Lake trout are known as fish of the deep.  Commonly referred to as lakers or just trout, lake trout are often found close to structure.  Lakers are also thought to actively feed at the greatest depths in the great lakes, although other species of game fish have been reported at similar depths in recent years.  Where the steelhead is a free spirit where it roams, the lake trout is just the opposite.  Often times, when a school of lake trout is located, they can be caught there all day, day after day.  In springtime, lakers are often caught at all depths, but as the summer months come on, lakers are mostly caught at deeper depths near structure that holds baitfish.  Lakers are often greenish in color with a pattern of spots on them.  Not known to fight like a King, they still do put up a good battle and can be some of the biggest fish of the trip.  Lakers mature slowly compared to the salmon, so regulations only allow them to be kept in the bag limit from May 1 through September 30 of each year.  Below are a couple pictures.

Michigan DNR description:

Lake Trout Salvelinus namaycush 

Identifying characteristics: (Native Fish) Two dorsal fins including one adipose fin, light spots on darker gray background, lower fins edged with white, tail forked, 11 rays in anal fin.

The lake trout or "salmon trout" as it is sometimes called, is the largest trout native to the Great lakes and other Michigan lake waters. This fish strongly prefers a water temperature of 45-55 degrees F. Thus, while the lake trout may be found in shallow water only 10 to 15 feet deep in spring and fall, it follows these frigid water temperatures to depths of 100 to 200 feet in the summer and winter. This restless denizen of the cold, deep waters is a true wanderer, often ranging many miles in search of prey. A relentless hunter, the lake trout feeds primarily on other fish. Although it seems to have a peculiar penchant for ciscoes, it also concentrates on alewives, smelt or sculpin (dead or alive), and sometimes takes crustaceans, insects, other fish, and even small mammals.

Many lake trout seem to return each fall to use the same spawning beds, although some don't show this homing behavior. The eggs are deposited after dark, often on shoals. Young lake trout become sexually mature at 6 or 7 years of age. The average adult weighs in at 9 - 10 pounds but some individuals weigh up to 50 pounds (the Michigan record is 61 1bs and 8 oz). The life-span of the lake trout may exceed 25 years.

Parasitization by sea lampreys severely reduced the lake trout populations in Michigan from 1935 to 1965. Chemical contaminants and over-fishing pressures have also contributed to the problem, but with better fishing management and control of the lamprey and pollution problems, the invaluable lake trout is coming back.

An unusual from of lake trout occurs in the deep waters of Lake Superior, and is called a cisowet. This "fat trout" spawns at depths greater than 300 feet and is edible only when smoked. In Lake Superior individuals exist covering the entire spectrum from this odd type to the familiar form of lake trout.

Lake trout have also be successfully hybridized with brook trout to form the "splake," obtained by fertilizing lake trout eggs with brook trout sperm. Splake released in the Great Lakes and recaptured 5 or 6 years later have weighed up to 16 pounds. Splake are intermediate between the parent species in appearance.

Lake trout are avidly sought after by both commercial and sport anglers, for food as well as for the sport.