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39 Table 17. C tches (all sampling gear combined) of Colorado squawfish y ung-of-the-year (YOY) in the Yampa River, Colorado, 1980-1984. Size (mm TL) Location Estimated N~ er of clY~ (river km) of Colorado squawfish Year YOY c llected collected YOY collectionsa spawning datesb 1980 14.0-29.0 0.2-13.9 7/02-8/08 1981 9.0-22.0 0.2-28.8 7/06-30 1982 9.9-21.0 0.5-19.6 7/24-8/08 1983 7.3-16.6 1.1-32.5 7/11-8/19 1984 7.2-15.1 0.2-25.4 7/04-8/06 aDistance fr m Yampa River mouth (river km 0) bDerived fro back-calculated age estimates of YOY cDoes not in 1ude 27 larvae collected in drift-nets at State Line (Green River) As in th Colorado River, Colorado squawfish spawning in the lower Yampa River coinci ed with times of decreasing flow and rising water temperature (Fig. 6 and able 5). Spawning in 1980 was estimated to have begun as early as 2 July (T ble 17) and ceased on or about 8 August. During that period, maximum flow ranged from 111 to 8.5 m3/sec and maxim~ mainchannel water temperature anged from 21.5 to 25-29 C, respectively. In the low flow year of 1981, the estimated spawning period was from 6 July to 30 July; maxim~ flow ranged rom 30 to 10 m3/sec, and maxim~ mainchannel water temperature ranged from 2 to 25 C, respectively. Maxim~ flow in 1982 was somewhat greater than the previous year and ranged from 74 to 43 m3/sec during the estimated 24 July-8 August spawning period. Maximum mainchannel water temperature uring that period was 26 C. In 1983, the estimated spawning period was 1 July-19 August. Maximum flow during that period ranged from 214 to 29 m3 sec and maximum mainchannel water temperature ranged from 17.5 to 24.0 C, r spectively. Mean water temperature ranged from 22 to 25 C during peak pawning activity in 1983. In 19843 maximum flow on the earliest e~timated sp wning date (4 July) exceeded 200 m /sec and was about 40 m /sec when pawning apparently ceased (6 August). Maximum mainchannel water temper ture during that period ranged from 19 to 22 C, respectively. During peak pawning (13-23 July), mean water temperature ranged from 22 to 23 C, respec ively. ~