Difference Between Sea Trout and Salmon

Sea Trout Vs Salmon

The sea trout (salmo trutta) is regarded as something of an enigma. Between July and November they migrate from their home in the sea to rivers and streams to spawn, where the females lay about 10,000 eggs. After spawning they return to the sea where they tend to remain close to the coast, favoring areas where fresh water enters the sea.

Atlantic salmon (salmo salar) are known as the “king of fish.” They, too, make a tremendous journey during their lifetime, migrating from the fresh water streams of their youth to feeding grounds in the North Atlantic Ocean and back again to spawn. Their capacity to return to the same stream where they were hatched has captivated and mystified biologists for hundreds of years.

Both, therefore, are migratory species, with large sea trout often being mistaken for salmon. The difficulty, for many, is to correctly identify each species since they are of comparable size.

To distinguish between them there is a waterside test that clearly establishes the species. Take a scale count on an oblique line from the rear end of the adipose fin down to the lateral line. For a salmon there will be 10 to 13 scales, and for a sea trout 13 to 16.

The maxillary bone is the external bone that extends backwards on the top side of the fishes mouths. Note the relative positions of maxillary bone to the eye. A sea trout has a larger and longer mouth than a salmon. The rear edge of a trout’s mouth extends a little beyond an imaginary line drawn down from the eye, whereas with a salmon the eye and mouth edge are almost in line.

The tail of a large sea trout may also be convex when opened out and in any case is nearly square. Salmon have distinctly forked tails.

In general, the sea trout is stouter than the salmon, and broader at the neck of the tail. It is said that when held by the tail, a sea trout will slip through the fingers, while a salmon will hold steady.

In appearance, the salmon is slender and streamlined, while the sea trout is more round and thickset. The salmon’s head is pointed, but the sea trout’s is rounder. A salmon’s color has relatively few spots, but the sea trout is often heavily spotted.

In summary, the two species differ in the following aspects:

1. A salmon’s scale count is 10-13 whereas a sea trout’s is 13-16.

2. A sea trout has a larger and longer mouth than a salmon.

3. A sea trout’s tail is convex, but a salmon’s is forked.

4. The salmon’s head is pointed while the sea trout’s is round.

5. The sea trout is heavily spotted, the salmon is not.

6. The sea trout is stouter than the salmon.

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