Brown Trout, Salmo trutta
Brown Trout, Salmo trutta. Fish caught from Fountain Creek, Manito Springs, Colorado, April 2018. Length: 8 cm (3.2 inches). Catch, photograph and identification courtesy of Ryan Crutchfield, Tampa, Florida.
Brown Trout, Salmo trutta. Fish caught from Fountain Creek, Manito Springs, Colorado, April 2018. Length: 20 cm (7.9 inches). Catch, photograph and identification courtesy of Ben Cantrell, San Diego, California.
Brown Trout, Salmo trutta. Fish caught from the Spraque River, Spraque River, Oregon, April 2016. Length: 42 cm (17 inches). Catch, photograph and identification courtesy of Luke Ovgard, Klamath Falls, Oregon.
Brown Trout, Salmo trutta. Fish caught from Fountain Creek, Manito Springs, Colorado, April 2018. Length: 43 cm (17 inches). Catch, photograph, and identification courtesy of Josh Leisen (joshadventures.com), Gaylord, Michigan.
Brown Trout, Salmo trutta. Fish caught from Fountain Creek, Manito Springs, Colorado, April 2018. Length: 43 cm (17 inches). Catch, photograph and identification courtesy of Eli (obsessiveangling.wordpress.com).
Brown Trout, Salmo trutta. Fish caught from Fountain Creek, Manito Springs, Colorado, April 2018. Length: 43 cm (17 inches). Catch, photograph and identification courtesy of Eli (obsessiveangling.wordpress.com).
The Brown Trout, Salmo trutta, is a member of the Salmon and Trout or Salmonidae Family, that are also known as the German Brown and in Mexico as truite brune. Globally, there are fifty species in the genus Salmo, of which only this species is found in Mexico’s freshwater systems. The Brown Trout is considered to be the most valuable exotic fish introduced to North America.
The Brown Trout has a slender fusiform body that is laterally compressed with a long, narrow head. They vary significantly in color from individual to individual and from location to location. In general, they are a reddish to olive brown dorsally to mid side, often with a brassy appearance and transition of tan to yellow and then white ventrally. They have olive brown to black and orange to red spots, some encircled in white or pale blue. Their anal, pectoral and pelvic fins are yellow to olive to amber have white margins with a dark band just above; their dorsal fin is yellow-olive with brown to black spots. When aggressive they have the ability to darken their colors and they also have the ability to change their colors to match their backgrounds. Breeding males develop a long, hooked jaw, and will be brighter in overall color, and rounded anal fin; breeding females have a hooked anal fin. They have a relatively small terminal mouth that is equipped with teeth on the upper and lower jaws and vomerine teeth on the roof of their mouth. Their anal fin has 3 or 4 spines and 10 to 13 rays; their caudal fin can be forked, straight, or rounded; their dorsal fin has 3 or 4 spines and 14 to 16 rays; their pectoral fins have 12 or 15 rays; and, their pelvic fins have 9 or 10 rays.
The Brown Trout is a freshwater species that is found in cold, clean, unpolluted, well oxygenated fast flowing streams that range in temperature between 16oC (60oF) and 18oC (65oF). They have a greater tolerance for warmer waters than Brook Trout or Rainbow Trout. They reach a maximum of 1.03 m (3 feet 5 10 inches) in length and 19.1 kg (42 lbs 1 oz) in weight As of January 1, 2024, the International Game Fish Association world record stood at 20.1 kg (44 lbs 5 oz) in weight, with the fish caught in New Zealand in October 2020. They feed 24 hours a day consuming aquatic insects, birds, fish, invertebrates, and mice. In turn they are preyed upon by water snakes, mink and several species of birds. Brown Trout are known to be highly territorial and will aggressively defend their space. Brown Trout are potamodromous migrating to the headwaters for streams for spawning which occurs in the fall. These efforts are significant hampered barriers constructed by humans which the Brown Trout cannot pass. Spawning occurs at water temperatures of between 6.5°C (44°F) and 9°C (48°F). Each female excavates a shallow hole within a clean gravel bottom and deposits on average 2,000 eggs per year. The male fertilizes the eggs as they are deposited, and the female follows and covers the eggs with gravel. Each pair of trout will deposit eggs within a series of small nests. The eggs overwinter in the gravel requiring a continual flow of cold, clean, well-oxygenated water and hatch in the spring. Newly hatched fry remain in the gravel until their yolk sac is absorbed and move to shallow areas of the stream, with low water speeds, taking shelter in submerged aquatic vegetation or near the shoreline. Greater than 95% of the fry die within the first year; a high percentage of the males die after spawning. They are known to hybridize with the Brook Trout, Salvelinus fontinalis, but produce sterile offspring. They have life spans of up to twenty years.
The Brown Trout originated in Europe and was introduced to North America in 1883 via the shipment of eggs from Europe. They have been widely introduced and are now found throughout the world. In Mexico they are found in the State of Mexico in and around Mexico City. They provide a product of high economical and nutritional vale and local employment opportunities within rural communities. They adapt quickly at elevations above 1,800 m (6,000 feet).
The Brown Trout is a straight forward identification that cannot be confused with any other species. They can coexist with both Brook Trout, Salvelinus fontinalis, and Rainbow Trout, Oncorhynchus mykiss, but can also be replaced by them.
From a conservation perspective the Brown Trout is currently considered to be of Least Concern with stable, widely distributed populations. Their global introductions as both a food fish and a sportsfish have had some significant negative impacts on many local aquatic habitats. They have been implicated in reducing native fish populations via predation, displacement, and food competition and have been attributed to the eradication of several species from their native ranges including the Bluehead Sucker, Catostomus discobolus, the Cutthroat Trout, Oncorhynchus clarkia; the Dolly Varden, Salmo malma, the Golden Trout, Oncorhynchus aguabonita, the Lahontan Cutthroat Trout, Oncorhynchus clarkia henshawi, the Modoc Sucker, Catostomus microps , and the Utah Chub, Gila atraria. They also strongly compete with the Brook Trout, Salvelinus fontinalis, in the same environments. They are heavily pursued by recreational anglers and in many regions, they are heavily regulated. In many locations their native populations have been significantly reduced by human developments, acid rain, overfishing that removes mature females, the introductions of Brook Trout and Rainbow Trout, and artificial propagation leading to introgression. They are subject to die-offs caused by elevated water temperatures, floods, droughts, and water pollution caused by agricultural fertilizer runoffs. They are a major focus of recreational anglers and fly fishermen. In small streams they are an important predator of macroinveretebrates and are essential to maintain the ecological balance within the stream. The Brown Trout is raised by aquaculture for food, being less popular than Rainbow Trout due to their slow growth rates. Farm raised fish are easily recognized by their damage fins.