A member of the char family rather than a true trout, the brook trout is a magnificent sporting fish. Wherever it has been introduced it has won the angler’s heart
The brook trout, Salvelinus fontinalis, is becoming a major British game species because of its outstanding sporting and culinary qualities. Nevertheless, it is not indigenous, occurring naturally only in North America. There, its natural range is from the mountain streams of northern Alabama and Georgia, in the south, to the Atlantic coast of Labrador in the north-east of Canada, and from the East Coast of the United States to the Great Lakes region, as far as Minnesota. Also, because it is held in such high regard by American anglers, it has been introduced to suitable streams in Michigan, Wisconsin, parts of the Rocky Mountains, and the streams and creeks of the Allegheny Mountains, in the central eastern USA.
Although a member of the salmon family, the brook trout is not a true trout, but a species of char. It is a relative of the arctic char, Salvelinus alpinus, found in a land-locked environment in the Lake District and some Welsh lakes.
Char are colourful fish, but the brook trout is perhaps the most beautiful of all. Though varying according to its environment, its normal colouring is olive green, darker on the back and growing lighter towards the belly. It has light olive markings on a dark skin, by contrast with the brown trout, which has dark spots on a light skin. These olive spots merge together on the back to form wavy lines of colour, and there are also a few bright red spots along the flanks.
Handsome fish at spawning time
In its spawning livery, the cock brook trout is particularly handsome, having a bright orange stripe on either side of the belly and a mauve band along the flanks, much the same as the rainbow trout.
Apart from the spawning dress of the cock, the species can be distinguished from true trout by its larger head and a white strip along the front edge of the pectoral, pelvic and anal fins. It differs from the arctic char by its square tail (that of the arctic char is forked) and its mottled dorsal and tail fins.
Brook trout thrive best in cool, spring-fed rivers and deep lakes, but fare quite well in most pools and lakes if the water temperature does not rise too high. They are tolerant of acid conditions as low as pH 6.0 but breeding efficiency will be impaired, and will survive without much trouble in waters short of natural foods – provided the competition from other fish is not too severe.
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The life history of the brook trout is similar to that of our native brown trout. In late summer it begins to run upstream to seek gravelly shallows where springs rise or where there is at least some upsurge of water through the stream bed. (It will, however, spawn in deeper water.
In late October or early November, according to the temperature, it begins to spawn. Like the brown trout, the hen makes a spawning redd by excavating (with undulating movements of her body) a trench 2-8in deep and about 1ft in diameter.
Fertilization of the eggs During this time, the cock busies himself chasing away rivals. But when the hen is ready to shed her eggs he enters the redd to fertilize them. After this he concerns himself with driving off the small fish intent upon eating the eggs which have drifted downstream on the current.
Meanwhile the hen moves a little way upstream and begins to cut another redd. The gravel she shifts from this second depression is carried downstream and fills the redd in which the eggs have been laid, thus covering them with clean gravel. If there is more than enough to fill the depression, a little pile is left, marking the redd.
A hen fish will make several redds until she has deposited all her eggs, taking as long as eight hours to do so. She then drifts downstream in search of quieter water to rest. The male remains near the redds for anything up to three weeks after spawning, fending off predators. Eventually, however, he too drops downstream to regain condition.
The number of eggs laid depends on the hen’s size and age. Approximately 1,300 eggs per pound of body weight is the usual number in the wild, but in hatcheries many more may be produced. The time taken for the eggs to hatch depends on the water temperature. In cold water it may be three months, at 11 °C (52°F) about six weeks, and if the water is three degrees warmer incubation lasts about five weeks.
Absorption of yolk sac
When newly hatched, the alevins are still attached to the yolk sac. They feed on this during the first weeks of their lives, the time taken for it to be absorbed depending on the water temperature. In cold waters it can take as long as two months, but in warmer temperatures this pre-feeding period is only about 22 days.
When the fry begin to feed, they can, at first, only take very small food, such as midge larvae, zooplankton, ephemerid nymphs and the larvae of reed smuts. As they grow, they take larger food items, such as young freshwater shrimps, tiny snails, worms, water boatmen, water beetles and various small fish.
Given the same conditions, brook trout grow much faster than brown trout, and during their first years they may even exceed the growth rate of rainbows. They are not fussy about what food they eat, quickly adapting to whatever is available. Larger fish are fond of the fry of coarse species, and would make very satisfactory predators in cooler coarse fish waters.
Though considered a new introduction by many, brook trout were first introduced into Britain in 1869, and until the turn of the century were offered for sale by several trout farms. But many of the early introductions were unsuccessful. Nevertheless, one farm stocks ‘brookies’ and from here they have been introduced to other farms.
Why did so many early introductions fail? Many experts believe that the environments chosen were unsuitable. However, a few breeding populations have survived. One is in a loch situated at over 2,000ft in Wester Ross, and another is in Llyn-y-Tarw, a shallowish lake 1,450ft up in Powys in North Wales.
A stock of brook trout is also kept at the Freshwater Fisheries Laboratory, Pitlochry, Perthshire, where scientists are examining the feasibility of stocking some of the Scottish lochs with brook trout. So far the results of their experiments have been encouraging, for it has been found that brook trout feed well and put on weight during the winter, whereas brown and rainbow trout do not. They also breed satisfactorily in Stillwater, because they do not needing running water like the other salmonids.
At Pitlochry they have reared brood stock (between two and three years old) to over 3lb, and one- to two-year old fish of 5lb. This is a high growth rate and means that their life span will be comparatively short, although not as short as that of the rainbow, and they will not grow to the 10 years plus of the brown trout.
Brook trout have been introduced to many lakes, notably Old Manor Park Fishery at Great Brickhill, Buckinghamshire, where they have been flourishing in the lakes. The world record rod-caught brook trout weighed 14 1/2 lb, while the British record (rod caught) fish, taken by A Pearson in 1979 at the Avington Fishery, Hants, weighed 5lb 6oz.
As a result of the renewed interest in the brook trout, some fish farmers are working on crosses with brown or rainbow trout. These hybrids have limited fertility and good growth rates. The more successful of the two crosses is that with the brown trout, where the eggs from a brown trout are fertilized with sperm from a male brook trout.
The resulting hybrids are called ‘tiger trout’ and are very striking in apperance, having no spots at all, and an olive coloured wavy line pattern right down the flanks. Pioneer work in this country on tiger trout was carried out at the Itchen Valley Trout Farm at Alresford, Hamp-shire, and at a private hatchery on the River Test. The cross with rainbow trout is extremely difficult to achieve but progress has been made with the so-called ‘cheetah trout’.
Sensitivity to high temperature
Like their close relatives, the char, brook trout are sensitive to high temperature. They prefer water between 13° and 16°C (55-61°F) and do not grow well at temperatures between 20 and 22°C (68-72°F). Their upper lethal limit is relatively high at 25°C (77 °F). Brown trout will not tolerate temperatures more than a 381 couple of degrees above this figure.
In a normal British summer, brook trout can survive without any trouble, but during abnormally long, hot summers, trouble with them may be anticipated. Cool, deep reservoirs and gravels pits are ideal, but they do not breed successfully where brown trout are also present. They have been introduced to the famous River Test in Hampshire on a trial basis and to Trenchford Reservoir, Devon, controlled by the South West Water Authority.
At Trenchford, 300 sizeable brook trout were introduced from the authority’s own hatchery, and on the first day of the new season 85 of these fish had been taken. Anglers found that they would rise remarkably freely and take almost any fly offered. Their fighting qualities received high praise and applications to fish for them were overwhelming. The same interest was shown in brook trout at the Ladywell Lakes trout fishery at Alresford, Hampshire. There they were equally obliging, and anglers motored long distances to fish for them. Stocks of hatchery-bred brookies are now maintained at many fisheries controlled by river water authorities.
Not so easy to catch Early experience of the brook trout suggests that it is an easy fish to catch, but this is not always the case. They are easy if they are fished for within about three weeks of their being introduced to a water – which makes them an ideal ‘put-and-take’ fish – but in established waters that are not heavily fished, they have proved difficult to take.
Brook trout are fond of surface feeding, but when the water warms up they go deeper, where the water is nearer their preferred temperature. Here they find rich feeding on midge larvae, snails, caddis larvae, beetles, and small fish. If they are introduced to a deep Stillwater which has an abundant population of coarse fish, they will wax fat on the fry of large species and on small species such as sticklebacks, bullheads and gudgeon.
Since brook trout will eat almost anything that moves, there is little difficulty in selecting a fly or lure. The usual wet- and dry-fly patterns used for brown and rainbow trout will catch a brookie. Coachman, Black Gnat, Professor, Teal and Red, Invicta, Dunkeld, plus the usual nymph and pupae patterns, are all suitable for surface and semi-surface fishing. For deep fishing, any of the popular lures will take fish, and so it is not necessary to fish with very large flies, although these will no doubt take brook trout. A sporting fish such as this deserves a sporting chance.
Apart from their fighting qualities, their fast growth rate, their tolerance of acidity, and their good looks, brook trout are second to none on the table. They have firm, red flesh similar to the best salmon. With so many good points in their favour, it is hardly surprising that they are becoming increasingly popular and more and more waters are being stocked with them.