Some brown trout have been reported to reach weights of up to thirty pounds (13.6 kg) and lengths of three feet (91 cm).
Communication Channels: visual ; tactile ; chemical
Perception Channels: visual ; tactile ; chemical
Brown trout are an abundant and widespread species, and so are not considered in need of special conservation efforts to preserve the species as a whole. Since they are a popular game fish, they are often protected by local fishing regulations.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
IUCN Red List of Threatened Species: least concern
When introduced outside their native range, brown trout compete with and prey upon native trout and other fish and amphibian species. Introduction of brown trout has been associated with declines in native brook trout in the eastern U.S. and frog species in the west. In some locations, brown trout may act as a prey base for parasitic sea lampreys (Petromyzon marinus). This may increase lamprey pressure on other native species. Introductions of brown trout may also bring fish diseases that can attack native species as well.
The main economic benefit of brown trout is the sport of fishing for the species. Many people pursue the sport fishing and some flyfish for browns. Many fisherman donate money to conservation groups to keep the sport alive. Also, browns make a delicious meal.
Positive Impacts: food ; ecotourism
Smaller brown trout feed primarily on insects. The most important insects vary with the season but the bulk of them are mayflies, caddisflies, midges or terrestrial insects. Browns in smaller streams are also dependent on food washed from the banks. Small browns select an area for feeding in a drift and do not move from it until a predator is introduced. This foraging site is characterized by a good view of the drift near refuge sites such as deep water or complex structure. Small browns never feed immediately upstream of a larger fish. Large browns' diets are more diverse than that of younger browns. Smaller trout account for 80% of the large brown's diet. The remaining diet consists of large aquatic insects such as Hexagania and Brown Drake (Ephemera simulans) mayflies and larger species of caddisflies (Trichoptera), crustaceans, snails, amphibians, and food washed from the bank. Also, the feeding habits of large browns is primarily nocturnal. They eat whatever is in the immediate area, preferably about 4 inches from the stream's floor in riffles, pools, or eddies. In contrast to young browns, large brown trout do not sit and wait for food, they hunt it actively.
Animal Foods: fish; insects; terrestrial non-insect arthropods; aquatic crustaceans; zooplankton
Primary Diet: carnivore (Piscivore , Insectivore )
Brown trout are native to Europe. The species is found in Iceland and on the Northwest coast of Europe, along the Mediterranean and south to India. They have been introduced to appropriate streams all over the world.
Biogeographic Regions: nearctic (Introduced ); palearctic (Native ); oriental (Introduced ); ethiopian (Introduced ); neotropical (Introduced ); australian (Introduced )
Other Geographic Terms: cosmopolitan
The species can live in a higher temperature than most other trouts, and this is probably why they were introduced to North America. They are a succesful and aggressive species who are permanent residents in most of the regions where they have been released.
Habitat Regions: temperate ; freshwater
Aquatic Biomes: rivers and streams
Average lifespan
Status: wild: 11.0 years.
Average lifespan
Status: wild: 8.0 years.
Average lifespan
Status: captivity: 10.0 years.
Average lifespan
Status: wild: 18.0 years.
Adult browns are generally 13 to 16 inches (33-40.6 cm) in length, although old individuals can reach a much larger size. Their bodies are olive brown or green shading to a yellowish white on the belly. The sides of the fish have beautiful red spots surrounded by a pale halo.
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry
When brown trout spawn, the male and female are not monogamous. These trout mate every year, and they are not likely to have the same mate year after year. Occasionally, large males take over a bed already occupied by a smaller, less aggressive trout.
Mating System: polygynandrous (promiscuous)
Brown trout mature at about 3 or 4 years of age. They spawn in the fall from October into December. When they spawn, they head into shallow headwater brooks of the river. The female scoops out a hollow on a gravel "redd" where she can lay her eggs. As she releases the eggs on the redd, the male simultaneously releases milt to fertilize them. The pair continues this process until all of the female's eggs are spent. The female then covers the fertilized eggs with sand or gravel for protection. The eggs are then left to develop and hatch the following spring. Browns do not necessarily come back to the same gravel bed to spawn each year, but they come back to the same general area of the river.
Key Reproductive Features: semelparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (External ); oviparous
Average number of offspring: 8000.
Female brown trout invest nutrients in yolk for eggs, but do not provide any care after the eggs are laid. Male brown trout provide no investment in offspring after fertilization.
Parental Investment: pre-fertilization (Provisioning)
