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Every October, thousands of salmon assemble at the mouth of the Frese River in Canada and then swim upstream to their birthplace. In front of the fish's "lateral line is perceptible enough."

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Every October, thousands of salmon assemble at the mouth of the Frese River in Canada and then swim upstream to their birthplace. On the way in front of the fish's "side line" is enough to sense the speed of the water flowing in, they are greeted by countless rapids and shoals, stone walls and dams, as well as the blood basin mouths of sharks and whales, and the dense nets of fishermen.

They can lose their lives at any time, but year after year they fight against the current, and they follow this tragic journey of life one after another. In fact, not only salmon, but most fish have this special migratory behavior. Why would they risk their lives to migrate?

Scientists have put forward many views on this. There is an opinion that the long-distance migration of fish is mostly caused by the action of water currents.

First of all, for juvenile migratory fish, they lack the necessary motor ability to fight with strong currents, so they can only be "held hostage" by the currents to move.

Second, the current largely influences the migration of many adult fish. It should be noted that because the sensory organs on both sides of the fish's body- the "lateral line" is very sensitive to the stimulation of the water flow, which can help the fish determine the speed of the water flow and identify the direction, so different fish respond differently to the stimulation of the water flow, some against the current, some down the river.

Another view is that in addition to being affected by the external environment, the migration of fish may also come from the physiological needs of the fish itself, and this migration is mainly carried out during the reproductive period, which is called reproductive migration, and the migratory behavior of salmon belongs to this list.

When the gonads of a fish have reached a certain stage of development, the sex hormones secreted into the blood by the reproductive glands will play a role, forcing it to swim to the waters along the coast where the water temperature is high and the salinity is low to spawn. After arriving at the spawning ground, they often do not care about resting, and dig pits in pairs to lay eggs. After laying eggs, they died exhausted.

There is also the idea that sunspots also have an effect on the migration of fish. Scientists have found in their research that the intensity of sunspot activity affects the heat emitted by the sun and the number of particles emitted by the sun, and this change can lead to changes in water temperature by causing changes in atmospheric circulation.

The researchers observed that when sunspot activity is intense and atmospheric and sea temperatures rise, the cod's migration route is greatly affected. Studies have shown that sunspots produce intense activity every 11 years, and the migratory route of cod also changes every 11 years, and the cycle of change between the two coincides, indicating that there may be a correlation between the two. #三文鱼 #

Every October, thousands of salmon assemble at the mouth of the Frese River in Canada and then swim upstream to their birthplace. In front of the fish's "lateral line is perceptible enough."
Every October, thousands of salmon assemble at the mouth of the Frese River in Canada and then swim upstream to their birthplace. In front of the fish's "lateral line is perceptible enough."
Every October, thousands of salmon assemble at the mouth of the Frese River in Canada and then swim upstream to their birthplace. In front of the fish's "lateral line is perceptible enough."

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