Kamchatka steelhead salmon (Parasalmo penshinensis)
When the Siberian Cossacks in the end of the 17th century first came to the Kamchatka Peninsula, they were simply astonished by the number and diversity of “salmon breeds.” The rarest and most precious fish, entering rivers of the region, reminded the knowledgeable people of “noble” Atlantic salmon, which bears the Russian name “syomga.” The Sea of Okhotsk at that time was called in Russian Penzhinskoye More, the Sea of Penzhina. Penzhina is the name of a large river, flowing into the northeastern corner of the sea. This new salmon got the name Penzhinskaya syomga (Penzhina salmon) from the name of the sea — not the river. No other salmon species from the Pacific Ocean was called semga.
A brightly-colored, voracious, landlocked fish with a native name mykyz was also well-known in Kamchatka. A Russian version of this native name is “mikizha.” The first scientist who made a description of these species in 1740–1741 was the famous Georg Steller, the naturalist of the Second Bering Expedition. Much later, in the end of the 20th century, the scientists had found out, that both syomga and mikizha are different forms of one and the same trout species.
Anadromous steelhead and resident rainbow trout were described on the Pacific coast of North America in 1816 as Salmo gairdneri and Salmo irideus. These two forms were also first considered two separate species; later they were “converged” into one. At last, all these “noble Pacific trout” from the waters of Asia and America became one species, Parasalmo mykiss.
The scientific name of the species originated from its native name, also used by George Steller. Recently, some American fish biologists have placed this species into the genus of Pacific salmon — Oncorhynchus. The most Russian fish biologists do not agree with that change.
The steelhead salmon is the anadromous form of the Kamchatka rainbow trout – same as the European sea trout is anadromous brown trout. Steelhead inhabit rivers of the Western Kamchatka, flowing into the Sea of Okhotsk from the Amanina River in the north to the Bolshaya River in the south. There is unproved information that some steelhead stocks are also present on the eastern, Pacific side of the peninsula.
Anadromous fish in studied rivers form united, indivisible populations with landlocked rainbow trout. The spawning grounds of Kamchatka steelhead are situated not too far from the sea — usually at 15–80 km upriver. Typical steelhead rivers are usually less than 150 km long, have dark-colored water, and not too much gradient. In bigger rivers steelhead enter only some marshy tributaries of their lower reaches.
Young steelhead spend the first two to three (sometimes four) years of their lives in freshwater. During this time they look like small rainbow trout. Their downstream migration into the sea occurs in June. The first sea journey most often lasts for two or three years. The durations of the second and next sea migrations are shorter than the first one; usually the Kamchatka steelhead feed in the sea for only three-and-a-half to four months, from June until October.
Severe climate of the Western Kamchatka and low winter water temperatures in the Sea of Okhotsk notably restrict migration patterns and, in general, the possible population structure of the species. The majority of Kamchatka steelhead enter freshwater when it is already cold The typical water temperature at the beginning of the main run is 7°C, at the end less than 2°C.
A big part of the Kamchatka steelhead populations consists of repeatedly spawning specimens, which can reproduce up to seven times during their lives! The average size of Kamchatka steelhead in the north of the range is about 80 cm, the weight 6.5 kg. The biggest steelhead caught in Kamchatka was slightly longer than a meter and weighed about 15 kg. Kamchatka steelhead of the same length are much heavier compared with specimens from American populations.
The most numerous steelhead stocks are in the north of the species range, in the territory of the Tigilsky district of the Koryaksky National Okrug. Quite high number of steelhead enter rivers near the Utkholoksky Cape (Utkholok, Kvachina, and Snatolvayam), and also the Sopochnaya and Saichik rivers. In the central part of the range, in the territory of the Sobolevski district, steelhead stocks are not well-studied. Steelhead-type rivers of this area are the Krutogorova, Bryumka, Udova, and Kekhta. In the southwest of the peninsula (Bolsheretski district), steelhead used to exist in the Utka, Mitoga, and Amchagacha rivers. Now the numbers of steelhead here are low because of illegal fishing pressure.
Fresh from the sea Kamchatka steelhead is bright silver with large dark spots. After entering fresh water it is gradually acquiring its spawning colors. The ales begin to darken before the females, which often retain fresh silver marine colours far upriver. In a month, the fish have pearly pink strip on the sides of the body and pink spots on the gill covers. Later the general tone of the body becomes pinkish, the back and head darken, and the stripes on the sides become bright crimson. The spawning fish look like large rainbow trout. After spawnoing they look unpresentable – they are skinny and almost black in color. Such kelts begin to actively eat already in the river; Having gone to sea, they quickly eat off at a plentiful feed.
Kamchatka steelhead is listed in the Red Book of Russia in the Category II (rare species with decreasing numbers). In many river drainages of the Kamchatka Peninsula steelhead stocks are under the threat of disappearing. A lot of populations are still poorly studied and the only existing information on many rivers is that this species is currently present, or was once present.