There is always some variation in color, but usually the back is quite dark, turning to bluish on the sides and light silver below. As the spawning season approaches, the jaws of the males become lengthened and badly distorted and the color changes to more of a pinkish hue and blotched in appearance. The gills are never alike on both sides, varying from 15 to 19 in number. ([See plate] giving names of all parts mentioned.)
BLUEBACK, OR SOCK-EYE SALMON, REDFISH
(Oncorhynchus nerka)
This species is next in commercial value to the chinook. It has been taken occasionally in the Sacramento river but it is not common south of the Columbia river. The run of this species begins about the first of April and the fish go as far as Salmon river, Idaho, fully 1000 miles from the sea to spawn. By a peculiar instinct this species only run up such rivers as have lakes at their heads, and spawn in the lakes or at the mouths of little streams emptying into them, in many of the lakes of Oregon and Washington are found the young of the blue-back salmon which are commonly called redfish. These fish never leave these lakes and therefore never attain a size of more than five to seven pounds.
Head, short and pointed and light olive in color; under jaw, white; body, long, slim and rather flattened; back, blue; sides, silver; belly, dull white; dorsal fin, dark; others flesh color; tail, rather narrow and well forked; gills, 13 to 15. As the spawning season approaches the whole fish takes on a decided reddish cast, which sometimes becomes as dark as a brick-red. The jaw becomes very much hooked, and a few spots appear.
THE SILVER SALMON
(Oncorhynchus kisutch)
In line of importance the silver salmon occupies the next place. It is also known by a number of names, among which are koho, skowitz and kisutch. It is a small fish, rarely exceeding 16 inches in length and never reaching more than ten pounds in weight. Its range is from Alaska south to Monterey Bay, where it has recently been planted and seems to flourish. It spawns in the smaller coast streams, never going far from the salt water. Its run begins about the first of September, spawning in October and November.
Head, short with blunt snout; opercles or gill covers, very convex; body, shaped very much like the chinook; back, bluish green; sides, silver white. It has but few spots and these are confined pretty much to the head, upper fins and tail. Gills, 13 or 14.
THE HUMP-BACK SALMON