FEWER NORTHERN FUR SEAL PUPS BORN IN 2002

NOAA Fisheries scientists have finished their 2002 count of northern fur seals (Callorhinus ursinus) in the Pribilof Islands and reported that fewer pups have been born this year, and each year since 1998. The reasons behind the decline are not known. The National Oceanic and Atmospheric Administration (NOAA) is an agency of the Commerce Department.

Approximately 800,000 fur seals live in the North Pacific. Researchers report that pup produced has declined by about 5 percent per year for at least the last four years.

Northern fur seals range from southern California north to the Bering Sea and west to the Okhotsk Sea and Honshu Island of Japan. NOAA Fisheries identifies two populations of northern fur seals in U.S. waters – one in the Pribilof Islands, which is designated under federal marine mammal law as depleted, and one on San Miguel Island in California. The Pribilof Islands rookeries are home to almost all of the northern fur seals inside U.S. waters, and up to 72 percent of the world’s population.

Studies are providing information about foraging areas for lactating female northern fur seals during the breeding and pup rearing season in the Pribilofs. Managers hope to use this information to refine their protections for and conservation of the seals.

In 1993, NOAA Fisheries managers developed a conservation plan for northern fur seals. Since then, NOAA Fisheries and the Tribal Governments of the Pribilof Islands of St. Paul and St. George agreed to cooperatively manage the fur seal population. The managers are now re-drafting the conservation plan, taking into account the most recent scientific findings, population trends and traditional knowledge. The revised plan is expected to be completed in 2003 and will be phased in over a five-year period.

History:

Millions of northern fur seals were killed from the late 1700s into the mid-1980s for their high quality pelts. Historical records show that from 1786 until 1828 about 100,000 fur seals per year were harvested commercially. That dropped to about 70,000 seals harvested annually through 1839. By the final years of the Russian occupation of Alaska, about 35,000 seals were taken each year. Many seals were also taken at sea: at the peak of such open-water seal hunting, about 42,000 seals (mostly lactating females) were taken each year in the Bering Sea, with more taken from the waters off British Columbia.

In 1911, Great Britain (for Canada), Japan, Russia, and the United States ratified the Treaty for the Preservation and Protection of Fur Seals and Sea Otters, which prohibited taking seals at sea and limited the take on land.

From 1956 to 1968, a commercial harvest of females was implemented to intentionally reduce the size of the herd. Once the female harvest was stopped, the herd began to slowly increase, but in the mid to late 1970s pup production again began to decrease and continued to decline. The total world population is approximately 40 percent of the 1956 estimated population size. The commercial take of female seals between 1956 and 1968 is believed to have significantly contributed to the population decline.

The commercial harvest of northern fur seals in the Pribilof Islands has been prohibited on St. George and St. Paul Islands since 1973 and 1985, respectively. In 1986 the harvest was limited to Alaskan Native subsistence purposes only. Subsistence hunters harvested less than 2,000 non-breeding male seals each year from 1986 to the mid-1990s. Fewer than 1,000 seals have been taken annually during the past several years. Subsistence harvests are not considered a major factor in the current decline.

In the mid-1960s, scientists observed young seals entangled in trawl nets and packing band debris used by the fishing industry at that time. Such entanglements may have contributed significantly to declining trends of the population on the Pribilof Islands during the late 1970's. From then until the late 1990s, entanglements decreased but recent surveys and disentanglement efforts by the Tribal Government of St. Paul show an increase in male fur seal entanglements on Saint Paul Island. Entanglements are not thought to be a major factor in the current population trend.

Possible current causes of population decline:

The ebb and flow of available prey, perhaps influenced by large-scale fishing and natural ecosystem fluctuations, may also be contributing to northern fur seals’ decline. Though malnutrition is the primary cause of mortality among fur seal pups, the complexity of ecosystem interactions and limitations of data and models make it difficult to determine how fishery removals may have influenced the population.

Other factors which may contribute to the recent decline of northern fur seals include parasites and disease, injuries, pollutants, nutrition, and predation by killer whales.

NOAA National Marine Fisheries Service (NOAA Fisheries) is dedicated to protecting and preserving our nation’s living marine resources through scientific research, management, enforcement, and the conservation of marine mammals and other protected marine species and their habitat.

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