Coastal Cutthroat Trout (Oncorhynchus clarkii) occur as sea-run or resident (non-sea run) forms in streams and lakes along the coastal range from lower Southeast Alaska to Prince William Sound and are the most common trout species in the region. The resident form lives in a wide variety of habitats from small headwater tributaries and bog ponds to large lakes and rivers. Sea-run cutthroat are usually found in river or stream systems with accessible lakes, mostly south of Fredrick Sound. In some watersheds, like the Taku River, the two forms are found together. The extent of breeding between the two forms is unknown, and the reason that some fish migrate to sea while others stay in fresh water remains an intriguing question.
General description: Juveniles are 1 to 6 inches long and silver or yellowish, with about ten oval parr marks overlaid with small black spots. Some juveniles will have a faint red or pink along the lateral line and on the gill covers. Adult coloration varies widely with habitat and life history: resident fish living in bog ponds are 6 to 16 inches long, are golden yellow with dark spots on the body, dorsal, and caudal fin, and have a vivid red slash mark under the jaw (hence the name cutthroat); free-swimming residents in large landlocked lakes can exceed 24 inches long, are uniformly silver with black spots, rosy gill covers, and a faint slash mark. Sea-run cutthroat are smaller, seldom more than 18 inches long. They are bluish-silver with dark or olive backs and less conspicuous black spots-the characteristic slash is a faint yellow. Lack of a distinct slash mark in sea-run and resident forms has led anglers to confuse the fish with rainbow trout. Cutthroat can be positively identified (though with difficulty) by the presence of minute teeth between the gills behind the base of the tongue.
Life history: Resident and sea-run coastal cutthroat trout have similar early life histories. Adults spawn in small, isolated headwater streams from late April to early June, and young cutthroat emerge from the gravel in July. Selection of isolated spawning areas is thought to reduce interaction of young cutthroat with more aggressive juvenile steelhead and coho salmon. Later, the young occupy beaver ponds, sloughs, or lakes. Sea-run juveniles can be displaced to downstream mainstem and estuarine areas where they reside for the summer, then migrate back upstream with the onset of winter floods. Sea-run cutthroat rear for three to four years in fresh water and migrate to sea during May when they are about 8 inches long. Time at sea varies from a few days to over a hundred days before they return to their natal stream. During their migration, they follow the shoreline and do not cross open bodies of water and seldom venture farther than 30 to 45 miles from their home stream. In the fall they return to their home stream where they mature during the winter months. Homing is very precise; cutthroat can return to the same tributary stream where they emerged and reared. Fish mature at 5 to 7 years and live to be 9 to 10 years old. Survival through the winter and return to salt water is about 40 percent. Furthermore, about 60 percent of the migrants are sexually mature, a characteristic that tends to limit egg deposition and reproductive potential. Resident coastal cutthroat remain in fresh water after emergence and live in streams, beaver ponds, sloughs, and lakes. In lakes, smaller cutthroat hide among lily pads, sunken logs, or rubble from which they dart out and seize insects and small fish. Some fish abandon this "sit and wait" feeding strategy when they reach about 14 inches and become cruisers, pursuing and eating other fish. Cutthroat that adapt this feeding strategy can grow from 24 to 28 inches, weigh 8 pounds, and live to be over 12 years old. These trophy-class cutthroat are always found in large landlocked lakes with populations of kokanee (landlocked sockeye salmon (Oncorhynchus nerka)).
Sport fishing: Cutthroat trout are aggressive feeders and will hit almost any lure, spinner, or fly. Sea-run cutthroat can be taken in fresh water in the spring or during the fall when they enter fresh water to overwinter. Often they are caught when fishing for steelhead trout (Salmo gairdneri). They stay close to the bottom of deep pools or sloughs, and gear must be fished close to the bottom to ensure a hit. During their migrations, they are caught in their home stream estuary or bays and salt chucks in the vicinity. Because sea-run cutthroat smolt are large, they are often confused with mature, catchable fish and some runs have been depleted by overfishing the smolt run. Resident cutthroat can be caught with spinners, or spoons fished deep in pools or along lake shorelines, especially where there is abundant submerged debris. Dry or wet flies fished off inlet streams work well. A muddler minnow on a fast sinking line fished along shores with submerged cover is a sure bet. Large trophy-class cutthroat are best caught by trolling off steep shorelines of landlocked lakes. Coastal cutthroat trout are a handsome and exciting fish to catch. Their appeal is that they can be found in nearly any freshwater habitat. However, lakes and streams in Southeast Alaska are unproductive. Hence, cutthroat trout are slow-growing, have low density populations, and a low reproductive rate. Furthermore, sea-run forms are known from only 88 watersheds, mostly south of Frederick Sound. These factors make cutthroat sensitive to overharvest. Cutthroat populations have been protected by their remoteness where watersheds have become accessible by road, populations have been depleted. As Southeast Alaska is developed, management of wild cutthroat trout populations will become a major challenge for future biologists.
Text: Steve Elliott
Revised and reprinted 1994