Brook Trout

What's In a Name?
Brook trout: named for the habitat in which it is found

Salvelinus (sal-veh-lynn´-uss) taken from a word meaning "little salmon"
fontinalis (fon-ten-al´-iss) means "living in springs" in Latin

Where Do They Live?
Brook trout are native to headwaters and small streams of northeastern and southeastern Minnesota but have been introduced to many parts of the state. Their preferred habitat includes headwater spring ponds and small spring-fed streams that have cool, clear waters with sand and gravel bottoms and moderate amounts of vegetation. They also congregate behind beaver dams. Brook trout often share this habitat with mottled sculpins, white suckers, creek chubs, brook sticklebacks, and pearl dace.

How Big Do They Get?
How Long Do They Live?
How big a brook trout gets is dependent on what stream it comes from. The common size that many anglers catch from heavily fished streams or lakes is 150 to 250 mm (6 to 10 in), but in areas of little fishing, they can get as large as 400 mm (15 in). Those that live along the shores of Lake Superior reach 600 mm (24 in). The state angling record is 3 kg (6 lbs. 5oz). This fish was caught from the Pigeon River in Cook County. The world record is 6.6 kg (14.5 lbs).

In Minnesota streams, brook trout commonly live for 3-4 years. A few make it to the age of 5 or 6 years.

What Do They Eat?
The food of the young brook trout is mostly small insects. Older fish eat larger invertebrates including many types of aquatic (water) insects, sideswimmers, snails, and worms. They also feed on minnows and other small fishes.

What Eats Them?
Brook trout have few aquatic predators because few piscivorous ("fish-eating") fish live where they do. Larger trout, especially brown trout, eat smaller brook trout. They are more likely to be eaten by such fish-eating birds as herons, and kingfishers. Otters and snapping turtles also prey upon them.

How Do They Reproduce?
Many brook trout females and some males reach sexual maturity in their first year of life. Unlike Pacific coast salmon, brook trout do not die after spawning. They spawn each year of their adult life. In Minnesota, the spawning season for the brook trout is normally in the autumn months, roughly October and November. Sometimes spawning in streams flowing into Lake Superior begins in late September. During these spawning times the water temperatures are usually 4.5- 9.5° C (40-49° F).

In streams, brook trout move to riffles where spring water passes through the gravel. Here the female constructs a nest by swimming hard into the gravel and vibrating her body and sweeping her tail. She repeats this action many times over a period of a day or two. A male may defend this area while the female builds the nest. After the nest is ready, the female lies in it and is briefly courted by the male. Eventually, the male lies along side of the female and arches his body over hers. The two vibrate and release their eggs and sperm at the same time. The female then uses her tail to cover the eggs with gravel. Flow from the spring seeps into the gravel keeps the eggs oxygenated and clear of silt. The eggs hatch after 50-150 days depending on water temperatures. The colder the water temperature is the longer the development period.

Conservation and Management
Brook trout are managed as a cold-water sport fish species.

from
Natural History of Minnesota Fishes

Photographs by Konrad P. Schmidt and Donald Biemborn
Text by Nicole Paulson & Jay T. Hatch in cooperation with
the Minnesota Department of Natural Resources' MinnAqua Aquatic Program