It has a slender body covered in small scales. Its back and sides feature numerous small, rounded spots, mostly black, often red, and often surrounded by a light halo.
The ventral and anal fins sometimes have a color similar to that of the brook trout. The coloration varies depending on the environment, but even in the same environment, no two specimens are identical; different environments are inhabited by populations in which greenish-brown, yellowish, or blackish hues prevail. The head and mouth are large; the dentition is robust, consisting of small, sharp teeth.
It reaches lengths of 30-35 cm. When migrating to lake environments, the brown trout tends to take on a silvery color, devoid of red spots and dotted with a few black spots, some X-shaped, and can reach larger sizes: over 60 centimeters in length and weighing a few kilograms.
It is one of the most common fish in the waters of Trentino. It thrives in clear, cool (temperatures below 18°C), well-oxygenated waters with fast-flowing currents and rocky and pebbled bottoms. It inhabits both the main rivers and their small and large tributaries, up to high altitudes. It is certainly the most common fish species in the mountainous areas, partly due to the constant restocking by amateur fishing associations, even in high-altitude lakes previously inhabited by Arctic char, with negative consequences for the latter.
It has territorial habits and tends to be distributed evenly along a watercourse. Juvenile stages occupy shallow niches near the banks, while adults settle in areas where the water is deeper and the current is slower, under submerged rocks, roots, or riparian vegetation that extends into the water.
It feeds primarily on benthic invertebrates (insect larvae, crustaceans, worms, mollusks) that colonize waterways, but also on winged insects that land on the surface. Larger trout also eat fish: minnows, bullheads, and smaller trout.
Males generally reach sexual maturity in their second year and females in their third. Reproduction occurs in autumn (October to December), but can also extend into winter due to the wide variety of non-native strains introduced into our waters.
In the wild, adult trout swim upstream for varying lengths of time, seeking gravel beds. Each female lays approximately 2,000 eggs per kilogram of body weight. The incubation period for the eggs depends on water temperature and is approximately 450 degrees Celsius (842 degrees Fahrenheit) per day. This means that if the average water temperature is 4°C (39°F), eggs laid in November hatch in early March. After hatching, the fry shelter under the gravel until their yolk sacs are absorbed (up to several weeks if the water is cold). They then emerge from the gravel pile and remain nearby for some time. Any activity that disturbs the riverbed during this period, including the inadvertent swarming of fishermen over spawning grounds, can jeopardize the success of these first, delicate developmental stages.
Brown trout is the most sought-after species by most sport fishermen, and it faces a much greater fishing pressure than other species, requiring continuous releases. To protect wild populations, catches in individual bodies of water should be scaled based on natural production, limiting restocking to the most degraded areas.
Dialect: fario, truta, truta de mont .
G. TOMASI, 2004 - The Three Hundred Lakes of Trentino. Ed. Artimedia – Temi, Trento, 535 pp.
