The UK introduced new rules in 2021 making it a mandatory requirement under fishing vessel licence conditions for fishers to report any marine mammal bycatch to the MMO. On the introduction of this requirement, communications were sent out by Defra, the Devolved Administrations and the MMO to ensure that industry understood the new obligations. Responsibility for enforcing licence conditions in Scotland and Northern Ireland is a matter for the Devolved Administrations. The Sea Mammal Research Unit have carried out monitoring of pelagic trawlers targeting herring and mackerel for a number of years and reported no bycatch of marine mammals in these fisheries in recent years, whilst other sections of the UK pelagic fleet are working on bycatch mitigation projects to reduce the likelihood of these events occurring more broadly.