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e e ~ Virgin River. The spring survey demonstrated a low adult popula- tion in the upper Virgin River. The fall survey demonstrated excellent reproduction throughout the river. A study funded by the Bureau of Land Management and conducted by the Fish and Wildl i fe Service and Environmental Consultants was completed this summer. This study used the Instream Flow Methodology to develop flow requirements for woundfin in the Virgin River during different seasons of the year. The recovery team is presently considering the potential for reintroduction of this species in areas of its historical range. Dr. James E. Deacon, Professor of Biology, University of Nevada, Las Vegas, will give a paper on the effects of low flows on woundfin later in this symposium. Research by the Fish and Wildlife Service continues on the endangered humpback chub (Gila cypha) in the Little Colorado River. Funding for this study has been provided by the upper and lower regions of Water and Power and by the Fish and Wildl ife Service. This effort is part of a study under direction of the Fish and Wildlife Service in the upper Colorado River basin. The desert pupfish (Cyprinodon macularius) was listed as endangered by the state of California in July of this year. A contract has recently been awarded by the California Department of Fish and Game to complete electrophoretic work on selected populations of pupfish presently recognized as C. macul arius. Work is progressing on preparing a listing package for proposing the desert pupfish as endangered on the Federal list. Observations of the desert pupfish in the Santa Clara Slough, Sonora Mexico during Clapper Rail Surveys this spring suggest that this population remains stable. Several exotics (e.g. Tilapia sp, Poecilia latipinna) are filil1ly established in the slough. Desert pupfish were also observed in the El Doctor Seep during these surveys. Water and Power biologists completed a population census in October on the Devil 's Hole pupfish (Cyprinodon diabolis) in the Hoover Dam Refugium. The last census was completed by biologists from the University of Nevada, Las Vegas in October of 1979. Results of this years census indicate that the population is up. Estimates of the total population were 80. This is the highest population level recorded during a census since 1974. The male to female ratio was 1.6:1. Surveys by the Arizona Game and Fish Department and reports from anglers indicate that Machete (Elops affinis) are quite common in the Colorado River in an area above Morelos Dam near Yuma. Arizona. It appears that the increased flows because of water from the Gila River has allowed Machete to migrate from_ the Gulf of California. 20