noun, noun or participle which takes 'suru'
downstream migration to the sea
Biological term for fish or other aquatic animals moving downstream to the ocean, often as part of their life cycle. Used as a noun or with する.
サケの稚魚は春に降海する。
Salmon fry migrate downstream to the sea in spring.
降海型の魚は海で成長する。
Sea-run fish grow in the ocean.