Pribilof Islands the previous November. Much of this weight loss in newly weaned pups can probably be attributed to harsh storms and adverse oceanographic conditions encountered during the first winter at sea, and to inability to catch fish as efficiently as the older seals (pups are about 4-5 months old when they begin their southbound migration). Kenyon et al. (1954) reported that the highest mortality occurs during the fur seal's first year of life and weather may cause most of this mortality. Strandings of seals older than pups/yearlings are uncommon. Possibly these deaths are caused by disease or other factors unrelated to the direct effect of weather.

B. The Northern Fur Seal (Callorhinus ursinus)

1. Range and Breeding Islands

Information on the life history and population range of this species is available in Fiscus (1978, 1980) and Kajimura (1980, 1982).

The northern fur seal is a member of the family Otariidae (eared seals). This family also includes the sea lion. The northern fur seal is the only member of the genus Callorhinus. One of the most distinctive physical features of this species is its dense fur which serves to insulate the body from the cold temperatures of its environment. The commercial value of its fur has made this species the subject of often intense harvesting pressures that led to the species' decline in abundance in the early part of this century.

The northern fur seal is rarely found on land except on its home islands during the breeding season. Its range includes the subarctic waters of the North Pacific Ocean and portions of the Sea of Japan and the Okhotsk and Bering Seas (Figure 2). The southern boundary of its range in the eastern North Pacific extends to about 32°N (CaliforniaMexican border) and in the western North Pacific to about 36°N off Honshu Island, Japan. In the Sea of Japan it ranges south to about 37°N on the Korean coast. There have been a few sightings of fur seals south of these latitudes, although fur seals are rare in waters with surface temperatures above 15°C. The northern limit of its range is delineated by sea-ice which in winter covers much of the Okhotsk and Bering Seas and about half of the Sea of Japan.

Most adult seals return each summer to the island of their birth, where females give birth to a single pup and mate with a territorial bull within the first few days of arrival. The breeding islands of the northern fur seal are: Robben Island in the Okhotsk Sea; Kamennye Lovushki Rocks and Sredney Rocks of the Kurile Islands in the western North Pacific; Commander Islands in the western Bering Sea; the Pribilof Islands in the eastern Bering Sea and San Miguel Island in the eastern North Pacific off southern California. A small breeding colony has recently been found on Bogoslof Island in the Aleutian chain of the southern Bering Sea.

At present it is known that most fur seals found in the eastern North Pacific Ocean are from the Pribilof Islands (St. Paul, St. George, and Sea Lion Rock; Otter and Walrus Islands have no fur seal rookeries) in the eastern Bering Sea, which are the principal breeding grounds of the northern fur seal. Fur seals from the western Bering Sea (Commander Islands), the western North Pacific (Kurile Islands) and the Okhotsk Sea (Robben Island) do not contribute significantly to this population. Two additional rookeries in the eastern North Pacific Ocean are off southern California on San Miguel Island and nearby Castle Rock near the southern limit of the fur seal's range. The San Miguel colony of fur seals was discovered in 1968 with about 100 fur seals. The Castle Rock colony was discovered in 1972.

The Soviet Union manages rookeries on islands in the western North Pacific, including Commander Islands (Copper and Bering Island) in the western Bering Sea, Robben (Tuyleniy) Island off Sakhalin Island in the Okhotsk Sea, and a few of the Kurile Islands. Recoveries of tagged animals have shown that seals from the eastern and western breeding islands intermix to some small extent at sea and on the breeding islands.

2. Estimates of Abundance

The current estimate of the North Pacific fur seal population is 1.2 million. The population native to each island group is as follows:

The number of fur seals harvested on the U.S. owned Pribilof Islands, 1950-1984, is presented in Table 1. Harvest data 1960-1983 for USSR owned islands is given in Table 2.

The U.S. Government currently harvests approximately 22,000-24,000 animals per year on St. Paul Island and shares 30 percent of the seal skins with Canada and Japan. Except for those females taken accidentally or for research, only males between the ages of two and six years are taken. About ninety percent of the animals are three and four years of age. Through 1972, seals were harvested each year on both major islands of the Pribilof group; however, since 1973 no seals have been taken commercially on St. George Island. In that year a moratorium on sealing was agreed to by Party Governments and St. George was set aside as a research study area. A commercial harvest of female seals on the Pribilof Islands occurred during the period 1956-1968.

Reports on the methods used to harvest northern fur seals may be found in Simpson (1967), Virginia Mason Research Foundation (1971), Veterinary Panel (1971), Battelle, Columbus Laboratories (1973) and Keyes (1980).

Northern fur seals are killed by manual stunning quickly followed by exsanguination. Stunning is accomplished by a sharp blow to the head with a long club. Because the bones of the fur seal skull are so thin, a fur seal may be rendered unconscious and insensitive to pain instantaneously with even a moderate blow to the head. Many seals are killed by the blow alone before they are bled. Exsanguination is accomplished by opening the chest cavity and piercing the heart or the large vessels leading from the heart.

Many individuals and animal welfare organizations have criticized these traditional methods of harvesting fur seals on the Pribilof Islands and questioned whether or not these methods constitute humane killing. However, independent studies by a number of prominent veterinarians, including the Panel on Euthanasia of the American Veterinary Medical Association, have led to the conclusion that clubbing is a rapid, highly efficient and humane method of rendering the animals unconscious when properly performed. Stunning, followed by exsanguination, constitutes painless, humane killing. Harvesting methods on the Pribilofs are comparable to the best methods used in the slaughter of domestic livestock.

There is a limited harvest season of five weeks ending on or about August 5th. Each bachelor hauling ground is harvested once each week, or five times during the season. Since at any one time, many of these seals are away from the Island and feeding at sea, it has been found that a sufficient number of young seals escape the harvest to return to breed in later years. Because the fur seal is polygynous, many more females are needed for reproduction than males. Regulation of the take in terms of season, sex and length limits and killing techniques, ensures that only those seals not needed as replacements for the breeding stock are taken, and that the harvest is carried out in the most humane way possible without undue stress to the animals.

Questions have been raised as to the genetic effects of the age/sex specific harvest.The NMFS research scientists have consulted with other researchers in this field on possible experimental procedures which could be used to answer these questions. As yet no specific research program has been formulated, and the magnitude and direction of any possible genetic changes in the population are unknown.

4. Migration and Distribution at Sea

The following discussion of the migratory patterns and at-sea distribution of the northern fur seal, with emphasis on the eastern North Pacific, is from Kajimura (1980, 1982).

Basic information on the migrations of fur seals was first obtained from pelagic fur sealing which developed as a commercial enterprise by 1871 and continued until 1911. In the eastern Bering Sea pelagic sealing began about 1880 and by 1884 most vessels had begun sealing along the northwest coast during the winter and followed the fur seal herd north into the Bering Sea to complete the season in September. Commercial pelagic sealing was a mothership-type operation. Sealing schooners transported hunters and canoes to offshore sealing grounds where the canoes stayed with the herd during northbound migration to the Pribilof Islands. Townsend (1899) first summarized distribution and migration data from logbooks of pelagic sealers. Figure 3 depicts the general migration and distribution based on 304,713 fur seals collected by 123 vessels engaged in commercial pelagic sealing from 1883 to 1897. Two additional migration charts, Zeusler (1936) and Ognev (1935) are presented in Figures 4 and 5. The general pattern of movements depicted in these early charts agree quite well since the primary data source is commercial sealing records.

The first major study of the pelagic life of the northern fur seal was conducted by C.H. Townsend and F. A Lucas in conjunction with commercial sealers in 1896 and 1897. In 1947, the research vessel Black Douglas covered the area from Seattle to the Pribilof Islands and return, including one trip along the Aleutian Islands westward to Attu Island. In 1948, the Black Douglas sailed from Seattle to Unalaska, to San Francisco and then returned northward along the coast to Seattle. Information on fur seal migration and distribution available up to 1952, including the surveys of the Black Douglas, was summarized by Kenyon and Wilke (1953).

Most of the information since 1952 on the pelagic life of the northern fur seal in the eastern North Pacific is from an analysis of the results of the pelagic research cruises conducted by the United States and Canada, 1958-74. Until 1963, however, Party Governments were required by treaty to fulfill a "quota" of pelagic collections. During 1958-63 therefore, when most of the seals were collected, the data on fur seal at-sea distribution is biased toward areas of highest concentration. Effort was directed toward collecting seals and away from systematic surveys to determine density, distribution or relative abundance of fur seals by time and area. Collections were made from areas of concentration known from sealing logs and earlier research cruises; marginal area were neglected. The quota requirements were dropped from the Convention in 1963; however, several transect surveys were made off California and Washington, and in the Bering Sea near the Pribilof Islands (1965-74). Figure 6a, b, and c provides monthly summaries of fur seal sightings per hour of observation by the pelagic research cruises of 1958-74.

The 57,927 fur seal sightings shown in Figure 7 are from data obtained primarily from pelagic research cruises with supplemental data from other sources to provide a better picture of fur seal distribution at sea. Sightings of seals in the western North Pacific Ocean area are primarily from Japanese pelagic fur seal research cruises (195878), the NMFS Dall's Porpoise Program (1978-80) and from salmon research cruises of U.S. vessels (1955-72). Sightings of seals in the eastern North Pacific Ocean are primarily from Canadian and U.S. pelagic fur seal cruises (1958-74); other sightings are from NMFS programs which include the Platforms of Opportunity Program (POP), Outer Continental Shelf Environmental Assessment Program (OCSEAP) and Dall's Porpoise Program.

Some northern fur seals are found throughout their range in the eastern North Pacific Ocean in nearly all months of the year, with periods of peak abundance varying by time and area. Many immature seals of both sexes remain at sea during the first year or two of life and do not return to their island of birth until ages 2 or 3 years. Most fur seals spend about half the year at sea (November through May-June) and the remainder (July-October) on and around their home islands during the breeding season.

Fur seals are most frequently seen from about 20 to 40 nautical miles from land and usually in greatest numbers along the continental shelf and slope throughout their range primarily because of abundant food resources in this area. Most fur seals are still on or near the Pribilof Islands in October but by the end of November only about 30 percent or less of the population remains near the Pribilof Islands. This is at a time when the first

seals have completed their North Pacific (Gulf of Alaska) crossing and are beginning to appear off the coasts of southeastern Alaska, British Columbia, and Washington. During research cruises off California, Oregon, and Washington, the first seals were sighted on 5 December and on 25 and 27 November, respectively.

From January to March, fur seals are found along the continental shelf and slope, entering coastal waters in pursuit of prey, from the Gulf of Alaska southward to California. Fur seals continue to increase in abundance during December and January off Washington and California. In February and March, seals are most abundant from California to Sitka, Alaska. The numbers of fur seals wintering off California reach a peak during late January through March and decrease as they begin their northward migration starting in late March. Most seals have left this area by early June.

In April, fur seals are widely dispersed from Kodiak Island, Alaska, to California with the population reaching its peak in the Gulf of Alaska during May. The northbound migration begins March-June, first in the southern limits of the range off California and proceeding past Washington in April and May, the Gulf of Alaska in May and June, and westward into the Bering Sea in June. In June, fur seals are scattered throughout the North Pacific Ocean. Fur seals are in the eastern Bering Sea and on or near the breeding islands of St. Paul, St. George, and Sea Lion Rock (Pribilof Islands) in greatest numbers during July, August, and September (most age groups of both sexes).

Any discussion of fur seal distribution in the eastern North Pacific Ocean refers primarily to females because they represent about 90 percent of the pelagic catch (with some variation by time and area). Older females (age 5 years and up) are generally more abundant off California than off Washington, while the younger seals are not fully represented. Females of all ages (and young males 1-4 years old) are found in the Gulf of Alaska and the eastern North Pacific Ocean during winter and spring. Only the younger immature males (ages 1-5 years) have been found south of Alaskan waters with a few exceptions. Nearly all of the older males winter in Alaskan waters primarily in the Gulf of Alaska, north and south of the eastern Aleutian Islands, and probably in the Bering Sea. The catch of males diminished south of latitude 46°N (Washington-Oregon border). Of the 3,612 fur seals taken off California, only 2 percent, or 56 animals, were males of ages 1-5 years and only one male seal was 5 years old. The seals on which these percentages were based were taken prior to 1967, and the San Miguel Island males would at that time not have contributed to the offshore population. No attempt has been made to verify the distribution of older males because poor weather conditions during late autumn, winter, and early spring in the Gulf of Alaska and Bering Sea would severely limit vessel operations and reduce sightings or catches.

Fur seals congregate in social groups on land but at sea they are usually solitary. Solitary seals predominated in all areas. The frequency of solitary seals was highest in the Bering Sea (38-68 percent) where seals are more abundant during the breeding season. Off California, solitary seals represented 30 to 50 percent of the total sightings, whereas off Washington they comprised 30-64 percent. Larger groups of up to 20 seals have on occasion been sighted usually during spring migration but groups of this size are unusual. A few groups of seals numbering more that 20 have been seen off Washington and California when they were actively feeding on large schools of prey.