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<br />-7- <br /> <br />Fish Tal!l!iDl! Ooerations <br /> <br />'> <br /> <br />Trout marking began during electrofishing operations in April 1991. Most captured brown, rainbow, <br />and cutthroat trout (~ 20 cm or 8 in.) were marked with a Visual Implant (VI) subcutaneous alpha- <br />numeric (letters and numbers) coded tag inserted under the skin behind the right eye. Electrofishing <br />and tagging operations conducted in April, May, August, and October 1991 resulted in 476 trout <br />being tagged, including 289 brown, 157 rainbow, and 30 Snake River cutthroat trout. Fish were <br />tagged to acquire age, growth, mortality, and movement information. <br /> <br />Fish TraDDinl! Ooerations <br /> <br />Fish trapping operations were conducted during two 11H1ay periods in July and August 1991. The <br />three trapping sites were located at points approximately 3, 5.5, and 8.8 miles downstream from <br />McPhee Dam as shown in Figure 1. Trapping operations were conducted to document any mid- <br />summer upstream movement induced by reduced flows and/or elevated water temperatures. <br /> <br />At each trap site, the river was completely screened off with 112-inch mesh hardware cloth (34 foot <br />width screen) supported vertically by steel posts driven into the river bed, and anchored to the bottom <br />with rocks. The hardware cloth formed the wings of the fish trap that directed any fish swimming <br />upstream into the deeper portion of the channel and into a box trap constructed of perforated steel. <br />Signs posted at the traps indicated they were installed by the CDOW to study fish movement. The <br />traps were padlocked shut to prevent vandalism and/or removal of any fish in the traps. The traps <br />were checked twice each day for fish. Trapped fish were identified to species, measured, and <br />released upstream of the trap. Trout larger than 20 cm were marked with a VI tag and released <br />upstream of the trap as well. The traps were operated 24 hours a day from July 15-26, 1991 and <br />again August 12-21, 1991. <br /> <br />Trout PODulation Estimations <br /> <br />Trout population and biomass estimates were completed on three sections of the river (800-1000 feet) <br />in April and October 1991. These were the same sections that have been electrofished each fall since <br />1986. In addition, a total trout population estimate was completed between Metaska Campground and <br />the Bradfield Bridge from May 13-16, 1991. The numbers, size, and species of trout captured in <br />each of the 11 river segments (Fig. 1) were recorded. This facilitated trout population and biomass <br />estimates by river section during the May 1991 estimation period. A single pass electrofishing effort <br />was completed at 11 sites in August 1991. <br /> <br />These studies were conducted for a number of purposes. The first objective was to determine if there <br />was any evidence of disease or stress in the trout population during the warmest period of the <br />summer. Second, we wanted to collect length (cm) and weight (g) data to evaluate growth rates and <br />body condition factors in mid-summer and compare that information with similar data collected in <br />October of previous years, as well as that from April 1991. Our third objective was to capture trout <br />that had been marked with VI tags to document individual growth rates during the summer of 1991 <br />and assess movement and migration trends. Finally, we wanted to document density (nlha) and <br />biomass (kg/ha) in a serial (upstream to downstream) manner. This would allow us to determine at <br />what distance (if any) downstream from McPhee Dam trout habitat quality and quantity was degraded <br />(as evidenced by decreasing trout density and biomass) due to stream flow reductions and elevated <br />water temperatures. <br />