Masu Salmon Reproduction

Unlike all other Pacific Salmon, the Masu Salmon migrates from the ocean to the rivers and streams in the spring.

How They Differ From Other Pacific Salmon

All other species of the Pacific Salmon spawn in late summer and continue in to late fall. Some species even survive to spawn another year, some even as many as three times.

However, like other Pacific Salmon, its life cycle is subdivided into marine and freshwater periods. When the Masu Salmon is living in rivers and streams, it feeds and seeks shelter until it is between one to three years old and ready to migrate to the ocean.

However, not all Masu Salmon migrate to the ocean. Some spend their entire lives living in fresh water. The Formosan Salmon is a subspecies of the Masu Salmon that spends its entire life living in fresh water.

Once the Masu Salmon, of the sea going species, makes it to the ocean, it can spend anywhere from two and a half years to three years there before making it inland to spawn in freshwater rivers and streams.

All said, Masu Salmon are usually about seven years old once they reach their spawning year.

Not All Masu Salmon Die

Not all Masu Salmon die after spawning. A few males managed to live to spawn the next year. Some research reports state that all Masu Salmon die after spawning. This is a misrepresentation of the truth for several reasons.

The first being that most Pacific Salmon die after spawning: both males and females. And, those that do live to spawn another year may be as little as 2 percent. At best, 15 to 10 percent of Chinook may live to spawn another year.

Young Masu Salmon

Young Masu Salmon stay close to their redd before finding shelter and seeking out food. They remain in the river system for as long as three years before making their way to the ocean.

They remain in the upper end of their birth rivers and streams for the first year or so before moving downstream and eventually to the ocean. The Masu Salmon eventually heads into the sea in its second, occasionally even third year of life.

Sub Species and Variations

Learning about Masu Salmon can be very difficult because there are several variations and sub species. The differences in appearance and habitat is what adds to the confusion.

A river bound variation looks very different in appearance than an ocean going variety.

Oncorhynchus masou rhodurus: Also known as the Biwa trout

Oncorhynchus masou masou: The Masu Salmon