The various species and sub¬species of salmon are the most highly-regarded of all the fish that can be caught in fresh water, both for their angling value and for their flesh. The Atlantic salmon (Salmo salar), for instance, can be guaranteed to put up a strong and often spectacular fight when hooked, and its flesh can be cooked or smoked to provide one of the finest of foods.
Although hatched in fresh water, the Atlantic salmon spends most of its life at sea, returning to fresh water only to spawn. In the sea, the salmon travel widely, and many make transatlantic mig¬rations to feeding grounds off Greenland or in the Norwegian Sea.
Unfortunately, many of these isolated feeding grounds have been discovered and over-exploited by commercial fishing interests, and this has resulted in a marked decline in stocks throughout the known range of the Atlantic salmon.
Atlantic salmon normally return to their parent river after about 3 or 4 years at sea, although some return sooner. They often die after spawning, but many survive to make two or more spawning runs.
The Atlantic salmon spawn far upriver in November and January, the eggs being deposited in a redd, a nest scooped out in the gravel by the hen fish. Once buried in the gravel, the eggs remain in place until they hatch in late April or early May. The fry remain in the gravel for 3 to 5 weeks, until they’re free of their egg sacs, and begin to feed actively as soon as they emerge.
At this stage, the small fish (or parr, as they are called) swim and feed in shoals, but as they grow they spread out along the length of the river. After some 3 to 5 years in the river, the parr, now about 6 inches long, lose their mottled colors and become silvery, ready for their journey to the sea.
In the sea, mature Atlantic salmon are normally green-blue on the back, with silvery white sides and underparts. This coloring changes as the fish approach the spawning stage, when they become brown or bronze with spots of red and black, and the fins darken. After spawning, many salmon die, but the few weak and emaciated survivors, known as kelts, slowly make their way downstream to the sea.
Although adult salmon are believed not to feed while they are in fresh water, they will none¬theless attack a fly, spinner, plug, prawn or bunch of earthworms, possibly out of bad temper.
The Pacific salmon (Onchor-hynchus spp), unlike their Atlantic cousins, all die after spawning. However, apart from this rather tragic wipeout of the parent fish, the life cycle of most of the species is comparable to that of the Atlantic salmon.
There are six species of Pacific salmon, one of which – the cherry salmon (Onchorhynchus masou) — is found only in Asian waters. Of the others, the chum salmon (0. keta) is occasionally encountered by anglers but mostly caught by commercial netting. This fish is commonest off Alaksa.
The king salmon (O. tshawy-tscha), also called the chinook, is the largest of the Pacific salmon. The biggest recorded – a commercially-caught fish — weighed in at a staggering 126 pounds, but most rod-caught chinook are less than 20 pounds.
The other Pacific salmon species are the coho salmon (O. kisutch), the pink salmon (O. gorbuscha) and the sockeye salmon (O. nerka). A small, landlocked form of sockeye, the kokanee, was once found only in lakes from Oregon to Alaska, but has been introduced into lakes and reservoirs in many parts of the USA.
There is also a landlocked form of Atlantic salmon, found originally in New England and the Maritime Provinces of Canada but since introduced into other areas, is known as the landlocked salmon in the USA and as the ouananiche in Canada.
In Europe, there is a landlocked relative of the Atlantic salmon known as the huchen (Hucho hucho). The huchen, which originated in the Danube Basin, has been successfully introduced into rivers in eastern France. There was also an unsuccessful attempt to introduce it into the River Thames.
This huge fish, which is usually confined to the upper reaches of its resident river system, can attain a weight of over 45 pounds. The huchen has a greeny-blue back, silvery sides and white underparts, and the sides have a subtle pink sheen and delicate, X-shaped markings.
A voracious feeder, the predatory huchen is normally caught on spinners or wobbled deadbaits. Unfortunately, in many areas the huchen has been severely overfished, but efforts are being made to replenish stocks.