SALMO SALAR (TROUT)

Contents hide

1) Introduction

2) Classification of Salmo Salar (Trout)

3) Geographical distribution

4) Habit and habitat

5) General Characteristics

6) Ecological Importance

7) Conservation Status

8) Special features

9) Identification

Introduction

The Atlantic salmon (Salmo salar) is a species of ray-finned fish in the family Salmonidae. It is the third largest of the Salmonidae and can grow up to a meter in length. Atlantic salmon are anadromous, meaning they begin their life in freshwater, migrate to the ocean to feed and grow, and then return to freshwater to spawn in rivers.

Classification of Salmo Salar (Trout)

Phylum :- Chordata (Dorsal tubular nerve cord, notochord and gill-slits present.)
Group :- Craniata (Cranium with brain present.)
Sub phylum :- Vertebrata (Vertebral column present.)
Division :- Gnathostomata (Jaws and paired appendages present.)
Super Class :- Pisces (Paired fins, gills and skin with scales.)
Class :- Osteichthyes (Bony fishes. Skin contains dermal scales. Paired lateral fins present. Gills, air bladder present. Cleavage meroblastic.)
Sub-Class :- Actinopterygii (Modern fishes. Vertebrae amphicoelous. Caudal fin homocercal, Scales cycloid or ctenoid. Nostrils do not communicate with mouth cavity.
Order :- Isospondyli (Bony fish proper. Tail homocercal. Fins without spiny rays. Air bladder communicates with pharynx by a duct. Maxillae included in gap of mouth.)
Family :- Salmonidae (Gill membranes extending far forward, free from isthmus. Pelvic axillary process present.)
Genus :- Salmo
Species :- sola

Geographical distribution

Fresh-water and marine fish. It is found in temperate and Arctic zones of northern hemisphere such as North America-California to Alaska, Europe and Canada. It has been introduced in Kashmir and the Nilgiris. Jurassic to Recent.

Habit and habitat

Salmon is found in sea water. They are famous for their beauty, migratory habits and colour changes. Young migrate to sea and mature in 2 to 8 years, return to fresh-water, spawn once and die.

General Characteristics

Commonly known as trout, weights 10 to 15 kg.
Elegant spindle-shaped body is covered with overlapping scales. Body is divided into head, trunk and tail.
Head is conical in shape and contains eyes and nostrils.
The margins of upper jaw are formed by pre-maxillaries and maxillaries.
Paired fins are pectoral and pelvic fins.
Pectoral fin is close to operculum. First dorsal fin in middle and second dorsal fin between first
dorsal fin and caudal fin. Anal fin just below second dorsal fin. Fins without fin rays.
Tail homocercal. Air bladder having open duct to pharynx. Operculum and lateral line distinct.
Ova shed in abdominal cavity before passing to exterior.

Ecological Importance

Nutrient Transfer: They play a crucial role in transferring nutrients from the ocean to freshwater ecosystems. Their migration represents a massive nutrient transfer, rich in nitrogen, sulfur, carbon, and phosphorus, from the ocean to inland freshwater ecosystems. Predation by land animals along the journey serves to transfer the nutrients from the water to land, and decomposition of salmon carcasses benefits the forest ecosystem.
Food Source: They serve as a significant food source for a variety of predators, including birds, mammals, and other fish species, thus maintaining the balance within the food web.

Conservation Status

The conservation status of Atlantic salmon varies by region. In the United States, certain distinct population segments (DPS) of anadromous Atlantic salmon have been listed as endangered under the U.S. Endangered Species Act.
In the UK, the Atlantic salmon is a widespread species found in several hundred rivers; however, the latest estimates of the UK spawning population size are about 50% down on the ten-year average.

Special features

Anadromous Life Cycle: Atlantic salmon are anadromous migratory fish that begin their life in freshwater, migrate to the ocean to feed and grow, and then return to freshwater to spawn in rivers.
Leaping Ability: The species name salar means “the leaper.” These fish are very fast swimmers and can jump almost 12 feet, enabling them to navigate obstacles during their upstream migration.
Cultural and Economic Significance: Atlantic salmon have been a vital resource for human societies, valued for their nutritional content and as a game fish, contributing to local economies and cultural heritage.