Brown trout (Salmo trutta) and landlocked Atlantic salmon ( Salmo salar) are established in various freshwater environments following their introduction to Patagonia at the beginning of the 20th century. This study evaluated the growth and nutrient utilization of juvenile landlocked Atlantic salmon and brown trout from hatchery stocks that originated from these wild populations.
We used six groups of juvenile Atlantic salmon with an initial weight of 20.3 g (15 fish per group) and six groups of juvenile brown trout with an initial weight of 15.4 g (20 fish per group), all held in 50-liter tanks with an open system. Two commercial trout feeds were supplied in triplicate in a 2x2 factorial design: D1, with 20.8 MJ/kg gross energy, and D2, with 23.1 MJ/kg gross energy. The groups were named S1, S2, T1, and T2. At the conclusion of the experiment, parameters were evaluated using a two-way ANOVA and Tukey’s test (p<0.05).
Landlocked Atlantic salmon showed superior performance, achieving higher growth index, weight gain, feed rate, feed efficiency, and protein efficiency compared to brown trout. The higher-energy diet improved feed and protein efficiency in salmon, but adversely affected these same parameters in brown trout. Furthermore, the D2 diet led to a higher content of lipids and energy, along with increased HSI and VSI, and lower ash content in both species. The salmon were more efficient than the trout in retaining protein and energy.
In conclusion, landlocked Atlantic salmon performed well on commercial diets and benefited from the higher-energy diet. Brown trout, however, appear to require specific diets with a lower energy content.