ill., 1 map (sketched) ; Report title; "Drought conditions are continuing in 1994, at the writing of this report in March of 1994, Crater Lake National Park had received approximately 50% of the annual average accumulated precipatation to date." - P. 17.;
Abstract: A survey of fish populations and instream habitat in Sun Creek, Klamath River Basin, Oregon, during the summer of 1989 revealed a remnant population of resident bull trout (Salvelinus confluentus) sympatric with introduced brook trout (5. fontinalis) in a 1.9 km reach near an upper edge of useable habitat. Hybridization and competition with the brook trout appeared to threaten the bull trout population with a high risk of extinction. A bull trout restoration plan was drafted and peer reviewed in October, 1991. The objectives of the plan were to restore the remnant population of bull trout to historic numbers and distribution in Sun Creek (within the park), remove the brook trout, and prevent re-invasion of non-native species in the future. During the summer of 1992, a restoration program was initiated. Brook trout were removed from Sun Creek with electroshockers within and upstream of the bull trout zone, and with a piscicide, antimycin, downstream of the bull trout. Two log and rock barriers were constructed near the park boundary to prevent re-invasion of non-native fishes. Genetic analysis on a small sample of trout suggested that identification of bull trout-brook trout hybrids from field marks was not reliable. Brook trout removal will continue and a monitoring program is in place to evaluate bull trout and macroinvertebrate recovery. Introduction: Bull trout (Salvelinus confluentus) are widely distributed throughout the Northwestern United States and Western Canada although many populations are declining in abundance and distribution and local extinctions have likely occurred (Bond 1992, Goetz 1989, Ratliff and Howell 1992, Roberts 1982). Bull 2