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Utah biologists find increase in 'juvenile' squawfish on Green River Find may be result of Flaming Gorge operational changes By Brent Stettler Infonnalion & Education Mgr. Utah Div. of Wildlne Resources PRICE, UTAH - Utah Division of Wildlife Resources biologists netted 70 "juvenile" and adult 'Colorado squawfish on the Green River'during research last summer. About 90 per- cent of those were 2~to-5- year-old juvenile fish, which may mean more Colorado squawfish are surviving and successfully reproducing; Researchers usually find a relatively large number of, recently-hatched Colorado squawfish. But it is unusual to find many that have sur- ' vived two or more years. Most often;researchers find only IS to 20 Colorado squawfish in the lower Green, and nearly all are adults. ' ,,"We're seeing some recruitment on the Green River, and that's encourag- ing," Utah Division of Wildlife Resources biologist Tom Chart said. 'The popu- lation will be much more sta- ble if there are fish from vari- ous ages, which means we should have more young fish growing to reproductive adults." Biologists hope this increase in young fish is a result of changes in the oper- ation of Ranting Gorge Dam, on the upper Green River, to more closely match natural low, stable summer flows. Plloto by Miles Moretti Utah biologist Tom Chart (left) and temporary wO!1(er Scott Gritters hold a 5-pound Colorado squawflsh netted In 1987 on the Green River as part of research on long- tenn population trends. The fish was weighed, measured, tagged and then released. Squawfish and other native fish need these ~ flows to reproduce successfully. But the young fish also could be hatchery-raised sqmiwfish stocked in Kenney , Reservoir" on the While River in Colorado that have drifted downstream to the Green River. Researchers marked the hatchery fish by making small clips in one of their fins before stocking the fish in KelUley Reservoir. But the clipped areas can grow back, making the fish difficult to identify as hatchery-raiSed. These findings are part of the Utah biologists' fifih year of research to detennine pop- ulation trends of endangered Colorado squawfish, hump- back chub and bonytail chub; the research is expected to continue anolher 12 years. To collect the fish, biolo- gists use "electro-fishing" gear on several miles of the Colorado and Green rivers. The shock temporarily stuns the fish and allows biologists to count, weigh and measure them before releasing them back into the river. The endangered fish are indicators of the heallh of the :~ 2 Colorado River system, Chart said. "The squawfish is the largest naturally'occurring predator in the Colorado sys- tem;' he said. "They indicate how well the entire system is functioning." Researchers also floated Desolation Canyon of the Green River and Westwater and Cataract Canyon of the Colorado last summer look- ing for humpback and bony- tail chub. "Humpbacks key into spe- cific habitats," O1art said. "In the Green and Colorado rivers, they seem .to prefer deep ,water along sheer rock walls." The population in Westwater Canyon was found to be strongest, where 20 could be found in a day's effort. Desolation Canyon yielded five humpbacks per day and Cataract Canyon one per day. These findings are sim ilar to those of recent years. Fall investigations focused on backwater habitats, including coves and backs of canyons, where biologists hoped to find evidence of summer reproduction. Dragging rme-meshed nets, they collected samples of wiggling. guppy-sized fish. One hundred seine hauls on the Colorado yielded 175 young-{)f-the-year squawflSh, while the same effort on the Green produced 350. Reproduction on the Colorado was considered good compared to previous yeatS. But the count on the the Green was down. As many as 2,000 squawfish had been collected there in past years. One possibility for this decrease may be the low spring snowmelt in 1990. Researchers believe that high spring flows serve two func- tions for the squawfish: cleaning the spawning areas in preparation for spawning and "cueing" the fish to reproduce. Recovering the fish would preserve a part of the heritage of Ihe West. O1art said. 'These fish were here long before we were and are as much a part of the mystique of the canyons as anyirung else," he said. It's our respon- sibility to preserve that"