In Oregon, the breeding season for harbor seals begins in mid-April which corresponds with the season's first harbor seal pups showing up on Oregon's beaches. The pups weigh about 25 pounds at birth, but they grow quickly, doubling their weight within the first month. The mother's milk is about 40% fat, so she must forage for food as often as possible to keep her energy up and provide for her pup. While she is in search of food, she will leave her pup to rest on the beach (like all newborn babies, seal pups need a lot of sleep). Though you may not be able to see her, she is always nearby. Well-intentioned people sometimes think that a seal pup alone on the beach has been abandoned by its mother, but this is rarely the case. If the pup is moved, it has no chance of reuniting with its mother. If you see a seal pup on the beach, give it plenty of space and leave it alone. On the Northern Oregon Coast you can call the Seaside Aquarium at (503) 738-6211 and someone will post signs around the pup encouraging everyone to stay away. If you are elsewhere, you can contact the Marine Mammal Stranding Network Hotline at 541-270-6830.
Seal pups actually begin their "lives at sea" in small tide pools, bays, or estuaries where they spend their first four weeks of life learning to hunt and becoming self-sufficient. After this first month, the mother leaves the pup and continues on her way.
The pup's whiskers (also call vibrissae) play an integral part in helping them find, track, and catch their prey. The vibrissae are incredibly sensitive, and function as a kind of underwater "radar sense." Studies have shown that they not only enable the seal to discern the shape and size of a fish, but also allow the seal to track the fish even up to 35 seconds after the fish has passed by. As you might imagine, this is incredibly useful in murky or deep water.
Young pups start off feeding on small sculpins and surf perch, but as they get older their diet varies and includes such items as sole, flounder, hake, cod, herring, octopus and squid.
