Several types of fisheries, especially bottom-set gill nets may occasionally catch these small cetaceans. By-catch levels higher than the EcoQO level are considered to be unacceptable, as they are likely to affect population size of the harbour porpoise in the long term.
Possible measures to diminish levels of by-catch are to reduce the effort of fishing effort using the gears posing most risk to harbour porpoise, and the deployment of acoustic devices (so called pingers) that encourage porpoises away from nets.