(Speckled trout)
Salvelinus fontinalis (Mitchill, 1814)
Taxonomy and Nomenclature
Taxonomic Hierarchy
Kingdom Animalia -- Animal, animals, animaux
Phylum Chordata -- chordates, cordado, cordés
Subphylum Vertebrata -- vertebrado, vertebrates, vertébrés
Superclass Osteichthyes -- bony fishes, osteíceto, peixe ósseo, poissons osseux
Class Actinopterygii -- poisson épineux, poissons à nageoires rayonnées, ray-finned fishes, spiny rayed fishes
Subclass Neopterygii -- neopterygians
Infraclass Teleostei
Superorder Protacanthopterygii
Order Salmoniformes -- salmons, saumons
Family Salmonidae -- salmonids, salmons, trouts, trouts and salmons, truchas y salmones, truites et saumons
Subfamily Salmoninae
Genus Salvelinus Richardson, 1836 -- chars
Species Salvelinus fontinalis (Mitchill, 1814) -- brook trout, charr, omble de fontaine, salter, sea trout, trucha de arroyo
Taxonomic Rank: Species
Synonym(s): Common Name(s): brook trout [English]
charr [English]
omble de fontaine [French]
salter [English]
sea trout [English]
trucha de arroyo [Spanish] (itis.gov)
Physical Description
The brook trout's body is elongate with an average length of 38.1-50.8 cm, is only slightly laterally compressed; the body has its greatest depth at or in front of the origin of the dorsal fin (Scott and Crossman, 1985). Another physical characteristic of the brook trout is an adipose fin and a caudal fin that is slightly forked (Hubbs and Lagler, 1949). Brook trout have 10-14 principle dorsal rays, 9-13 principle anal rays, 8-10 pelvic rays, and 11-14 pectoral rays (Scott and Crossman, 1985). The brook trout also has a large terminal mouth with breeding males developing a hook or kype on the front of the lower jaw (Scott and Crossman, 1985).
The coloration of the brook trout is very distinct and can be spectacular. The back of the brook trout is dark olive-green to dark brown, sometimes almost black, the sides are lighter and become silvery white ventrally (Scott and Crossman, 1985). On the back and top of the head there are wormy cream colored wavy lines known as vermiculations which break up into spots on the side (Scott and Crossman, 1985). In addition to the pale spots on the side there are smaller more discrete red spots with bluish halos (Scott and Crossman 1985). The fins of the brook trout are also distinct; the dorsal fin has heavy black wavy lines, the caudal fin has black lines, the anal, pelvic and pectoral fins have white edges followed by black and then reddish coloration (Scott and Crossman, 1985). (Hubbs and Lagler, 1949; Scott and Crossman, 1985)Some key physical features: ectothermic ; heterothermic ; bilateral symmetry. (umich.edu)
Native Range and Habitat
Brook trout are found as far south as Georgia in the Appalachian mountain range and extend north all the way to Hudson Bay. From the east coast their native range extends westward to eastern Manitoba and the Great Lakes (Willers, 1991). The fish has been introduced, very successfully in some areas, into many parts of the world including western North America, South America, New Zealand, Asia, and many parts of Europe (umich.edu)
The brook trout is native to small streams, creeks, lakes, and spring ponds. Some brook trout are anadromous. Though commonly considered a trout, the brook trout is actually a char, along with lake trout, bull trout, Dolly Varden and the Arctic char. It is native to a wide area of eastern North America, including most of Canada from the Hudson Bay basin east, the Great Lakes–Saint Lawrence system, and the Mississippi River drainage in the United States as far south as northern Georgia. (Wikipedia)
Temperature Requirement
Brook trout require cool, clear, spring-fed streams and pools. They can be found under cover of rocks, logs, and undercut banks and have been described as stationary. Larger brook trout often inhabit deep pools moving to shallow water only to feed. They prefer temperatures from 57–60 degrees F. (Michigan.gov)
Feed/Diet
Brook trout have been described as voracious feeders with the potential to consume large numbers of zooplankton, crustaceans, worms, fish, terrestrial insects, and aquatic insects. Ephemeroptera, Trichoptera, and Diptera often make up a large component of their diet. However, they will often feed on whatever is most readily available.
Brook trout are avidly sought after by sport anglers, for food as well as for the sport. They can be caught by using various bait and lures including worms, crickets, grasshoppers, wet and dry flies, spoons, and spinners. (Michigan.gov)
Commercial Production
The potential for commercial production of brook trout Salvelinus fontinalis, however, is constrained by the lack of published protocols for producing the sex-reversed males required to create monosex female stocks. Immersion and immersion plus feeding treatments with 17α-methyltestosterone (MT) and 17α-methyldihydrotestosterone (MDHT) were applied to genotypically female gynogenetic brook trout to induce phenotypic sex reversal. The fry were exposed to a 6-h immersion in a solution of MT or MDHT on day 10 following completion of hatch and/or to a steroid-treated diet for 60 d beginning at first feeding. Immersion dosages were 0.5 or 1.0 mg/L, and feeding dosages were 1.0 or 2.0 mg/kg of feed for MT and 0.5 or 1.0 mg/kg for MDHT. Phenotypic sex of the fish was determined 19 or 22 months after first feeding. Control gynogenetic fish were 100% phenotypic females. Treatments with MT had minimal effect: most fish remained female, with only a low incidence of phenotypic males (1-3% in four of the treatments), intersex fish, or sterile fish. In contrast. a substantial number of phenotypic males were observed in several of the MDHT treatments, with the highest proportion (45%) occurring in the 0.5 mg/L immersion plus 0.5 mg/kg feeding treatment. Sperm was obtained from 29 males from five MDHT treatment groups and one MT treatment group examined at maturity (22 months) and was used in progeny tests of these males. The progeny were 100% female, confirming the male parents to be genotypically female. These protocols may be used to create sex-reversed brook trout males for the production of monosex female progeny, although additional trials are ongoing to test similar MDHT immersion dosages applied once or multiple times, with or without feeding treatments, to identify protocols with increased efficacy. (cat.inist.fr)
The brook trout is very popular with anglers, particularly fly fishermen. Today, many anglers practice catch-and-release tactics to preserve remaining brook trout populations, and organizations such as Trout Unlimited have been in the forefront of efforts to institute air and water quality standards sufficient to protect the brook trout. Revenues derived from the sale of fishing licenses have been used to restore many sections of creeks and streams to brook trout habitat. Brook trout are also commercially raised in large numbers for food production, being sold for human consumption in both fresh and smoked forms. Because of its dependence on pure water and a variety of aquatic and insect life forms, the brook trout is also used for scientific experimentation in assessing the effects of pollution. (Wikipedia)
Spawning Requirements
Brook trout spawn in the fall within sand and gravel areas where upwelling groundwater occurs. Lake-dwelling fish spawn in tributary streams or along the shoreline. Spawning takes place from late September to November during daytime, by contrast with night-time spawning lake trout. As spawning season approaches the colors of brook trout are greatly intensified, especially in males whose flanks and belly become orange-red with a black stripe along each side. Aggregations of spawning brook trout can often be observed in small tributaries and along lake shorelines, with solitary females seen digging and remaining within the perimeter of shallow nests, and numerous males looking for an opportunity to dart into these nests to fertilize eggs deposited by the resident female. Brook trout "redds" or nests are often found in large aggregations.
Surviving brook trout eggs hatch from February to April, still buried within their gravel spawning beds. Young brook trout grow faster than lake trout because small brook trout are able to live in warmer nearshore and tributary areas that produce abundant insect larvae and other small crustaceans. Larger brook trout are able to feed upon small fish and crayfish, though these fish are also restricted to cold, deepwater habitats during warm mid-summer conditions. Although brook trout are relatively acid-tolerant and can withstand pH conditions as low as 5.0, many brook trout populations in the southwestern Adirondacks and Catskills have been eliminated or greatly reduced due to decades of acid rain deposition. Brook trout have also been eliminated from suitable coldwater habitats within lakes and streams due to predation and competition with non-native smallmouth bass and brown trout. (Cornell.edu)
Brook trout spawn in late summer or autumn depending on the latitude and temperature (Scott and Crossman, 1985). The type of area required for brook trout spawning is one that offers loose, clean gravel in shallow riffles or shoreline area with an excellent supply of upwelling, oxygen-rich water (LaConte, 1997). Mature fish have been known to travel many miles upstream to reach adequate spawning grounds (Scott and Crossman, 1985). Females are able to detect upwelling springs or other areas of ground-water flow, which make for excellent spawning grounds. Brook trout reach maturity on an average at the age of two and spawn every year, although their size at first maturity depends on growth rate and the productivity of thier habitat (Everhart, 1961). Males often outnumber females at the spawning site, but only rarely is more than one male able to fertilize the eggs in a particular redd (Scott and Crossman, 1985; Blanchfield et al., 2003). The females clear away debris and silt with rapid fanning of her caudal fin while on her side, creating a redd (Scott and Crossman, 1985). The redd is where the eggs will be deposited and fertilized after the males compete for spawning right to the female (Scott and Crossman, 1985). The redd actually resembles a pit that is 4-12 inches in depth (Everhart, 1961). To gain the spawning right of the female the males compete for position by nipping and displaying themselves to the competitor males (Mills, 1971). When spawning is actually taking place the male takes a position to hold the female against the bottom of the redd and both of the fish vibrate intensely while eggs and milt are simultaneously discharged (Scott and Crossman, 1985). Very shortly after this exchange takes place the female works to cover the fertilized eggs with gravel by digging slightly upstream and letting the current carry the gravel down to fill the redd (Everhart, 1961). The eggs are initially adhesive to prevent them from washing away so they are able to incubate within the gravel (Scott and Crossman, 1985). The total time of incubation depends on factors such as temperature and oxygen (Scott and Crossman, 1985). After hatch the fry remain in the gravel until the yolk sac is absorbed then the fry swim up out of the gravel to begin the next stage of their life (Scott and Crossman, 1985). (Blanchfield, Ridgway, and Wilson, 2003; Everhart, 1961; LaConte, 1997; Mills, 1971; Scott and Crossman, 1985 (umich.edu)
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