Crater Lake, located in the High Cascades of Oregon and part of the National Park system, hosts healthy populations of rainbow trout and kokanee salmon that descended from fingerlings planted between 1888 and 1942. But these alien fish are considered an intrusion on Crater Lake’s natural ecosystem, so there’s no bag limit and no fishing-license requirement, and anglers can keep what they catch. The salmon and trout go in alternating up-and-down cycles. Right now, the kokanees are numerous but small, around 10 inches; the 12- to 24-inch rainbows are not as abundant but forage on the salmon. Cleetwood Cove Trail (a one-mile hike and the only route to the lakeshore) descends 700 feet from the caldera’s rim to the water’s edge, where anglers can access a mile of shoreline including the boat dock. For the adventurous, however, the best fishing is on Wizard Island, where the salmon feed on plankton and rainbows cruise the shallows in search of young kokanees and aquatic insects. (A tour boat can take you out to the island.) The gin-clear water allows a unique “spot-and-cast” fishery. Spinners and spoons work well and the fish will rise to flies during low-light conditions. Live bait is not allowed. Wizard Island is accessible only by tour boat from the dock at Cleetwood Cove. No float tubes or canoes are allowed on the lake. Contact: Scott Girder, National Park Service fish biologist at Crater Lake (541-594-2211); for boat information, try 541-830-8700 or www.crater-lake.com/.