7384 - Laserfiche WebLink

Home Browse Search

t ~t presumably aids the fish undertake these migrations, which must require a significant energy expenditure. Strategy involved with migrations is not fully understood, but habitat selection and recruitment success (fitness) are no doubt important factors. Reproductively active adults seek relatively depauparate whitewater canyons for depositing their eggs in summer. After egg deposition, adults return to the same areas previously occupied in the spring, where they reside during the fall (Figure 2), and winter (Valdez and Masslich 1988, Wick and Hawkins 1988). There are no indications that adult fish stray distances from occupied fall-spring locations, although this seems likely for fish that undergo such strenuous migrations. Spawning Isolated captures of ripe Colorado squawfish were reported from the Green River in the late 1960 (Vanicek and Kramer 1969) and early 1970's (Holden and Stalnaker 1975, Seethaler 1978), and two ma3or spawning migrations and spawning areas have been identified in the Green River Basin by tracking radiotagged large Colorado squawfish to Yampa Canyon (Yampa River, km 0-32). One migration was identified in 1981 in the Yampa and Green River (Tyus and McAda 1984), studied again in 1982 (Wick et al 1983), and 1983-85 (Tyus et al 1987), and 1986 to present (Tyus and Karp 1988). The other migration to Gray Canyon of the Green River (km 232-256) was suspected in 1982, but sufficient fish were not radiotracked to that site to confirm it until 1983 (Tyus 1985). This site has also been monitored continously since that time (Tyus et al 1987, IISFWS unpublished data), and ripe adults have been captured in both .sites each year since their discovery. Successful reproduction on the spawning 7