If you think of whitefish as bothersome diversions between trout, why not eat a few? Check out northwestern Montana's Flathead Lake. I hit the big lake every year in August, just as its huge population of Lake Superior whitefish begin their spawning run up the Flathead River. When the fish are biting it's possible to take several dozen whites in a day. These aren't puny river-dwelling mountain whitefish; they average three pounds but grow to six or seven pounds. But the real attraction is that when you encounter big whites on the main lake, it means that the big macks-the lakers, some to 20 pounds-are right in the same area. The big macks are a kick on 8-pound-test line and hit the same thing you should use for whitefish: jigging spoons and small green-hackled flies baited with maggots. The whitefish action starts in Elmo Bay, on the west side of Flathead Lake, and moves north through the month. By Labor Day most fish will be off the mouth of the Flathead River, and by later in September, anglers jig the river between Kalispell and Columbia Falls for 100-fish limits.