Brown Trout

Appearance

The brown trout is a medium-sized fish, growing to 20 kg or more and a length of about 100 cm in some localities, although in many smaller rivers, a mature weight of 1 kg or less is common. Salmo trutta lacustris reaches an average length of 40-80 cm with a maximum length of 140 cm and about 60 pounds.
The spawning behaviour of brown trout is similar to that of the closely related Atlantic salmon. A typical female produces about 2,000 eggs per kilogram of body weight at spawning.
On Sept. 11, 2009, a 41.45-lb brown trout was caught by Tom Healy in the Manistee River system in Michigan, setting a new state record. As of late December 2009, the fish captured by Mr. Healy was confirmed by both the International Game Fish Association and the Fresh Water Fishing Hall of Fame as the new all-tackle world record for the species. This fish now supplants the former world record from the Little Red River in Arkansas.

Brown trout can live to ages of 20 years. But as with the Atlantic salmon, a high proportion of males die after spawning, and probably fewer than 20% of anadromous female kelts recover from spawning. The migratory forms grow to significantly larger sizes for their age due to abundant forage fish in the waters where they spend most of their lives. Sea trout are more commonly female in less nutrient rich rivers. Brown trout are active both by day and by night and are opportunistic feeders. While in fresh water, their diets will 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 is what allows trout to be a favoured target for fly fishing. Sea trout are especially fished for at night using wet flies. Brown trout can be caught with lures such as spoons, spinners, jigs, plugs, plastic worm imitations, and live or dead baitfish.
Freshwater brown trout range in colour 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. Regional variants include the so-called "Loch Leven" trout, distinguished by larger fins, a slimmer body, and heavy black spotting, but lacking red spots. The continental European strain features a lighter golden cast with some red spotting and fewer dark spots. Notably, both strains can show considerable individual variation from this general description. Early stocking efforts in the United States used fish taken from Scotland and Germany. The Loch Leven strain is more often found in the western United States, while the "German brown" is found more toward the Midwest and East.

Brown trout rarely form hybrids with other species; if they do, they are almost invariably infertile. One such example is the tiger trout, a hybrid with the brook trout.

Naming

The specific epithet "trutta" derives from the Latin "trutta", meaning, literally, "trout".

Status

The fish is not considered to be endangered, although, in some cases, individual stocks are under various degrees of stress mainly through habitat degradation, overharvest and artificial propagation leading to introgression.

Food

Field studies have demonstrated that brown trout fed on several animal preys, aquatic invertebrates being the most abundant prey items. However, brown trout also feed on other taxa such as terrestrial invertebrates or fishes. Moreover, in brown trout, as in many other fish species, there is normally a change in the diet composition during the life of the fish, and piscivorous behaviour is most frequent in large brown trout. These shifts in the diet during fish life stage transitions may be accompanied by a marked reduction in intra-specific competition in the fish population, facilitating the partitioning of resources.

First feeding of newly emerged fry is very important for brown trout survival in this phase of the life cycle, and in newborns of brown trout first feeding can occur even prior to emergence. Newborns start to feed before complete yolk absorption and the diet composition of newly emerged brown trout is composed by small prey such as chironomid larvae or baetid nymphs.