Researchers have shown that levels of anisakid worms -- a common marine parasite -- rose in two salmon species in the Gulf of Alaska and Bristol Bay over a 42-year period. The team discovered this by studying salmon caught, killed and canned from 1979 to 2021. Since anisakid worms have a complex life cycle involving multiple types of hosts, the researchers interpret their rising numbers as a potential sign of ecosystem recovery, possibly driven by rising numbers of marine mammals thanks to the 1972 Marine Mammal Protection Act.