Recovering the Mohave tui chub
By John Wullschleger, Debra Hughson, and Danette Woo

The Mohave tui chub (Siphateles bicolor mohavensis) evolved as the only native fish in the Mojave River system during the Pleistocene Epoch, a period when the river flowed into three large lakes in the heart of the present-day Mojave Desert. This fish is one of several subspecies that descended from a common ancestor that occupied intermittently connected Pleistocene lakes covering much of the western United States. Speciation began as the lakes receded, isolating populations in separate basins.

In the early 20th century, dams and diversions in the Mohave River watershed began to modify natural flow regimes and alter riverine habitat; these activities were the primary cause for the decline of the Mohave tui chub. Introduced species, particularly the arroyo chub, also hastened its demise. By 1970 the Mohave tui chub seemed to have been extirpated from the Mojave River and was federally listed as endangered. Fortunately, a relict population persisted in an isolated spring on the edge of Soda Lake playa, near the river’s terminus. In 1984 the recovery plan called for the establishment of six self-sustaining populations for downlisting and three additional populations in the river for delisting. Although fish from the Soda Springs site were used to establish populations both inside and outside the Mojave River basin, most of these populations failed.

NPS/John Wullschleger

NPS/John Wullschleger

Sampling allows biologists to assess the status and trend of populations the Mohave tui chub in Lake Tuendae, an artificial pond that is now home to the federally listed endangered fish species. Located in Mojave National Preserve, Lake Tuendae lies on the edge of the Soda Lake playa.

In an effort to reinvigorate recovery efforts, Mojave National Preserve, California, hosted a workshop in September 2003. Participants representing multiple agencies reviewed the 1984 recovery plan and determined that securing the species would require more than the six populations necessary for downlisting; they also identified potential sites for new populations. Participants discussed emerging threats and made recommendations for research to better quantify and reduce or eliminate these threats. Participants also recognized the need for an active public education program that would build support for recovery.

Human population growth and increased water demand in the Mojave River drainage may make delisting the Mohave tui chub impossible. However, the renewed interest generated by the workshop already has had positive results. For example, studies of the effects of the Asian tape worm and the ecology and population dynamics in lakes have been funded. In addition, a Safe Harbor Agreement with the Lewis Center for Educational Research may allow reintroduction of Mohave tui chub into a section of the Mojave River. If this proves feasible, it will constitute the first attempt to reestablish the species within its native range

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