A fine sporting fish which at times can be maddeningly coy, rainbow trout have gained the respect of trout fishermen fA everywhere since first introduced in the last century w Xi
The rainbow trout, Salmo gairdneri is a native of the Pacific coast, rivers and lakes of the North American Continent, ranging from the Bering Sea in the north, to the southern Californian coasts in the south. Since 1884 the species has been introduced to suitable waters all over the world with varying degrees of success. In Britain it has rarely bred successfully and in most cases now exists only as a result of continual restocking from fish farms which have successfully bred the species by modern stripping techniques.
In its American habitat the rainbow fills a niche comparable to that occupied in Britain by our native brown trout. Similarly it exhibits numerous variants (each once believed to be a distinct species) and provides a similar range of migratory and non-migratory fish. Its growth rates vary widely according to type and environment, and it provides excellent sport for anglers. Brown and rainbow trout, are however, of a quite different species—although related to the Salmo genus.
Generally a far hardier fish than the brown trout, the rainbow can withstand high temperatures, low oxygen levels, and murky waters. It is also a far more active fish, being a free riser to the fly and living and moving in loose shoals, with a strong urge to migrate upstream for spawning, falling back into lakes or lower reaches for the rest of the season. At the extreme it is anadromous, like sea trout, migrating from dense to less dense water to breed.
In appearance it is similar to the brown trout apart from a distinctive wide lateral band of iridescent magenta along the middle flanks. It is usually black spotted, and the spots, unlike those of the brown trout, grow more quickly. Rainbow trout grow to a larger maximum size than the brown trout. It also spawns later than brown trout, and is therefore in excellent condition in British rivers and enclosed waters at the very end of the season.
The history, literature and tax-onomy of rainbow trout in North America is every bit as confusing as that of its British cousin, the brown trout. Nineteenth century American and European zoologists identified and named a variety of species of trout. In Europe, for example, Gun-ther described some ten different species each with its own scientific name, while in America a similar number of trout were similarly iden-tified, described and named by various authorities.
During the early part of the present century the zoological view that a species should be regarded primarily as a breeding unit, despite minor physical differences, gained ascendency. It was shown under laboratory conditions that all the known British trouts were able to produce fertile progeny when cross-bred. More than anything, this led to their reallocation to a single species Salmo trutta. The same sort of study of species in America resulted in an all-American trout being classified into the species Salmo gairdneri. All trout were subsumed under this heading with the single not-able exception of the brook trout, which in fact turned out to be a char and now enjoys the separate specific title of Salvelinus fontinalis.
In America, however, the char is still commonly known as a trout, but can be distinguished from the rain-bow by its green-brown colour with lighter ‘worm-track’ patterns on the back, and reddish tinge on the underside. Examination of the vomerine bone on the upper palate will also provide distinguishing features. Rainbow trout have single rows of teeth set in a ‘T’ shape. Chars, on the other hand, bear only a group or cluster of teeth on this bone. The North American brook trout has also been introduced to some waters in Britain and these should not be confused with either brown or rainbow trout.
Rainbows normally feed on a very similar diet to brownies. When young they exist on daphnia, cyclops and other infusoria, but once past the alevin stage quickly graduate to shrimp and insects, and on to snails and fish fry in addition within a year. Not only are rainbows more prone to rise than brown trout, but they are far more active in their search for food, ranging between the bottom and the surface continuously and taking good advantage of midges, nymphs, mayflies and their larvae, and in the evening on sedges and daddy long legs. In waters where coarse fish fry are plentiful, rainbows soon get used to supplementing their diet with such delicacies. It is not unusual for anglers to find fish of 14in with roach of three of four inches in their stomachs. Such fish become as predatory as pike, and as rainbows move in loose shoals they are sometimes seen driving shoals of small fish into the shallows where they hunt them down voraciously.
When to use the dry fly
At the other end of the scale, rain-bows often rise freely in boisterous weather, feeding well on the surface during high winds, following the wind lanes in large groups and fearlessly rising under the bows of the angler’s boat. They will often cruise upwind in such conditions, dropping into the depths when they come to the far shores, and then feed earnestly either in mid-water, or on the bottom.
In calmer weather, when the sur-face is like a millpond and the angler despairs of getting his wet flies to work without creating a heavy wake, the rainbows will often rise maddening at midges and other small flies on the surface, ignoring the wet flies offered by the fisher man. Then the dry fly is often useful. Takes are sudden, and the rainbow is usually moving fast when it hits the fly. Smash-takes occur in these conditions, even when the cast is realistically heavy. It behoves the angler to ensure that his rod is not left pointing at the fly so that such a take is absorbed by the rod when the fish often hooks itself.
Under normal conditions, with a many more anglers, and most reservoir anglers welcome the rainbow and the exciting sport it offers in a hundred subtly different ways in different conditions. It can be as coy as the brown trout, and loves to cruise on the surface on hot days, sipping in the green pea-soup which the water often becomes in these conditions. Then it can be maddeningly difficult to tempt.
Light popple on the water, and a gen-tle breeze, the angler is able to fish without the wind interfering with his casting. The broken surface of the water will prevent fish spotting the angler’s movements too easily, as well as covering up his mistakes when working the fly. In such conditions the traditional wet fly method is a joy, both from the bank or from a boat. A team of three wet flies is used with a long cast which, fished slowly, presents them at different levels, often enabling the angler to locate the best depth. Sometimes it also indicates the ‘taking’ fly. Medium casting from the bank, or short lining from a boat can, in the circumstances, be very productive.
Lures and flashers
When the fish are dour and not showing, the angler must fish the water, covering as much territory as he can to get fish moving, or locate moving fish. A lure is sometimes successful and several patterns should be tried at various depths and different speeds. Sometimes the angler is reduced to ‘scratching the bottom’ with a leaded lure fished slow. Alternatively, a flasher fished fast may be used. Rainbows can often be tempted when high water temperatures have caused the brown trout to go completely off feeding. They will also move quite fast from comparatively deep water to a tempting fly realistically fished on or near the surface, following it until it is about to break surface.
The buzzer rise
When the buzzer rise occurs in the evening, fish will sip delicately at the nymph or smash at it, leaping out of the water and landing on the nymph with a boil. In late summer, when the sedges are on the water, rainbow trout will take both boldly and hearteningly.
When fish are hooked high in the water they will often leap and splash on the surface from the moment they are hooked. Sometimes it is essential to get the rod point down into the water to sink the line so as to absorb their acrobatics.