Research of development on midwater trawl for sampling larval and juvenile fish

中层拖网幼鱼取样开发研究

• 批准号: 10660175
• 负责人: MATUDA Ko
• 金额: $ 2.5万
• 依托单位: Tokyo University of Fisheries
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1998
• 资助国家: 日本
• 起止时间: 1998 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10660175/
• 关键词: larval and juvenile; quantitative collection; estimation of stock abundance; midwater trawl; cambered V-type depressor; practical test; towing depth; towing speed; 湾曲Vデプレッサー; デプレッサー; 模型実験; 潜行力

In order to continuously utilize the fisheries resource effectively, it is necessary to estimate the stock abundance of the target fish species accurately. The quantitative collection of the larval and juvenile is pointed out as one of the means. In this research, the new midwater trawl (MOHT) was developed with a square fixed frame and constant depth can be towed irrespective of the change in towing speed to collect pelagic larval and juvenile fish quantitatively. The results are shown as follows.(1) In the first year, the cambered V-type depressor was designed with the camber ratio of 15%, aspect ratio of 6.0 and dihedral angle of 20°. An experiment was carried out using 1/5 scale model in a circulating water tank. The maximum sinking force coefficient of 1.57 was obtained at the attack angle of 20°. It is larger about twice than the value of the flat shaped depressor. Next, this depressor was attached to the lower side of the net frame with four long bridles, the net depth by change … More of the flow velocity was measured. As the result, the fluctuating range of the net depth was slight 4.4 cm, and it was possible to maintain the constant depth almost in 30-100cm/s wide range of flow velocity. (2) In this fiscal year, first of all field experiment was carried out with the 1/5 scale model using training ship "Hiyodori" of Tokyo University of Fisheries in the Tokyo bay. As for the MOHT model that weight in the water of the net is adjusted to zero, it was confirmed to be able almost to towing constant depth within the range of towing speed of 1.0-2.0 m/s at warp length 20, 30, 40, and 50m. (3) The full scale of 12.5m in total length was made with net-mouth 2.25m x 2.25m based on the results of the model testing. The field experiments were carried out by the boarding to "Soyo-maru" of National Research Institute of Fisheries Science and T/RV "Umitaka-maru" of Tokyo University of Fisheries in Suruga Bay and the off Hawaii. As the results, the fluctuating range of the net depth was only 2.7m when the towing speed was accelerated from 1.0 m/s to 2.3 m/s in the case of warp length 100m and weight in water of the net was 30kg. Especially, it is possible that depressor always keeps setting angle of attack as one of the features of the net developed by this study. Therefore, the net position can be always controlled to the target depth regardless of the towing speed, if the warp length is equal even in the different operation.As mentioned above, in this research, the propose was achieved and the developed net has already been used to collect the juvenile fish with some research laboratories including National Research Institute of Fisheries Science. The spread as the standard fishing gear for resource investigation will be expected in the future. Less

为了持续有效地利用渔业资源，有必要对目标鱼种的种群丰度进行准确的估计。定量采集幼虫和幼鱼是一种有效的方法。本研究研制了一种新型中水拖网（MOHT），该拖网框架为方形固定框架，拖网深度恒定，不受拖网速度变化的影响，可定量采集远洋幼鱼和幼鱼。结果如下所示。(1)第一年设计了弧度v型降压器，弧度比为15%，长径比为6.0，二面角为20°。采用1/5比例模型在循环水箱中进行了试验。攻角为20°时，沉沉力系数最大，为1.57。它大约是扁型降压机的两倍。接下来，将该降压器用4根长缰绳固定在网框的下侧，通过改变网的深度来测量流速。结果表明，净深度波动范围为4.4 cm，在30 ~ 100cm/s的大流速范围内几乎可以保持深度不变。(2)本会计年度，首先在东京湾利用东京水产大学的训练舰“hiyodoori”进行了1/5比例模型的实地试验。将网水中重量调整为零的MOHT模型，在拖曳速度1.0 ~ 2.0 m/s范围内，经长为20、30、40、50m时，基本可以实现定深拖曳。(3)根据模型试验结果，制作全长12.5m的实物比例尺，净口为2.25m x 2.25m。在骏河湾和夏威夷外海，通过登上日本水产科学研究所的“Soyo-maru”和东京水产大学的T/RV“Umitaka-maru”进行了实地试验。结果表明，当拖曳速度由1.0 m/s加速到2.3 m/s时，当经纱长度为100m，网重为30kg时，网深波动范围仅为2.7m。特别是，有可能抑制剂一直将攻角设置为本研究开发的网络的特征之一。因此，如果经纱长度相等，即使在不同的操作中，无论拖曳速度如何，网位置始终可以控制到目标深度。如前所述，在本研究中，已实现了上述建议，并已与国家水产科学研究所等一些研究实验室将开发的网用于收集幼鱼。在今后的资源调查中，有望将其作为标准渔具。少

项目成果

Fuxinag HU: "Effects of drag coefficient of netting for dynamic similarity on model testing of fishing nets"Proceedings of the 3rd JSPS International Seminar on Fisheries Science in Tropical Area, Bali, Indonesia, August, 1999.

胡福新：“动态相似性网的阻力系数对渔网模型测试的影响”第三届 JSPS 国际热带地区渔业科学研讨会论文集，印度尼西亚巴厘岛，1999 年 8 月。

Fuxiang Hu: "Effects of drag coefficient of netting for dynamic similarity on model testing of fishing nets"Proceedings of the 3rd JSPS International Seminar on Fisheries Science in Tropical Area, Bali, Indonesia, August 1999. (2000)

胡福祥：“动态相似性网的阻力系数对渔网模型测试的影响”第三届 JSPS 国际热带地区渔业科学研讨会论文集，印度尼西亚巴厘岛，1999 年 8 月。（2000 年）