Species overview: The brown trout is not a native Pennsylvanian, although it is now naturalized and widespread here in the wild, even becoming the main trout species in streams previously dominated by brook trout. Brown trout were originally found in Eurasia and were stocked in the late 1800s in the United States as strains from various locations, including Scotland and Germany. Pennsylvania received its first brown trout in 1886. Brown trout are considered more difficult to catch than brook trout. The larger ones tend to feed at night. Brown trout are closely related to Atlantic salmon (Salmo salar). The genus name “Salmo” is the Latin name for the Atlantic salmon. The species name “trutta” is the Latin name for “trout.”
Identification: Brown trout are brownish in overall tone. The back and upper sides are dark-brown to gray-brown, with yellow-brown to silvery lower sides. Large, dark spots are outlined with pale halos on the sides, the back and dorsal fin, with reddish-orange or yellow spots scattered on the sides. The fins are clear, yellow-brown, and unmarked. The belly is white-yellow. Like other trout and salmon, breeding males develop a long, hooked jaw and brighten in color. Wild brown trout in infertile streams may grow only slightly larger than the brook trout there. But in more fertile streams brown trout that weigh a pound are common. A brown trout over 10 pounds is a trophy. Brown trout may exceed 30 inches in length. The state record is more than 19 pounds.
Life history: Brown trout spawn in the fall, a little later than brook trout, when water temperatures are in the mid-40s to high 40s. Eggs are deposited in a stream gravel depression that the female prepares with swimming actions of her fins and body. Large females produce 4,000 to 12,000 eggs. Several males may accompany the female during spawning. The eggs hatch the following spring, with no parental attention. Brown trout eat aquatic and terrestrial insects, crayfish and other crustaceans, and especially fish. The big ones may also eat small mammals (like mice), salamanders, frogs and turtles. Large browns feed mainly at night, especially during the summer. Their life span in the wild can be 10 to 12 years.
Gallery of Pennsylvania Fishes Chapter 15