Bigg (1982) examined the distribution of fur seals in areas more than 200 nautical miles offshore in the eastern North Pacific. This work was based on analysis of the U.S./Canadian pelagic collections, results of earlier studies and observations of a Canadian research vessel stationed about 650 nautical miles west of Vancouver Island. Bigg suggests that during northbound migration pregnant females leave the California coast in March and travel offshore to arrive in the Gulf of Alaska in April. Young seals (1-3 years) of both sexes appear to remain offshore between January and June. In DecemberJanuary, when the southern migration is underway, the offshore region probably contains essentially the entire population.

Clearly, all northern fur seals must spend some portion of their lives in waters outside the jurisdictions of both the United States and Canada. Pregnant females take a direct route from the West Coast to the Pribilofs each spring. This component of the population is the most sensitive to harvesting and at the greatest risk from any possible resumption of pelagic sealing.

5. Feeding Habits and Prey Consumption

Although northern fur seals feed on a variety of fishes and squids throughout their range, evidence suggests (based on abundance and distribution of principal prey species) that fur seals are opportunistic feeders preying on the most available species in the area (Kajimura 1982). Prey species taken by fur seals vary according to area, season and the migratory patterns of the prey but generally, smaller schooling fishes (including the neritic market squid) are usually the principal forage species over the continental shelf region and oceanic squids are important seaward of the continental slope in deepwater areas. The principal forage species utilized by fur seals throughout their subarctic range are given in Table 3.

Figure 8 shows the percent composition by prey species of the fur seals' diet in the eastern Bering Sea. The location of fur seal collection influences the importance of different prey species as the principal forage food. For example, if fur seals are taken near the Aleutian Islands and Passes, the principal prey appears to be capelin. If seals are taken beyond the shelf over deepwater, the forage species will likely be oceanic squids. Fur seals taken over the shelf are likely to be feeding on walleye pollock and Pacific herring (Perez and Bigg 1984).

Walleye pollock is one of the principal food species of fur seals in the eastern Bering Sea. Pollock is also the most abundant and widely distributed species over the Bering Sea continental shelf, and the most important demersal fish in terms of biomass and landings in the commercial fishery. McAlister and Perez (1977) estimate that as much as 80 percent of the fur seal diet is fish, and in the eastern Bering Sea, McAlister (1981) estimated that about 58 percent of the fish consumed by fur seals is walleye pollock.

A computer model of the Bering Sea ecosystem, Dynamical Numerical Marine Ecosystem Model or DYNUMES, has been developed by the Northwest and Alaska Fisheries Center of the NMFS. The model incorporates data on population size, distribution, reproduction rates and feeding of fur seals, as well as information on other marine mammals and oceanographic data. McAlister (1981) estimated fish consumption by marine mammals in the eastern Bering Sea and Aleutian Island area by calculating the food requirements of marine mammal species based on energy requirements, corrected environmental temperature, population estimates and prey distribution (Tables 4 and 5).

Based on these calculations, McAlister estimated the annual consumption of finfish by fur seals to be 476,000 metric tons (mt) (Table 4) compared to 2,287,000 mt consumed by all marine mammals in the area (Table 5). Total food consumption (including fish and squid) by the Pribilof Islands population of fur seals was estimated at 615,000 mt (Table 4).

McAlister estimated that marine mammals consumed approximately 5 percent of the standing stock of finfish in the eastern Bering Sea and Aleutian Island area (Table 5). In a similar study conducted in 1977 by McAlister and Perez, the value was calculated at 10 percent. A slight decrease in estimated total food consumption in the 1981 study of 2,287,000 mt compares to 2,647,000 in the 1977 study. McAlister (1981) states that the principal change is in the estimated increase of standing stocks of fish in the eastern Bering Sea and Aleutian Island areas from 27,260,000 mt to 48,988,000 mt. Based on estimates of consumption of fish in the eastern Bering Sea and Aleutian Island area, fur seals consume about 1 percent of the standing stock of fish, other pinnipeds consume a little over 2 percent and all marine mammals are estimated to consume 4.6 percent (Table 5).

6. Commercial Fisheries of the Bering Sea/Gulf of Alaska

Japan operates salmon gillnet fisheries in the Bering Sea and North Pacific Ocean from mid-May to the end of July. The fisheries are regulated by the International North Pacific Fisheries Commission (INPFC) established in 1953 by a convention among Japan, Canada, and the United States. In 1978, this treaty was renegotiated to conform with the 200-mile fisheries jurisdiction of the United States established by the Magnuson Act. The renegotiated convention limited the high seas salmon mothership fishery in the North Pacific to the area between 170° and 175° E, north of 46° N. In the Bering Sea, the fishery now operates predominately between 56° and 60°N and between 170°E and 175° W.

Sea birds and marine mammals are taken incidental to fishing operations in the Japanese fishery. In 1981 and 1982, U.S. observers monitored the incidental take of northern fur seals in commercial Japanese salmon gillnet operations. No incidental takes were observed in 1982. In 1981, four out of the nine reported incidental takes were observed. All but one of the incidental takes occurred in July, in one mothership fleet. Estimated incidental take for 1981 based on U.S. observer's data is approximately 94 fur seals in the Japanese salmon mothership fishery. The Japanese land-based salmon and squid gillnet fisheries may be additional sources of mortality.

Fourteen fur seals were entangled in Japanese salmon research gillnets in 1981 and eight in 1982. During the period 1979-1981, the animals were only observed entangled in larger mesh sizes ( 82 mm, stretch mesh), particularly 179 and 204 mm. Survival appears to be lower in these larger mesh sizes than in commercial mesh sizes (112-130 mm).

Although fur seals were commonly sighted at the nets during retrieval operations (45 percent of the sets), entanglements occurred in only 9 percent of the sets. Entanglement appears to be an uncommon event in this fishery. The low estimate of annual incidental take in commercial fishing operations calculated from U.S. observer data collected aboard the salmon catcherboats in 1981 may be more reliable than previous, higher estimates based on data from research operations.

A major commercial ground fish fishery began in the Bering Sea and Aleutian Island area in the 1950s. Harvests, primarily of yellowfin sole by Japan and the USSR, increased to over 500,000 mt in 1961 and then declined to about 85,000 mt in 1963. Peak harvests of primarily Pacific ocean perch occurred in 1965 in the Aleutian area. In the mid 1960s, the Japanese began an intensive walleye pollock fishery, and by 1972 total catches of ground fish exceeded 2.3 million mt. Walleye pollock accounted for an estimated 80 percent of this catch. Catches have declined since 1972 as catch restrictions were placed on pollock and other groundfish through bilateral agreements between the United States, and other countries. By 1976, catches were limited to about 1.5 million mt.

In 1981, Japan, the Republic of Korea (ROK), Taiwan, Poland and West Germany were the principal countries participating in the goundfish fisheries of the eastern Bering Sea and Aleutian Island regions. Total catches of ground fish and squid taken by the foreign fishery in this region in 1981 were 1,273,200 mt which was 21,800 mt less than in 1980. Although the 1981 catch was the lowest recorded in the Bering Sea and Aleutian Island region since implementation of U.S. extended jurisdiction, catches have not fluctuated substantially in this period, varying from a high of 1,383,300 mt in 1978 to a low of 1,273,200 mt in 1981.

In 1981, the Japanese fishery accounted for 81 percent of the total catch (929,362 mt) followed by the ROK (13 percent, 167,403 mt), Poland (4 percent, 55,023 mt), West Germany (1 percent, 11,873 mt), and Taiwan (1 percent, 5,978 mt). The USSR catcher vessels were not allowed to operate in the U.S. FCZ in 1981, although they were allowed to process catches taken by the U.S. fishing vessels. Foreign catches of groundfish in the eastern Bering Sea and Aleutian area are shown in Figures 9 and 10.

Japan's fisheries catch was 82 percent pollock (762,501 mt), 6.6 percent yellowfin sole (61,581 mt), 3 percent Pacific cod (27,970 mt), 4.4 percent other flatfish excluding turbot (41,309 mt), and 0.2 percent sablefish (92,099 mt). ROK fisheries targeted on 69.3 percent pollock (116,016 mt), 10.3 percent yellowfin sole (17,179 mt), and 7.4 percent Atka mackerel (12,385 mt). Polish fisheries also targeted on pollock which constituted 98.1 percent (53,984 mt) of their total catch. Similarly, West German catches were 86.8 percent (10,305 mt) pollock and the pollock catch of Taiwan fishermen (3,367 mt) was 56.3 percent of their total catch.

In joint venture fisheries, U.S. vessels delivered 78,535 mt of groundfish to Japanese, Polish, ROK, West German and USSR processing vessels. Pollock (42,083 mt), yellowfin sole (16,046 mt) and Pacific cod (9,159 mt) were the three major species targeted by the U.S. vessels in joint ventures.

With the passage of the Magnuson Act in 1976, the fishery resources of the eastern Bering Sea and Aleutian Islands came under the jurisdiction of the United States. Beginning in 1977, the U.S. annually established total allowable levels of foreign fishing based on the optimum yield of each fishery resource. Optimum yield is based on maximum sustainable yield modified by relevant economic, social and ecological factors. Optimum yields established for 1982 for major fishery species, in thousands of metric tons, are as follows:

Of the approximately 1.25 million mt of finfish removed from this area in 1981, 993,773 mt, or about 80 percent, was pollock (INPFC 1982).

7. Fur Seal Entanglement in Fishing Debris

Scordino and Fisher (1983) summarized information on fur seal entanglement in discarded fishing nets and other debris for the period 1969-1982:

Each year during the commercial harvest of male fur seals on St. Paul Island, a few seals (less than one percent of those harvested) are taken with net webbing, plastic packing bands, or other debris entangled primarily around the neck and less frequently around the head and shoulders. Entangled seals appearing on the Pribilof Islands have been reported since the early 1930s, and in 1967 the NPFSC recommended that its members make efforts to document the frequency of such occurrence and attempt to identify and record the types and origin of fishing gear responsible for the problem. Daily records have been kept since 1969 of entangled seals observed during the harvest on St. Paul Island and of observations of skins examined in the processing plant with scars around the neck that may have been caused by a past entanglement. Commencing in 1974, skins taken from entangled seals were tagged in the field. Thus observations in the processing plant consisted not only of these tagged entanglement skins but included other skins observed with scars or bruises which became apparent after the blubber was removed. These scars and bruises in the neck area, discovered after the blubber was removed, were very similar to those found on the skins from seals actually entangled and therefore are assumed to be caused by prior entanglements.

The number of entangled seals observed among the animals harvested on St. Paul Island since 1967 has averaged about 0.4 percent of those taken and varied from a low of 0.15 in 1967 to a high of 0.72 percent in 1975 (Table 6). The affected seals are usually entangled in trawl net scraps or plastic packing bands, but have been observed in other debris such as ropes, strings, rubber bands, monofilament gillnets, monofilament lines, plastic 6-pack holders, plastic hoops, and rice sacks. The debris sometimes has gooseneck barnacles attached to it. It is not known exactly where the seals are picking up the debris, but it is suspected that much of it is from the Bering Sea.

Japan examined samples of net webbing removed from fur seals by the United States in the late 1960s and reported that although most of the nets were made in Japan, the countries actually using the nets were unknown since large quantities of net material are exported. Most of the fragments were polyethylene and presumed to be parts of the lower wings and bellies of trawl nets. The mesh sizes of these polyethylene net fragments varied from 12 cm to 30 cm with those of 22 cm and 30 cm predominating.

The incidence of entanglement is not unique to males as female fur seals do occasionally appear on the haul-outs entangled in debris and have been taken in the harvest. Two entangled and mature female fur seals have been taken in the harvest in recent years; one in 1981 and another in 1979. Entangled females are also observed in the breeding areas, but the incidence of entanglement is considerably less than that observed among males taken in the harvest. Adult male fur seals are occasionally observed entangled, but these entangled animals are rarely seen on the breeding areas. Pups are sometimes observed under "billowing" pieces of net webbing attached to rocks, but individual pups with entangling debris are seldom reported. This element of the herd has yet to go to sea and become exposed to the potential of entanglement. In November 1982, local residents on St. Paul rescued one pup and two yearlings that were entangled in a single mass of net webbing that floated into the Village Cove area.

Entangled fur seals are sometimes reported stranded along the Aleutian Islands and along the western coast of North America. Entangled yearling fur seals have been sighted along the Aleutian Islands, and a resident of Nikolski, Umnak Island, reported that in some years ten to twenty of the dead yearlings that show up on the beach are entangled. The Washington Department of Game, Marine Mammal Project has recovered three fur seal carcasses in the last two years entangled in debris; a 118 cm long male fur seal was found in a heavy piece of 13.3 cm mesh trawl net in Oregon in December 1980, a 100 cm fur seal was found entangled in a mass of 27.9 cm mesh black and 29.2 cm mesh green trawl net webbing in Oregon in February 1982, and a 86 cm female fur seal was found with trawl net webbing around its neck in Washington in April 1982. A yearling fur seal tagged in September 1981 on San Miguel Island was recovered in British Columbia north of Vancouver Island in March 1982 entangled in net webbing. The northern fur seals breeding on San Miguel Island are sometimes observed entangled in debris.

Entangled fur seals are also observed during the harvest and on the rookeries in the western North Pacific Ocean. In 1981, the USSR reported 132 entangled seals on the Commander Islands, 70 on Robben Island, and 27 on the Kurile Islands. Of the 70 entangled fur seals observed on Robben Island, 11 were bulls, 5 sub-adult males, 19 bachelors, 32 females, and 3 were pups. The entangling debris on Robben Island consisted of net fragments (71.4 percent), ropes (20 percent), packing bands (5.9 percent), fishing lines (1.4 percent), and cords (1.4 percent). Entangled male seals are also observed during the harvest on the Robben and Commander Islands, and in 1979, the rate of entanglement was 1.09 percent on Robben Island, 0.98 percent on Southeastern Rookery, Medney Island, and 0.14 percent on Northern Rookery, Bering Island.

Other species of pinnipeds have also been observed entangled in discarded fishing debris. Hawaiian monk seals have been observed with net debris and plastic packing bands around their necks. Northern sea lions entangled in net webbing have been sighted on St. Paul Island by local residents. California sea lions, and northern elephant seals have been sighted with entangling debris on the Channel Islands off California