Puffins depend on dense schools of small, energy-rich “forage fish” that convert plankton production into food usable by seabirds. The Atlantic Puffin in the North Atlantic feeds primarily on species such as sandeels (Ammodytes), capelin (Mallotus villosus), and juvenile herring. These fish are ideal prey because they are lipid-rich, swim together in dense schools, and typically occur in the upper water column (e.g., less than 100 m) where puffins can reach them by diving. Atlantic puffins will also take invertebrates, including squid and krill, especially during the winter season. In the North Pacific, the Horned Puffin, Tufted Puffin, and Rhinoceros Auklet consume a broader mix of forage species. Common prey includes Pacific sand lance, capelin, juvenile walleye pollock, anchovy, smelt, and small squid. In general, these prey are nutritionally valuable due to their high fat and protein content, which supports rapid chick growth and fuels the high metabolic demands of diving seabirds.
The availability of these prey depends strongly on ocean conditions. Forage fish tend to aggregate along productive fronts, upwelling zones, and shelf edges, where nutrients drive plankton blooms and high productivity. Their vertical position in the water column is also critical: many species migrate daily, rising toward the surface at night or during certain light conditions, making them more accessible to diving birds. Abundance and distribution of forage fish can shift rapidly with sea temperature, climate variability (e.g., marine heatwaves or El Niño events), and ocean stratification, which influence plankton productivity and larval fish survival. Overfishing of forage stocks can further reduce availability, while mismatches between peak fish abundance and seabird breeding can limit chick provisioning. Thus, puffins are tightly linked to dynamic ocean systems that control when and where their prey can be found.