fishery inspection boat; fishery patrol boat
A vessel used by authorities to monitor fishing activities and enforce regulations at sea.
The fishery inspection boat is patrolling to check for illegal fishing.
巡視船 is a general patrol boat, often used by the coast guard, while 漁業監視船 specifically monitors fishing activities.
Compound of 漁業 (fishery) + 監視 (inspection/surveillance) + 船 (boat).