ON THE SWIMMING LAYER OF ENGRAULIS JAPONICA SHOALS IN BUNGO CHANNEL AND ITS ADJACENT WATERS
ON THE SWIMMING LAYER OF ENGRAULIS JAPONICA SHOALS IN BUNGO CHANNEL AND ITS ADJACENT WATERS
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丰后水道及邻近海域黄鳅浅滩泳层浅析
DOI：
10.2331/suisan.32.237
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发表时间：
1966
影响因子：
0.4
通讯作者：
J. Nozu
中科院分区：
文献类型：
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作者：
J. Nozu
1962 ~ 1965年，在对敦吾海峡和日本内海西部的海洋和气象条件进行常规观测时，用回声测深仪连续记录了日本鳀（Engraulisjapnica）浅滩的游泳层深度。在一系列的巡航中，发现了多达14351个学校。利用回声探测器追踪它们的行为，发现鱼群游泳深度的季节性和每日有节奏变化的趋势，以及它们随天气或风力的变化：（1）滞流季节，浅滩的游泳层较厚在对流季节（从秋季到冬季），大气层厚度较薄，从春季到夏季，大气层趋于轻微下沉。(2)在这些观测中检测到的最大游泳层深度为125米（春季）在丰后海峡和70米（夏季）在别府湾。(3)根据对海洋和气象条件的不同响应，将浅滩分为两类：0 ~ 30 m和30 m以下。后者的行为模式仅受水温的影响。(4)对游泳深度日变化规律的分析表明，浅滩在黎明和黄昏时有下沉的趋势，在白天有上浮至浅水层的趋势。(5)在雨天，鱼群在日本内海西部的深层游泳，但在丰后海峡的浅层游泳。(6)当风力超过博福特等级4级时，浅滩在较深的区域游泳，而不考虑位置。(7)本研究的结果表明，鱼群行为的数据不足，往往导致错误的结论，在浅海沃茨的数据往往是过分强调。此外，以往的调查和本研究的结果表明，这是重要的，在讨论这类问题，而不是只考虑一个因素，但所有可能的因素。
The depth of the swimming layer of Engraulis japnica shoals was continuously recorded by the echo-sounder during routine observations on the oceanographic and meteorological conditions in Dungo Channel and the western part of the Inland Sea (of Japan) from 1962 to 1965. During series of cruises, as many as 14, 351 schools were detected. The examination of their behaviour by the echo-sounder trace revealed following tendencies in seasonal and daily rhythmical changes of the swimming depth of the schools and their variations according to either the weather or the wind force: (1) The swimming layer of the shoals was thick in the stagnant season (from spring to summer), and was thinner in the convection season (from autumn to winter) and tended to sink slightly from spring to summer. (2) The greatest depth of the swimming layer detected in these observations was 125m (in spring) in the Bungo Channel and 70m (in summer) in the Beppu Bay. (3) Two types of shoals were distinguished by different responses to the oceanographic and meteorological conditions-those swimming in the zone of 0 to 30m depth and those in the zone below 30m. The behaviour pattern of the latter group is affected by the water temper-ature only. (4) The analysis of the daily rhythmical changes of the swimming depth indicates that the shoals have a tendency to sink at dawn and dusk and to come up to the shallow layers in the daytime. (5) In rainy weather the shoals swim at deeper layers in the western part of the Inland sea (of Japan), but at shallower layers in the Bungo Channel. (6) When the wind force is over the grade 4 on the Beaufort scale, the shoals swim in the deeper zone, regardless of locality. (7) Results of the present study indicate that insufficient data on behaviour of fish shoals often leads to erroneous conclusions, for data at the neritic waters tend to be overemphasized. Furthermore results of previous investigations and the present study demonstrate that it is important in discussing this kind of problem to consider not only one factor but all possible factors.