The extent of marine mammal bycatch in the Atlantic mackerel fishery is unclear. Bycatch from purse seining and trawling has not been a major issue. The National Marine Fisheries Service notes that while the Atlantic mackerel fishery has minimal interaction with sea turtles, interactions with other marine mammals have been recorded. It has been reported that mortalities and injuries of marine mammals in the Atlantic mackerel fishery exceeded 50% of the potential biological removal of the species. Observers reported dolphin mortalities in the fishery between 1977 and 1991, but the Monterey Bay Aquarium cautions that observer coverage in the fishery is low. Mammal bycatch has been declining, in part due to a shift away from bottom otter trawls, but remains a moderate concern, according to a Monterey Bay Aquarium report from 2011. Atlantic mackerel’s midwater trawl fisheries catch nontargeted fish such as river herring, dogfish, and shortfin squid, but the level of this bycatch is considered small and causes little concern.