Arctic Char vs Dolly Varden vs Bull Trout vs Salmon: Differences

Char, trout and salmon make up part of the “salmonid” group, which also includes freshwater whitefishes and grayling. They share a similar body shape, with pelvic fins placed relatively close to the tail, and are characterised by the presence of an adipose fin towards the rear of their backs.

Char vs trout and salmon

Although very similar in body shape, char can be distinguished from trout and salmon by their very fine scales and coloration. Trout and salmon have light-coloured bodies with dark spots, while char have dark-coloured bodies with light spots. Char also differ from trout and salmon in their migratory habits. Salmon and some species of trout (sea trout) are anadromous fishes. This means they hatch in small freshwater streams, then migrate to the sea to mature before returning to the same streams in order to spawn. The migratory pattern of char, on the other hand, is far more irregular, and depends on location, access to the sea, and the distribution and abundance of food. They are what is known as amphidromous fishes, which means they may migrate from fresh water to the sea, or vice versa, but not for the purpose of breeding. Unlike other salmonoid fishes, char lack teeth on the the upper palate of the mouth.

Salvelinus Alpinus - Arctic char

Salvelinus malma - Dolly Varden

Salvelinus confluentus - Bull trout

Arctic char vs bull trout and Dolly Varden

Found in lakes, rivers, streams and sometimes migrating back and forth between fresh and salt water (but not always), Dolly Varden, bull trout and Arctic char have puzzled fisheries biologists and ichthyologists (people who specialize in the study of fish) for decades. For a long time, it was believed that these fish were all strains of Arctic char (scientific name: Salvelinus alpinus), but scientists now agree that they are three distinct species, which look almost identical. Dolly Varden, scientific name: Salvelinus malma, have similar coloration and often inhabit the same locations as Arctic char. Generally speaking however, Arctic char tend to have a bronzish-yellow body, fewer and larger spots (larger than the pupil of an eye), a more deeply-forked tail, and a narrower caudal peduncle (the area before the tail fin). Dolly Varden generally have a greener body with many small (smaller than the pupil of the eye) spots. Spawning Arctic char are usually gold, orange, yellow or rose-coloured, and are only infrequently red. Spawning Dolly Varden, in contrast, are usually red or pink on the lower abdomen with bright red spots. Spawning male Dolly Varden have a much larger kype (hooked lower jaw) than spawning male Arctic char.

Bull trout vs Dolly Varden

Bull trout (scientific name: Salvelinus confluentus), like their cousins, the lake trout and brook trout, are not considered trout at all. Along with the Dolly Varden (and of course Arctic char), they are members of the char family. For years people believed that the bull trout was just a localised version of Dolly Varden, but it is now accepted that they are two different species. As you might expect, it is very difficult to distinguish between them. Dolly Varden (which take their name from a brightly clothed character in the Charles Dickens novel “Barnaby Rudge”) tend to have a more rounded body shape, while bull trout have a larger, more flattened head and a more pronounced kype. Some scientists have claimed that bull trout do not migrate to saltwater, but biologists have since discovered bull trout in Washington’s Puget Sound, which suggests this theory is unfounded. (In case you’re interested, seeing as the name ‘Dolly Varden’ is taken from a proper noun, it is one of the few species whose common name is capitalised.)

Bull trout and Dolly Varden vs brook trout

Unlike bull trout and Dolly Varden, the eastern brook trout’s red spots are surrounded by blue halos. Brook trout also have distinctive worm tracks on their backs, which are known as ‘vermiculations’. Sadly, however, it’s not that straightforward. Bull trout and brook trout have been known to spawn together, creating hybrid offspring that themselves are fertile. Ah, the wonders of nature!

Different types of Dolly Varden

There are actually two forms of Dolly Varden in Alaska – the southern form and the northern form. As well as by location, the two forms of Dolly Varden can be distinguished (by experts!) in several ways, including number of vertebrae (62–65 for southern form and 66–70 for northern form) and the number of chromosomes (82 for southern form and 78 for northern form). Northern form Dolly Varden grow much larger than their southern cousins and have been recorded at weights up to 27 pounds.

Conservation

Despite this being a confusing topic, one thing is clear: many species of salmon, trout and char are suffering from human population growth and environmental damage. Sport fishing regulations have traditionally been quite liberal but, in recent years, as indications of fish abundance have declined, more restrictive regulations have been introduced. Please remember, some of these species are extremely slow growing fish. Larger specimens may be ten years of age. Please make sure you know the rules. Always handle fish with care and practice catch and release as much as possible.

Sources:

Alaska Department of Fish and Game
Washington Department of Fish and Wildlife
Fishing with Rod
Fish Journal
Encyclopedia Britannica, Inc
Wikipedia

James Green About James Green

James Green loves nothing more than casting a fly in pursuit of salmon, seatrout or, when the opportunity arises, a tailing bonefish, tarpon or permit.