Multiple choice The most important pelagic fish found in the North Sea adjacent to U.K. is cod halibut herring mackerel Reveal answer Fill a bubble to check yourself C Correct answer Explanation Pelagic fish live in the water column of the open ocean rather than near the bottom. Herring is a major pelagic species in the North Sea, whereas Cod and Halibut are demersal (bottom-dwelling) fish.