Take some canned tuna, pack the meat into one-inch balls in gauze sacks and cast-that's the ticket for big chinook salmon in the South Fork Clearwater River this month. Cured salmon eggs and dyed shrimp also take the big kings that are heading for spawning shoals between Kooskia and Elk City. About 90,000 fish should enter the river. Hook the bait on barbless 3/0 hooks, with 25-pound-test line, and drift through deeper pools on chartreuse Corkies and yarn. Best holes are Dewey Mine Hole and Elk City Hole upstream and Wall Creek and Stites holes along Route 13 between Kooskia and the Harpster Grade. Contact: Idaho Fish and Game in Lewiston (208-799-5010).