ベーリング海東部における底曳網漁場の研究-II

Abstract

In the first paper, the authors discussed the changes in the bottom temperature and movements of yellow-fin sole, Limanda aspera (PALLAS), in the eastern Bering Sea, 1960. In the next paper, they compared the oceanographical conditions in 1963 with 1960, and reported on the distributions of yellow-fin sole and alaska pollack, Theragra chalcogramma (PALLAS), in 1963. The authors investigated oceanographical conditions on the continental shelf of the eastern Bering Sea in the summer every year from 1955 to 1967 with the exception of 1957, and examined the distribution and annual fluctuation of the bottom temperature and salinity during the past twelve years. The results obtained are summarized as follows: 1. In every year, the central portion of the cold water mass on the sea bottom was in the area south west of St. Lawrence Island, and extended from this area in the shape of a tongue along both sides of St. Matthew Island and the north side of St. Paul Island to Bristol Bay. 2. The low salinity water mass was along the coastal area of Alaska. The high salinity water mass reached from the edge of the continental shelf across the western Bering Sea to the Bering Strait. 3. The years of high water temperature coincided with the years of high salinity, and years of low water temperature and salinity also coincided. 4. Fluctuation of bottom water temperature and salinity seemed to depend on the cooling in winter and the strength of open sea water. The fluctuations were in 2 year cycles and 3-5 year cycles. A long term trends can also be seen. The temperature and salinity dropped during 1955 to 1959, followed by a steady increase from 1960 to 1967. 5. Annual fluctuation of oceanographical conditions has an influence on the distribution and migration of fish shoals. Alaska cod, Gadus macrocephalus TILESIUS, and alaska pollack stayed around the continental shelf edge in years of low temperature and salinity, and they migrated as far as the area south west of St. Lawrence Island in years of high temperature and salinity.