LAUSR

As gastrointestinal parasites affect the health of marine mammal species, they are a potentially consequential stressor. Although they are infrequently identified as a cause of mortality, gastrointestinal parasites could drive cryptic declines in individual fitness—including declines in nutritional status—by acting synergistically with other stressors. Nematodes in the family Anisakidae are ubiquitous throughout the world's oceans and are transmitted to marine mammal hosts through the consumption of fish and cephalopod prey. We sought to assess whether marine mammals face a rising risk of gastrointestinal infection due to an increase in anisakid burden of their prey species. We used data compiled from a recent meta‐analysis of anisakid abundance in fish and invertebrates from 1967 to 2015. We reviewed the diets of 113 marine mammal species to identify their known prey species. We extracted data on anisakid burden for each of the prey species and tested whether anisakid abundance in these intermediate hosts had increased over time. Our findings suggest that Anisakis spp. abundance has increased over the past half‐century, while Pseudoterranova spp. burden showed no significant change. Our findings suggest that the risk of Anisakis spp. infection is increasing for marine mammal hosts.