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Migration to Spawning Sites Previous radio telemetry studies (Miller et al. 1982; Wick et al. 1983; Tyus and McAda 1984; Osmundson and Kaeding 1989; Kaeding et al. 1990), revealed many aspects of Colorado squawfish movement. In 1980 and 1981, Tyus and McAda (1984) noted three movement patterns in radiotagged Colorado squawfish. The first pattern was a slow steady downstream movement attributable to poor health. Two fish exhibited this behavior and were later found dead. The second and third were high mobility and sedentary, respectively. Highly mobile fish migrated up to 205 km one way to spawning areas. Tyus (1990) summarized eight years of Colorado squawfish data migration and reproduction in the Green River basin. He reported that the average migration to spawning sites on the Green and Yampa rivers is approximately 141 km. The range of migration was from 32-373 km in the Green River and 32-302 km in the Yampa River. Wick et al. (1983) reported round trip migrations of 200-300 km. Osmundson and Kaeding (1989) reported one squawfish moving from upper Lake Powell (in April) to just above Grand Junction, Colorado; a distance of 319 km. This fish arrived in late September, after the spawning period, and to no established spawning site. This does, however, indicate the distance the Colorado squawfish is capable of migrating. Spawning migrations ended in the Green River sub-basin as fish returned to their original capture sites in August and September (Miller et al. 1982; Wick et al 1983; Tyus and McAda 1984; Tyus 1990). Subsequent monitoring (Wick et al. 1985, 1986; Tyus 1990) confirmed this migration pattern to and from the lower 32 km of the Yampa River (Yampa Canyon) and identified two other spawning sites on the Green River - Desolation and Gray canyons, Migrating squawfish may be guided to specific spawning sites by an olfactory homing behavior (Wick et al. 1983; Tyus and McAda 1984; Tyus 1985). These authors noted freshwater springs near the Yampa Canyon spawning area. Tyus (1985, 1990) reported all migrating squawfish enroute to the Gray Canyon spawning site (Green River) had to pass by Florence Creek and numerous groundwater seeps. Tyus (1990) reported 76% of the migrations were downstream. Wick et al. (1983) also observed downstream migrations in the Yampa River. Both authors reported fish moving through the spawning site until they reached Warm Springs then backtracking upstream when conditions were favorable for spawning. Wick et al. (1983) suggested squawfish use a downstream "holding pattern," feeding and conditioning, until temperatures physiologically prepared them for spawning. They suggested embryonic or larval squawfish may imprint on odors and later, as adults, orient themselves to spawning sites by these odors. Tyus (1990) suggested that sexual by-products may also serve as olfactory cues to locate specific sites within the area. Not all radio tracked Colorado squawfish have migrated to specific spawning sites year after year. Osmundson and Kaeding (1989) studied 15 miles of the Colorado River near Grand Junction, Colorado. They found squawfish migrating into and out of their study area during the spawning period (24 June to 14 July). Although they did document successful reproduction in the reach, tagged squawfish did not show fidelity towards one site or another for any particular year. They hypothesized that if conditions are not suitable the fish seek alternate sites. McAda and Kaeding (1991) found no specific spawning sites from Lake Powell, Utah to Palisade, Colorado (a 350 km reach). Final Report - Colorado squawfish habitat Page 3 Miller Ecological Consultants, Inc. December 17, 1997