Seema

Taxobox
name = Seema, or cherry salmon


image_width = 300px
regnum = Animalia
phylum = Chordata
classis = Actinopterygii
ordo = Salmoniformes
familia = Salmonidae
genus = "Oncorhynchus"
species = "O. masou"
binomial = "Oncorhynchus masou"
binomial_authority = (Brevoort, 1856)

Seema, also sima and sema (Russian сима, Japanese サクラマス or ヤマメ), Japanese salmon, Masu salmon, or cherry salmon, "Oncorhynchus masou", is a salmon of the western Pacific Ocean: (Kamchatka, Kuril Islands, Sakhalin, Primorsky Krai, Korea, Japan). A landlocked subspecies commonly called the Taiwanese salmon or Formosan salmon ("Oncorhynchus masou formosanum") also exists in Taiwan.

This fish prefers a temperate climate, around the area of 65° N - 58° N, and in the sea, it prefers a depth range of 0 - 200 m.

Appearance

A seema which has reached sexual maturity has a darkened back, and the stripes on the body sides become bright red with crimson tinge to merge on the abdomen into one common longitudinal band of lighter color. It is for this reason that it was given the name Cherry Salmon.

As adults, seema tend to weigh 2 to 2.5 kg and measure roughly 50 cm in length. [Augerot, X., Atlas of Pacific Salmon, University of California Press, 2005.] The maximum size that can be attained by this species (which is in the region of Primorsky Krai) is 71 cm long and 9 kg in weight. They are called Cherry salmon for their redish color.

Life cycle

Like other Pacific salmon, its life cycle is subdivided into marine and freshwater periods; in rivers, this species lives from 1 to 3 years and can form living fresh-water forms. The sea life cycle, depending on the age of the young, continues for 2 to 3.5 years. In the sea, the seema feeds intensely on crustaceans, less often on young fish. On attaining sexual maturity, in its third to seventh years of life it enters rivers to spawn. Its spawning run starts earlier than that of other salmon species.

After spawning, most passing fish die, and those that remain alive (preferentially dwarf males) participate in spawning next year, too. Emerging from the nest, the young do not roll into the sea but remain in spawning areas, in the upper reaches of rivers, and on shallows with weak currents. The young move to pools and rolls of the river core to feed on chironomid, stone fly and may fly larvae, and on air insects. The seema rolls into the sea in its second, occasionally even third year of life.

Economic importance

This salmon, like most others, is a highly commercial species caught in fisheries, raised for aquaculture, and sought after as a game fish. It is marketed fresh and frozen and is often eaten broiled or baked.

The Taiwanese subspecies

The Formosan land-locked salmon ("Oncorhynchus masou formosanus") (台灣鮭魚) is a subspecies of the seema found in Taiwan. This subspecies is critically endangered, being at high risk for extinction, and is protected in its native habitat. In fact, the Formosan land-locked salmon is one of the rarest fish in the world. Once a staple of the Taiwanese aborigine diet, there are now barely more than 400 of these type of salmon left. Overfishing has led to its decline. Conservationists are trying to save this subspecies which is threatened nowadays mainly by pollution.

The Formosan landlocked salmon is a subspecies with a legacy from the last Ice Age, becoming landlocked during the glacial epoch in frigid mountain streams, and thus its discovery in Taiwan, a subtropical island, was truly a miracle in the history of biology. This fish needs clean cold water under 18 degrees Celsius to thrive.

Formosan landlocked salmon are about a foot in length and inhabit cold, slow-flowing streams with gently sloping beds at elevations above 1,500 m, such as the Chichiawan Stream and the Kaoshan Stream (formerly named Hsuehshan Stream/Wuling Stream) in the upper reaches of the Tachia River.

ee also

* Trout
* Biwa trout (subspecies)

References

* [http://www.fishbase.org/Summary/SpeciesSummary.cfm?ID=242&genusname=Oncorhynchus&speciesname=masou%20masou FishBase]