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son 1980). Squawfish spawn in early to <br />mid-summer when water temperatures <br />reach 68-72° F (Haynes, et al. 1984). <br />Males and females gather over gravel bars <br />in deep water to spawn (Haynes 1982). The <br />same study indicates that spawning fish <br />seek out the same spawning sites year <br />after year, traveling long distances to <br />reach these sites. Haynes, et al. (1984) <br />believe squawfish spawn as spring flows <br />subside and water temperatures rise, with <br />spawning activity occuring from mid June <br />to August in the Colorado and Yampa <br />rivers. <br />Years ago when the squawfish was very <br />common, it was sold commercially and <br />called "salmon" or "white salmon". The <br />cause of the species' decline to current <br />levels is not completely understood, <br />although many factors contributed. Dams <br />have been constructed throughout the <br />Colorado River Basin. These dams restrict <br />spawning migrations. One tagged squaw- <br />fish moved 136 miles in two weeks down <br />the White River to the Green River, up the <br />Yampa River and back to the White River <br />apparently after spawning. Dams stop <br />migrating fish from moving upstream <br />and, as a result, many mature adults may <br />not be able to reach the required spawn- <br />ing sites. Coldwater releases from dams <br />could naturally be expected to eliminate <br />some historic spawning sites as fertilized <br />eggs would not develop in the lower <br />temperatures. Irrigation and channeliza- <br />tion practices have lowered summer flows. <br />Lower flows mean a decrease in the back- <br />water eddies needed for nursery areas. <br />Also, many other fish species (see the red- <br />side shiner) have been introduced into <br />West Slope waters of Colorado. Biotic <br />interaction with these additional species <br />may also have impacted the Colorado <br />squawfish in ways not yet understood. <br />--r--7- <br />I <br />I <br />-_ ? 1 r?-Y -'I o <br />I ` ?J I <br />---7-T <br />t (I <br />I ? ? f? ) I ? ?`\\\J111 <br />-7 I <br />-T _7 > <br />y ? I I ? I ,r, i <br />Distribution by County of the Colorado squawfish. <br />t`--? <br />I <br />I ? <br />i <br />i <br />, <br />I -? <br />r <br />I - <br />I <br />I <br />-1 --y <br />I ? <br />I I <br />Colorado's Little Fish 26 <br />Juvenile Colorado squawfish about seven inches long. Note the dark blotch at the base of <br />the tail.