Fish that live in the upper water column of the ocean are targeted by pelagic/ mid-water trawls. The funnel-shaped trawl nets are hauled by either one or two boats (pair trawls).
Pelagic boats generally fish for a single species (unlike the demersal trawls). On very large vessels, fish such as herring and mackerel are pumped onboard the vessel through a large pipe placed in the end of the net.
Smaller vessels bring nets onboard. Once captured, the fish is either kept chilled on board or processed and deep-frozen at sea.
In the UK an industry-science partnership programme is investigating technical measures to reduce bycatch of juvenile mackerel and improve fuel efficiency in pelagic trawls. Certain waters in the UK have been closed to pair-trawling to prevent dolphin bycatch, but is still permitted in other areas of the Channel.