Salmon is a delicious and famous fish species, known for spawning in freshwater streams. Some salmon only live for a short time in rivers before swimming out to the ocean. Once they reach maturity, they return to their original rivers to spawn. Anyone who has seen salmon leaping upstream to return to their birthplace is filled with admiration for their courage and instinctual strength.
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| Mature salmon return to their original rivers to spawn (Photo: frontrangeanglers) |
The vast ocean and long rivers pose a question: how can salmon recognize their original rivers from the expansive sea? This is truly a mystery. Only recently have biologists begun to apply scientific methods to research and find answers.
Some scientists propose a theory based on smell. American biologist Hasler, who often spent his childhood vacations back home, recalls walking along paths filled with the scent of flowers and moss. Now, each time he encounters that aroma, he is reminded of his childhood days. This memory led him to contemplate the return journey of salmon. He embarked on research focused on scent.
After more than 20 years of experiments, it was discovered that each river possesses a unique scent that strongly impacts young salmon. As they grow, they follow the familiar scent trail back to their birthplace.
However, while in the ocean, how do they navigate to return to the place with the familiar scent? This remains an unanswered puzzle to this day.
