Fish and Aquatic Conservation



illustration of a Moapa dace

Moapa dace

Moapa coriacea, (Hubbs & Miller 1948)

Cool Facts

The Moapa Valley Refuge was the first refuge established for the sole purpose of protecting an endangered species of fish in 1979.

SIZE: The maximum reported length of the Moapa dace is 9.0 cm (3.5 in).

RANGE: The natural range of the Moapa dace population is limited to the warm springs of the Moapa River in southeastern Nevada of the United States.

HABITAT: The Moapa dace inhabits pools of the Moapa River and feeder springs over gravel, sand and mud. This species can survive a range of temperatures from 19.5 to 33.9 degrees Celsius (67.1 to 93 degrees Fahrenheit). The waters these fish inhabit contain abundant amounts of algae and are shaded by cover.

DIET: The omnivorous Moapa dace feed on both plant and animal material.

Natural History

Moapa dace spawn throughout the year with peak spawning occurring during the spring. Moapa dace spawn within 150 meters of warm water spring discharge in the headwater tributaries of the Moapa (Muddy) River where water temperatures range between 30‐32 degrees Celsius (86‐89.6 degrees Fahrenheit). Juvenile Moapa dace prefer tributaries and habitats with increasing flow velocities while adult Moapa dace prefer both the tributaries and the main stem of the Moapa (Muddy) River.

Conservation

The Moapa dace is listed as Critically Endangered because its habitat is less than 10 sq. km. Recently, it was determined that the abundance of this species is declining. The Moapa dace is still facing multiple ongoing threats.

In 1967, the Moapa dace was federally listed as Endangered in 1967. In 1986 and 1988 this species was classified as Vulnerable. In 1990 and 1994 Moapa dace were listed again as Endangered. During June of 1994, a fire at the Moapa National Wildlife Refuge caused a decline in the Moapa dace population. Finally, in 1996, the Moapa dace was listed as Critically Endangered.

Factors contributing to the demise of the Moapa dace include alteration of habitat by resort development, depletion or capping of head spring waters, the introduction of non‐native fishes such as the blue tilapia, the shortfin molly, the common carp, the channel catfish, largemouth bass, fathead minnow and the black bullhead, which infest the wetlands downstream of the Moapa dace occupied springs.

Conservation measures facilitating the growth of native deciduous trees and the removal non‐native fish species from the remaining Moapa dace habitat would significantly benefit the Moapa dace.