浅海围网养殖鱼类捕捞网箱的设计与试验

The design and experiments of the harvesting cage for the enclosure culture in shallow seawater

为解决浅海围网设施养殖鱼类的捕捞和分级,以浮绳式围网养殖为研究对象,根据养殖围网设施的结构和大小、敷设技术和主要性能,结合围网养鱼方式和养殖生产的特点,设计并制作了一种分级捕捞网箱。网箱由框架钢筋、网衣、绳索、分级栅等构件制作而成,网箱网身呈圆柱形,顶部呈倒圆台形,整体高1 515 mm,体积约为1 m3,分为入鱼口、分级栅、取鱼口等3部分。在实验室用鲫鱼对分级栅进行了试验,结果表明,分级栅间距为15 mm和20 mm时,小规格鱼残留率平均为7.78%和4.75%,大规格鱼逃逸率平均为2.38%和3.00%。海上试验结果显示,大规格鱼捕获率90%以上。研究表明,通过日常投饵养鱼驯化将养殖鱼引诱至网箱内,通过提升网箱、驱使箱内小规格鱼群从分级栅游离,剩下的大规格鱼提出水面后迅速放入活鱼舱,从而达到捕大留小的目的。

In order to facilitate the harvesting and grading operations of the farmed fish in the shallow sea water enclosure facilities,floating-rope enclosure culture system was selected as the research object in this paper.According to the structure,size,the laying techniques and the key performance of the enclosure culture facility,combining with culture method and the production characteristics,a grading harvesting cage was designed and fabricated. The main body of the cage included steel bar frame,netting,ropes,grading gate and other materials. The cage body was cylindrical,and the top of the cage was inverted cone shape. Thetotal height was 1 515 mm,and the volume was about 1 m3. The structure was divided into 3 parts： the fish entrance,grading gate and harvesting part. The results of fish grading test in the lab were as follows： when grading grid space was 15 mm,the averaged residual rate of small-size fish was 7. 78% and the averaged escape rate of large-size fish was 2. 38%; when grading grid space was 20 mm,the averaged residual rate of small-size fish was 4. 75% and the averaged escape rate of large-size fish was 3. 00 %. The results of the trial in the sea were as follows： the harvesting rate of the large-size fish was more than 90%. The study showed that through the acclimatization of daily feeding,fish could be attracted to enter the cage,then the large-size fish could be harvested to the live fish tanks after lifting cages and driving the small fish inside to escape from the grading gate,so as to achieve the aim of harvesting large-size fish and leave the small-size fish.