Laserfiche WebLink
<br />Study Abstracts <br /> <br />All reports completed under the Flaming Gorge Interagency Agreement of <br />1986 were abstracted. Abstracts were copied verbatim if the report contained <br />an abstract, or one was subsequently published. In cases in which no abstract <br />was furnished by the authors, we abstracted the conclusions section. Abstracts <br />are generally organized under the appropriate initiative, but there was some <br />overlap between studies. <br /> <br />Study 1: Summer and autumn requirements of age-O Colorado squawfish in the <br />Green River. <br /> <br />Report 1- Distribution, habitat use, and growth of age-O Colorado squawfish <br />in the Green River Basin, Colorado and Utah. (Tyus and Haines 1991) <br /> <br />Age-O Colorado squawfish Ptvchocheilus lucius (n = 11,379) were captured <br />as larvae and postlarvae in drift nets and seines in the Green and Yampa <br />rivers from 1979 to 1988. larvae were captured in drift nets {n = 601} for <br />about 2 to 6 weeks in June and July. Small post1arvae were captured by seining <br />shoreline habitats (n = 3,079) in July and August. In September and October, <br />postlarvae were most abundant (n = 6,459) in low-gradient reaches of the <br />Green River. Catch data indicated that the postlarvae moved from the Yampa and <br />Green River spawning areas and were concentrated about 150 km downstream by <br />autumn of each year. Spring sampling indicated that young fish (n = 1,240) <br />overwintered in areas occupied the previous autumn. Postlarvae captured in <br />the Green River (n = 5,043) most frequently occupied shoreline embayments <br />(backwaters) that were relatively warm (x = 17.0 OC), deep (X = 38 cm), large <br />(x = 826 mZ) and turbid. Abundance and size of young Colorado squawfish in the <br />Green River were inversely correlated with high summer and autumn flows which <br />inundated nursery habitats. Seine catches of young squawfish in four years of <br />sampling the upper and lower Green River in autumn and the following spring <br />were not reliable in assessing overwintering mortality of age-O Colorado <br />squawfish, presumably due to differences in capture vulnerability between <br />seasons. Survival of small fish in spring indicated their tolerance to <br />prevailing winter conditions. (Abstract) <br /> <br />Report 2- Movements and habitat use of young Colorado squawfish in the Green <br />River, Utah. (Tyus 1991) <br /> <br />Habitat use and movements of young Colorado squawfish Ptvchocheilus <br />lucius were determined by seining 1,194 of the fish in shoreline areas. A <br />total of 922 of these were fin-clipped in selected habitats and 230 (25%) were <br />subsequently recaptured. Most young Colorado squawfish were captured in <br />shallow shoreline embayments (backwaters; B5% of captures), where they were <br />most abundant in spring (April; 68%). Some individuals used more than one <br />habitat and moved between backwaters, shoreline eddies, and main-channel <br />runs. A diel pattern of backwater use was associated with warmer water <br />temperatures, especially in spring (April) when backwater temperatures <br />exceeded river temperatures. (Abstract) <br /> <br />8 <br />