LAKE TROUT OR MACKINAW Salvelinus namaycush

DISTINGUISHING CHARACTERISTICS
The background color of the body is usually dark gray, but varies from pale to almost black. The entire body except for the belly is covered with large pale spots. The dorsal and caudal fins are marked with dark wavy lines and spots. The caudal fin is deeply forked. The head is pointed and the body is relatively slender.

DISTRIBUTION IN CALIFORNIA
Self-sustaining populations of lake trout are present in Lake Tahoe, Fallen Leaf Lake, Stony Ridge Lake, and Donner Lake, all of which are in the Truckee River drainage. Lake trout have recently been introduced into other waters.

INTERESTING FACTS
This trout tends to live in the deeper pans of lakes and is usually caught by trolling with wire line, to which large spinners and frequently minnows are attached. It commonly feeds upon other fish and grows to large sizes; 15 pounds is not rare. This is the only trout which does not construct some sort of nest and cover its eggs with gravel. Its eggs are dropped into the loose rock or ledges and shelves on the lake bottom.  The lake trout or mackinaw, as it is often called in California, was brought here from Michigan in 1894. It has not been widely distributed because of its tendency to feed upon other trout. It is sometimes blamed for the disappearance of the Lahontan cutthroat from Lake Tahoe. This trout was originally described in 1792 by Johann Walbaum from fish taken in Hudson Bay and called namaycush, an Indian name.

BROWN TROUT Salmo trutta

RAINBOW TROUT Salmo gairdnerii

DISTINGUISHING CHARACTERISTICS
The black spots vary in size from pin points up to about one-eighth inch in diameter, but are rarely large or perfectly round. They are usually found on the upper half of the head, on the upper half of the body, and on the dorsal and caudal fins. The lateral band is usually conspicuous, reddish to violet, extending from the head to the caudal fin. The lower side of the head is commonly reddish. There are no "cutthroat" dashes of red on the membrane beneath the jaw in typical rainbow, although some rainbow in some areas may show small orange marks similar to those of a cutthroat. There are no small red spots on the sides, nor wavy marks or bars on the back or dorsal fin. All trout vary somewhat in their coloration, but the rainbow are extremely variable. Rainbow in some lakes and reservoirs may be quite silvery except on the back; they may have very few spots and these may be indistinct, and the red on the head and sides may be completely lacking. The rainbow trout illustrated above could be a yearling or a two year old fish and represents an average sized trout of this species. In older, larger rainbows the body proportions may be somewhat different, particularly in the older males, in which the lower jaw is much more prominent.

DISTRIBUTION IN CALIFORNIA
The rainbow trout is widely scattered over California. It originally occurred in a large part of the trout streams of the State and in a few lakes. Since this is the fish most commonly raised in the trout hatcheries of California, it has been planted in nearly every lake and stream which is suitable for trout.  Therefore, it is by far the most widely distributed trout in California. In many coastal streams this species is represented by the migratory steelhead in the lower portions and by resident fish in the headwaters. In some streams the ranges of the two overlap. Rainbows of one subspecies will hybridize with other subspecies and with cutthroat trout when their ranges are not separated by some barrier.

INTERESTING FACTS
Resident rainbow rarely attain a large size in California. Steelhead rainbow grow much larger because they migrate to the ocean and spend one or more years under conditions much more favorable to rapid growth than are found in fresh water. However, in a few of the larger reservoirs and lakes in California rainbow do grow rapidly and one weighing 18 pounds was recorded from Lake Almanor.

KOKANEE SALMON Oncorhynchus nerka

DISTINGUISHING CHARACTERISTICS
The back is a dark blue and the sides are silvery. As the spawning season approaches, both male and female kokanee turn a deep red (as pictured above), and the lower jaw of the male develops a characteristic hook common to Pacific salmon. Rays in anal fin 13 to 17 (usually 14 or 15), opposed to 9 to 12 (rarely 13) in trout.

DISTRIBUTION IN CALIFORNIA
Kokanee have been planted in 35 lakes in California since their initial introduction in 1941 but have established self-perpetuating populations only in 10, including Lake Tahoe. Donner Lake, for example, has a good population of kokanee, but limited now by spawning area.

INTERESTING FACTS
Kokanee are not trout but belong to the same family as the trout. Kokanee are primarily plankton feeders, found in the open water areas of a lake. They like the same cool waters preferred by trout. Kokanee compete with small trout for food but provide forage for large lake trout. Mature kokanee ascend streams and gather over gravel bars in lakes in the fall to spawn. Taylor Creek, which flows from Fallen Leaf Lake down into the southwest corner of Lake Tahoe, is one such stream. A stream profile chamber has been built on Taylor Creek permitting the public to view the upstream ascent of these salmon. Kokanee are the landlocked form of sockeye salmon and, like their ocean-going brothers, die after spawning. Kokanee can be caught with flies, bait, or lures. When trolling, a rubber band between line and leader prevents the hook from tearing out of their soft mouths. Oncorhynchus nerka was originally described by Walbaum in 1792 from sockeye taken in Kamchatka. The scientific name is Greek for "hooked nose of flowing waters".

LAHONTAN CUTTHROAT TROUT Salmo clarkii henshawi (now extinct in Lake Tahoe)

DISTINGUISHING CHARACTERISTICS
The body is usually a dark, yellowish-olive color from back to belly. The side has a broad pinkish stripe. The sides of the head are often scarlet. The entire body is covered with large, black spots. Cutthroat living in deep water may be silvery with narrow, elongated spots. There are two distinct red stripes on the membrane beneath the jaw. The black spots on the body are not always as numerous as shown above.

DISTRIBUTION IN CALIFORNIA
In California the Lahontan cutthroat is a native of the Truckee, Walker, and Carson drainages and does not occur naturally in waters draining into the Pacific Ocean. This range has been extended somewhat by hatchery planting.

INTERESTING FACTS
This fish has been known as the Tahoe trout, for it was very abundant in Lake Tahoe until it became extinct or virtually so in the 1940s. Very large individuals ascended the tributary streams to spawn in April. Years ago there was a considerable market fishery for this fish, which was known as the "black-spotted trout". In the late 1800's and early 1900's Lake Tahoe supported two large commercial fishing operations which used nets to harvest the trout. The most likely reason for its extinction was the introduction of the lake and rainbow trouts, although insurmountable irrigation dams on the Truckee River and the commercial fishery may well have been contributing factors.

TROUT SENSES
Although much is known about the senses of sight, hearing, taste, smell, and touch in trout, a good deal remains to be learned.

SIGHT
In its general form the eye of a fish is not unlike that of land vertebrates, but it is necessarily somewhat modified for vision under water. As most anglers know, trout do see quite well.  "Can trout distinguish colors?"  It is an old question that was partially answered by tests conducted by Department of Fish and Game biologists. Trout can distinguish certain colors. They respond to red and all shades of red, including light pink. Perhaps they can distinguish many other colors too, but in these tests they were attracted only by red. The tests also proved conclusively that trout can see and are attracted by red objects entirely out of the water.

HEARING
Although fish have no external or middle ear, they can respond to vibrations of the water and so do "hear". The swim bladder is the main sound receiver, transmitting its vibrations to the inner ear, but the lateral line system is also a hearing organ. The latter is particularly sensitive in the low-frequency and subsonic range, and at short distances it can locate sound sources. The internal ear of a trout is well developed and operates in essentially the same manner as it does in humans. Thus, trout have a good sense of balance. The lateral line of a trout can be seen as a series of pores in the scales along each side. These pores open into tubes in the scales and one tube connects with the next, forming a continuous canal extending from the head to the rail The canal is filled with mucus, which conducts vibrations to the nerve endings beneath. These nerve impulses, caused by vibrations in the water, are carried to the brain by a long nerve extending along the side of the fish beneath its skin.

TASTE
Fish have a reasonably well developed sense of taste and trout seem to be able to distinguish foods from inedible objects fairly well. A feeding trout will take almost anything into its mouth, but only those objects that taste right will be swallowed. There are taste buds in the mouth of a trout similar to those in higher animals. It is not clear why we find objects such as pine needles, which have no food value, in a trout's stomach. It is doubtful if they taste like food. Some debris found quite often in a trout's stomach comes from the cases of caddis larvae, which are a favorite food. A good trout bait must appeal both to a trout's sense of smell and taste. A fish can sense food by either smelling or tasting the water.

SMELL
The sense of smell in fishes is relatively acute, as has been proved by numerous experiments. Trout are no exception. There is a pair of nostrils on either side of the snout of a trout, but these are not used for breathing. Water enters one nostril, then passes over several folds of skin and out the other. It is wel known that salmon are keenly aware of various odors, including the odors of a man's hand placed in the water. It is likely that trout have as keen or nearly as keen a sense of smell as do salmon.

TOUCH
A fish has nerve endings scattered over most of its body surface and responds to touch stimuli, but its response is often unlike that of man and many other higher animals. This is largely because its brain is not developed to such an extent that the fish can do much "thinking" about its touch sensations. That is why a fish can be stuck by a hook and return in a moment to strike at the hook again. Without doubt it has felt the hook, but whether or not it has felt pain is difficult to say, since we judge such matters only by our own standards.

RESPIRATION
When a fish takes water into its mouth it is breathing, not drinking. The water passes across the hundreds of tiny gill filaments and then out through the gill slits, one on either side of the head. In each gill filament is a capillary through which the red blood cells are continually flowing. There is an exceedingly thin membrane separating the blood from the water, and oxygen in the water is exchanged for the carbon dioxide of the blood. Trout require more oxygen than some other kinds of fish, so we normally find trout living in well aerated waters.

SWIMMING SPEED
Trout are not the swiftest of all fish, but they are certainly not slow. They swim slowly most of the time, but when occasion demands they can develop reasonably high speeds for short distances. Tests have been run to determine the approximate swimming speed of trout, but speeds vary, depending upon the size and species of the trout, the temperature of the water, the health of the fish, and the amount of rapid swimming the particular fish has been doing. In a very general way, a rule of thumb approximation is that the swimming speed of trout in feet per second is equal to their length in inches. Thus, a three-inch trout can swim about three feet per second and a 12-inch trout can swim about 12 feet per second. Three feet per second is a trifle over two miles per hour and 12 feet per second is a little over eight miles per hour. Of course, these speeds can only be maintained for very short distances.

THE SCALES OF TROUT
In many kinds of fishes the scales are the best indicators of age. Under a microscope a fish's scale is found to be marked by many concentric lines, like the growth rings on a tree trunk. When the growth is slow these circuli are close together and, conversely, when the growth is rapid they are far apart. Fish usually grow rather slowly or not at all when the water is cold in the winter and when food is scarce. Thus, each winter the circuli on the scales are close together and one can count these bands of circuli and tell how old the fish is. When a trout spawns the edge of the scale is often absorbed. After spawning is over and the fish begins to grow again a check which is easily noted by a specialist in this field of study is left on the scale. Thus, one can tell the age, the speed of growth, and the number of times a trout has spawned by studying its scales under a microscope.

THE COLOR OF TROUT
A highly colored golden trout or an eastern brook trout at spawning time compares favorably with the more brilliantly colored tropical fishes. From these extremes of high coloration trout become less colorful until, in the case of a rainbow from some lakes, the back is dull green and the sides and belly range from silver to pure white.  A rainbow from a deeply shaded mountain stream is often quite dark. Even the belly may be dark gray. The black spots, the parr marks, and the fine black stippling found on most trout are caused by great numbers of melanophores or black pigment cells filled with microscopic black pigment granules. Similarly, the red and yellow colors are produced by cells filled with red and yellow pigments. Trout and many other kinds of fishes are able to change their colors quite rapidly and they do this by contracting or expanding these pigment cells. When thousands of these tiny cells are expanded the pigment granules are spread out and the fish becomes dark or red or yellow, as the case may be. Then, these cells may be stimulated by nerve impulses and made to contract into pin points of black or of color and immediately the fish becomes much lighter. In addition to this rapid means of modifying color or the intensity of the color, a trout may lose or gain pigment, but this is a relatively slow process. Beneath the skin of a trout is a layer of guanin crystals in cells called guanophores. It is the guanin that gives the trout its silvery appearance. The pigment granules in the chromatophores (black, orange, or yellow) have several different shades of color and different combinations of these shades, together with the guanin, are sufficient to produce all the colors seen in a trout.

Information above provided courtesy of the California Department of Fish and Game.