Speckled Dace Rhinichthys Osculus Research Articles

Responses of Native and Nonnative Fishes to Natural Flow Regime Mimicry in the San Juan River

AbstractThe maintenance or restoration of natural flow regimes has been proposed as one means of conserving native fishes. Native fish conservation is enhanced either through the restoration of natural fluvial geomorphic processes (and thus the maintenance of essential habitats) or by the suppression of nonnative fishes. The San Juan River of Colorado, New Mexico, and Utah was dammed in 1962 and its natural flow regime was lost. Beginning in 1993, the river was regulated to mimic a natural flow regime by increasing reservoir releases to mimic timing, but only partially to mimic amplitude, volume, and duration of spring snowmelt discharge. We evaluated the responses of native and nonnative fishes to this natural flow regime mimicry by comparing their autumn densities (number/m2) in San Juan River secondary channels to those during spring runoff and summer base flow over a 9‐year period. Densities of native speckled dace Rhinichthys osculus, bluehead sucker Catostomus discobolus, and flannelmouth sucker C. latipinnis increased with elevated spring discharge. Total native fish density was 10 times greater in 1993 (the year of highest spring discharge) than in 2000 (the year of lowest spring discharge). Collectively, nonnative fish density was negatively related to spring discharge, but western mosquitofish Gambusia affinis was the only commonly collected nonnative that had a significant relationship. Mean daily summer discharge did not affect the density of native or nonnative fishes. Nonnative fishes, however, responded positively to sustained low summer flows (days discharge was less than 14 m3/s). Densities of red shiner Cyprinella lutrensis, common carp Cyprinus carpio, and western mosquitofish were four or more times greater in 2000 (a year of sustained low summer discharge) than in years with comparatively high summer discharge. Speckled dace was the only native species negatively affected by extended low summer discharge. Our results suggest that manipulating spring discharge to mimic a natural flow regime enhances native fish recruitment but might have limited effect in suppressing nonnative fishes, particularly fecund, rapidly growing, small‐bodied species.

Differences in Swimming Ability and Behavior in Response to High Water Velocities among Native and Nonnative Fishes

We conducted swimming performance tests on native and nonnative fishes commonly found in Arizona streams to evaluate the extent of differences in swimming ability among species. Fishes with similar mean lengths were subjected to stepwise increases in water velocity in a laboratory swim tunnel until fish could no longer maintain position. Nonnative fathead minnows Pimephales promelas and red shiners Cyprinellalutrensis exhibited swimming abilities similar to native longfin dace Agosia chrysogaster, speckled dace Rhinichthys osculus and spikedace Meda fulgida. Nonnative mosquitofish Gambusia affinis exhibited swimming ability similar to native Gila topminnows Poeciliopsis occidentalis. Desert suckers Catostomus clarki, bluehead suckers Catostomus discobolus and speckled dace exhibited behavioral responses to high water velocities that may confer energetic advantages in swift water. Differences in swimming ability do not appear to adequately explain the disproportionate removal of nonnative fishes via flooding. Behavioral responses to high flows are more likely the mechanism that allows native fish to persist in streams during flood events.

Juvenile Growth of Native Fishes in the Little Colorado River and in a Thermally Modified Portion of the Colorado River

We estimated juvenile growth rates of four native fish species using the von Bertalanffy growth equation and length data from fish captured during 1991–1994 in the Little Colorado River, a tributary to the Colorado River in Arizona in the Grand Canyon. We compared growth rates to water temperatures for all four species and modeled the effects of warming the Colorado River (through a proposed retrofit of Glen Canyon Dam) on the growth of age-0 emigrants from the tributary. Juvenile growth rates in the Little Colorado River were fastest for flannelmouth sucker Catostomus latipinnis, slowest for speckled dace Rhinichthys osculus, and intermediate for humpback chub Gila cypha and bluehead sucker Catostomus discobolus. Growth rates for each species were positively correlated with water temperature; flannelmouth sucker exhibited the strongest relationship, followed by speckled dace, humpback chub, and bluehead sucker. Our model indicates that native fish immigrating into the cold Colorado River (8–12°C) from the relatively warm Little Colorado River during their first 3 months of life will grow very little by the end of their first year. According to other studies, older, larger fish that disperse into the Colorado River are more likely to survive than those that migrate as larvae. Growth, and possibly survival, of native fish larvae that drift from tributaries into the Colorado River could be increased if water released from Glen Canyon Dam is warmed during the period of larval drift.

Dispersal of Larval Fishes in a Regulated River Tributary

Abstract We investigated longitudinal distributions, nearshore movements, and drift of larval native fishes (humpback chub Gila cypha, speckled dace Rhinichthys osculus, bluehead sucker Catostomus discobolus, and flannelmouth sucker Catostomus latipinnis) in the Little Colorado River, a tributary to the regulated Colorado River in Grand Canyon, Arizona, to determine spawning sites, larval dispersal patterns, and amount of drift into the mainstem Colorado River. Larval distributions and drift indicated native fishes spawned throughout the terminal 14.2 km of the Little Colorado River. In addition, distribution, drift, and trap data suggest an active component to dispersal for all four native species. Drift of larval native fish was greater near shore than midchannel, and except for speckled dace larvae, which were prone to drift at night, larval native fish did not exhibit diel periodicity in drift. During a 46-d period in 1993, we estimated that over 370,000 native fish larvae drifted out of the Little Co...

Resource Use by Larval and Early Juvenile Native Fishes in the Little Colorado River, Grand Canyon, Arizona

We investigated resource use by early life stage (≤30 mm, total length) humpback chub Gila cypha, speckled dace Rhinichthys osculus, bluehead suckers Catostomus discobolus, and flannelmouth suckers C. latipinnis in the Little Colorado River, a tributary to the Colorado River in Grand Canyon, Arizona. Significant logistic regression models for habitat use were developed for all species pairwise combinations except flannelmouth sucker–humpback chub and flannelmouth sucker–speckled dace; correct classification probabilities ranged from 54% to 81%. Parameters used in discriminating among habitat use included depth, distance from shore, cover, and substrate. Logistic models were also developed to compare habitat use among larval stages within species, and most combinations produced significant models. Classification probabilities ranged from 60% to 95% in these models with the variables of depth, distance from shore, current velocity, cover, and substrate contributing to the various models. Behavioral observations revealed significant differences in vertical use of the water column and feeding locations among bluehead suckers and the two cyprinids. Diet analysis supported differences observed in feeding location and also identified some differences in diel feeding patterns. These differences in habitat use, behavioral time budgets, and diet indicate that some resource partitioning occurs among larval fishes in the Little Colorado River. Further laboratory study is needed to verify the mechanisms that sustain differential resource use in this system.

Relative Abundance and Lengths of Kendall Warm Springs Dace Captured from Different Habitats in a Specially Designed Trap

A trap was designed to capture endangered Kendall Warm Springs dace Rhinichthys osculus thermalis (a subspecies of speckled dace Rhinichthys osculus) without being destructive to the habitat of the fish in Kendall Warm Springs Creek, Wyoming. Four experiments were conducted to determine differences in catch per unit effort (CPUE) and length frequencies of fish among differing habitat types. The CPUE was highest in channel habitats with current, and one experiment indicated that it was particularly high at vertical interfaces with vegetation. Longer fish were captured in channel habitats away from vegetation than in vegetated areas. The CPUE was significantly greater during the day than at night during one experiment, but no significant differences were observed among the other three experiments. The traps were easy and inexpensive to construct, could be used in a variety of stream habitats, and may have applications in other small streams for sampling small, benthic fishes.

Physical habitat utilization of fish in a Sonoran Desert stream, Arizona, southwestern United States

Abstract– The physical habitat utilization of 7 species of native fishes in a Sonoran Desert stream, Aravaipa Creek, Arizona is described. The species occupied significantly different depths and velocities of water. Longfin dace (Agosia chrysogaster), speckled dace (Rhinichthys osculus) and loach minnow (Tiaroga cobitis) used similar depths and velocities. Two of the three larger species (Sonora sucker [Catostomus insignis] and roundtail chub [Gila robusta]) used areas of greater depth and reduced velocity. Desert sucker (Catostomus clarki) grouped with loach minnow and speckled dace in the velocity of water occupied, but utilized deeper waters. The spikedace (Meda fulgida) aligned very closely with desert sucker in use of all 3 physical habitat variables.

Influence of Habitat Complexity on Resistance to Flooding and Resilience of Stream Fish Assemblages

Abstract The structure of fish assemblages in five reaches of a high desert stream in north-central Oregon was determined by snorkeling before and after a summer flash flood and two spring floods. One reach in each of two other streams that were unaffected by the first flood was used as a reference system. Stream reaches varied in habitat complexity as measured by hydraulic retention. Following the floods, hydraulically complex stream reaches lost proportionately fewer fish, had generally higher fish diversities, and had higher fish assemblage similarity than hydraulically simple stream reaches. Fish assemblages were resilient, and certain species such as speckled dace Rhinichthys osculus were exceptionally good at recolonizing disturbed habitats. Successful recruitment of different fish species depended, in part, on flood timing. Young of the year of species that spawn in early spring (e.g., rainbow trout Oncorhynchus mykiss) were more negatively affected by early spring floods than summer floods. Specie...

Laboratory Spawning and Rearing of Speckled Dace

Abstract Speckled dace (Rhinichthys osculus) spawned from April to July, in both rearing and spawning aquaria, when maintained at 21–29°C under a natural photoperiod. In other experiments, they spawned 1–2 d after the water temperature was increased to 18 or 24°C in late August–early September, after they had been kept at 15°C and in a photoperiod of 14 h light 10 h dark since June. Both adults and young were easily reared on commercially prepared dried diets.

Fish Associations and Environmental Variables in Age-0 Colorado Squawfish Habitats, Green River, Utah

ABSTRACT Age-0 Colorado squawfish Ptychocheilus lucius were sympatric with seven native and 15 introduced fishes in the Green River, Utah, 1979–88. Larval Colorado squawfish was the most abundant fish captured in summer drift (38%), which included suckers Catostomus spp. (33%), speckled dace Rhinichthys osculus (14%), and channel catfish Ictalurus punctatus (3%). However, ephemeral shoreline embayments (backwaters) used by Colorado squawfish as nursery habitats were dominated by introduced fishes, including red shiner Notropis lutrensis (87%) in summer, and red shiner (65%) and fathead minnow Pimephales promelas (16%) in autumn. Abundance of most fishes was highest in years of lower, more historic summer flows. Most fishes in backwaters inhabited a wide range of environmental conditions, but were most abundant in habitats deeper than 15 cm. We detected no segregation in habitat use between young Colorado squawfish and non-native fishes. Hydrologic conditions in the regulated Green River presumably favor t...

Microhabitat Use by an Assemblage of California Stream Fishes: Developing Criteria for Instream Flow Determinations

Microhabitat requirements were determined for eight species of native California stream fishes: Rainbow trout Salmo gairdneri; Sacramento sucker Catostomus occidentalis; Sacramento squawfish Ptychocheilus grandis; hardhead Mylopharodon conocephalus; California roach Hesperoleucus symmetricus; speckled dace Rhinichthys osculus; tule perch Hysterocarpus traski; and riffle sculpin Cottus gulosus. Two or three size classes were evaluated for each species. Each species had a preferred microhabitat (defined on the basis of depth, velocity, substrate), as did each size class within each species, but there was much similarity in microhabitat use within and among species. The amount of microhabitat available to each species differed in three stream reaches in which availability was quantified, but the differences were not enough to explain the differences in composition of the fish assemblage found at each site. This study indicates that recommendations for instream flows should be based on microhabitat use data collected on site together with habitat availability data. Even on-site data should be used cautiously because intraspecific interactions and changes in a streamˈs physical characteristics, especially in its temperature regime, may cause unexpected shifts in microhabitat use.

Competitive Interactions Between Benthic Stream Fishes, Riffle Sculpin, Cottus gulosus, and Speckled Dace, Rhinichthys osculus

Two morphologically dissimilar stream fishes occupied the same microhabitat in different riffles of Deer Creek, Tehama County, California. In a 12.5 km reach of the creek, speckled dace (Rhinichthys osculus) dominated riffles at the lower end while riffle sculpin (Cottus gulosus) dominated the riffles at the upper end, where dace were confined to slower water. Between these sets of riffles, relative abundances of the two species were negatively correlated. Routine metabolic rates of sculpin increased rapidly with temperature and indicated that sculpins were unable to tolerate temperatures in the low elevation riffles in the summer. Dace swimming performance appeared to be adequate at low temperatures to permit them to occupy the sculpin-dominated riffles. However, stream tank experiments indicated that at low temperatures sculpin were able to displace dace from cover in high velocity water. Our analysis thus demonstrated that competitive interactions between dace and sculpin for preferred microhabitat were mediated by temperature.Key words: competition, critical swimming velocity, experimental stream, microhabitat utilization, routine metabolism

Distribution of Fishes in the White River, Utah

ABSTRACr.-A survey of the White River, Utah, was made during the summer of 1978 and 1979 to determine the abundance and distribution of endemic fishes during and after spring runoff. The fish population was similar to that in other eastern Utah streams. Red shiners (Notropis lutrensis) were most abundant, followed, in order, by roundtail chubs (Gila robusta), flannelmouth suckers (Catostomus latipinnis), speckled dace (Rhinichthys osculus), fathead minnows (Pimephales promelas), carp (Cyprinus carpio), and channel catfish (Ictalurus punctatus). Bluehead suckers (Catostomus discobolus), black bullheads (Ictalurus melas), green sunfish (Lepomis cyanellus), brown trout (Salmo trutta), and Colorado squawfish (Ptychocheilus lucius) individually comprised less than 0.5% of the total number of fish. Native fishes dominated the fish fauna at upstream stations; introduced fishes dominated at downstream stations. A total of 15 adult Colorado squawfish, an endangered fish, was captured or observed.

Comparative Responses of Speckled Dace and Cutthroat Trout to Air-Supersaturated Water

Abstract Speckled dace (Rhinichthys osculus) are more tolerant of air-supersaturated water than adult or juvenile cutthroat trout (Salmo clarki). Speckled dace were tested in concentrations from 110 to 142% saturation and had a 96-hour median lethal concentration (LC50) of 140%, a 7-day LC50 of 137%, and 2-week LC50's of 129 and 131% saturation. The estimated mean threshold concentration, based on time to 50% death (TM50), was 123% saturation. The speckled dace also exhibited consistent external signs of gas bubble disease. Cutthroat trout were tested from 111 to 130% saturation and had 96-hour LC50's of 119 and 120% (adults) and 119 and 119% (juveniles) saturation. Estimated mean threshold concentrations (from TM50 values) were 117% (adults) and 114% (juveniles) saturation. Signs of gas bubble disease exhibited by the cutthroat trout were similar to those seen with other salmonids examined in earlier studies.

Distribution of Fishes in the San Rafael River System of the Upper Colorado River Basin

The San Rafael River and lower reaches of four major tributaries, Cottonwood, Huntington, Ferron, and Rock Canyon creeks, were sampled for fish and water quality in March-April, June, and October, 1977. Native species of fish included speckled dace (Rhinichthys osculus), flannelmouth suckers (Cato- stomus latipinnis), bluehead suckers (C. discobolus), and roundtail chubs (Gila robusta). Red shiners (Notropis lutrensis), fathead minnows (Pimephales prom- elas), black bullheads (Ictalurus melas), and channel catfish (I. punctatus) were recorded introduced species. A single young-of-the-year Colorado squawfish (Ptychocheilus lucius) was caught in the lower San Rafael River in October. This is the first documented record of Colorado squawfish in the San Rafael River. Native fish were dominant at seven stations in the tributary streams and middle section of the San Rafael River and introduced fish dominated the fauna near the mouth of the river.