Seals are marine mammals that consume a varied diet, primarily of marine life. As predators, they occupy an important position in marine food webs. Their feeding habits demonstrate adaptability, allowing them to thrive in diverse ocean habitats.
Common Fish in Seal Diets
Seals consume a wide range of fish species, with specific types depending on local availability. Harbor seals, for instance, are opportunistic feeders that commonly prey on walleye pollock, Pacific cod, capelin, Pacific herring, and sand lance in Alaskan waters. They also consume flatfish like flounder and sole, salmon, and sculpin. In the Gulf of Maine, harbor seals frequently eat silver hake, red/white hake, and Atlantic herring.
Grey seals in the North Atlantic often feed on benthic or demersal species, which live on or near the seabed. Sand eels are a significant part of their diet in many regions. Other common fish for grey seals include cod, haddock, whiting, pollock, and various flatfish. These seals eat what is plentiful and nearby, making them generalist feeders.
Influences on a Seal’s Menu
A seal’s diet is highly variable and influenced by several factors. Different seal species have adapted to varying environments, leading to distinct dietary preferences; for example, crabeater seals primarily consume krill, while elephant seals mostly eat fish and squid. Geographic location plays a significant role, as prey availability differs across regions. Seals inhabiting colder waters, such as ringed seals and harp seals, may consume more fish and crustaceans, while those in warmer waters often have a wider variety of prey.
Seasonal changes also affect what seals eat, often aligning with the migratory patterns of their prey. During certain months, schooling fish like herring and sand lance might be more abundant in their diet, shifting to benthic fish at other times. The age and size of a seal can also influence its diet, as larger or older seals may target different prey than younger individuals. The overall abundance of specific fish populations in a given area dictates the primary components of a seal’s menu.
Beyond Fish: Other Food Sources
While fish constitute the majority of a seal’s diet, they are not the only food source. Seals regularly supplement their meals with marine invertebrates. Common examples include squid, octopus, and crustaceans such as shrimp and crabs. Harbor seals, for instance, are known to eat squid, mollusks, and crustaceans.
Some larger seal species occasionally prey on other vertebrates, though this is less common for most seals. Leopard seals, for example, are apex predators that may consume smaller pinnipeds and birds, particularly penguins. Grey seals have also been observed to eat seabirds. Fish remain the dominant and most consistent food source across most seal species.
How Seals Hunt and Eat
Seals possess adaptations and hunting strategies that make them efficient predators in their aquatic habitats. Their streamlined bodies allow for speed and agility underwater, enabling them to pursue and capture fast-moving prey. Excellent underwater vision and hearing assist them in locating fish in their marine environment.
Sensitive whiskers, known as vibrissae, are important for detecting prey, especially in dark or murky waters. These whiskers can sense subtle water movements and vibrations caused by swimming fish. Once prey is caught, seals swallow fish whole or tear larger catches into manageable pieces. Their specialized teeth are suited for gripping and sometimes crushing harder-shelled prey like crustaceans.