Coho or silver salmon (Oncorhynchus kisutsch)
It is easy to distinguish coho salmon from bright chum salmon by the small black dots on their backs and the upper parts of their caudal fins, and by their wider caudal peduncles. Contrary to Chinook, these dots never cover the lower part of coho’s caudal fin, and the gums of its lower jaw are not black. After about two weeks spent in fresh water, silver fish turn light pink or pale brown — males do this before females. Some fish in this period can bear slight brown stripes across their sides. Dark coho in full spawning colors have no stripes — they are red-brown or dark crimson fish. The males in this phase have a wide body and a big “nose” (kype), formed on the snout and hanging over the tip of the lower jaw.
Unlike pink and chum salmon, young coho do not migrate out into the ocean in their first summer. Coho parr spend one or two, sometimes even three years of their life in freshwater, in deep pools with slow current and in sloughs; the typical coho habitat often looks like real “pike-water.” In rivers, coho parr prefer quiet, deep places with a slow current, near snags, log jams, or other cover. Often you can meet the schools of salmon fingerlings in sloughs without any current, even in some lakes that are connected with a river. Coho are more closely ecologically connected with freshwaters than pink or chum salmon. In several lakes of the Kamchatka Peninsula and Bering Island, there are lake-resident populations of coho. The landlocked fish are smaller than the ones from the anadromous stocks.
Silver salmon usually spend one whole year and one more summer in the sea. Most smolts leave freshwater in June and come back into the river in late summer or fall of the next year. The average migration speed of bright coho in a river is about 15 km a day. In the sea, adult coho feed mostly on small fish. The record weight for silver salmon is about 14 kg; the average fish on the mainland coast of the Sea of Okhotsk is about 3–4 kg, and in Kamchatka 2.5–3 kg. Some fish enter freshwater after only two or three months spent in the ocean. These are the grilse — small anadromous males that weigh less than 1 kg.
The run of silver salmon normally begins in the first days of August; the main run in the lower part of the rivers near Magadan and Okhotsk is starting about mid August. In many rivers of Kamchatka it occurs one week later. A lot of fish enter freshwater in September, and quite a few also come in October and even in November. Among these late-run fish there are lots of grilse.