPR detections and electroﬁshing surveys, a total of seven individual Razorback Suckers were identiﬁed in Cottonwood Creek between April 18 and June 8 (Table 3). Additional unidentiﬁed Razorback Suckers may have used the creek as SPRs were not operating and electroﬁshing was not possible for much of May. One individual (ﬁsh A; Table 3) was captured and detected multiple times between April 18 and June 8. Of the 1,613 larvae examined, 1,171 were identiﬁed as catostomids, but no Razorback Suckers were found. One hundred eighteen catostomid larvae had uncertain taxonomic identity due to intermediacy of characters from possible hybridization or due to physical damage, but none were classiﬁed as possible Razorback Suckers. DISCUSSION Our observations indicated that naturally intermittent tributaries may be more important for Razorback Suckers than generally recognized. This ﬁnding expands on recent observations of the species using intermittent tributaries (Cathcart et al. 2015, 2018) and larger, perennial tributaries (Bottcher et al. 2013; Webber et al. 2013). Cathcart et al. (2018) suggested that Razorback Suckers use intermittent tributaries for reasons other than spawning, but our ﬁndings comport with historical evidence that Razorback Suckers participated in spawning migrations into tributaries of the upper Colorado River basin (Quartarone 1995). Roubideau Creek supported use of Razorback Suckers since at least 2015, and in 2019 we detected unprecedented numbers for an intermittent stream. In 2019, we also observed the ﬁrst recorded use of Cottonwood Creek by Razorback Suckers, and the condition of �5 MANAGEMENT BRIEF FIGURE 1. Number of PIT-tagged Razorback Suckers detected per week moving upstream or downstream (solid black line = entering; dotted black line = exiting) past the passive interrogation array (PIA) in lower Roubideau Creek, Colorado in 2019 compared to weekly stream discharge. TABLE 2. Stocking year (release) and year-class (hatching year) for Razorback Suckers detected on the Roubideau Creek, Colorado PIT tag passive interrogation array in 2019. Year-class Stocking year 2006 2007 2010 2012 2013 2014 2015 2016 2017 2018 2019 Total 2009 2011 2012 2013 2015 2016 2017 2018 Unknown Total 1 1 1 1 1 1 4 8 23 59 8 1 3 110 1 1 4 8 23 59 8 1 1 1 4 31 ﬁsh handled indicated they were potentially spawning in Cottonwood Creek, the ﬁrst such occurrence documented in an intermittent stream. All Razorback Suckers in our study area were presumed hatchery-reared ﬁsh. The single untagged individual (ﬁsh D; Table 3) was handled in Cottonwood Creek, but we have no way of knowing whether it was wild or a hatchery-reared individual that never received a tag or 59 8 1 3 3 2 had a faulty or lost tag. However, because Razorback Suckers were from 11 different stocking years and represented at least eight age-classes of ﬁsh, documented tributary use behavior is likely not the result of a speciﬁc stocking scenario or cohort-based behavioral similarity. No ﬁsh were ever stocked in our study area but instead were all stocked in the Gunnison River and moved into our study streams. We think these behaviors may also �6 HOOLEY-UNDERWOOD ET AL. TABLE 3. Encounter type for seven PIT-tagged Razorback Suckers in Cottonwood Creek, Colorado in 2019 between April 18 and June 8. Individual D was not tagged at capture. Date Apr 18, 2019 Apr 19, 2019 Apr 23, 2019 May 24, 2019 May 24, 2019 May 29, 2019 May 29, 2019 May 30, 2019 Jun 7, 2019 Jun 7, 2019 Jun 8, 2019 Individual A A B C D A E A F A G Encounter type Detection Detection Detection Electroﬁshing Electroﬁshing Electroﬁshing Electroﬁshing Detection Electroﬁshing Electroﬁshing Detection apply to wild ﬁsh if they exist, as hatchery-reared and wild Razorback Suckers have been shown to respond to similar cues and select the same spawning habitats (Modde et al. 2005). Bottcher et al. (2013) documented frequent use of the San Rafael River (Green River tributary, near Green River, Utah,) by Razorback Suckers and suggested that historical usage of that stream may have been high. The San Rafael River is larger than Roubideau Creek and was a perennial stream historically but is occasionally intermittent recently due to diversions and upstream water storage. We suspect that historical use could also have been high in Roubideau Creek when Razorback Suckers were abundant in the Gunnison River drainage. Razorback Suckers frequented tributaries in the area, based on observations of “old-timers,” some of whom speciﬁcally recall sucker spawning migrations that included Razorback Suckers into tributaries (Quartarone 1995) and because they were historically abundant enough to support a small commercial ﬁshery (Bestgen 1990). If populations in the CRB expand via continued stocking and eventually wild recruitment, Razorback Sucker selection for tributary spawning sites may be more prevalent. We did not identify Razorback Sucker larvae in Cottonwood Creek and therefore cannot conﬁrm that the ripe ﬁsh captured there successfully reproduced. However, over 10,000 individual Bluehead and Flannelmouth suckers access the creek annually (except in drought years when dry) to spawn, in addition to abundant nonnative White Suckers C. commersonii and other suckers of hybrid origin. These suckers successfully spawn and produce large numbers of larvae (Hooley-Underwood et al. 2019). The ratio of Razorback Suckers to other suckers was therefore very small, and the chance of ﬁnding Razorback Suckers among the abundant other larvae was likewise small. The presence of individuals that were producing gametes at the time of capture suggests that Razorback Suckers selected Cottonwood Creek for spawning in 2019. Low reproduction has been documented in the larger dam-regulated Gunnison River by Razorback Suckers (Osmundson and Seal 2009), and it is possible that better reproductive success may be realized as stocked ﬁsh expand into new habitats such as intermittent streams. Reproduction of other native catostomids occurs in these habitats, and these ﬁshes exhibit high ﬁdelity (61–71% of individuals return annually), which indicates that recruitment occurs (Hooley-Underwood et al. 2019). Therefore, it is possible that these streams could support reproduction and recruitment of Razorback Suckers as well. Alternatively, there is a risk that intermittent habitats may act as ecological traps for Razorback Suckers, as their larvae may not possess the instinct to evacuate these streams rapidly before ﬂow ceases. Robertson and Hutto (2006) suggested that variability in habitat selection under differing settlement cues (i.e., above average runoff in Roubideau Creek), along with low site ﬁdelity, are signs of a potential ecological trap. Numerous ﬁshes rely on intermittent waters, opportunistically selecting those habitats to fulﬁll various life history events (Datry et al. 2014, 2017). Intermittent stream habitats often differ from adjacent perennial habitats due to their limited wetted season and may thus be better suited to support certain life history stages and activities. For example, Schultz (2014) found that Northern Leatherside Chub Lepidomeda copei occupied intermittent habitats during their spawning season and noted an abundance of clean gravel substrate in those habitats. Likewise, in our study area, clean gravel and cobble substrates occurred in the intermittent habitats, and we suspect that Razorback Suckers and native Catostomous and Gila species select those habitats in part for those substrates. Despite the risk of entrapment and desiccation, juvenile ﬁshes hatched in intermittent waters often have better survival and a substantial competitive advantage over their counterparts produced in perennial waters because they experience warmer temperatures, increased primary production, and are protected from predatory and nonnative ﬁshes (Wigington et al. 2006; Hughes et al. 2019). We suspect that native Catostomous and Gila ﬁshes that are produced in Cottonwood and Roubideau creeks experience similar beneﬁts. Whether Razorback Suckers beneﬁt from using these creeks as well should be further examined. Conclusions Our observations indicate that Razorback Suckers will use small, intermittent tributaries during spring, especially under above-average runoff conditions. Therefore, systems like Roubideau and Cottonwood creeks warrant scrutiny for their potential contribution to recovery of Razorback �MANAGEMENT BRIEF Suckers in the CRB. We observed indications of possible spawning by Razorback Suckers in an intermittent stream, and we suggest similar streams should be evaluated to determine whether they support spawning Razorback Suckers that could contribute to wild recruitment. The general recognition of intermittent streams as habitat used by Razorback Suckers and other native ﬁshes needs to be elevated as well, perhaps with protections for such habitat extended per the original 2015 Waters of the United States designations (USEPA 2015). Our observations contribute to the arguments posited by Laub et al. (2018) and Colvin et al. (2019) that intermittent streams are used by diverse native ﬁshes in North America and should be considered conservation habitat. ACKNOWLEDGMENTS We thank D. Cammack, T. Duncan, R. Japuntich, D. Kowalski, R. Samuelson, and R. Schleicher for assistance with electroﬁshing surveys. S. Seal of the Larval Fish Laboratory, Colorado State University, identiﬁed all larval samples. Data on the PIT-tagged Razorback Suckers that we detected were downloaded from the the Species Tagging, Research and Monitoring System Database, a compendium of PIT tag data associated with the Upper Colorado and San Juan River Endangered Fish Recovery Programs and managed by the Colorado Natural Heritage Program (STReaMS 2019). We thank two anonymous reviewers who provided valuable feedback on an earlier draft of our manuscript. There is no conﬂict of interest declared in this article. ORCID Zachary E. Hooley-Underwood https://orcid.org/00000001-5268-8028 Kevin R. Bestgen https://orcid.org/0000-0001-8691-2227 REFERENCES Aymes, J. C., and J. Rives. 2009. Detection efﬁciency of multiplexed passive integrated transponder antennas is inﬂuenced by environmental conditions and ﬁsh swimming behavior. Ecology of Freshwater Fish 18:507–513. Bestgen, K. R. 1990. Status review of the Razorback Sucker, Xyrauchen texanus. Colorado State University, Larval Fish Laboratory Contribution 44, Fort Collins. Bestgen, K. R., T. E. Dowling, B. Albrecht, and K. A. Zelasko. 2020. Large-river ﬁsh conservation in the Colorado River basin: progress and challenges with endangered Razorback Sucker. Pages 317–333 in D. L. Propst, J. E. Williams, K. R. Bestgen, and C. W. Hoagstrom, editors. Standing between life and extinction: ethics and ecology of conserving aquatic species in the American Southwest. University of Chicago Press, Chicago. Bottcher, J. L., T. E. Walsworth, G. P. Thiede, P. Budy, and D. W. Speas. 2013. Frequent usage of tributaries by the endangered ﬁshes of the upper Colorado River basin: observations from the San Rafael 7 River, Utah. North American Journal of Fisheries Management 33:585–594. Cathcart, C. N., K. B. Gido, and M. C. McKinstry. 2015. Fish community distributions and movements in two tributaries of the San Juan River, USA. Transactions of the American Fisheries Society 144:1013–1028. Cathcart, C. N., K. B. Gido, M. C. McKinstry, and P. D. MacKinnon. 2018. Patterns of Fish movement at a desert river conﬂuence. Ecology of Freshwater Fishes 27:492–505. Colvin, S. A. R., S. M. P. Sullivan, P. D. Shirey, R. W. Colvin, K. O. Winemiller, R. M. Hughes, K. D. Fausch, D. M. Infante, J. D. Olden, K. R. Bestgen, R. J. Danehy, and L. Eby. 2019. Headwater streams and wetlands are critical for sustaining ﬁsh, ﬁsheries, and ecosystem services. Fisheries 2:73–91. Datry, T., N. Bonada, and A. Boulton, editors. 2017. Intermittent rivers and ephemeral streams ecology and management. Academic Press, London. Datry, T., S. T. Larned, and K. Tockner. 2014. Intermittent rivers: a challenge for freshwater ecology. BioScience 64:229–235. Downing, D. M., C. Winer, and L. D. Wood. 2003. Navigating through Clean Water Act jurisdiction: a legal review. Wetlands 23:475–493. Fraser, G. S., K. R. Bestgen, D. L. Winkelman, and K. G. Thompson. 2019. Temperature – not ﬂow – predicts native ﬁsh reproduction with implications for climate change. Transactions of the American Fisheries Society 148:509–527. Fraser, G. S., D. L. Winkelman, K. R. Bestgen, and K. G. Thompson. 2017. Tributary use by imperiled Flannelmouth and Bluehead suckers in the upper Colorado River basin. Transactions of the American Fisheries Society 146:858–870. Hooley-Underwood, Z. E., S. B. Stevens, N. R. Salinas, and K. G. Thompson. 2019. An intermittent stream supports extensive spawning of large-river native ﬁshes. Transactions of the American Fisheries Society 148:426–441. Hughes, R. M., B. L. Bangs, S. V. Gregory, P. D. Scheerer, R. C. Wildman, and J. S. Ziller. 2019. Recovery of Willamette River ﬁsh assemblages: successes and remaining threats. Pages 157–184 in C. Krueger, W. Taylor, and S.-J. Youn, editors. From catastrophe to recovery: stories of ﬁsh management success. American Fisheries Society, Bethesda, Maryland. Laub, B. G., G. P. Thiede, W. T. Macfarlane, and P. Budy. 2018. Evaluating the conservation potential of tributaries for native ﬁshes in the upper Colorado River basin. Fisheries 43:194–206. Minckley, W. L. 1983. Status of the Razorback Sucker, Xyrauchen texanus (Abbott), in the lower Colorado River basin. Southwestern Naturalist 28:165–187. Modde, T., Z. H. Bowen, and D. C. Kitcheyan. 2005. Spatial and temporal use of a spawning site in the middle Green River by wild and hatchery-reared Razorback Suckers. Transactions of the American Fisheries Society 134:937–944. Modde, T., and D. B. Irving. 1998. Use of multiple spawning sites and seasonal movement by Razorback Suckers in the middle Green River, Utah. North American Journal of Fisheries Management 18:318–326. Mueller, G. A., J. Carpenter, and P. C. Marsh. 2005. Cibola High Levee Pond annual report 2004. U.S. Geological Survey, Biological Resources Discipline, Open-File Report 2005-1075, Reston, Virginia. Mueller, G. A., and P. C. Marsh. 2002. Lost: a desert river and its native ﬁshes—a historical perspective on the lower Colorado River. U.S. Geological Survey, Information Technology Report USGS/BRD/ ITR-2002-0010, Denver. Osmundson, D. B., and S. C. Seal. 2009. Successful spawning by Razorback Sucker in the Gunnison and Colorado rivers, as evidenced by larval ﬁsh collections, 2002–2007. U.S. Fish and Wildlife Service, Final Report, Grand Junction, Colorado. Available: https://www.c oloradoriverrecovery.org/documents-publications/technical-reports/rsc h/121FINALrev.pdf. (February 2021). �8 HOOLEY-UNDERWOOD ET AL. Quartarone, F. 1995. Historical accounts of upper Colorado River basin endangered ﬁsh. Final Report to the Information and Education Committee of the Recovery Program for Endangered Fish of the Upper Colorado River Basin. Available: https://coloradoriverrecove ry.org/general-information/general-publications/historical-accounts-doc ument.html. (October 2020). Robertson, B. A., and R. L. Hutto. 2006. A framework for understanding ecological traps and an evaluation of existing evidence. Ecology 87:1075–1085. Schultz, L. D. 2014. Use of seasonally available habitat by Northern Leatherside in Wyoming. Southwestern Naturalist 59:118–120. STReaMS (Species Tagging, Research and Monitoring System). 2019. STReaM System online database. Available: https://streamsystem.org. (December 2019). Tyus, H. M. 1987. Distribution, reproduction, and habitat use of the Razorback Sucker in the Green River, Utah, 1979–1986. Transactions of the American Fisheries Society 116:111–116. USEPA (U.S. Environmental Protection Agency). 2015. Connectivity of streams and wetlands to downstream waters: a review and synthesis of the scientiﬁc evidence. USEPA, EPA/600/R-14/475F, Technical Report, Washington, D.C. USEPA (U.S. Environmental Protection Agency). 2019. STReaM System online database. Deﬁnition of ‘‘Waters of the United States’’— recodiﬁcation of pre-existing rules. Federal Register 84:204(22 October 2019):56626–56670. USFWS (U.S. Fish and Wildlife Service). 1991. Endangered and threatened wildlife and plants: the Razorback Sucker (Xyrauchen texanus) determined to be an endangered species. Federal Register 56:205(23 October 1991):54957–54967. USFWS (U.S. Fish and Wildlife Service). 1994. Endangered and threatened wildlife and plants; determination of critical habitat for the Colorado River endangered ﬁshes: Razorback Sucker, Colorado Squawﬁsh, Humpback Chub, and Bonytail Chub, ﬁnal rule. Federal Register 59:54(21 March 1994):13374–13400. Webber, P. A., K. R. Bestgen, and G. B. Haines. 2013. Tributary spawning by endangered Colorado River basin ﬁshes in the White River. North American Journal of Fisheries Management 33:1166–1171. Weiss, S. J., E. O. Otis, and O. E. Maughan. 1998. Spawning ecology of Flannelmouth Sucker, Catostomus latipinnis (Catostomidae), in two small tributaries of the lower Colorado River. Environmental Biology of Fishes 52:419–433. Wigington, P. J. Jr., J. L. Ebersole, M. E. Colvin, S. G. Leibowitz, B. Miller, B. Hansen, H. R. Lavigne, D. White, J. P. Baker, M. R. Church, J. R. Brooks, M. A. Cairns, and J. E. Compton. 2006. Coho Salmon dependence on intermittent streams. Frontiers in Ecology and the Environment 4:513–518. � Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Journal Articles Description An account of the resource CPW peer-reviewed journal publications Text A resource consisting primarily of words for reading. Examples include books, letters, dissertations, poems, newspapers, articles, archives of mailing lists. Note that facsimiles or images of texts are still of the genre Text. Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Razorback sucker spawning in an intermittent Colorado tributary Description An account of the resource Endangered and endemic Razorback Suckers Xyrauchen texanus of the Colorado River basin largely spawn in main-stem rivers and reservoirs. While documenting other native fish use of two intermittent tributaries of the Gunnison River, Colorado, USA, we detected PIT-tagged Razorback Suckers during the 2015–2019 spawning seasons (April–June) and captured reproductively ready individuals. Because the species is rarely documented in small tributaries, we highlight this occurrence. Prior to 2019, up to 30 individual Razorback Suckers were detected annually in Roubideau Creek, a tributary to the Gunnison River near Delta, Colorado. In 2019, use increased as we detected 110 individual Razorback Suckers in Roubideau Creek, and, for the first time, we handled or detected seven in Cottonwood Creek. These fish represented multiple age-classes of hatchery-reared fish repatriated to the Gunnison River to aid recovery. We collected and identified 1,171 larval catostomids from Cottonwood Creek, but none were Razorback Suckers, and even though ripe adults were collected, it remains unclear if reproduction occurred. We suspect that high runoff in 2019 drove increased use of the system. Presence of Razorback Suckers in five consecutive years indicated that intermittent tributaries might be of greater importance than previously thought for this species, and these streams warrant further investigation and protection. Bibliographic Citation A bibliographic reference for the resource. Recommended practice is to include sufficient bibliographic detail to identify the resource as unambiguously as possible. Hooley‐Underwood, Z. E., K. G. Thompson, and K. R. Bestgen. 2021. Razorback sucker spawning in an intermittent Colorado tributary. North American Journal of Fisheries Management. Creator An entity primarily responsible for making the resource Hooley-Underwood, Zachary E. Thompson, Kevin G. Bestgen, Kevin R. Subject The topic of the resource Razorback Suckers Xyrauchen texanus Colorado River basin Reproduction PIT-tagged Extent The size or duration of the resource. 8 pages Date Created Date of creation of the resource. 2021-04-19 Rights Information about rights held in and over the resource <a href="http://rightsstatements.org/vocab/InC-NC/1.0/" target="_blank" rel="noreferrer noopener">In Copyright - Non-Commercial Use Permitted</a> <a href="https://creativecommons.org/licenses/by-nc-nd/4.0/" target="_blank" rel="noreferrer noopener">Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)</a> Format The file format, physical medium, or dimensions of the resource application/pdf Language A language of the resource English Is Part Of A related resource in which the described resource is physically or logically included. North American Journal of Fisheries Management Type The nature or genre of the resource Article