Status, Distribution, and Conservation of Native Freshwater Fishes of Western North America

A Review of the Distribution and Management of Bonytail in the Lower Colorado River Basin

Charles O. Minckley and Mitch S. Thorson

doi: https://doi.org/10.47886/9781888569896.ch13

ABSTRACT The bonytail Gila elegans is endemic to the Colorado River drainage of the American West. In the lower basin, this unique cyprinid historically occurred in the Colorado River main stem and its tributaries from Glen Canyon Dam downstream into Mexico. The species is distinct morphologically and genetically although intermediate forms have been noted from the upper basin. Today, wild individuals may persist in the lower basin in Lake Mojave, Arizona–Nevada. Management activities include broodstock development, the development of grow-out ponds and native fish habitats, and the stocking of bonytail into lakes Mojave and Havasu. Smaller bonytail (<10 cm) were first stocked in Lake Mojave in 1980. Very few of these bonytail have been collected during annual monitoring of the lake during the last 25 years. Today, larger fish (>25 cm) are stocked after being passive integrated transponder-tagged. Predation, particularly on the smaller fish, is thought to be the main reason for the lack of recruitment. Bonytail were stocked in Lake Havasu in 1994 using fish greater than 25 cm. To date, 19 fish have been collected. Although this is a small number of individuals, their recapture is encouraging and suggests that bonytail can be established by stocking larger individuals. A management plan for the big-river fishes of the lower Colorado River basin has been completed by a multi-agency committee.