Sea Trout (Salmo trutta)
The habits of this species are also very like those of the Salmon, and the females are said to run up the rivers before the males.
Trout breed in winter, from October to January, sometimes to February, usually in temperatures of 5-10°C (41-50°F). Sexual maturity occurs in males at two years, in females at three years of age. Spawning always occurs on gravelly shallows, in which the female cuts a redd by means of flexions of the tail. The eggs are shed and are fertilised immediately by the male, which stations himself beside but slightly behind the female. The eggs are buried by the female in later redd digging, and hatch in about forty days at a temperature of 10°C (50°F). The fry (alevins) hatch at a length of ½-1 in (15-25 mm), and the yolk sac is absorbed in four to six weeks, after which they commence feeding. A general downstream migration follows hatching.