There are five species of salmon (Oncorhynchus) in the waters of the North Pacific, all found on both sides, besides one other which is known only from the waters of Japan. These species may be called: (1) the quinnat, or king-salmon, (2) the blue-back salmon, or redfish, (3) the silver salmon, (4) the dog-salmon, (5) the humpback salmon, and (6) the masu; or (1) Oncorhynchus tschawytscha, (2) Oncorhynchus nerka, (3) Oncorhynchus milktschitsch, (4) Oncorhynchus keta, (5) Oncorhynchus gorbuscha, (6) Oncorhynchus masou. All these species save the last are now known to occur in the waters of Kamchatka, as well as in those of Alaska and Oregon. These species, in all their varied conditions, may usually be distinguished by the characters given below. Other differences of form, color, and appearance are absolutely valueless for distinction, unless specimens of the same age, sex, and condition are compared.
The quinnat salmon (Oncorhynchus tschawytscha),[[7]] called quinnat, tyee, chinook, or king-salmon, has an average weight of 22 pounds, but individuals weighing 70 to 100 pounds are occasionally taken. It has about 16 anal rays, 15 to 19 branchiostegals, 23 (9 + 14) gill-rakers on the anterior gill-arch, and 140 to 185 pyloric cœca. The scales are comparatively large, there being from 130 to 155 in a longitudinal series. In the spring the body is silvery, the back, dorsal fin, and caudal fin having more or less of round black spots, and the sides of the head having a peculiar tin-colored metallic luster. In the fall the color is often black or dirty red, and the species can then be distinguished from the dog-salmon by its larger size and by its technical characters. The flesh is rich and salmon-red, becoming suddenly pale as the spawning season draws near.
[7]. For valuable accounts of the habits of this species the reader is referred to papers by the late Cloudsley Rutter, ichthyologist of the Albatross, in the publications of the United States Fish Commission, the Popular Science Monthly, and the Overland Monthly.
Fig. 53.—Quinnat Salmon (female), Oncorhynchus tschawytscha (Walbaum). Columbia River.
Fig. 54.—King-salmon grilse, Oncorhynchus tschawytscha (Walbaum). (Photograph by Cloudsley Rutter.)
Fig. 55.—Male Red Salmon in September, Oncorhynchus nerka (Walbaum). Payette Lake, Idaho.
The blue-back salmon (Oncorhynchus nerka),[[8]] also called red salmon, sukkegh, or sockeye, usually weighs from 5 to 8 pounds. It has about 14 developed anal rays, 14 branchiostegals, and 75 to 95 pyloric cœca. The gill-rakers are more numerous than in any other salmon, the number being usually about 39 (16 + 23). The scales are larger, there being 130 to 140 in the lateral line. In the spring the form is plumply rounded, and the color is a clear bright blue above, silvery below, and everywhere immaculate. Young fishes often show a few round black spots, which disappear when they enter the sea. Fall specimens in the lakes are bright crimson in color, the head clear olive-green, and they become in a high degree hook-nosed and slab-sided, and bear little resemblance to the spring run. Young spawning male grilse follow the changes which take place in the adult, although often not more than half a pound in weight. These little fishes often appear in mountain lakes, but whether they are landlocked or have come up from the sea is still unsettled. These dwarf forms, called kokos by the Indians and benimasu in Japan, form the subspecies Oncorhynchus nerka kennerlyi. The flesh in this species is firmer than that of any other and very red, of good flavor, though drier and less rich than the king-salmon.