I am the wiser in respect to all knowledge and the better qualified for all fortunes for knowing that there is a minnow in that brook."—Thoreau.
There is still considerable argument about the identification and classification of the sea trout. Some authorities still claim the sea trout is a distinct species; others declare it to be the brook trout, Salvelinus fontinalis, that goes to sea from the fresh water ponds and streams.
The squeteague (vulgo weakfish, wheatfish, sea bass, white sea bass, carvina, checutts, shecutts, yellowfin, drummer, bluefish, squit, suckermang, succoteague, squitee, chickwit, gray trout, sun trout, salmon, salmon trout, shad trout, sea trout, salt-water trout, spotted trout, etc.) is not a trout of any sort; so this species need not be considered in this sea trout discussion.
My personal theory concerning the sea trout is that any trout that goes to sea is a sea trout, and that more than one species of trout go to sea—whenever they have the opportunity.
The small-stream trout that visit the ocean do so mainly in search of a change in food; the sea-going trout of large rivers are impelled to leave their fresh water retreats for the ocean waters also to satisfy a desire for new varieties of food, but more so because of an instinct that warns them of the danger of remaining in the fresh-water rivers during certain periods of the year—the coldest seasons when the waters freeze to the river bottom, and in the melting time, when the ice thaws into huge sharp-edge chunks, and the mass of ice, swift-running water, and rocks turn the rivers into raging, roaring floods that would cut and bruise the trout unmercifully.
Nature makes these large-river brook trout in the calm periods of spring, summer, and autumn, and sea trout in severe winter weather and during dangerous flood time.
The broad streams of the west coast of Newfoundland—Fishels River, Crabs River, Big and Little Codroy Rivers, Big and Little Barachois Rivers, and Robinson's River—afford the best evidence of trout migrating to the sea to escape the fury of the flood, and any of the little trout streams in any part of the world where the streams flow into salt water will afford the student means of observing the trout's fondness for marine excursions in search of a change of diet.
Just as the different species of trout are widely contrasting in colors, shapes, sizes, traits, etc., while in their natural habitat—fresh water—so are they confoundingly different in these matters while sojourning in salt water.
The true brook trout (Salvelinus fontinalis) is of various shades, shapes and sizes, these depending upon the character of the water he inhabits. In shallow, swift streams of a light color pebble bottom the specimens in general are likely to be thin, narrow, and of a bright gray hue, though, of course, there are individual specimens in this condition of water that are exceptions to the rule—a few old specimens who have sheltered themselves for years in dark, deep, steady spots under the protruding bank of the stream, or along the side of a sunken tree stump, etc. This autocrat of the eddy is fat, stocky, and dark in color, just the opposite of his younger relatives of the swift-running part of the stream.
The brook trout of deep, still dark-bottom ponds are fatter, darker, broader, of duller color and of slower motion than their brothers of the rapid waters. The trout's shape, weight, size, and color are influenced by its food, its age, its activity, its habitat, and its habits. Its color corresponds to the color of the water bottom, and will change as the water bottom changes. If removed to a new water, where the bottom color is different from the bottom color of its first abode—lighter or darker, as the case may be—it will gradually grow to a corresponding shade, blending with its new habitat just as its colors suited the stones and grasses and earthy materials of its native domain.