Cherry salmon (Oncorhynchus masu)
Cherry salmon is the most ancient species among all Pacific salmon. This means it has the closest kindred to the common ancestral form, which was similar to rainbow trout and steelhead.
Cherry salmon resemble rainbow trout or steelhead from many points of view. For instance, cherry parr and dwarf males are very similar to small rainbow trout both in their appearance and ecology. Cherry parr even have an orange stripe along their sides, which looks like the well-known pink rainbow stripe of a trout. Although 100% of sea-run cherry salmon die after the first spawning, they stay in freshwater much longer than the rest of the Pacific salmon species, and even retain a tendency toward feeding.
The cherry salmon range is located only on the Asian coast of the Pacific. This is the most thermophilic sea-run salmon; it cannot survive in cold areas. This species is not found north of the Kamchatka Peninsula with its rather mild climate. On the severe mainland coast of the Sea of Okhotsk, this fish is never found north from the Amur River mouth and Sakhalin Island.
In the Amur River, this salmon is rare; it spawns only in some tributaries of its lower reaches such as the Amgun or Anyi. On the other hand, its range stretches much farther to the south compared to other salmon, including even the coast of Korea and Kyushu Island in Japan. In Japan, there are not only sea-run, but also landlocked, river-resident and lake-resident cherry salmon. Japanese call the river-dwelling fish yamame. Yamame can be up to 30 cm long and are numerous in some of the mountainous streams of Hokkaido and Honshu. This fish occupies the niche analogous to rainbow or brook trout.
In the Kamchatka Peninsula and in the central part of Sakhalin Island, cherry salmon are always sea-run; they are rather small, not bigger than pink salmon. In the southern part of Sakhalin this salmon is tiny. The fish of these stocks weigh about 1 kg, and only a few specimens ever exceed 2 kg. This small size is the adaptation to very shallow spawning creeks and brooks. The spawning runs of the fish in these regions occur mostly from the end of May till mid June.
On the mainland coast of the Sea of Japan (in Russia this area is called Primorye), there are two forms of cherry salmon: early (summer) and late (fall). The early form is bigger and predominates north from the 45th parallel. The most numerous summer stocks of cherry salmon inhabit the
Tumnin, Koppi, and Samarga Rivers. Average adult weight in these stocks is 2.5–3 kg. Some specimens can be up to 90 cm long and weigh over 9 kg! The smaller, late cherry salmon form prevails in rivers in the southern part of the mainland range south of the 45th parallel. This late fish enter freshwater in mid-summer, and spawn in September and October.
Some cherry salmon males become mature in freshwater without going out into the sea; their weight is not more than 100 g. Both parr and dwarf males of cherry salmon are called by the local fishermen pestrukha, which means “mottled.” This fish is considered a separate species from the sea-run cherry salmon. Some anglers (not only kids) catch them for fun and food. In populated areas, this harms the cherry salmon stocks.