Scientific Classification

SCIENTIFIC CLASSIFICATION.

SCIENTIFIC CLASSIFICATION

COMMON NAME: California sea lion, Galapagos sea lion KINGDOM: Animalia PHYLUM: Chordata CLASS: Mammalia ORDER: Pinnipedia FAMILY: Otariidae GENUS SPECIES: Zalophus (lophus translates into crest) californianus

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FAST FACTS

DESCRIPTION: Like other "eared" seals, California sea lions have prominent external ear flaps and long foreflippers covered in fur past the wrist and tiny claws. The hind flippers are shorter and also have short claws at the ends of the digits. MALE Adult male California sea lions have a prominent sagittal (cranial) crest, making them easy to distinguish from females and immature males. Mature males also tend to be a much darker brown color and are substantially larger than adult females. Unlike many other species of sea lion, California sea lion males lack a well-defined mane. FEMALE Mature females and immature males are light yellowish to tan in color and lack the prominent sagittal crest of the adult male.

SIZE: Newborns are about 75 cm (30 in.) long MALE Up to 2-2.5 m (6.5-8 ft.) long FEMALE Up to1.5-2 m (5-6.6 ft.) long

WEIGHT: At birth, sea lion pups weigh about 6 kg (13 lb.) MALE 200-400 kg (441-882 lb.) FEMALE 50-110 kg (110-243 lb.)

DIET: Fishes, squid and octopus

GESTATION: Gestational period 11 months; possibly up to 3 months of delayed implantation ESTRAL PERIOD About 3 weeks after giving birth in June and July NURSING DURATION 6 months to a year (wean)

SEXUAL MATURITY: 4-5 years for both males and females

LIFE SPAN: 15-25 years

RANGE: British Columbia to northern Mexico

HABITAT: Inhabit rocky and sandy beaches of coastal islands and mainland shorelines along the coasts

POPULATION: GLOBAL About 200,000 for the California subspecies; the Japanese subspecies is considered extinct

STATUS: IUCN Not listed CITES Not listed USFWS Not listed

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FUN FACTS

1. Sea lions are adapted for movement on land as well as in the water. Wing-like front flippers have a bone structure similar to that in our arms and hands. Swimming with these flippers propels the sea lion forward, while the hind flippers steer. Both pairs of flippers enable a sea lion to walk on land. 2. Sea lions produce loud roars help explain why they're named after lions. Males of some sea lion species even grow thick manes around their necks. 3. Most sea lion pups are born in late June. Pups are well developed at birth. Their eyes are open, they can vocalize, and even swim a little. Several days after the pup's birth, the mother leaves the pup in the crowded rookery as she searches for food in the ocean. When she returns, the mother emits a loud trumpeting vocalization, which elicits a bleating response from her pup. This exchange continues until the mother and pup find each other. She makes her final identification by smelling her pup. 4. California sea lions are among the most gregarious marine mammals, forming dense aggregations of a thousand or more animals on land. They also may travel, socialize or rest at the surface in groups of ten or more near haul out areas. 5. For more information about California sea lions, explore the CALIFORNIA SEA LION INFO BOOK.

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ECOLOGY AND CONSERVATION

As for other marine mammals, the U.S. Marine Mammal Protection Act of 1972 protects California sea lions.

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BIBLIOGRAPHY

Byrum, J. Pinnipeds From Pole to Pole: Seals, Sea Lions and Walruses. SeaWorld Education Department Publication. San Diego. SeaWorld, Inc. 2000. Jefferson, T.J. Leatherwood, S. and M.A. Webber. FAO Species Identification Guide. Marine Mammals of the World. Rome. FAO, 1993. Nowak, Ronald M. (ed.). Walker's Mammals of the World. Vol. II. Baltimore: Johns Hopkins University Press, 1991. Parker, S. (ed.). Grizmek's Encyclopedia of Mammals. Vol. IV. New York: McGraw-Hill Publishing Co., 1990. Reeves, R. R., Stewart, B.S., Clapman, P.J., and J.A. Powell (Peter Folkens illustrator). National Audubon Society: Guide to Marine Mammals of the World. New York: Random House, 2002. Reeves, R.R., Stewart, B.S. and S. Stephen. The Sierra Club Handbook of Seals and Sirenians. San Francisco: Sierra Club Books, 1992. Riedman, M. The Pinnipeds: Seals, Sea Lions and Walruses. Berkeley and Los Angeles. University of California Press. 1990.

Source: http://www.swbg-adventurecamps.com/

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Videos

Videos

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Reproductive

Sea Lion Reproduction

Sea Lion Breeding and Reproduction

Male Sea Lions are mature about at about 3 years of age. However, in most instances they won’t end up mating until they are at least 8 years old. This is because they have to be strong enough to be able to stand their ground against other males and to attract females. The females will begin to mate when they are about 4 years old. They will look for the strongest males to be with.

The males compete fiercely for the right to reproduce with the females. They males strive to form a harem that will consist of as many females as possible for him to breed with. It isn’t unusually for them to have 10 to 15 females. It is also the job of this male to protect all of the females in his harem from harm.

The males go to shore around May to stake out the land and to make their claims. The females will come to the shore a couple of weeks later. It is important to note that the females will already be pregnant at this time with the pups from the previous mating season.

When it is time for the mating season to start the males will start to bark more aggressively than in the past. This type of communication is a way for them to attract females to them. They also use these barks to intimidate other male Sea Lions that happen to be in the area. They want to make it know that they have staked their claim to a certain area as well to the females found there.

Females give live birth to the pups on land. Generally only one pup will be born at a time but occasionally there will be twins. The pups immediately start to consume milk from their mother’s body. This milk contains more than 50% fat which helps them to grow at a very fast rate. This is also responsible for helping the young Sea Lions to develop the layers of fat called blubber that they need to stay warm.

These layers of fat need to start forming before the young pups will be able to survive in the water. When they are born they do feature a coat of hair that does protect them from the cold until they develop enough blubber. Then this hair will start to fall off, and it will be almost completely gone by the time they first enter the water with their mother.

The mating with the male she is now with will occur in either late June or July. So she will be nursing her current pup while pregnant with another. The gestation period is approximately 11 months and by this time the pup she is caring for right now will be able to take care of itself.

The mother’s will remain on land or ice with their pups for the first couple of weeks of life. Then they are ready to move into the waters. While they instinctively know how to swim, they are taught how to move about in a way that is going to help them based on the behavior of the waters. They also start to learn how to hunt for fish even though they will continue to get their main nutrition from drinking the milk their mother produces.

The young Sea Lions are also taught by their mothers to stay away from predators. They are very vulnerable during the first six months of life. This is due to their coloring being more brown until that time. They can also be trampled on land from other Sea Lions when there is reason to be scared and a stampede starts.


Source: sealion-world.com

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Species

Sea Lion Species

There are seven known Sea Lion species that have been identified. Sadly, one of them has already become extinct. That would be the Japanese Sea Lion and their end was definitely a wake up call to researchers and conversationalists. However, they have been gone since the 1950’s and it has just been in the past decade that the best of efforts have taken place for their survival.

The Steller Sea Lion is the largest of them all and lives in the Northern Pacific, especially around Alaska. They were first discovered in 1741 and the number of them continues to decline. Researchers aren’t able to identify what is causing this drop in numbers so they are focusing more attention on them. Hopefully careful observation will give them the answers they need.

The Australian Sea Lions are only found along the South and West of this continent. There are only about 10,000 of them left and they are protected under the National Parks and Wildlife Act of 1972. One of the main reasons why their numbers are low is due to the males often killing the pups. They do so because they view them as a threat to their own dominance.

The South American Sea Lion is most often seen in the area of Peru. They have a decent population of approximately 265,000. In fact there are indicators that the number of them has increased along both Chile and Argentina. Their biggest threat comes from humans because they tend to compete with fishermen for the available food in the waters there.

The New Zealand Sea Lions are also referred to as the Hooker Sea Lions by many people. This particular species has been under protection since 1890. At that point it was extremely close to extinction. Even with such efforts though the numbers are climbing at a very slow rate. Today there are only about 18,000 of them.

The most well known is the California Sea Lion. Tourists come from all over to see them in their natural environment. This is one area that has gone to great lengths to help protect the natural habitat of these animals though. These are the types of seals you will most often see in zoos, the circus, working with the military, and learning tricks to perform at Sea World.

Last is the Galapagos Sea Lion which is only found on the Galapagos Islands and Isla de la Plata. They are said to be the most social of all Sea Lions and they are also the species with the highest recorded numbers. They are protected by law but at times they are threatened by various types of destructive weather in that area.

In 2002 a very interesting mix of Sea Lion was found by researchers. After extensive research scientists from France verified that it was a hybrid species. These Sea Lions were a cross between the California Sea Lion and the South American Sea Lion. They found this mix to be one that is very interesting. Still, we don’t know too much about them today. It is believed that this hybrid mixing is rare so that makes it harder to observe the offspring in depth.

Many of the different Sea Lion species are in danger of becoming extinct. This is why so many efforts are in place out there to help preserve their natural environment. There are also efforts to prevent the hunting or the harming of Sea Lions. So far such efforts have been successful but there is still plenty more than has to be done in order for their numbers to climb out of the danger zone.

Source:sealion-world.com

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Diet

Sea Lion Diet

The objectives of the sea lion diet study being conducted by Coastal Marine Mammal Program are to:

1. Identify prey species being consumed by sea lions in order to determine which are most important to the sea lion population.  Prey species are identified by hard parts, such as fish otoliths and squid beaks found in scats.  See the recently published
   Photographic Catalog of California Marine Fish Otoliths: Prey of California Sea Lions (Zalophus californianus).
2. Monitor seasonal, annual, and multi-year variability in consumption of prey species.
3. Determine if dietary changes can be used to signal when the population reaches carrying capacity,
4. Estimate consumption by the sea lion population.
5. Use sea lion diet data as a fishery-independent index of abundance for commercial species of fish and squid.

California sea lions pup and breed at four of the nine Channel Islands in southern California. Since 1981, CMMP has been conducting a diet study of sea lions at San Clemente Island (a small rookery) and San Nicolas Island (a large rookery). Information on the diet of sea lions is obtained from analyzing scats (i.e., fecal samples) and spewings (i.e., vomitus) collected at those two rookeries in January (winter), April (spring), July (summer), and October (autumn). Otoliths (a crystalline structure within the ear organ) from fish and beaks (mandibles composed of chitin) from cephalopods are recovered from the samples by washing each sample through sieves of varying mesh size. Otoliths and beaks, which are shaped and sized differently for each species of fish and cephalopod, respectively, are used to identify and enumerate fish, and cephalopods consumed by sea lions. Also, otoliths and beaks are measured for estimating size of prey being consumed by sea lions. Northern anchovy (Engraulis mordax), Pacific sardine (Sardinops sagax), Pacific whiting (Merluccius productus), Pacific mackerel (Scomber japonicus), jack mackerel (Trachurus symmetricus), shortbelly rockfish (Sebastes jordani), and market squid (Loligo opalescens) are the main prey of California sea lions in southern California. They also consume a variety of other fish and squid, but at lesser amounts than those just mentioned. The study has also revealed that not only are there seasonal cycles to consumption of certain prey (such as market squid being consumed mainly in autumn and winter), but that multi-year cycles in consumption of prey also take place that appear to be governed by multi-year differences in abundance and availability of various prey species. The study has also determined that the diet of sea lions becomes more variable during El Nino oceanographic events due to decreased abundance and availability of their preferred prey. It is anticipated that the dietary response to El Nino will also occur when the population reaches the maximum size sustainable by the environment (i.e., it will reach carrying capacity).

The principal investigator is Mark Lowry of the EEZ Mammals and Acoustics Program.

Throughout the years of the study, various personnel from CMMP and Protected Resources Division (PRD) have helped with the study. Information about this project can be obtained from the following publications:

Lowry, M. S., C. W. Oliver, C. Macky, and J. B. Wexler. 1990. Food habits of California sea lions, Zalophus californianus, at San Clemente Island, California, 1981-86. Fish. Bull., U. S. 88:509-521.

Lowry, M. S., B. S. Stewart, C. B. Heath, P. K. Yochem, and J. M. Francis. 1991. Seasonal and annual variability in the diet of California sea lions, Zalophus californianus, at San Nicolas Island, California, 1981-86. Fish. Bull., U. S. 89:331-336.

Lowry, M. S. and J. V. Carretta. 1999. Market squid (Loligo opalescens) in the diet of California sea lions (Zalophus californianus) in southern California (1981-1995). CalCOFI Rep. 40:196-207.

Source: http://swfsc.noaa.gov 

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Behavior

Behavior

California sea lions are very social animals, and groups often rest closely packed together at favored haul-out sites on land or float together on the ocean's surface in "rafts." They are sometimes seen "porpoising," or jumping out of the water, presumably to speed up their swimming. Sea lions have also been seen "surfing" breaking waves. California sea lions are opportunistic eaters, feeding on squid, octopus, herring, rockfish, mackerel, and small sharks. In turn, sea lions are preyed upon by Orcas (killer whales) and great white sharks.

Source:marinemammalcenter.org

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