Seasons in the Sea - A month-by-month guide to Central California sea life

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Gray whale fluke: Image credit-Steven Swartz, NOAA

Marine mammals

in June

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Whales and dolphins

By June, you can often see humpback whales in Monterey Bay, hunting large schools of anchovies or krill over the continental shelf.

Blue whales, on the other hand, are still fairly sparse, with the first spring migrants beginning to arrive from Central America. Blue whales don't usually become common on the Central Coast until krill are both abundant and large, having matured and reached their maximum size. Only then is it worthwhile for blue whales (which eat almost entirely krill) to congregate on the Central Coast.

Among the smaller marine mammals, you can occasionally see pods of Dall's porpoise or harbor porpoise swimming rapidly along the sea surface. These spring and summer visitors are usually out looking for market squid, hake, and young rockfish.

Young harbor seals venture out on their own

In June you are likely to see, young harbor seals exploring, as they begin to leave their pupping beaches and explore the surrounding coastal areas. Not quiet weaned, these active pups require increasing quantities of milk from their nursing mother.

If a nursing female harbor seal has to travel too far to find food, or if she can't find food at all, she may not be able to express enough milk for her pup. This sometimes means that the pup can't put on the fat it needs to survive its first few months on its own. Even during normal years, when plenty of food is available, about one out of five young harbor seals will die during their first year.

El Nino years are particularly hard on both adult and young harbor seals. In the spring of 1998, during a strong El Nino event, the harbor-seal rookery at Point Pinos had half as many adult and young seals as during the previous year.many of the pups will have been weaned, and will be starting to forage on their own. A few pups will continue to nurse for another month or two before heading out on their own.

By late June (after about six weeks of nursing), the young harbor seals will be fully weaned and have to forage on their own. At this point, they will leave the pupping areas and swim along the coast, exploring their surroundings and looking for good hunting areas.

Even after they head out on their own, it takes the young harbor seals a month or two to become efficient hunters. During this time, they rely on the fat they stored up while nursing.

Young harbor seal pups are very inquisitive, and will often swim up to surfers and divers and stare with wide-eyed curiosity. Some of the youngsters gather at wind-protected haul-out areas, such as sand bars in Elkhorn Slough and other estuaries. There they feed on the young fish that have been growing in the slough waters all spring and are heading back out to sea in June.

Just after the harbor seal pups are weaned (in June or July), adult male harbor seals arrive at the pupping areas. Both male and female harbor seals are typically solitary animals. Pretty much the only time of year you will see large groups of males and females in one place is when they are moulting or mating.

Harbor seals mature at between three and six years old. During early summer, you can sometimes see pairs of harbor seals mating in the kelp beds or other nearshore areas. As with sea otters, mating is a boisterous process, involving lots of rolling, splashing, diving, and underwater acrobatics. [Add more info on harbor sea mating]

Although a single male harbor seal may mate with several females (and vis versa), harbor seals do not maintain harems, as do elephant seals or California sea lions. In fact, the males and females may never even meet on land.

Although harbor seals have a gestation period of about seven to nine months, female harbor seal do not become "pregnant" until a month or two after mating, because of a process known as "delayed implantation." This means that the fertilized egg does not attache to the wall of the uterus and begin developing until several months after mating. This process may provide the animals with a natural form of "birth control" because the egg may never implant if conditions are such that the mother can't obtain enough food to eat.

After pupping season, you can often see both juvenile and adult harbor seals hanging out at sheltered haul-out sites, usually within a few feet of the water's edge. They prefer inaccessible offshore rocks or remote spots that are protected from wind and wave action (several sand bars in Elkhorn Slough are very popular). After spending most of the day resting, they will slip into the water in late afternoon or early evening to head out for an evening of foraging.

Adult elephant seals return to moult

In early June, at the elephant-seal rookeries along the Big Sur coast and at Ano Nuevo, you may see a few female elephant seals on the beach, moulting. However, by late June these females will have headed back out to sea, to spend the next seven months foraging in the Gulf of Alaska.

But the molting areas will not remain empty for long. Just as the females leave, a wave of adolescent males will come ashore to moult. Then adult males will use the same beaches for moulting in June or July.

Most mammals shed their hair (moult) more or less continuously. Elephant seals, on the other hand undergo what is called a "catastrophic moult," losing all of their hair over just a few weeks. During this time, the normally streamlined animals look positively mangy. Worse yet, they cannot dive into the depths to hunt prey. All they can do is lounge on the shore, conserve their energy, and wait it out.

Steller sea lions give birth

The Central Coast is also the southernmost breeding area for Steller sea lion. In June, Steller sea lions give birth on Ano Nuevo Island. Soon after giving birth, the females mate.

Steller sea lions are coastal animals that do most of their hurting within five miles of shore. They feed on a wide variety of prey, including hake, salmon, herring, squid and octopus, skates, and smelts. Like harbor seals, they seldom actually come ashore, but often sun themselves on offshore islands, reefs, and isolated ledges.

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