降こう海かい

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.

• サケの稚ち魚ぎょは春はるに降こう海かいする。

  Salmon fry migrate downstream to the sea in spring.

• 降こう海かい型がたの魚さかなは海うみで成せい長ちょうする。

  Sea-run fish grow in the ocean.