The brown trout, known by its scientific name Salmo trutta is a European species of salmonid fish that has been widely introduced into suitable environments globally, including into San Bernardino County such as in Deep Creek on the north side of the San Bernardino Mountains.
The brown trout available locally is of the fish’s freshwater population or riverine ecotype, Salmo trutta morpha fario, and a lacustrine ecotype, S. trutta morpha lacustris, also called the lake trout. The anadromous forms known as the sea trout, or S. trutta morpha trutta, are of the order that migrate to the oceans for much of their lives and return to fresh water only to spawn. These are not extant in San Bernardino County.
The Salmo trutta, with its original native range from northern Norway and White Sea tributaries in Russia in the Arctic Ocean and Iceland in the north Atlantic in the Arctic Ocean to the Atlas Mountains in North Africa and the Aral Sea tributaries in Afghanistan and Pakistan, has been widely introduced into suitable environments around the world, including North America.
The brown trout is a medium-sized fish, growing to 44 pounds or more and a length of about 39 inches in some localities, although in many smaller rivers, such as Deep Creek, a mature weight of 2 pounds or less is common. S. t. lacustris reaches an average length of 16-to-31 inches with a maximum length of 55 inches and about 60 pounds. The spawning behavior of brown trout is similar to that of the closely related Atlantic salmon. A typical female produces about 1,000 eggs per pound of body weight at spawning.
Brown trout can live 20 years, but a high proportion of males die after spawning.
Brown trout are active both by day and by night and are opportunistic feeders. While in fresh water, their diets frequently include invertebrates from the streambed, other fish, frogs, mice, birds, and insects flying near the water’s surface. The high dietary reliance upon insect larvae, pupae, nymphs, and adults allows trout to be a favored target for fly fishing.
The brown trout typically experiences a change in diet composition during its life, and feeding on other fish is most frequent in large brown trout.
Cover or structure is important to trout, and they are more likely to be found near submerged rocks and logs, undercut banks, and overhanging vegetation. Structure provides protection from predators, bright sunlight, and higher water temperatures. Access to deep water for protection in winter freezes, or fast water for protection from low oxygen levels in summer are also ideal. Trout are more often found in heavy and strong currents.
Brown trout can be caught with lures such as spoons, spinners, jigs, plugs, plastic worm imitations, helgramites, and live or dead baitfish. Freshwater brown trout range in color from largely silver with relatively few spots and a white belly, to the more well-known brassy brown cast fading to creamy white on the fish’s belly, with medium-sized spots surrounded by lighter halos. The more silver forms can be mistaken for rainbow trout.