Salmon Hatchery

* The Ranunculas nipponicus var. submersus (water crowfoot) belongs to the Ranunculaceae family of freshwater plants. Its blooms are little white flowers that resemble plum blossoms. The waterweed is called baikamo in Japanese and can only grow in clear streams with a water temperature of around 14°C. Therefore, it is found in a limited number of places throughout Japan. 

Ushiwatari River - The salmon’s mysterious journey back to the river of its birth

  The salmon hatchery that uses water from the Ushiwatari River is about 5 minutes by car from Fukuura Station. Ushiwatari River merges with Gakko River. 

  As if impatient for the snow to melt, in early spring salmon fry weighing little more than 1 gram and measuring around 8 centimeters drift down the river of their birth and begin their journey to the expansive ocean. After becoming accustomed to ocean waters at the mouth of Gakko River, which empties into Fukuura Port, they head out to the northern seas. Four or five years later, their long journey ends when the full-grown salmon measuring 70–80 centimeters return to the waters of the Gakko River where they were born.

  Only about five out of a thousand salmon make it back to the river after having migrated tens of thousands of kilometers in northern waters. Thus, only the most vigorous salmon succeed in producing offspring. The river of their birth is also the river where they give life to the next generation and end their own.

  A homing instinct brings the salmon back to the river of their birth, which is one of the many that flow into the Japan Sea along the coast of Hokkaido to the town of Yuza, though it remains a mystery as to why the salmon can unfailingly find the same river in which they were born. It is surmised that perhaps creatures know direction because they possess a kind of internal clock, or can find the southern direction from the position of the sun, or remember the smell of the river, but none of the many explanations have been proven and there is no accepted theory.

  An important task must be completed before the salmon swim upstream. Spring water from Mt. Chokai must be directly drawn to the salmon hatchery. This ensures that during the period from egg collection to incubation, the embryonated eggs are nurtured in hatching tanks filled with fresh water of a constant temperature. A source of spring water nearby the hatchery is enclosed with boards, and the spring water is directly drawn to the hatching tanks through a thick pipe. The association chief, Mr. Kazuo Togashi explains that, “All the water in Ushiwatari River is clear water that flows underground from Mt. Chokai, but we directly provide spring water to the eggs until they are hatched. When they become fry and require lots of oxygen, we use an abundance of water from the Ushiwatari River.”

  In other words, the hatchery salmon are nurtured with pure underground water from Mt. Chokai from the time they are fertilized eggs. Without a doubt, the clear waters of the Gakko River where the salmon are born feel like home to them.