Brown Trout

Names in dialect: fario, truta, truta de mont.

Brown trout have slim bodies covered in small scales. The back and sides have a large number of small round markings, mainly black, but often also red, frequently surrounded by a white halo. The ventral and anal fins sometimes have a similar colouring to brook trout. Their dress changes according to their environment, and even in the same environment. Indeed, no two specimens are alike; different environments are inhabited with populations in which greenish-brown, or yellow or black colorations prevail. Brown trout have large heads and mouths and small, sharp, strong teeth.
Brown trout can reach lengths of 30-35 cm. When they move into a lake habitat, they tend to grow bigger in size and adopt a silvery colouring, with no red markings, just a smattering of black dots, some cross shaped: They can exceed 60 centimetres in length and weigh several kilos.
They are one of the most common fish in Trentino’s water. Their ideal habitat is clear, cool, well-oxygenated waters (temperatures below 18°C) with fast-flowing currents and stony or pebbly bottoms. They inhabit both main rivers and their tributaries, whether large or small, up to high altitudes. They are certainly the most common fish species in mountain areas, also as a result of the on-going repopulation work carried out by amateur fishing associations. They are even found in high-altitude lakes formerly inhabited by Arctic char, unfortunately to the detriment of the latter.
Brown trout are territorial and tend to be distributed evenly along a watercourse. During the juvenile stage, they occupy shallow niches near the riverbanks, while adults settle in areas where the water is deeper and the current not so strong, under submerged rocks, roots or bank vegetation extending out into the water.

They feed mainly on benthic invertebrates (insect larvae, crustaceans, worms and molluscs) that colonise watercourses, but also winged insects landing on the water’s surface. The bigger trout also eat fish: minnows, bullheads, and smaller trout.
The males generally reach sexual maturity in their second year and the females in their third year. Spawning takes place in autumn (from October to December), but can also extend into the winter period for the larger varieties of stock introduced into our waters from outside.
To spawn in the natural environment, adult trout swim up watercourses until they find gravel-bottomed riverbeds. Each female lays about 2,000 eggs per kilo of body weight. Egg incubation times depend on the temperature of the water. This means that if the average water temperature is 4 °C, the eggs laid in November hatch at the beginning of March. After hatching, the fry stay in the shelter of gravel until the yolk sac has been reabsorbed (it may take a few weeks if the water is cold). They then leave the mound of gravel, remaining in the vicinity of it for a while. Any activity that disturbs the riverbed in this period, including a fisherman accidentally treading on the spawning area, may jeopardise these highly delicate initial stages of development.
Brown trout are the most sought-after species by most sports fishermen and this certainly leads to more pressure being put on it than on other species, and requires continuous introduction of new stock. To safeguard wild populations, fishing in individual bodies of water needs to be proportionate to natural production, and repopulation needs to be limited to the areas that have suffered the greatest decline.