Salmonids: the fish that inhabit our rivers and mountain lakes

Salmonids are a mythical family of fish found in French rivers and mountain lakes. Every fish in the Salmonidae family is as beautiful as it is cunning and combative. This combination makes them a highly prized family for all lure anglers. In this article, we take a closer look at the wonderful family of salmonids.

Characteristics and habitat of salmonids

Salmonids are a family of freshwater fish remarkable for their diversity, beauty and adaptation to specific environments. All salmonids have a spindle-shaped body and radiating fins to help them adapt to the swift currents of our rivers. One anatomical feature distinguishes them: the presence of an adipose fin. This small fleshy growth is located between the dorsal fin and the tail.

Salmonids are particularly fond of cold, well-oxygenated waters. They generally live in water temperatures of between 8 and 14°C. This is why they are mainly found in first-category rivers, characterised by a lively current and crystal-clear water.

Here is a list of the main characteristics of salmonid habitats:

• Cold water (8-14°C)
• High oxygenation
• Live current
• Stony or gravelly bottoms

Salmonids have particularly acute senses. They have keen eyesight, a keen sense of smell and a lateral line that is highly sensitive to vibrations. What's more, their ability to camouflage themselves sometimes makes them almost invisible underwater. This makes them formidable predators, but also very difficult to target and approach.

A very diverse family

The salmonid family includes several species. Each species has its own specific characteristics. Among the best known are trout, salmon, char and grayling. In France, some species are emblematic and are the delight of anglers.

Here is a summary table of the main salmonid species present in French waters:

Species	Features	Preferred habitat
Brown trout	Emblematic species, spotted	Rivers and streams
Rainbow trout	Introduced species	Lakes and rivers
Salmon	Migratory, great fighter	Coastal rivers
Arctic char	Fish from large Alpine lakes	Deep, cold lakes
Common Grayling	Characteristic dorsal fin	Rivers with moderate currents
Fountain salmon	Fish from mountain lakes	Lakes and rivers
Cristivomer	Mountain lake fish. Introduced from Canada	Deep, cold lakes

The different salmonids in detail

• Brown trouta real jewel of our rivers, is undoubtedly the most widespread and sought-after species by anglers.
• Rainbow trout  is a species of salmonid native to the North American subcontinent, introduced to Europe in the 19th century.
• Grayling can now be fished in a number of rivers where it is well established: Dordogne, Ain, Aude, Haut Rhône, Haute Loire, Allier
• Arctic char is essentially a lake fish. It is found mainly in the three major Alpine lakes: Léman, Bourget and Annecy..
• Brook salmon differs from the Arctic char in having a greenish back with irregular yellowish spots. Its lighter-coloured sides are dotted with yellowish, black and red spots.
• The cristivomer is a fish introduced in the 1950s that can only be found in mountain lakes in Savoie and the Pyrenees.
• The Atlantic salmonis a captivating migratory species. Its life cycle, which sees it born in a river, grow up in the sea and then return to its birthplace to reproduce, is awe-inspiring. Unfortunately, this species faces many threats, mainly linked to obstacles on its migratory route and overfishing.

Behaviour and life cycle of salmonids

Salmonids feed mainly on insects, crustaceans and small fish. Their diet varies according to species and season.

The reproduction of salmonids is an interesting spectacle that generally takes place in winter, between November and December. The females dig nests, called spawning grounds, in the gravelly bottoms of rivers. This is where they lay their eggs. The eggs are then fertilised by the males.

Certain species of salmonids, such as Atlantic salmon, are anadromous. They are born in freshwater and migrate to the sea to grow up. They then return to their native river to reproduce. This complex migratory cycle is a real challenge for these fish. In addition to the predators they have to avoid, they also have to overcome numerous natural and artificial obstacles.

Their presence in a watercourse is often synonymous with good environmental quality, as salmonids are very sensitive to pollution and disturbance of their habitat. This is why they are considered to be excellent bio-indicators of water quality.

The importance of this species in the ecosystem

Salmonids play a central role in the world of sport fishing. Their legendary fighting spirit and the difficulty of catching them make them formidable opponents. Whether you're fishing with a fly, lure or natural bait, salmon fishing requires technique, patience and respect for the environment.

In addition to their sporting appeal, these fish play an important crucial role in our ecosystem. They help to regulate insect and small fish populations, while serving as prey for other predators such as fish-eating birds and semi-aquatic mammals. Their migration, particularly that of salmon, brings essential nutrients from the oceans to rivers, enriching freshwater ecosystems.

Unfortunately, many salmonid species face serious threats:

1. Water pollution
2. Dams and other human obstacles
3. Overfishing
4. Global warming affecting water temperatures
5. Destruction of natural habitats

In response to these challenges, conservation and reintroduction efforts are underway in many regions. As responsible fishermen, we have a duty to participate in these conservation efforts, by complying with regulations and adopting sustainable fishing practices.

Salmonids are the jewels of our fresh waters. They deserve our full attention and respect. Their presence in our rivers is not only a pleasure for anglers, but also a precious indicator of the health of our waters. Let's continue to study them, protect them and pass on our passion for these exceptional fish to future generations.