[8]. For valuable records of the natural history of this species the reader is referred to various papers by Dr. Barton Warren Evermann in the Bulletins of the United States Fish Commission and elsewhere.
The silver salmon, or coho (Oncorhynchus milktschitsch, or kisutch), reaches a weight of 5 to 8 pounds. It has 13 developed rays in the anal, 13 branchiostegals, 23 (10 + 13) gill-rakers, and 45 to 80 pyloric cœca. There are about 127 scales in the lateral line. The scales are thin and all except those of the lateral line readily fall off. This feature distinguishes the species readily from the red salmon. In color it is silvery in spring, greenish above, and with a few faint black spots on the upper parts only. In the fall the males are mostly of a dirty red. The flesh in this species is of excellent flavor, but pale in color, and hence less valued than that of the quinnat and the red salmon.
The dog-salmon, calico salmon, or chum, called saké in Japan (Oncorhynchus keta), reaches an average weight of about 7 to 10 pounds. It has about 14 anal rays, 14 branchiostegals, 24 (9 + 15) gill-rakers, and 140 to 185 pyloric cœca. There are about 150 scales in the lateral line. In spring it is dirty silvery, immaculate, or sprinkled with small black specks, the fins dusky, the sides with faint traces of gridiron-like bars. In the fall the male is brick-red or blackish, and its jaws are greatly distorted. The pale flesh is well flavored when fresh, but pale and mushy in texture and muddy in taste when canned. It is said to take salt well, and great numbers of salt dog-salmon are consumed in Japan.
The humpback salmon, or pink salmon (Oncorhynchus gorbuscha), is the smallest of the American species, weighing from 3 to 5 pounds. It has usually 15 anal rays, 12 branchiostegals, 28 (13 + 15) gill-rakers, and about 180 pyloric cœca. Its scales are much smaller than in any other salmon, there being 180 to 240 in the lateral line. In color it is bluish above, silvery below, the posterior and upper parts with many round black spots, the caudal fin always having a few large black spots oblong in form. The males in fall are dirty red, and are more extravagantly distorted than in any other of the Salmonidæ. The flesh is softer than in the other species; it is pale in color, and, while of fair flavor when fresh, is distinctly inferior when canned.
Fig. 56.—Humpback Salmon (female), Oncorhynchus gorbuscha (Walbaum). Cook's Inlet.
The masu, or yezomasu (Oncorhynchus masou), is very similar to the humpback, the scales a little larger, the caudal without black spots, the back usually immaculate. It is one of the smaller salmon, and is fairly abundant in the streams of Hokkaido, the island formerly known as Yezo.
Fig 57.—Masu (female), Oncorhynchus masou (Brevoort). Aomori, Japan.
Of these species the blue-back or red salmon predominates in Frazer River and in most of the small rivers of Alaska, including all those which flow from lakes. The greatest salmon rivers of the world are the Nushegak and Karluk in Alaska, with the Columbia River, Frazer River, and Sacramento River farther south. The red and the silver salmon predominate in Puget Sound, the quinnat in the Columbia and the Sacramento, and the silver salmon in most of the smaller streams along the coast. All the species occur, however, from the Columbia northward; but the blue-back is not found in the Sacramento. Only the quinnat and the dog-salmon have been noticed south of San Francisco. In Japan keta is by far the most abundant species of salmon. It is known as saké, and largely salted and sold in the markets. Nerka is known in Japan only as landlocked in Lake Akan in northern Hokkaido. Milktschitsch is generally common, and with masou is known as masu, or small salmon, as distinguished from the large salmon, or saké. Tschawytscha and gorbuscha are unknown in Japan. Masou has not been found elsewhere.