The ringed seal (\(Pusa\) \(hispida\)) is the smallest and most numerous seal species inhabiting the circumpolar Arctic. This marine mammal is uniquely adapted to life in ice-covered waters, relying on a flexible yet specialized diet to exploit the limited resources of the polar seas. Its ability to thrive across its vast range is linked to its capacity to switch between different prey categories as availability fluctuates. Understanding the ringed seal’s diet provides insight into the health and complexity of the Arctic food web, where they serve as a primary energy conduit.
The Core Components of the Ringed Seal Diet
The ringed seal’s diet primarily consists of two main categories of prey: small fish and marine invertebrates. Arctic cod (\(Boreogadus\) \(saida\)) is the most significant fish species, often dominating the diet and frequently accounting for over 60% of the ingested biomass in many regions. This small, energy-rich fish is a preferred item due to its abundance and tendency to aggregate, making it an efficient food source. Invertebrates, particularly various crustaceans, form the second main pillar of their consumption, including pelagic amphipods, euphausiids, and mysids.
Ringed seals are opportunistic feeders, typically consuming only 10 to 15 different species in any area, with only a few considered regularly important. They prefer small prey, generally consuming fish in the 5 to 10-centimeter range and crustaceans between 2 and 6 centimeters.
How Diet Changes with Age and Season
The composition of the ringed seal’s diet shifts considerably based on the seal’s life stage and the time of year. Younger seals, including pups and juveniles, consume a greater proportion of smaller, slower-moving prey, relying heavily on crustaceans like amphipods. This preference for invertebrates reflects the young seals’ smaller size and less developed hunting skills.
Seasonal changes in sea ice coverage and prey migration drive distinct annual shifts in adult feeding patterns. During winter and early spring, when the sea is heavily ice-covered, cod family fish dominate the diet. Conversely, the open-water season of summer and fall sees an increased importance of invertebrates, which become more accessible. Seals also reduce feeding during the spring molt (mid-May to mid-July) as energy is redirected toward shedding their coat.
Hunting Strategies and Foraging Habitat
Ringed seals are solitary hunters that have evolved specific methods to forage beneath the Arctic ice. They are strongly associated with sea ice, utilizing it to create and maintain breathing holes, or aglus. These holes are kept open by their stout claws, even through thick ice, allowing them access to the water column for feeding.
Foraging dives are repetitive and frequently target continental shelf waters, often reaching depths of 35 to 150 feet or more. They appear to target smaller, non-schooling Arctic cod, a behavior that contrasts with larger predators. Foraging success is maximized through visual hunting in low-light conditions, with deeper dives common during the midday hours of the dark winter. During the open-water period, they exhibit pelagic feeding to replenish fat reserves, switching to increased benthic foraging when ice cover returns.