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Common questions about Colorado River endangeredfish (Editor's note: This and upcoming issues of the newsletter will feature questions often asked about the endangered fish and the program to recover them, The answers below are from an information packet prepared for the media.) Why Bre these fish endangered? The fish are endangered because of human impact on their habitat over the past 100 years. The twe types of habi- tat alterations that probably have had the greatest impact have been water development and introductions of non-native fish, Water development Human population growth since the turn of the century created a signif- icant demand for water and hydroelec- tric power in Western states, To meet that demand, hundreds of water pro- jects, including dams, canals and ini- gation projects, have been constructed on the Colorado River and its tribu- taries, Most of these projects were constructed prior to the Endangered Species Act .of 1973. This law requires each federal agency to review its activities and proposed projects to detennine the impact on endangered species, Water projects have restricted the fish to about 25 percent of their for- mer range and have blocked some .of the spawning migration routes of the Colorado squaw fish and other species, The remaining habitat has been changed considerably, Many of the rivers' "backwaters" have disap- peared, To survive and grow, young native fish need the protection of backwaters, which have wanner water and are separated from the river's main channel. Also, tailwaters six to 20 miles downstream from dams can be as much as 15 degrees colder than the rare fishes' preferred habitat. And in the lower Celorado River Basin, below Lake Powell, water develop- ment has transfonned the once free- flowing, silty and wann waters of the Colorado River into a series of lakes connected by cold, clear waters dewn- stream of dams. The native fish have been unable to adapt to these habitat changes, Non-native fish Introductiens of non-native fish into rivers, lakes and reservoirs also have taken a toll on the native fish, Construction of dams led to increased public demand for fishing in lakes and reservoirs, To increase fishing .oppor- tunities, private citizens and state and federal wildlife agencies began stock- ing non-native fish in the Colorado River in the late 1800s, These non- natives compete with native fish for food and space, probably with more success, Historically, there were only 14 fish species in the upper Colorado River Basin. But now the four endan- gered fish have to compete with an additional 41 non-native species, Also, some of the non-natives are efficient prcdalOrs that prey on the eggs and young of endangered fish, Other factars Some native fish have been killed intentionally, Some local residents may prefer to catch nonhem pike, channel catfish and other non-native sport-fish they may consider more desirable, When they hook a native fish, they may simply toss it on the riverbank to die, Arid in the mid-1960s, the chemi- cal rotenone was used to reduce native fish pepulations and make way for non-riative spon fish in portions of the upper Green and San Juan rivers before the closure of dams at Flaming Gorge and Navajo reservoirs, Follow-up studies found the total number of fish had dropped, but the ratios .of various species remained about the same. Researchers conclud- ed there was no lasting effect on the native fish species, Since then, the public has come to appreciate wildlife for mere than consumption, and public policy now reflects that attitude shi ft Other factors that may have can- lributed to the fishes' decline include pollution and parasites, Among the chubs, hybridization may also be a factor, Colorado squawfish: voracious predators with no teeth Predator, Irem Page 3 used a fledgling blackbird to catch a 4-foot squawfish an the Yampa River at the lower end of LiI y Parle "I got a real hard bite and finally hauled in a (squawfish) about 4 feet long, but got my hands 'rope-burned' by the fish line before I had the fish on the bank," Cary Barber .of Maybell, Colo., was quoted in the 1981 story as saying, After that successful experi- ence, Barber lried yet anether tactic, "Not having another blackbird for bait, [ hunted up a nest of mice, baited up with them and went fishing," he said, "Right off, a whopper latched an to the mice and was hooked, This fish was the biggest [ had ever caught or ever seen." "Right off, a whopper latched on to the mice and was hooked. This fish was the biggest I had ever caught or ever seen." Cal'/ Barber The fact that these fish have no teeth makes their ability to eat birds 4 and small mammals even more amaz- ing, A squawfish consumes its food whole; bony structures at the back of its throat gradually propel the prey into the fishes' stomach. Could a 6-faot squawfish eat a 4-foot alligator? Bioiogists don't like to speculate about such notions, and since alligators and squaw fish nonnal- Iy exist in different pans of the world, no one really knows for sure, Colorado squawfish were called "Colerado salmon" .or "white salmon" by early settlers, who used them as food, These fish have been known to migl1lte 200 or more miles to spawn,