How many young does a whale give birth to at one time?

Most of the larger whales have a very low reproductive rate: females only have a single calf every 2-4 years. With very small populations, this low rate of reproduction means that it may takes decades for some species to recover to their former population levels. Even under the best conditions, it will take over a hundred years for the right whale to recover.

For some species of whales, the calves are born during the part of the annual cycle when the animals are in warmer waters, and the adults are not feeding. Unlike dolphins and porpoises, a calf spends a relatively short period of time with its mother. Calves usually become independent within a single year. During that time, a calf gains weight very rapidly. Whale milk is very rich, and a blue whale calf may gain almost 200 pounds per day.

What are the main threats to whales these days?

dead whale being hauled up on dock Although commercial whaling currently does not present a threat to the survival of the baleen whales, loss of habitat and other human activities may make recovery more difficult. Collisions with vessels, oil spills and other changes in water quality, coastal development, and increasing noise created from the use of oceanic resources may all affect the whales.

Fisheries may affect whales in two ways. First, whales may become entangled in fishing gear. As an example, each year several humpback whales are entangled in fishing gear along the east coast of the United States and Canada. Second, fisheries may compete with whales for food, such as herring.

Increased noise or boat traffic may cause whales to alter their behavior. There is evidence that humpback whales in Hawaii may have changed their use of near-shore waters where calves are raised by their mothers because of increasing human activity. Migrating bowhead whales may move further offshore to avoid human-caused noise.

Although we do not have a full understanding of the possible impacts, pollution could also affect whales. Many contaminants are stored in a whale's blubber for long periods of time. Pollutant loads are usually lower in baleen whales than in dolphins and porpoises. Deterioration of the environment could possibly affect the whales in another way: if pollution and other factors reduce the number of fish and crustaceans, the food available to the whales could also be reduced.

What are Pinnipeds?

Fur Seal Seals, Sea lions and Walrus are currently placed in a Sub-order, the Pinnipedia, of the Order Carnivora which also includes the bears, dogs, racoons, weasles (including otters), hyaenas cats, and mongooses. There have many recent studies on the genetic and fossil history of these groups and their place in the scheme of mammalian classifcation may well change in the near future.

Three families of living pinnipeds are recognized, the Phocidae (hair seals or true seals), the Otaridae (fur seals and sea lions) and the Odobenidae (walrus). The term pinnipedia translates from Latin as "fin foot". All of these animals must come ashore to breed, give birth and nurse their young, though some species are at sea for several months at a time while others return to the shore every day.

How many Pinnipeds are on the Endangered Species List?

There are currently four species of pinnipeds in the U.S. on the endangered species list. These include the Caribbean monk seal, the Guadalupe fur seal, the Hawaiian monk seal and the Steller sea lion. The Caribbean monk seal and the Hawaiian mink seal are listed as endangered, while the Guadalupe fur seal and Steller sea lion are currently listed as threatened.

Commercial hunting of seals in the 18th and 19th century, and in the early years of this century played a large role in pinniped population declines. Other factors involved have been coastal development and competition with man for prey species.

Are Hawaiian monk seals coming back?

The Hawaiian monk seal was listed as endangered throughout its range on November 23, 1976. Counts have been made at the atolls, islands and reefs where they haul out in the northwest Hawaiian Islands since the late 1950s. By 1982, the population had declined to half of its 1957-1958 level. Since the mid-1980's, beach counts have declined at five percent per year. NMFS estimates that currently there are approximately 1400 animals. The number of births declined significantly at all five major breeding locations in 1990, followed by some recovery in subsequent years. However, the number of births has not reached the level observed in the mid-to-late 1980's, and is not expected to in the near future because of the high losses of immature seals at French Frigate Shoals and mobbed seals at Laysan and Lisianski Islands.

How many Caribbean monk seals are left?

The Caribbean monk seal was listed as endangered throughout its range on April 10, 1979. The last reliable sighting of a Caribbean monk seal occurred in 1952. None were seen in aerial surveys in 1973, and no confirmed sightings have been reported since then. Many scientists believe that the species has been extinct since the early 1950s. No recovery effort is being made for this species.

How are Steller Sea Lions doing?

Artwork by K. Zecca The Steller or northern sea lion was listed as threatened throughout its range on December 4, 1990. Steller sea lion population west of 144 degrees wes t longitude was declared endangered as of June 1997. The centers of abundance and distribution are the Gulf of Alaska and Aleutian Islands, respectively. Rookeries (breeding colonies) are found from the central Kuril Islands to Ano Nuevo Island, California; most large rookeries are in the Gulf of Alaska and Aleutian Islands. More than 50 Steller sea lion rookeries and a greater number of haulout sites have been identified. Species abundance estimates during the late 1970s ranged from 248,000 to 300,000 adult and juvenile animals. However, counts at rookeries and haulout sites throughout most of Alaska and the USSR in 1989, plus estimates from surveys conducted in recent years at locations not counted in 1989, provide a range-wide Steller sea lion population estimate of about 116,000. In 1994, an estimated 67,100 occurred in U.S. waters.

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All Artwork on this page is by Katherine Zecca of the Alaska Fisheries Science Center
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(File Modified Jun. 16 2011)