northern waters; northern seas
Refers to the seas or ocean areas in the north, often used in contexts like fishing, shipping, or geography (e.g., 北洋漁業, northern-sea fisheries).
The northern salmon fishery has opened.
The ship sailed through the rough seas of the north.
northern-sea fisheries
Compound of 北 (north) and 洋 (ocean, sea). The reading ほくよう is the standard on'yomi combination.