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Radiotelemetry of Colorado squawfish in the Green River in 1980 <br />suggested that long-distance movement in late June-early July was <br />associated with spawning. Evidence for this conclusion is found in data <br />from 1981 trammel net collections made in the lower Yampa River near the <br />area of radiotagged fish. Collections made in the lower Yampa River <br />from 1 July to 9 July 1981 produced 34 Colorado squawfish in spawning <br />condition. These fish were predominately ripe males (25) or spent <br />females (8) and catches reflected a very high catch per effort of ripe <br />Colorado squawfish from short pool-riffle-pool habitat sections in the <br />lower Yampa Canyon. <br />Eight radiotagged Colorado squawfish, seven from the Yampa River <br />and one from the Green River, migrated to the lower Yampa River in 1981. <br />One of these fish (No. 1300) moved past the initial capture point and <br />relocated 93 km upstream. Contact with fish No. 1310 was lost on the <br />spawning grounds; however, since the fish was originally tagged in <br />October at RK 85 (RM 52) by the Colorado Division of Wildlife (CDOW) and <br />recaptured two years later at this same location, the assumption is made <br />that this fish returned (with an inoperable radiotag). The remaining <br />six fish exhibited a spawning migration in June and July (Fig. 7) that <br />accounted for 96% of the total movement during the study period. <br />Data from Carlin dangler tag recaptures (Miller et al. 1982b,c) sub- <br />stantiated the movement exhibited by the radiotelemetered fish. Four <br />tagged Colorado squawfish were recaptured on the spawning grounds. Two <br />of these (Table 3) were tagged in the upper Yampa during August 1978 and <br />1980 respectively, one was tagged in the upper Green during May 1981, <br />and the fourth was a local recapture. <br />Nine Colorado squawfish were implanted with radiotransmitters in <br />the White River in 1981 (Table 2). Unfortunately, contact with these <br />fish was difficult to maintain, primarily because of radio interference <br />apparently associated with energy development in the area. Contact with <br />three of these fish (No's 1559, 1603 and 1680) was lost immediately, and <br />contact was maintained for less than a month with four fish (No's 1605, <br />1538, 1583 and 1603). One explanation for the loss of contact was <br />transmitter failure. Colorado squawfish No. 1603 was recaptured (el-ectro- <br />fishing) on October 28, 1981 only 26 km upstream of its April 15 release. <br />The fish was apparently in good condition. Although many radio searches <br />were made of this area, contact was not reestablished after April 20, <br />indicating that the transmitter failed not long after release. The <br />remaining two fish (No's 1601 and 1624) were monitored for 4 to 5 months <br />and they exhibited the same two behavior patterns as fish in the Green <br />River in 1980, i.e. one fish (No. 1601) was relatively sedentary, the <br />other (No. 1624) highly mobile. <br />The sedentary Colorado squawfish (No. 1601) moved slowly downstream. <br />from April to September, traveling a distance of 86 km in 5 months. The <br />mobile Colorado squawfish (No. 1624) moved 611 km in 5 months (Fig. 8), <br />including downstream movement of 200 km to Gray Canyon of the Green <br />River and return to the White River to RK 80 where it remained for a <br />month until contact was lost. <br />The results of this study indicated two movement patterns of <br />Colorado squawfish, sedentary and mobile. Other workers have postulated <br />the existence of sedentary and mobile behavior patterns in stream fish <br />14