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<br />. <br /> <br />., <br /> <br />10 <br /> <br />Grand Valley, provide the best indication of use of the IS-mile reach above the <br />confluence of the Gunnison River at one time or another during the field season. <br />Movement of tIlese fish during a field season generally was limited to 25 to <br />30 mil es. <br /> <br />During 1986, tile Fishery Project radio-telemetered three adult Colorado <br />sQuawfish collected from the 15-mi 1 e reach above the Gunni son River in June <br />(Kaeding and llsIunelson 1987>. The fish exhibited a diversity of localized <br />mvement but speIIt a major part of the next 6 months in the reach upstream of <br />the GunniSClllliver. Two remained in the reach throughout the estimated spawning <br />period. <br /> <br />Spawning ActmtJ <br /> <br />A suspected prespalIIing aggregation of adult Colorado sQuawfish was observed by <br />fishery Pnijst penonnel at river mile 178.3 in the 15-mile reach above the <br />Gunnison cOlIfJuellCe in mid-July 1982. In the first observation, three radio- <br />tagged fish IIere tracked to one riverine pool area, and nine adul ts at or near <br />spawni ng cooditiOll were hand 1 ed after limited net samp ling efforts. The <br />aggregatiOll atcurred a few days after mean dai ly water tellJlerature had reached <br />ZOO C and ckJrlll!l a time when runoff flows were dropping off sharply. A second <br />aggregatioollaS noted at river mile 175.3, 12 days after the initial <br />observatioo. Drifting trammel nets through an area occupied by two fi sh <br />equipped wia tranSllitters yielded an additional male Colorado sQuawfish in <br />spawning coofition. During this same time period, an adult female was captured <br />near river 1Ii1e 115 that weighed nearly 1 pound more than when previously <br />captured a IIIIItb earlier. suggesting the development of spawning (gravid) <br />condition. <br /> <br />larva 1 Occurl'lKl! <br /> <br />fi shery Pniject studies i nc 1 uded the rout i ne samp ling of the larva l-fi sh <br />coommity boawitllin and downstream of the IS-mile reach. During 5 years of <br />investigatiOl. 4 larval sQuawfish were collected with fine-mesh hand nets from <br />two 15-mile rtIKIIrs of the Colorado River immediately upstream and downstream of <br />its confluence with the Gunnison River. Although the sal!llling effort was <br />similar in URbD river reaches, 96 percent of the larval captures occurred <br />illlllediately.. tile Gunnison River confluence (river miles 162 to 164>. Only <br />two (4 peres) of tile larvae were coll ected from the upstream reach. These <br />observations ~ indicate that most fi sh were spawned in the downstream reach or <br />that the la~ IIere spawned in the upstream reach and drifted downstream to the <br />area where.. of tile captures were recorded. <br /> <br />Postlarval '-.-.r-fear Occurrence <br /> <br />No postlarYI1~f-year Colorado sQuawfiSh greater than 25 mm total length <br />were col1ectellrr.ibove the Gunnison River confluence in a total of 57 samples <br />co 11 ected in dIf fan of 1982 to 1986. However. a total of 62 Colorado <br />