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Study on acoustic estimation of myctophid fishes biomass

菌类鱼类生物量声学估算研究

基本信息

批准号：
14560142
负责人：
AOKI Ichiro
金额：
$ 1.73万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2003
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-14560142/
关键词：
micronekton acoustic measurement target strength myctophid fishes swimbladder

项目摘要

1.a soft-X ray system was used to observe swimbladders of 14 species of myctophids. The shape and size of the swimbladder varied with developmental stage. In most species the sswimbladders varied with developmental stage. In most species the swimbladders did not grow in proportion with body length, and in a few species the swimbladders began to degenerate at a certain life stage.2.the body density ration (g) ranged from 1.003 to 1.020 for 5 species examined except Myctophum asperum. Especially, two species of Stenobranchius had a low density ratio (1.004) similar to sea water density. The sound speed ratio (h) of fish body to sea water changed depending on temperature. Therefore, considering temperature in habitat of fish, the sound speed rations were estimated 1.032-1.039 for Stenobranchius leucopsarus, 1.024-1.036 for Notoscopelus japonicus, and 1.012-1.024 for Myctophum asperum.3.based on the morphological measurement and values of g and h obtained above, the theoretical target strength (TS) was calculated using PSM and DCM scattering models. For fish with swimbladder, though there was a 2-5 dB difference in TS between the two models, measured TS in a tank was in accord with PSM. On the other hand, TS patterns of swimbladder-less fish calculated by PSM and DCM were similar, and accord with measured TS patterns in the broadside region.4.TS was less dependent on the tilt angle at frequencies of 38-200kHz, because the swimbladders of myctophids were spherical and very small. Normalized TS (TScm) was consistently below -70dB in this frequency range. TS of myctophids was not in proportion to square of body length because of irregular growth of swimbladders.5,8 million tons with density of 50-100gm^<-2>. Similarly, biomass of Diaphus theta was estimated 75 thousand tons with mean density of 35gm^<-2>.

1.利用软X射线系统对14种真菌的鳔进行了观察。鳔的形态和大小随发育阶段而变化。大多数种的鳔随发育阶段而变化。大多数种类的鱼鳔与体长不成比例增长，少数种类的鱼鳔在一定的生活阶段开始退化。2.除粗枝鱼外，其它5种鱼的体密度比（g）在1.003 ~ 1.020之间。特别是两种狭鳃鱼的密度比很低（1.004），与海水密度相似。鱼体与海水的声速比（h）随温度的变化而变化。因此，考虑到鱼类栖息地的温度，估算出白鳍狭鳃鱼、背鳃鱼和糙灯笼鱼的声速比分别为1.032-1.039、1.024-1.036和1.012-1.024。使用PSM和DCM散射模型计算理论目标强度（TS）。对于有鳔的鱼，尽管两种模型的TS值相差2-5 dB，但在水槽中测得的TS值与PSM值符合雅阁。无鳔鱼类的TS模式与PSM和DCM计算的TS模式相似，在舷侧区域与实测TS模式雅阁。4.在38- 200 kHz频率范围内，TS对倾斜角的依赖性较小，这是因为软体动物的鳔呈球形且非常小。在该频率范围内，标准化TS（TScm）始终低于-70 dB。由于浮游生物的不规则生长，使其总生物量与体长的平方不成正比<-2>。类似地，Diaphus theta的生物量估计为7.5万吨，平均密度为35 gm ^2<-2>。