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<br />sucker~. latioinnis (N), bluehead sucker Pantosteus discobolus (N), <br />green sunfish Leoomis cvanellus (I), and mottled sculpin Cottus bairdi <br />(N) . <br /> <br />A total of 99 drift net samples were collected from the Green River <br />just upstream of the Yampa River. Those samples have been picked but <br />not yet identified. Qualitative inspection of the samples indicated <br />that of the few fish captured, most were speckled dace and bluehead <br />suckers. <br /> <br />Three trips were conducted to assess the distribution and abundance of <br />adult fishes in the Green River upstream of the Yampa River. Sampling <br />techniques consisted of raft electrofishing, trammel netting, and <br />angling. With the exception of green sunfish, all species collected by <br />seining were collected by the combined effort of these gears. <br />Additional species collected included rainbow trout Oncorhvchus mvkiss <br />(I), Snake River cutthroat trout Oncorhvnchus clarki (I), hybrid <br />rainbow x cutthroat trout Oncorhvnchus clarki, northern pike Esox <br />lucius (I), Colorado squawfish Ptvchocheilus lucius (N), white x <br />flannelmouth, white x bluehead, and flannelmouth x bluehead sucker <br />hybrids, and channel catfish Ictalurus ounctatus (I). Hybrid suckers <br />represented nearly 5% of all suckers captured. <br /> <br />A total of six Colorado squawfish were captured or observed during <br />these sampling trips, three by electrofishing and three by angling. <br />Colorado squawfish distribution was from river mile (RM) 237.4 (about <br />5 RM downstream of the top of Lodore Canyon) downstream to RM 225.5 <br />(just upstream of the Yampa River). The most upstream "capture" was an <br />adult fish and the largest Colorado squawfish observed in this study. <br />This fish was not netted but was positively identified by myself and <br />was estimated to be about 700 mm total length (TL). The five other <br />Colorado squawfish captured were from the lower end of the Green River <br />study area from RM 225.5 (Yampa River confluence is about RM 225) <br />upstream to RM 227.8. These specimens were 477 to 563 mm TL, a size <br />range considered by most investigators to be juvenile or sub-adult <br />fish. All five of these Colorado squawfish were PIT tagged and <br />released in good condition. <br /> <br />Five northern pike also were captured during this study, all from the <br />downstream part of the Green River study area from RM 225.5 upstream to <br />RM 227.2. These specimens ranged in length from 620-800 mm TL. The <br />largest northern pike (800 mm TL) and the smallest Colorado squawfish <br />(477 rom TL) were caught at the same time from the same pool at RM <br />227.1. The large size and abundance of northern pike relative to <br />abundance of Colorado squawfish, and occupancy of similar pool and eddy <br />habitat, may indicate potential for negative interactions between these <br />two species. <br /> <br />Also of note were reliable records of Colorado squawfish caught by <br />anglers in the Green River in Lodore Canyon, most of which were <br />provided by U. S. Park Service (NPS) personnel. At least 12 Colorado <br />squawfish were caught by anglers in the summer 1994 and were <br />distributed in the Green River from the Yampa River confluence (RM 225) <br />upstream to RM 234. Estimated lengths of these fish were from 18 to 25 <br />inches (457-635 mm TL). <br /> <br />2 <br />