419 DISTRIBUTION OF MARINE DEBRIS AND NORTHERN FUR SEALS IN THE EASTERN BERING SEA Norihisa Baba, Masashi Kiyota, and Kazumoto Yoshida National Research Institute of Far Seas Fisheries Shimizu-shi, Shizuoka, 424 Japan Fisheries Agency, the Government of Japan ABSTRACT To obtain basic information about entanglement rate and mortality of the northern fur seal, Callorhinus ursinus, at sea, we conducted sighting surveys of fur seals and marine debris along eight transect lines in 1984 and four in 1985 and 1988 in summer near the Pribilof Islands in the eastern Bering Sea. These southeast to northwest transects were approximately 300- 500 km long. We observed 710 fur seals and 7 debris items of fisheries origin in 1984, 345 seals and 17 debris items in 1985, and 343 seals and 18 debris items in 1988. In 1985, one dead male fur seal was observed entangled in a trawl net fragment weighing 40 kg. Distributions of both marine debris and fur seals were concentrated in the area along the continental slope west of the Pribilof Islands. It is considered that this co- occurrence is a result of the mutual relationship between fish resources, seals' feeding, fishing grounds of trawlers in the area, and northward-flowingcurrent. INTRODUCTION Japanese trawlers began operating in the eastern Bering Sea in 1933 and other nations have begun fishing there later the U.S.S.R. in 1959, South Korea in 1968, Taiwan in 1974, Poland in 1979, and West Germany in 1980. The estimated total number of trawl-fishingvessels off Alaska increased from 5 in 1933 to 432 in 1963, and dropped to 317 in 1983 (Low et al. 1985). At the 10th meeting of the North Pacific Fur Seal Commission (NPFSC), the survival rate of fur seals that were entangled in fishing net fragments was reported (NPFSC 1967). Since then, the United States has been actively collecting data on entanglement of fur seals (Scordino 1985). Japan-United States joint research started in 1983 (Bengtson et al. 1988; Scordino et al. 1988). The fur seal population on the Pribilof Islands has steadily declined since the 1960's, and entanglement of seals has been suggested as a partial cause (Fowler 1982). In R. S. Shomura and M. L. Godfrey (editors), Proceedings of the Second International Conference on Marine Debris, 2-1 April 1989, Honoluiu, Hawaii. U.S Dep. Comer.. NOM Tech. Memo. NMFS. NOM-TM-NMFS-SUFSC-154. 1990.