- Scientific Name: Salmo trutta
- Kingdom: Animalia
- Phylum: Chordata
- Class: Actinopterygii
- Order: Salmoniformes
- Family: Salmonidae
- Subfamily: Salmoninae
- Genus: Salmo
- Species: Salmo trutta
Brown trout are members of the Atlantic trout and salmon subgroup of the salmon family (Salmonidae) which also includes the Sevan trout, Ohrid trout, Adriatic trout, flathead trout and Atlantic salmon. Of these, only the Atlantic salmon is native to North America, the remaining species, including brown trout are Eurasian species.
Considered the most valuable exotic fish introduced to North America, the brown trout is known by few other names, the most commonly used being the "German" brown, a reference to the dominant brood stock propagated in North America. The name trutta is Latin for trout. Brown trout have higher tolerance for warmer waters than either brook or rainbow trout.
Within the few park streams inhabited by brown trout, individual fish typically range from 7 to 14 inches in total length with exceptional individuals approaching 20 inches. The largest brown trout in Virginia occupy large dam outflow habitats and large reservoirs where waters are cooler. The current state record specimen (14 pounds, 12 ounces) was captured in the South Fork, HolstonRiver in southwestern Virginia on May 24, 1990.
Brown trout are tawny to olive brown dorsally to mid side, often with a brassy appearance. Sides grade from tan to yellow. Their back and sides are marked with olive brown to black spots. Their sides also marked with orange to red spots, some haloed with white to pale blue. Their undersides, including the lower jaw, are white to pearl. The dorsal fin is typically yellow-olive, marked with brown to black spots. Lower fins including the pectoral, pelvic and anal have white margins, paralleled just above by a dark zone and are otherwise yellow-olive to amber, sometimes yellow orange. Breeding males develop a long, hooked jaw and tend to brighten in overall coloration.
Life Span and Reproduction
The life span of wild brown trout is variable depending on the size and condition of their habitat. Generally, brown trout have greater longevity than brook trout, averaging about five years. In many naturalized populations, some individuals reach ages in excess of 10 years. In most park streams, maturation age (breeding) occurs between 1 and 3 years.
In Virginia streams, brown trout spawn in the fall, nearly overlapping the brook trout spawning season from October through November, sometimes extending into December. Typical water temperatures at the onset of spawning range from 6.5 to nearly 9°C. Redds are typically excavated by females in gravelly transition zones between pool and riffle habitats. Spawning, incubation period and the timing of hatching are similar to those of the brook trout. Growth is defined by the quality and availability of forage and habitat also similar to the brook trout. In the few park streams that contain naturalized brown trout populations, juvenile browns reach sizes of four inches and greater by the end of their first summer.
Hybridization with brook trout has been documented in every park stream containing cohabitant populations of both species. The progeny resulting from male brook trout and female brown trout are known generally as "tiger trout". Within the few park streams where both species coexist, tiger trout are occasionally encountered. Interestingly, tiger trout observations seem to occur during periods when the brown trout population is depressed creating conditions where female brown trout are more likely to be encountered and spawned by male brook trout . Reciprocal crosses between male brown trout and female brook trout have never been observed in the wild. These progeny, known as "leopard trout", have only been produced artificially among captives and are morphologically different in external comparison to tiger trout.