Coregonus clupeaformis (Mitchill, 1818): lake whitefish

Biological Description

Body elongate, deep, moderately compressed laterally; scales variable in number, the normal range is 75 to 90. Head short; eye small; snout projecting beyond the mouth and rounded; nostrils with two flaps; mouth slightly inferior and small; very weak teeth on jaws. Dorsal fin rays 11 to 13; adipose fin present; anal fin rays 10 to 14; caudal fin distinctly forked; axillary processes at angles of pelvic fins. Color olive green to light brown on back; sides white but not silvery; lower fins clear, sometimes dusky.

Two flaps between the nostrils of the lake whitefish distinguish it from the pygmy and mountain whitefishes, which have a single flap. In addition, in larger specimens the body has a concave shape between the head and nape, while in other species of whitefish found in Idaho this curvature is convex.

Life History

Lake whitefish become sexually mature in four or five years. Some males may mature at 2 years. Males generally precede females to the spawning grounds, the shallow gravel areas of the lake, usually during November. They do not migrate into streams. Spawning usually occurs during the evening or night hours when schools of fish move about vigorously during the spawning act and may extend over a period of several days. During the spawning act the eggs are more or less broadcast near the water surface, are semi buoyant but gradually sink to the bottom. With a water temperature of 50° F., the eggs incubate for about 30 days. It is reported that females normally produce 10,000 to 12,000 eggs per pound of body weight. Some females from northern lakes may spawn only in alternate years.

Lake whitefish attain a large size and may live for 17 years or more. Data for Lake Superior fish show that growth of males and females did not significantly differ. Growth rate in western waters is very slow and fish at one year of age normally average about four to five inches. The largest lake whitefish recorded to date in Idaho came from Lake Pend Oreille in 1958 when a 4 pound 12 ounce fish was taken in a gill net operated by the Idaho Department of Fish and Game.

Geographic Distribution

The lake whitefish occurs over a wide range from the Atlantic Coastal watersheds westward across Canada and northern United States. Its range may have included Montana. It does not occur naturally west of the Continental Divide.

Habits and Habitats The preferred habitat of this species is deep, clear, cold lakes. In Lake Pend Oreille it is known to inhabit the area below the 100 foot level. As the surface water becomes warm in late spring, lake whitefish move into deeper water. Diet

The food of lake whitefish consists primarily of zooplankton during the first year or two of life and then turns to a diet of bottom-dwelling insects, arthropods, and fingernail clams. Larger fish are in part bottom feeders, as is indicated by the small gravel and benthic organisms found in their stomachs. A few small fish (sticklebacks and sculpins) may be eaten by large lake whitefish. Feeding has been noted to be greatest in the twilight of dawn and dusk. Since it occupies a zone in the lake comparable to that of kamloops trout, it undoubtedly is an important item in the food chain of the kamloops.

Idaho Conservation Status Idaho Native or Import

It was first introduced into Idaho in 1889 when the United States Fish Commission placed 1,300,000 fry in Lake Pend Oreille, 1,900,000 in Coeur d'Alene Lake, and an additional allotment in Hayden Lake. In 1896 the U.S. Fish Commission delivered 2,940,000 fry and fingerlings to Montpelier, Idaho, where they were planted in Bear Lake near Fish Haven, Idaho. The species has established itself in Lake Pend Oreille. However, there is no evidence that any of the fish from the other releases survived. It is somewhat surprising that early fish cultural operations did not spread the range of the lake whitefish to other deep water lakes throughout the state.

Comments

The lake whitefish is classified as a game fish in Idaho although it contributes very little to the sport fishery. It is seldom taken on hook and line except during the late fall and early winter when the fish are in shallower water near the shoreline. Those fishermen who catch the lake whitefish classify its flesh as excellent and when it is taken commercially in other areas of its range it has high value. The white flesh of the lake whitefish makes an excellent smoked product. The most successful fishing method is still-fishing on the bottom with salmon eggs, maggots, or small earthworms.

CreditsSimpson and Wallace 1982.Wydoski and Whitney 1979. Image Copyright Joseph Tomelleri. Used by permission.

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