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How do Atlantic salmon migrate between rivers and the sea?
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Migration
A herd of common wildebeest (Connochaetes taurinus) migrating across a dusty savanna in Africa. The animal is a keystone species (i.e., a species with a disproportionately large effect on its biological community) in plains and acacia savanna ecosystems from southeastern Africa to central Kenya.
Atlantic salmon are anadromous fish, meaning they spend most of their lives in the sea but migrate to fresh water to spawn. Their migratory cycle involves several distinct stages:12
- Freshwater Development: Salmon spawn in cold, clear rivers or lakes, where eggs are laid in gravel beds. Young salmon remain in fresh water for two to six years.1
- Migration to the Sea: As they grow, juveniles (parr) transform into smolts and move down rivers toward the ocean.2
- Marine Life: Adult salmon typically spend one to three winters in the sea, where they grow and mature.1
- Return to Spawn: When ready to spawn, they return to their natal river. They navigate using environmental cues, including the Earth’s magnetic field, the Sun, and water chemistry. The sense of smell is particularly vital; through early experiential imprinting, they recognize the specific odours of their home stream.21
While some Atlantic salmon die after a single spawning, others survive to return to the sea and may migrate to their natal river multiple times in successive years.12