Brown Trout - Unlocking the SevernUnlocking the Severn

Characteristics

Brown trout are powerful predatory fish. When young trout hatch, they live in their natal redds. They hatch with yolk sacs attached to them which supply the young fish with a food supply. When they grow to a few centimetres in length they become known as parr and they can travel further afield. As their name suggests, they are a brown colour but have attractive markings on their backs which tend to be pale ‘rings’ filled with dark spots. They have speckled dorsal fins and a long jaw filled with small teeth. Although similar in appearance to salmon, these fish only usually grow to between 30 and 50 cm’s.

Diet

Similar to chub, brown trout are opportunist feeders. They are equally as happy feeding on the surface, mid water or near the bottom, hunting out anything that passes within range. They will take both freshwater and terrestrial invertebrates including crustaceans and molluscs. As they grow they will hunt small fish. Anglers are usually successful catching brown trout when fly fishing and using mayfly imitation flies.

Habitat

Brown Trout that remain in freshwater are territorial, defending the best feeding station from others, often very aggressively. However a proportion of trout are migratory, and any individual is physically capable of undergoing the transformation needed to migrate out to sea, to become known as sea trout. Local river brown trout populations are likely to have been founded by sea trout that migrated into new freshwater habitats to breed. They need water with a very high oxygen content, so will be mainly found in fast flowing stretches of rivers with lots of swells, and around weirs. To spawn they create their redds in shallow water with a substrate consisting of gravel between 10 and 40 mm’s in diameter. In the River Severn these fish are typically caught in the stretches just north of Bewdley upstream and in the tributaries. They are probably one of the widest distributed fish in UK freshwaters.

Did you know?

Brown trout that go to sea generally migrate along the coastline to a distance of around 150km from their river’s mouth. This is totally different to salmon that head to the North Atlantic. Some trout return after only one winter at sea, whilst some rivers are renowned for very large sea trout that may have spent years at sea before returning. The Severn actually has very few sea trout as the large river size means that there is plenty of freshwater habitat for the species so there is little advantages of undertaking the dangerous migration to sea.