Young elephant seals show up as bulls leave SLO County beaches

A few bulls remain on the beach at the elephant seal breeding grounds north of San Simeon, sharing it with youngsters that are arriving daily for their fall haul-out.

Late summer is a transition time for elephant seals.

Adult male elephant seals are completing their annual molt and setting off on their migration north. Juvenile seals replace them, spending the fall resting on the beach.

The seals don’t indicate whether they take notice of California’s heat wave or smoky air. Visitors find a respite from the heat at the beach, but Highway 1 to the north may be closed due to the Dolan Fire burning near Big Sur.

Without docents to chat them up, visitors rely on free brochures and the colorful signs to learn about the seals. The Piedras Blancas viewpoint continues to welcome all who stop to see the seals.

Elephant seal bulls still fighting on the beach

Bulls spend most of their summer resting on the beach, but some can’t resist a skirmish, even though there are few females and it’s not breeding season. They tussle in the water as well as on the sand.

The juveniles stay clear of the fighting. They’ve been at sea since their spring molt. Many are small, but every survivor is a success story.

Each seal spends four to six weeks on the beach, but they come and go individually. Juveniles will occupy the beach through the fall.

Most leave when the bulls return in November for the breeding season, but a few linger.

Young seals are survivors

The smallest seals are the young of the year, the pups that were born during the previous breeding season.

Only about half survive the first migration. Those that don’t return were either eaten by predators, unable to catch enough food to survive or fall victim to some malady.

Even on their first migration, pups are able to dive as deep as 4,000 feet.

We don’t know how they find their way north to hunt fish and squid along Canada’s west coast. Some get as far north as Alaska, where the adult males feed.

Marine mammals migrate north

How seals find their way remains mysterious to us, but the seals have figured it out. The marine environment is very structured as to temperature, density, salinity and other variables that aren’t obvious to humans, but may be significant to the seals that make the ocean their home.

“It’s a complex 3-D structure, although it’s not the physical structure of rocks and trees,” is the way UC Santa Cruz researcher Dan Costa, who leads the Costa Lab, puts it.

“Think about the ocean as having weather, like the air,” Costa said. “Elephant seals have two migrations each year, as far as 5,000 miles each time. In the ocean, they forage and gain weight to get them through the breeding season.”

Typically, a seal has a series of feeding dives, followed by processing dives. Elephant seals feed on the downward dive, then drift to process the food they have caught and eaten.

Males feed along the continental shelf, where it’s shallower — 500 to 2,000 feet deep. Females dive deeper and longer, out in the open ocean.

That’s their life at sea: eating, digesting and eating again. On the beach, they don’t eat at all, instead living on their blubber.

This story was originally published August 26, 2020 at 5:05 AM.