白令海阿留申海盆区夏季理化环境特征及其与狭鳕分布和移动的关系

THE CHARACTERISTICS OF PHYSICOCHEMICAL ENVIRONMENT AND THEIR RELATIONSHIPS TO THE DISTRIBUTION AND MIGRATION OF WALLEY POLLOCK THERAGRA CHALCOGRAMMA IN THE ALEUTIAN BASIN OF BERING SEA IN THE SUMMER

１９９３年６～８月，“北斗”号渔业资源调查船在白令海阿留申海盆区进行了狭鳕资源声学调查及渔场环境调查。应用本航次调查资料，本文阐述了调查海区温度、盐度及溶解氧分布特征，并分析了狭鳕分布和移动与理化环境的关系。结果表明：（１）阿留申海盆区为大面积低温水所覆盖，水温在１０℃以下。温盐水平分布特征为公海区低温高盐，调查区的其余水域则为高温低盐。溶解氧水平分布比较均匀，表层溶氧含量在１０ｍｇ／Ｌ左右；（２）温跃层位于２５米和５０米之间，一强冷水团控制着１００米到２００米左右的水层，其水温在３℃以下。盐度随深度增加而增加，溶解氧随深度的增加而降低；（３）狭鳕当年生幼鱼主要分布在海盆水系和东大陆架水系的混合区内，１００米层幼鱼密集区水温在３～５℃，盐度在３２．９～３３．１，溶解氧在８～９ｍｇ／Ｌ；（４）夏季狭鳕成鱼主要在冷水团范围以内垂直移动，２００米层成鱼密集区水温为３～４℃，盐度为３３．２～３３．６，溶解氧为６～８ｍｇ／Ｌ。

During June to August, 1993, the acoustic survey for walley pollock and the investigation of environment inhabited by them in the Aleutian Basin of Bering Sea were carried ort by R/V BEI DOU. Based on the data obtained from this survey, the distributions of temperature, salinity and dissolved oxygen in surveyed area are described in this paper, which also analyses the relationships between the distribution and migration of walley pollock and physicochemical environment. The results show that: (1) The Aleutian Basin waters were dominated by the extensive water of lower temperature, the temperature was below 10℃. The horizontal distributions of temperature and salinity were that the temperature and salinity in the High Seas area was lower and higher than those in the remaining part of surveyed area respectively. The horizontal distribution of dissolved oxygen (DO) was relatively homogeneous. At the surface the content of DO was about 10 mg/L. (2) The thermocline was observed. The water column between 100m and 200m in depth was dominated by a strong cold water-mass and its temperature was below 3℃. The salinity and and dissolved oxygen increased and decreased with increasing depth respectively. (3) The main distribution areas of age zero walley pollock were situated in the mixing zone between the Sea Basin Water-system and the Eastern Continental Shelf Water-system. In the high schooling areas of age zero walley pollock, the temperature, salinity and dissolved oxyen at the depth of 100m were 3-5℃, 32.9-33.1 and 8-9mg/L respectively. (4)In summer the vertical migration of adult walley pollock was generally within the cold water-mass limits. In the high schooling areas of adult fish, the temperature, salinity and dissoloved oxygen at the depth of 200m were 3-4℃, 33.2-33.6 and 6-8 mg/L respectively.