Brown trout

The brown trout (Salmo trutta) is a type of carnivorous ray-finned fish and the most common species in the salmonid genus Salmo. It is found naturally in most of Europe, West Asia, and parts of North Africa. Because it is popular among people who like to fish, brown trout have been placed in many places around the world. However, in areas where they are not native, they sometimes cause problems for local wildlife.

Brown trout are very flexible and have developed many different types. There are three main types: the river trout, which lives in rivers; the lake trout, which lives in large lakes (different from the lake trout found in North America); and the sea trout, which spends part of its life in the ocean. Sea trout have many local names depending on where you are, like sewin in Wales, finnock in Scotland, and white trout in Ireland.

All brown trout types lay their eggs in fresh water, usually in the gravel beds of small streams where the water is cold and clear. Sea trout are special because they start their lives in freshwater but move to the oceans as adults, returning only to freshwater to lay eggs. The river and lake types also move between different freshwater places, like rivers and lakes, especially during their breeding time. Scientists are still trying to understand what makes some brown trout choose to live in the ocean while others stay in freshwater.

Description

Brown trout have a slim body with a long, narrow head and a large mouth. They have special teeth on the roof of their mouths in a zig-zag pattern. Unlike their close relative, the Atlantic salmon, their tail fin is triangle-shaped and does not split into two parts. They often have dark and red spots on their sides, but these spots do not reach their tail. Young brown trout, called parr trout, usually have a red edge on a small fat fin and dark spots along their sides that fade as they grow older.

These fish can change color depending on where they live. In freshwater, they may look silver with few spots and a white belly, or they might have a brassy reddish-brown color that fades to a creamy white on the belly, with spots surrounded by lighter rings. Some brown trout, like the "Loch Leven" type, have larger fins, a slimmer body, and many black spots but no red spots. Another type found in Europe has a lighter golden color with some red spots and fewer dark spots. Brown trout can vary a lot even within these general descriptions.

Brown trout are medium-sized fish. Some can grow to be about 100 cm long and weigh as much as 20 kg, but in smaller rivers, they often weigh around 1 kg or less when fully grown. One well-known type, the lake trout, usually measures between 40 and 80 cm long, with some reaching up to 140 cm and weighing about 27 kg.

These fish eat many things, including insects, small fish, frogs, tadpoles, mice, and even small birds. They are especially known for eating insect larvae, pupae, nymphs, and adults, which makes them popular for fly fishing. Brown trout can live up to 20 years, though many males die after spawning. They are active both during the day and at night and adapt well to different environments.

Taxonomy

The brown trout is called Salmo trutta. The word trutta is from Latin and means "trout". In 1758, a scientist named Carl Linnaeus wrote about the brown trout in a book called Systema Naturae. This book helped make a way to name animals. Linnaeus used Salmo trutta for trout that live in rivers and the sea. He also named river trout (Salmo fario) and lake trout (Salmo lacustris).

Range

Brown trout live in many places around the world. They are found from northern Norway and White Sea tributaries in Russia to the Atlas Mountains in North Africa. In the west, they are found in Iceland, and they live as far east as Aral Sea tributaries in Afghanistan and Pakistan.

Brown trout have been moved to many new places. They now live in North and South America, Australasia, Asia, and South and East Africa. The first brown trout were brought to Australia in 1864, when eggs were taken from the River Itchen to Melbourne. From there, they spread to many rivers and lakes. They were also brought to South Africa in the late 1800s and to the Himalayas by the early 1900s. In the Americas, brown trout were first brought to Canada in 1883 and later to Argentina, Chile, Peru, and the Falklands. In the United States, the first brown trout were released into the Baldwin River in Michigan in 1884.

Conservation status

The brown trout is not considered endangered, but some groups face challenges. Problems include damage to their homes, too many people catching them, and adding other fish that mix with them. When the water gets too warm in summer, it can hold less oxygen, which sometimes causes fish to die if they cannot find cooler areas.

Catching too many large female fish reduces the number of eggs they lay. In small streams, brown trout help control other small water creatures. Climate change is a concern because brown trout prefer cooler water. They like to hide near rocks, logs, and plants for protection. Deep or fast-moving water also helps them stay safe.

Diet

Brown trout eat many small animals. Their favorite food is tiny water creatures. When they grow bigger, they may also eat other fish. This helps them share food better with other brown trout.

When brown trout are very young, they start eating right away. They eat small creatures like tiny water worms even before they finish growing out of their baby stage.

Relationship with humans

Stocking and trout farming

Brown trout have been moved to many places around the world, including North America, South America, Australia, and New Zealand, for sport fishing. The first time they were brought to the United States was on April 11, 1884, in Michigan. While people enjoy catching them as a game fish, brown trout can sometimes cause problems for other fish in new areas by competing with them or eating their young.

Angling

Brown trout have been popular with fishers for many years. An ancient Roman writer named Aelian wrote about fishing for trout with flies around 200 AD. Important books about fishing, like The Treatyse of Fysshynge with an Angle from 1496 and The Compleat Angler from 1653, talked mainly about brown trout. Over time, new ways to catch them were created. When brown trout were brought to the United States in the 1880s, they became a favorite for American fishers.

In places like Yellowstone National Park, bringing in brown trout made new and exciting fishing spots. Today, many areas around the world have successful brown trout fishing, attracting fishers from many places.