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7 COLORADO SQUAWFISH Status The Colorado squawfish evolved as the main predator in the Colorado River system. The diet of Colorado squawfish longer than 3 or 4 inches consists almost entirely of other fishes (Vanicek and Kramer 1969). The Colorado squawfish, the largest cyprinid fish (minnow family) native to North America, growing as large as 6 feet in length, and weighing nearly 100 pounds, lived to 25 to 50 years of age (Behnke and Benson 1983). Based on early fish collection records, archaeological finds, and other observations, the Colorado squawfish once was found throughout the warmwater reaches of the entire Colorado River Basin, including the San Juan River and, possibly, its major tributaries. Colorado squawfish apparently were never found in colder headwater areas. Seethaler (1978) concluded that t.he species was abundant in suitable habitats throughout the Colorado River Basin prior to the 1850's. Specific to the San Juan River, Seethaler's review of the literature identified the following reports: Minckley reported that each spring, just after closure of Glen Canyon Dam, squawfish moved into the San Juan arm of Lake Powell in presumed breeding aggregations. Three young squawfish were taken on 21 August 1960 by R.R., G,H., and F,L, Miller at Mexican Hat, Utah, and Lemons took a 12-1b (5,4-kg) squawfish in the Four Corners area of Colorado. Historical accounts by Koster of undocumented records of 5- to iO-1b (2.3- to 4.5-kg) squawfish as being fairly common in New Mexico with occasional individuals weighing 25 to 30 lb (11.3 to 13.6 kg). However, in June 1959, a 415-mm adult male was taken, and later a 590-mm adult female was captured on August 29, 1959. Both were captured in the same pool of the San Juan River about 3 miles (4.8 km) below the town of Rosa, New Mexico. A fisherman told Koster that squawfish were usually caught by persons angling for catfish, but persistent anglers caught no more than two or three a year. The largest caught in the area weighed 20 1b (9 kg). Koster reported that: k 1-;{ i~. I ~ " .~ :~ f" po( ~:~ ,< ,.'. '1' !.~ , i;: t,,' ?;;;, ';;'" ~. :;:li ::( "Salmon" have been caught in the San Juan River from the Navajo Dam Site which is just below the mouth of Los Pinos River, to the mouth of Las Piedras River in extreme southern Colorado. Although all are good-sized streams, "salmon" have not been taken in the Los Pinos, Las Piedras, or the San Juan above its junction with Las Piedras. . . . The future of the Ptvchochei1us population in the San Juan River is uncertain because the Navajo Dam, now under construction, will flood the entire portion of the river from which the species has been recorded. Olson reported that four squawfish were taken in the San Juan River in preimpoundment surveys of the Navajo Dam area. Together they weighed 12.0 lb (5.4 kg), or 12.8 percent of the total weight of all species collected.