Markings and Coloration
Brown trout are the true trout. They are native to Europe, western
Asia, and the extreme northeastern edge of Africa and have been introduced
to many waters suited to them around the globe. Fishing for sport--including
fly-fishing--evolved within the native range of brown trout. The word
"trout" itself apparently evolved with specific reference
to these fish and was later applied to such fish as rainbow, cutthroat,
and brook trout simply because of their resemblance to brown trout.
Although all brown trout are categorized as a single species,
the fish themselves may show wide variation in color and spotting
patterns, habitual foods, and behavior. Any angler who fishes a variety
of rivers may eventually encounter brown trout that somehow look different
from those he's used to catching and may even encounter two different-looking
brown trout in the same stream. Color along the dorsal surface (back)
varies from olive-brown through yellowish brown, becoming lighter
toward the whitish belly area. There are usually greater amounts of
an overall yellow tint along the flanks. Black spots are present on
the back and in diminishing numbers down the sides. Bright red spots
are found in lesser numbers along the sides. There are few, if any,
spots on the tail in contrast with rainbow, the tails of which are
heavily spotted. Unlike brook trout, brown trout have no vermiculations,
or wavy lines on their backs and have teeth along the full length
of the vomerine bone on the roof of their mouths. Brown-trout coloration
is much subdued in hatchery fish, but often assume the brighter colors
of wild fish after several months in the stream.
Brown trout are also unique in that they are able to change their
color quite rapidly as a means of concealment. Brown trout are also
the only fish ever to rest on the stream bottom. This also explains
their success in many waters: They are just plain hard to spot both
by predators and fishermen. NOTE: The color changes mentioned refer
to changes in the background color of the trout's skin--they can't
change their spots.
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Range and Habitat
The brown trout has a much wider range than the brook trout, and
it's been suggested they can survive in streams that will no longer
support brook trout. However, brown trout don't survive well in warm,
polluted water either. They can survive for a short period in 81 degree
Fahrenheit water, but usually the upper lethal limit for brown trout
is about 77 degrees. Brown trout prefer water ranging from 54 to 67
The main reason for the success of brown trout in streams depleted
of brook trout is probably because brown trout are harder to catch.
Brown trout are competitive with brook trout in the same stream to
the extent that the domi-nant brown trout were excluding brook trout
from favorable resting (not feeding) positions in the stream, thereby
making the brook trout more vul-nerable to predators. This competition
for space in combination with the brook trout's greater vulnerability
to angling clearly puts brook trout at a disadvantage when coexisting
with brown trout. This creates a situa-tion that's often aggravated
by many general angling regulations that allow the capture of a certain
number of trout per day without regard to species, thus encouraging
the removal of brook trout at a faster rate than brown trout.
Brown trout have also been accused of cannibalism-- feeding heavily
on young trout--this diet leading to a larger-sized fish as well.
Again, these characteristics have contributed to a decimated brook
trout population and the Park authorities efforts to protect the brook
Two aspects of brown-trout behavior that are of importance to anglers.
These two aspects can be divided based on the size of the fish. Smaller
brown trout (up to about 12 inches) are called "drift feeders."
They feed primarily on insects and other food items drifting in the
current. They typically hold a stationary feeding position and move
only to intercept food items in adjacent and faster currents to the
side or overhead. Larger brown trout (which grow beyond 12 inches)
start to feed on larger items such as crayfish, baitfish, and smaller
trout. Because of the difference in diet, they almost always grow
much larger than the drift feeders--these are the rare trophy-size
browns. Understanding the differences in behavior between these two
types of feeders can be vital to the angler.
Specifically, a study in the 1980s showed that a rising trout in
flowing water usually keeps rising in the same spot and, assuming
the continued availability of suitable surface food, an undisturbed
trout will usually rise in the same spot on the next day, and the
next, and so on unless the stream configuration changes. Trout fishermen
can learn these locations also, just by paying attention when they're
fishing and remembering precisely the locations of rising fish. Gaining
this knowledge is one of many ways in which experienced anglers "learn"
trout streams, and obviously has a lot to do with fishing success.
The study also showed they didn't spend most of their time hiding
under rocks or near the bank and did not feed only at dawn and dusk;
they fed all day as long as they were undisturbed (the shadow of a
passing bird, for example). Historically, the average angler hasn't
been able to observe this behavior, and doesn't know that after a
few minutes to a half hour, the fish may return to feeding once again.
Another example is any trout stream that gets heavy recreational
use from trout fisherman and others such as canoeists and inner-tube
floaters, on summer days--the conditions often found in the Great
Smoky Mountain streams during the summer months. The trout are probably
hiding under the bank-side or boulders. The trout will again move
out into the flats to feed in the late evening, well after the river
use has ceased or decreased--to be taken advantage of those fly fishermen
who know how to move in the water with the least disturbance. For
the areas in the Smokies streams which receive a lot of floaters and
swimmers, the message is clear: either fish early or fish late (the
brown trout is often nocturnal simply to avoid its predators--they
also hunt in the daytime).
As with other kinds of trout, the growth of brown trout is extremely
variable, depending primarily on the productivity of a particular
stream and also on the strain of brown trout. One-year-old fish may
average 3 inches long, and reach an average 6 inches in their second
year, 8 inches in their third year, and 12 inches in their fourth
year. A seven year life span is typical, unless their predators or
anglers get to them first.
The restoration efforts of Park resource managers have led them to
closing some streams and tributaries
to all fishing, and ensuring natural barriers such as waterfalls are
adequate to prevent the brown and rainbow trout from migrating upstream.