Cambrian: Opinion

Elephant seals at Piedras Blancas store up fat like camels of the sea

Weaner pups frolic in the water after March’s rains.
Weaner pups frolic in the water after March’s rains. Special to The Cambrian

Piles of young seals lie around on the beach in March. They are the weaned pups, weaners, preparing for their first migration.

Elephant seal pups are unable to swim when they are born. As newborns, they are in danger of drowning if a high tide engulfs them. This year, rough surf and high tides arrived late, after the pups had gained some weight and maturity. They weren’t at risk of drowning, as they would have been earlier in the season.

The heavy rains in March brought runoff from the ranchlands on the east side of Highway 1. Far from being in danger, weaners practiced holding their breath in the running water. Playful youngsters splashed beneath the culvert pipes.

They spend a lot of the day sleeping. Listen for their barks, and watch the energetic frolicking in the shallow water among the rocks, especially early in the morning.

They don’t get anything to eat at this stage of their lives. They survive on the blubber they gained from nursing for their first month of life. Their metabolism changes, from rapidly storing fat to meeting their energy needs by metabolizing the fat they gained. In some ways they are like desert animals. The way a camel goes without water by metabolizing the fat in its hump, seals live off their blubber.

Their bodies convert some of it into muscle. They also increase the amount of blood and the oxygen-carrying capacity of their muscles, important adaptations to allow them to dive deep. Young seals don’t dive as deep as adults, who can go more than a mile. They need to hunt at 1,000 feet and deeper.

The few adult males still on the beach are at their slimmest. They’ve been without food for three months. They seem exhausted by the rigors of the breeding season, the endless challenges of other males and vigilance over the females. They appear comfortable getting some rest.

They will soon lumber back into the ocean, heading north to Alaska to gorge and gain back the weight they lost over the winter. We won’t see them again until summer, when they return to molt their skin.

Some adult females have already returned to the beach. They, and juveniles of both sexes, will fill the beach during the spring. They shed their skin in patches. It’s called a catastrophic molt, in the sense that the skin comes off in chunks, rather than the less noticeable few hairs at a time.

Weaners stand out in their gray and silvery coats, especially their undersides. They have already molted the black coats they were born with.

At some point, each of the weaners feels the unknown call of the sea and enters the water to begin its first migration. They may not go as far as they will as adults this first year, but they somehow know where to go. A few wash up on local beaches and are rescued. They will get supportive feeding until they are able to take on the ocean for themselves, then be set free.

Nearly half never return, part of the cycle of life. Those that aren’t able to catch enough prey starve, and others become prey themselves. The circle of life.

Those that succeed will find their way back to island and mainland beaches along the West Coast in September. About three-quarters return to the beach where they were born.

Christine Heinrichs’ monthly column is special to The Cambrian.

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