The brook trout is a species of salmonid fish that is native to tributaries of the North Atlantic and Gulf of St. Lawrence in North America, especially those areas near the coast. It has been introduced to waters such as those in Iceland and southeast Asia. Introductions to other temperate zones are made for fishing purposes, not always with success.
A land-locked form of brook trout occurs naturally in the cold waters of the upper St. Lawrence River around Lake Ontario, but there is debate whether these fish are a natural subspecies or actually introduced brown trout. The "brookie" was first scientifically described as "Salmo fontinalis" by Carl Linnaeus in 1758. The type specimen was most likely a brook trout from the Rõuge river in southern Estonia, which was labeled "Salmo fontinalis" by Otto Friedrich Müller.
Brook trout are small to moderately large fish, typically ranging 18–30 inches (450–760 mm) in length. They range from 4–24 in (100–610 mm) in optimal conditions. They have a light green coloration with a single lateral line, which is easily distinguished from the brown trout or bull trout that share some of its range.
The average brook trout weighs between 0.7 and 2 pounds (.3-1 kg), although fish more than 4 pounds (1.8 kg) are exceptional. The maximum size brook trout can achieve is between 30 and 38 inches (760–970 mm). The average lifespan of a brook trout is 3 to 4 years, although some live as long as 8 years.
Male and female brook trout grow to an equal size; male brook trout become sexually mature at two years of age and females at three. They have a long breeding period, from March to June, during which they aggressively defend territories on the stream bottom. Females reach sexual maturity in their third year, but may not breed until some time later. In the northernmost reaches of the range, brook trout do not reproduce until they are almost six years old. Spawning usually begins in March and can continue until July, when the water temperature is between 48°F (9°C) and 65°F (18°C).
Brook trout spawn in small, relatively fast-moving streams with gravelly bottoms. Young brook trout remain in the spawning stream for 1 to 2 years before joining the lake population. Spawning habitat is small, shallow streams with cobble to boulder substrates.
The brook trout has a slightly sub-terminal mouth and a well-developed adipose fin; there are also two separate anal fins (one anteriorly positioned) and two separate dorsal fins (with the first much smaller than the second). In addition, the upper jaw of the brook trout extends beyond the rear margin of the eye. The brook trout has 24 to 30 anal fin rays and 42 to 48 vertebrae.
Brook trout have a long slender body with a brown or olive-green back and reddish sides fading into a white belly. Like other trout species, they have a lateral line system on both sides of their body that helps them to sense vibrations from prey as well as help them with navigation.
Global brook trout production
Brook trout are a popular game fish, and their global production is significant. In 2017, over 1.1 million tonnes of brook trout were produced worldwide, making them the fourth most popular type of trout in aquaculture.
The top-producing countries of brook trout are Chile, the United States, and Norway. Chile is the largest producer of farmed brook trout, with a production of over 500,000 tonnes in 2017. The United States is the second largest producer, with a production of nearly 400,000 tonnes in 2017. Norway is the third largest producer, with a production of over 100,000 tonnes in 2017. Brook trout are native to North America, and their popularity as a game fish has led to their introduction into many other parts of the world.
They are now found on every continent except Antarctica. Brook trout are highly adaptable and can live in a wide range of habitats, from cold, clear mountain streams to warm murky lakes. This versatility has made them one of the most popular fish for aquaculture.
Brook trout are a popular game fish due to their fighting ability and attractive appearance. They are also popular for aquaculture because they are relatively easy to farm and have a high growth rate. In addition, brook trout are native to many parts of the world, which makes them accessible to a wide range of potential customers.