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.. if'. r-. ~ .~ , t - " ~. - - --~ . - - - ... -- --"--- - -~-...~-~_.'""!""-- ,:j , . 'im - ~ '?i..~ t, ~-i .~ .~ _~:1>iE~:~~~i] Chuck McAda and Chuck Phillips seine for juvenife squawfish in Desolation Canyon under an endangered species contract issued by BLM. ~ other fish that have been intro- duced into the stream. Without the annual cycle of flooding, high silt loads and high water temperatures, the native fishes do not spawn. Under natu- ral conditions, these fish waited for floods to bring warm, silt- laden water into the stream be- fore they started the physical processes that led to spawnin . ~U1et back~waters 10 0 e . ~jded a ~om swift curre :s--fm "spaWf1ii1gana fOr raisin the newf t Iy hatched young ~Once th-e-dam were built, there was a drastic drop in the temperature of the water and in the amount of silt carried by the river. The dams also checked the annual flooding. Thus the native fish missed the cues that caused them to spawn. In addition, back- water created by the annual floods either disappeared or was so drastically changed in charac- ter that the fish lost their spawn- ing sites and a safe haven for their young. ~,^,here backwater did exist, it! /was as often a trap as a safe rearf i ing are~. Irregular releases or- water (rom the dams caused wa- ter levels to fluctuate as much as several feet in a single day. What seemed to be a safe spawning area one day became an isolated drying pool the next. 10 . Few outside species could sur- vive under the harsh conditions of the natural river. But once the dams were built, many new spe- cies found the changes in the river to'their liking. Early settlers had introduced carp and channel cat- fish around the turn of the centu- ry. After the reserv9irs were filled, game fish such as bass and perch were introduced and sur- vived. Minnows brought to the river as bait escaped from fisher- men's bait buckets and became established in the modified river. ITod~y these~s aretfie7 -Jmost numerous .fish in the Cofc9 4aOO-R~tive--s~d-1t hard to compete against such aggressive newcomers. Only in those few isolated stretches of the system where conditions are little changed do the native species survive. Per- haps the least changed are por- tions of Desolation and Gray can- yons of the Green River, a tribu- tary of the Colorado. This is the only stretch of the entire river system where all of the four threatened and endangered spe- cies have been found in recent years. In an arid land, water is life. The Colorado River and its tribu- taries are the only major source of water in a vast and thirsty land. Projects, dependent on water from the system, have been built, are being huilt, and arc in the planning ~tage. Co.,l, oil, gas, 011 shale and uranium, need(.d to help meet our energy necds, abound in the area. Their devel. opment requires large quantities of waler. Major electrical generat- ing plants, either built or pro- ' posed, will need large quanties of water. Furthermore, cities located in the area must look to the Colo- rado and its tributaries for the water needed to sustain contin- ued growth. As demands on the River have increased, so have efforts to pro- tect the remaining canyons. Por- tions of the Colorado have been proposed for inclusion in the Wild and Scenic Rivers System, and parts of the Colorado and Creen Rivers are now included within National Parks. Sportsmen, river fJolters, naturalists and envi- ronmentalists see this as a unique aquatic habitat and prime recrea- tional area that shpuld be pres- erved in its natural state. BLM is now involved in studies that will have an important bear- ing on the future of this canyon- land area. BLM Districts along the Colorado and Green Rivers are studying the natural history, rec- reational uses and other re- sources of the river and its envi- rons in cooperation with State and other Federal agencies. Specialists from the cooperat- ing agencies have formed into the "Colorado River Fishes Recovery Team" to protect and enhance the populations of threatened . and endangered fishes in the Riv- er System. The team is preparing recovery plans to serve as guide- lines to manage and protect the native populations. Studies of fish, water quality, river h~bitat and the impact of man's intrusion are outlined in the plan. Much of the area is still not well known because of its lack of accessibility, but the de- mands being made on the river require a better understanding of it~nique habitats. These studies are necessary if the native fish are to keep their tenuous hold in the canyons where they evolved. BLM will be involved in both the stud- ies and in the final management program of this endangered re- source. --- --.-------.----- --~-------"'-.-