Rhinichthys osculus nevadensis
Ash Meadows speckled dace-Endangered (Designated Critical Habitat in County)
Description:
The Ash Meadows speckled dace is sometimes referred to as the Nevada speckled dace. It differs from other known speckled dace species with its large head, short deep body, very small eyes, and the reduction of the ventral ray to a mere rudiment. It has a well-developed maxillary barbel, irregularly placed scales, and an incomplete lateral line. The fins are small, and the color on the upper sides is speckled and marbled with brown. The belly and lower sides are immaculate or sparsely spotted. A broad dark lateral stripe is usually present and a black spot is on the base of the tail. There is sometimes a dark stripe along the middle of the lower half of the sides.
Habitat:
This dace is a freshwater fish found in warm springs and their outflows.
Range:
This dace is found in Armagosa drainage system that begins near Springdale, north of Beatty, and disappears into the Armagosa Desert, at Ash Meadows.
Breeding:
The breeding season is bimodal with peaks in early spring and late summer. Spawning sites are referred to as the nest. These are usually a few inches in diameter, and located in quiet areas of pools of depth 2.5-10 cm (1-4 inches). The female enters the nest repeatedly, depositing eggs each time until she has finished spawning. Males then swim over the nest and deposit sperm on the eggs. Activity then shifts to new nests. Females generally become sexually mature at 2 years.
Diet:
The Nevada speckled dace is insectivorous, consuming large numbers of small dipterons. It also feeds on plant material.
Conservation Status:
The Jack Rabbit Springs and the Big Spring systems provide the most stable habitat for the Ash Meadows speckled dace. Some of their natural habitat has recovered from outflow channelization and pumping. The primary threat at the present time is the presence of exotic fish populations.
References:
La Rivers, I. 1994. Fishes and fisheries of Nevada. University of Nevada Press: Reno, Nevada.
Williams, J. & D. Sada. 1985. Southwestern naturalist. Status of two endangered fishes, Cyprinodon nevadensis mionectes and Rhinichthys osculus nevadensis, from two springs in Ash Meadows, Nevada. The Southwestern Association of Naturalists: Lubbock, Texas.