Juvenile seals take a break

Young seals rest, tussle, on the beach

Elephant Seal class of 2025 is arriving on the beach. The young seals, not yet in the breeding population, take over the beach. Adult females are out at sea, foraging, growing the pup that will be born in winter. Bossy bulls are away north, eating, putting on weight to dominate the breeding season. The young seals have the beach to themselves. It’s Juvenile Haul-Out.

This one hauled out over the Labor Day weekend, with a necklace of shark teeth marks scraped across the back of his neck. (Christine Heinrichs photo)

Last season’s pups, now the young of the year, left the beach after learning to swim and dive, in April. After practicing near the beach, at sea they had to master holding their breath longer and diving deeper, to 1,000 feet and more, to hunt for food. Fat weaned pups are buoyant at the start, and have to power down to find the fish and squid that are their prey. As they swim, their blubber becomes muscle.

Every migration they survive, they improve their diving and hunting skills. Two-year-old seals, veterans of four migrations, dive and forage as well as mature seals.

Young seals will fill the beach until late November, when the bulls start arriving for the breeding season. Not all the seals are on the beach the entire time. They come and go. It’s a good time to see seals of various sizes and levels of development. The males are too young to have a full trunk-like nose, but some have the beginnings of one. They are all elephant seals, on their way to maturity.

First migration

About half the young of the year survive this first migration. It’s not an easy journey. They could swim and dive when they left, but they had to navigate to feeding grounds on their own. They had to rely on instinct to hunt for food.

The young seals may have hauled out on other beaches along the way, as they migrated. Islands and remote peninsulas attached to the mainland present attractive new possibilities. Tagged females who later chose different beaches to give birth had stopped at those beaches as juveniles. They are “prospecting” for new, less crowded, locations, to have their pups. Young females are less likely to wean a pup successfully on a crowded beach, and those who fail at raising their  pups are likely to look for a different place the following year.

“The juveniles know what is available from their migrations,” Burney LeBoeuf wrote in The Quest for Darwinian Fitness: A Case Study of Elephant Seals. 

Juvenile Haul-Out

Juveniles were on the beach in spring to molt their skin, then lolled around until May or June, when they slipped away into the waves again. Since then, they have been growing and maturing. They are fat now, their smooth skins filled out.

The last bull left the beach over the Labor Day weekend. He and his brothers will be back in November for the breeding season. Bulls need to gain more blubber, to return at their biggest for the winter breeding season. They head straight for their feeding grounds.

 

In September and October, juveniles are arriving one by one. The immature seals take over the beach for six or eight weeks of rest. It’s a time of relative quiet, although thousands of seals will be on the beach. They sleep. Young males practice sparring, rehearsing for the serious fights of future breeding seasons.

 

These young males take each other on, but the other seals ignore them. (Christine Heinrichs photo)

On the beach, they pile on top of each other. Mostly it’s like a mound of puppies. Occasionally one takes offense, snapping his head around and roaring at the neighbor who rolled over on him. The disruption ripples through the assembled seal pile, then everyone settles back to sleeping again.

Elephant seals aren’t very playful. On rare occasions, I’ve seen one toss a piece of kelp around in a playful way. The young males spar with each other. The fighting isn’t as serious as when mature bulls battle over females during the breeding season, but it’s serious enough to them. Fighting is important to elephant seals – as adults, it determines who gets to breed and who doesn’t.

Visitors often remark on how much the tussling reminds them of their own teenage boys. It’s practice for adulthood.

One was sleeping peacefully when the other picked a fight.

It’s also exercise, which strengthens their bones. Because they spend so much time in the ocean, their bones lose density, a phenomenon that has been observed in astronauts when they spend time living in weightless conditions. Taking time on land twice during each annual cycle keeps them strong. As elephant seals return to land, subject to gravity’s greater pull, their bones get stronger. It’s another adaptation to their unusual life cycle.

No feeding time

Visitors expect to see the seals eating, or returning to the ocean for a daily meal, but there’s no Feeding Show at the viewpoint. These youngsters rest on the beach without interruption for a month or more. No need to hunt for food. They meet all their food and water needs from their blubber, fasting for the entire time.

Long fasts are common among marine mammals. Gray whales fast for six months while they are traveling south from the Arctic to their birthing grounds in Baja California. Elephant seals punctuate their months of constant eating with month-long and longer fasts. While they are on the beach, they don’t eat or drink.

They don’t drink at any time – what would they drink, in the ocean? Their large kidneys filter salt from the prey they eat and maintain their normal tissue balance.

Seals and Sharks

Each fall, adult and sub-adult White Sharks frequent the waters of the Greater Farallones National Marine Sanctuary, north of San Francisco, contiguous with the Monterey Bay NMS off the Central Coast.

Adult White Sharks are seen most frequently in the area between Tomales Point, Año Nuevo Island and the Farallon Islands, where there are lots of elephant seals and sea lions.

White Shark young of the year, the baby sharks born during the last breeding season, and juvenile White Sharks occupy the Southern California Bight and the coastal areas of central Baja Mexico, down to Vizcaino Bay. They start out eating fish, and as they mature, transition to eating marine mammals.

As white sharks get older, bigger and more mature, they need the concentrated food of marine mammal blubber. Juvenile elephant seals, migrating back to the Central Coast, make a good blubber meal.

Ranging from a few hundred pounds to well over a thousand, juvenile elephant seals are also easier prey than mature elephant seals. Especially bulls, at more than two tons. Sharks are stealth predators, attacking from behind and below. They take a bite, and then withdraw to give their prey time to bleed out and die.

If the bite isn’t fatal, the seal escapes, with a scar to tell the story.

This seal survived a terrible wound.

After feeding well on elephant seals in the fall, white sharks migrate out to the Shark Cafe. Sharks take a month to reach it, halfway between Hawaii and Baja California.

Officially called the Shared Offshore Foraging Area (SOFA) the White Shark Café it’s the only place so far identified where adult and sub-adult White Sharks from Mexico and California, males and females, intermingle.

Back in California, elephant seals with sharkbite scars are common on the beach. The Ones That Got Away.