Island-class OPVs after the Cod Wars

Would Island-class OPVs have reduced the need to deploy frigates and destroyers for fishery protection?

Yes. They were intended to handle this work without exposing expensive frigates to the severe collision damage experienced during the Cod Wars.

The Island class offered fishery protection vessels whose damage would cost less to repair than damage to a frigate or destroyer. Their procurement is linked directly to the Royal Navy's experience of ships being battered in the Cod Wars. The account describes unusually severe frigate attrition from those confrontations. A cheaper patrol hull would keep this recurring duty from consuming so much of the combat fleet's availability.