Species: Rhinichthys osculus

Speckled Dace

Species

Encyclopedia of Puget Sound

The following description is from Minckley (1973) and Sublette et al. (1990). The speckled dace is a chunky, rounded minnow. Adults reach lengths of 45-80 mm standard length (SL = length from tip of snout to end of hypural plate) (Wallace 1980). Usually there are 8 dorsal rays (6-9), 13-14 pectoral rays, 8 pelvic rays, and 7 anal rays. There are 60-90 scales along the lateral line. The mouth is subterminal, usually with no frenum. Pharyngeal arches contain teeth in two rows, usually 1,4-4,1 or 2,4-4,2. A single, small barbel is located at the edge of each jaw. Coloration is variable depending on geographic location, but often dark and blotchy dorsally, lighter ventrally. A lateral band extends from the dorsal fin onto the caudal peduncle. Breeding males have an intense red color at the base of paired fins, near the anal fin base, on the lower caudal lobe, near the upper part of the gill cleft, and on the mouth. Breeding tubercles are present on pectoral rays of males. Larval speckled dace from the upper and lower Colorado River basin were described by Snyder (1981) and Winn and Miller (1954), respectively.

Classification

Kingdom

Animalia

Phylum

Craniata

Class

Actinopterygii

Order

Cypriniformes

Family

Cyprinidae

Genus

Rhinichthys

NatureServe

Source:
ELEMENT_GLOBAL.2.100335

Classification

Informal Taxonomy

Animals, Vertebrates - Fishes - Bony Fishes - Minnows and Carps

Formal Taxonomy

Animalia - Craniata - Actinopterygii - Cypriniformes - Cyprinidae - Rhinichthys - .

Ecology and Life History

Short General Description

A small fish (dace).

Habitat Type Description

Freshwater

Migration

true - true - false - Lake populations may migrate short distances up inlet streams to spawn.

Non-migrant

true

Locally Migrant

true

Food Comments

An omnivorous benthic feeder, at times feeding on drift in mid-water or rarely at the surface (Schreiber and Minckley 1981). The diet consists mostly of benthic insects, also includes other invertebrates, algae, and detritus (little or no plant material or detritus in some areas) (Sublette et al. 1990, Woodbury 1933, Greger and Deacon 1988). Young feed mainly on zooplankton. Of 97 individuals collected in October from the Columbia River drainage, Canada, 28 percent had consumed only filamentous algae, 39 percent contained only insect remains, and the remaining 33 percent contained algae and insect remains (Peden and Hughes 1981). Schreiber and Minckley (1981) examined food habits in Aravaipa Creek, Arizona, during January, April, July, and October, 1975, and January 1976. The diet included primarily riffle-dwelling insects, reflecting the association with riffle habitats. Ephemeropteran larvae made up greater than 70 percent of the diet, excepting one sampling period. Plecopteran, trichopteran, and dipteran larvae were used when available Speckled dace from Little Creek, New Mexico, collected on 18-20 June 1986, consumed primarily dipteran larvae (81 percent by number), ephemeropteran larvae (7 percent), and trichopteran larvae (4 percent) (van Eimeren 1988). At the same location, speckled dace collected on 24-26 October 1986 consumed dipteran larvae (47 percent by number), ephemeropteran larvae (29 percent) and trichopteran larvae (23 percent). Additionally, van Eimeren found little diet overlap between Gila trout and speckled dace even though they shared the same habitats. Greger and Deacon (1988) examined food habits of speckled dace on 9 February, 20 June, 28 September, and 12 December 1979, in the Virgin River, Utah, Arizona, and Nevada. Dace fed mostly on simuliid larvae in February and June and on chironomid larvae in September and December.

Reproduction Comments

Cross (1975) collected ripe females in late June and mid-July 1973 from the Virgin River drainage in Utah. In Aravaipa Creek, Arizona, speckled dace were collected in breeding coloration or with tubercles from December to August, with mature gonads from November to March, or seen engaged in spawning activities from January to April. Larvae were collected from January to April. John (1963) studied reproduction in Cave Creek, Chiricahua Mountains, Arizona. Females matured at two years of age. Peaks in reproductive activity were in early spring and late summer. John believed spawning efforts were triggered by flash floods. Males defended territories, and activities of the male often resulted in circular, clean gravel areas that John (1963) called nests. A female entered a defended area and partially buried or wedged herself under the edge of a stone. Males took positions next to the buried female and the pair or group vibrated for a few seconds, after which the female departed. A female entered a nest several times, depositing a portion of her ripe eggs during each spawning event. John (1963) gave data for the total number of eggs laid in an aquarium by each of eight females. From these data, Vives calculated that the number of eggs laid was related to standard length by the equation: number of eggs laid = -264.41 + 10.45 SL (mm) (R- squared = 0.89, p < 0.001). Females ranged from 45 to 75 mm SL and numbers of eggs laid ranged from 174 to 514. Eggs hatched in 6 days at 18 to 19 C under laboratory conditions. Maximum age of speckled dace in streams of the Chiricahua Mountains is 3 years (John 1964). Moyle et al. (1989) stated that some may live up to 5-6 years. Females from the Kettle River, British Columbia, Canada, did not mature until the end of their second year (Peden and Hughes 1981).

Ecology Comments

Associated with several different faunas depending on location. In the Gila River drainage, native associates include the spikedace (MEDA FULGIDA), roundtail chub (GILA ROBUSTA), loach minnow (TIAROGA COBITIS), longfin dace (AGOSIA CHRYSOGASTER), Sonora sucker (CATOSTOMUS INSIGNIS), desert sucker (CATOSTOMUS CLARKI), and Gila trout (ONCORYNCHUS GILAE). Historical associates included the woundfin (PLAGOPTERUS ARGENTISSIMUS), bonytail (GILA ELEGANS), squawfish (PTYCHOCHEILUS LUCIUS), flannelmouth sucker (CATOSTOMUS LATIPINNIS), and razorback sucker (XYRAUCHEN TEXANUS), all now extirpated from the Gila River basin. Populations show large fluctuations in size (Minckley 1969, Deacon and Bradley 1972). LaBounty and Minckley (1972) noted that increasing populations of longfin dace may result in decreasing populations of speckled dace in areas of overlap at intermediate elevations. There is not enough data to understand the nature of this relationship (i.e., whether or not it is cause-effect). Predators include introduced trouts (ONCORHYNCHUS AND SALMO spp.) in the Colorado River mainstream, flathead catfish (PYLODICTUS OLIVARIS) in the Salt River basin, and also introduced basses (MICROPTERUS spp.) and green sunfish (CHAENOBRYTTUS CYANELLUS) (Minckley 1985). THAMNOPHIS CYRTOPSIS (black-necked garter snake) is known to feed on speckled dace (John 1964). Mpoame and Rinne (1983) recorded the protozoan ICHTHYOPHTHIRIUS MULTIFILIIS, trematode ORNITHODIPLOSTOMUM PTYCHOCHEILUS, and the cestode LIGULA INTESTINALIS as parasites of speckled dace in Aravaipa and Hurricane creeks, Arizona. Generally occurs in small, loose groups.

Length

Conservation Status

NatureServe Global Status Rank

Global Status Last Reviewed

1996-09-25

Global Status Last Changed

1996-09-25

Distribution

Conservation Status Map

Global Range

The most ubiquitous fish in the western U.S. (Page and Burr 1991), ranging from the Columbia River drainage (north to southern British Columbia) to the southern Gila River drainage of Arizona and Sonora, Mexico (Peden and Hughes 1981, Minckley et al. 1986, Varela-Romero 1990, Wallace 1980); ecological range extends from small springs of Death Valley to high mountain brooks (Minckley 1985), including waters of the Columbia River basin, Klamath River basin, Oregon lakes, Lahontan basin, Bonneville basin, North-Central basins, Death Valley system, Sacramento River basin, Colorado River basin, and South California Coastal Region (Minckley et al. 1986). [Subspecies osculus was described from Babocomari Creek, Arizona (Girard 1856), but is extirpated there. R. o. osculus now occurs only in about half a dozen locations, including Aravaipa Creek, Cave Creek (Chiricahua Mountains), Redfield Canyon, and Sonoita Creek, Arizona (Minckley 1981, Minckley 1991).]

ELEMENT_GLOBAL.2.100335