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Seema, Oncorhynchus masou

Seema, also known as Sima and Sema Japanese salmon, Cherry salmon, or Masu salmon (Oncorhynchus masou) is a salmon of the western Pacific Ocean which includes the Kuril Islands, Kamchatka, Primorsky Krai, Japan, Korea and Sakhalin. In Taiwan a landlocked subspecies known as the Taiwanese salmon or the Formosan salmon (Oncorhynchus masou Formosanum) also exists.

The Seema favors a temperate climate that is around the area of 65 degrees north to 58 degrees north in the sea. The Seema also favors a depth range of 0-656 feet.

When a Seema reaches a sexual maturity its back darkens and the stripes on the sides of the body become bright red with crimson tinge that merges on the abdomen into one simple longitudinal band of a lighter color. This is the reason the Seema is sometimes referred to as the Cherry salmon.

An adult Seema may weigh 4 to 4.5 pounds and may measure 20 inches in length. The largest size that may be reached by the Seema is 31 inches, and it can weigh up to 19 pounds.

The life cycle of a Seema is subdivided like other Pacific salmon. Their life is subdivided into the marine and freshwater periods. The Seema lives in rivers for 1 to 3 years. Depending on the age of the young, the sea life cycle continues for 2 to 3.5 years. The Seema feeds primarily on crustaceans in the sea. In the Seema’s third to seventh year of life the fish enters the rivers to spawn. The spawning run begins sooner than those of other salmon species. Most passing fish die after spawning, and those that continue to exist (superior dwarf males) take part in the spawning the following year. After coming out from their nest, young Seema remain in spawning area such as upper reaches of rivers, and on fragile currents. They move to the rolls of the river core and on to pools to feed on chironomid, may fly larvae, air insects, and stone flies. In the Seema’s second and even third year of life they roll into the sea.

Like most other salmon the Seema is highly commercialized and is caught in fisheries and raised for aquaculture. The Seema is a gamefish and is marketed fresh and frozen.

The Formosan Land-locked salmon (Oncorhynchus masou formosanus) is found in Taiwan and is a subspecies of the Seema. This subspecies is endangered. The fish has a high chance of extinction though it is protected in its habitat. Once a major part of a Taiwanese aborigine diet there are hardly more than 400 of the Formosan Land-locked salmon, making this one of the world’s rarest fish. The subspecies are threatened by pollution; however, conservationists are trying to save them.

Formosan Land-locked salmon had a legacy from the last Ice Age. After becoming landlocked in the frigid mountain streams the fish was found in Taiwan, which is a subtropical island. In the history of biology it is considered a miracle. To thrive, this fish needs cold, clean water below 64 degrees Fahrenheit.

This fish inhabits slow-flowing streams with considerate sloping beds above 4,921 feet in elevation such as the Kaoshan Stream (also known as Hsuehshan Stream/Wuling Stream) in the upper reaches of the Tachia River and the Chichiawan Stream. The Formosan Land-locked salmon can be up to a foot in length.

Image Caption: Cherry Salmon in Lake Tanzawa, Kanagawa Prefecture. Credit: Wikipedia

Seema Oncorhynchus masou


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