Understanding the Atlantic Salmon: Salmo salar
There are several species of salmon, but Salmo salar, the Atlantic salmon, is the only one found in British waters, unless one counts a few errant Pacific Spring salmon from Russian stocking of north European rivers. The salmon can be confused only with large SEA-TROUT, both fish having the same silver sheen and, of course, the adipose fin of the salmon family. However, they are easily told apart. The sea-trout has the characteristic long upper jaw-bone of the trout, extending beyond the centre of the eye; in the salmon this bone ends about level with the middle of the pupil. Again, the salmon has about ten scales diagonally between dorsal fin and lateral line, and the sea-trout has sixteen.
The Atlantic salmon has been described as the greatest freshwater fish in the world. This is only half true, for the salmon spends the larger part of its lifetime in the sea and only returns to freshwater to spawn. In so doing it becomes the angler’s most prized quarry. The life-cycle of the salmon is a fascinating one. It is hatched on the redds, or shallow gravel spawning beds, often in the tiniest hill streams. It spends the first two weeks of its life fighting its way up through that gravel and living between the stones, which it uses as a shelter from its many enemies. During this period it lives on a yolk-sac, containing nourishment, which is fixed beneath its throat like a small balloon. After this, it lives in the river for about two years as a, during which time it would look remarkably like a small brown TROUT were it not for the characteristic parr markings (rather like bluish finger prints) along its flanks. Next, it changes its coat to silver and moves down to the sea, when it is known as a . In the sea it puts on weight at a great rate, owing to the rich feeding there, but the mystery is that no one knows precisely where in the ocean the salmon go for this feeding, for they are seldom caught in trawls.
The salmon may return to the river to spawn at one, two, or three years. If it returns within one year, it is known as a grilse on this maiden, spawning run. A percentage of salmon find their way back to their own rivers, the ones in which they were born, but by no means all.
The salmon return to the rivers in spring and fight their way upstream with every fresh surge of rainwater that comes down from the hills until they reach the spawning shallows, or redds. There the female excavates a deep hole. She uses her tail to do this, but the tail itself does not do the digging; it is the vortex created by its movements that shifts gravel and quite large stones from the river bed. After courtship — in which the male fish lies alongside and moves against her — she deposits hundreds of eggs at a time in the redd. As she does so the male instantly becomes excited and sheds his milt. Recently it has been discovered that, possibly as an insurance against infertility, a salmon parr is usually present at the spawning and sheds his tiny cloud of sperm too. Because he is right under the female’s oviduct this results in a high fertility level. The amazing thing is that this little fish, who has not yet even put on his sea-going coat, is already sexually mature.
After spawning, the female covers each clutch of eggs with gravel again. Finally, after several such spawnings, the exhausted salmon try to fight their way back to the sea. They are then emaciated like eels and are called. It is illegal to catch kelts. A high percentage of them die before they reach the sea and few of the survivors return to the river after several more years of sea life to spawn again.
As far as the angler is concerned, the salmon’s whereabouts in the river are highly predictable. The homing salmon is a travelling fish with a sense of purpose and a goal ahead of it. When conditions are right, ie. when fresh water is coming down to urge it on, it moves on upstream and is usually uncatchable. However, it must rest, and the resting places or holding pools are where the angler finds it. In these pools the salmon lies are usually well known and do not vary except when flood conditions alter the contours of the river bed. Salmon often pack into a pool in numbers when water conditions become low. They are then usually torpid and uninterested in any fly or bait. The strange thing is that salmon do not eat when in the river but live off their sea fat. However, they will still snap at the angler’s artificial offering.
Three-quarters of the success attained in salmon fishing results from knowing where fish lie. This is especially true in spring, when the uniformly high level of water tends to make most parts of the river look alike.
Salmon are fond of stones and rock, since sands and muds irritate their gills. The rock salmon-lodges in most rivers have names because they have been noted for generations. A walk along the river with an experienced rod is the best way of learning its more obvious taking places. Failing such helpful advice the angler will have to make up his own mind on where fish lie. Naked bed-rock on the bank-side is usually a good indicator, for quite probably it extends underwater, where it will be hollowed into caves and pockets. Fish will tenant these desirable places. Almost any ‘ease’ or quiet spot out of the main current around such bed-rock is likely to harbour a salmon.
Some rivers are peppered with boulders, but most of these can be ignored unless they fringe deep holes or pots where fish can take cover. Long featureless pools, especially those with mud or clay bottoms, can also be ignored. But close attention should be given to ‘necks’ where gravel banks abut the stream. Rocks may well be embedded in the gravel underwater, affording fish a harbourage.
Croys or piers are constructed on many rivers and I never cease to bless the men who constructed them, often a century ago. A successful croy usually has a deep hole at its foot where the fish lie. Quite often, however, the salmon will creep many yards up or downstream into the slack water at the sides of the adjoining runs. Some croy-pools no longer hold fish, usually because the current is too fast, the stream having changed over the years.
The lies or taking-places mentioned here assume that the river is at average spring level — full but not flooded. In flood conditions, before fish have taken up their lies, they can be expected almost anywhere, but especially in the broad shallow tails of the big pools.