A 2022 creel survey of Lake KachessAn evaluation of Kokanee and Cutthroat Trout Stocking and angling impacts on Bull Trout

Lake Kachess (Kittitas County), a 1,800 ha reservoir in the upper Yakima River basin, since the 1930’s. To date, there is no quantifiable data on the results of stocking efforts. Naturally reproducing adfluvial Bull Trout, listed as threatened under the Endangered Species Act, also reside in Lake Kachess and angling impacts on their numbers is lacking. Therefore, a creel survey was conducted from June 12th to September 25th, 2022, to evaluate the fishery. The primary objectives of this survey were to: (1) quantify angling and recreation utilization on Lake Kachess by activity (shore angler, boat angler, recreational boater/angler, and recreational boater), county of residence and outing satisfaction. (2) quantify angler effort, catch, and harvest of gamefish species, and (3) quantify angler impacts on Bull Trout. Recreational boaters accounted for most of those recreating at Lake Kachess during the survey (i.e., 66%), while boat anglers comprised 31% of users. Shore anglers comprised only three percent. Most of those recreating at Lake Kachess were Washington residents with 51% coming from King County in western Washington and 21% from Kittitas County in eastern Washington, while six were from Oregon and a few from as far away as California and Nevada. Both anglers and recreational boaters enjoyed their day and rated their outing as good to excellent. Boat anglers accounted for 93% (10,403 hours) of angling effort, while recreational boater/angler and shore angling were minimal (475 and 340 hours, respectively). Mean angler catch rates for boat anglers was 0.33 fish per hour, followed by shore anglers at 0.10 fish per hour, and finally recreational boater/anglers at 0.01 fish per hour. Kokanee were the primary species targeted by anglers who caught 3,072 (2,419 harvested). Gamefish species caught also included Rainbow Trout (Oncorhynchus mykiss) (30), Cutthroat Trout (42) and Burbot (Lota lota) (178), while Northern Pikeminnow (Ptychocheilus oregonensis) (359) were also caught. An estimated 25 Bull Trout were reported as caught and released, all of which were caught by boat anglers. Seventy-eight fish caught were reported as unidentified and released by anglers, some of which were likely Bull Trout. Survey results indicate that Lake Kachess provides a viable Kokanee fishery worth $212,244.00 of economic value to the economy (i.e., 2,307 boat angler trips x $92.00 per trip) and the current stocking program of 395,000 Kokanee fry annually should continue. Cutthroat trout angling effort and catch was low. Considering Washington’s annual hatchery production of Cutthroat is variable, the results of this survey indicate that the continued stocking of Cutthroat Trout fry in Lake Kachess be considered a low priority in years when hatchery production is limited. The number of Bull Trout caught and released in the fishery (27) was relatively low (i.e., approximately one percent) when compared to Kokanee, the primary target species of anglers. The count may be slightly higher if some portion of the 78 fish reported as unidentified and released were Bull Trout. Although all the Bull Trout caught during this survey were released, hooking mortality is a concern considering their low abundance in the reservoir (i.e., averaging an estimated 43-54 adult spawners per year). Hooking mortality rates in the literature vary and few have investigated the hooking mortality of Bull Trout. While bait and hook restrictions have been reported to offer some protection from hooking mortality in some fisheries, at least two publications have reported that the hooking mortality of Bull Trout in troll-caught fisheries was low (i.e., < one percent), especially when compared to natural mortality. Angling for Bull Trout is prohibited under Washington’s statewide restrictive regulations and any Bull Trout incidentally caught are required to be released. Anglers interviewed during this survey were found to be adhering to these protective regulations and no Bull Trout were observed in the creel. Considering this, terminal tackle restrictions may have little benefit in further protecting Lake Kachess Bull Trout.