A trial for the development of a separation device for a danish seine (Koteguri-ami), 2

As part of the improvement of the Danish seine termed Koteguri-ami, we developed a separation device to separate and allow the escape of young fish during hauling. We surveyed the respective size groups to clarify their separation efficiencies. Three experimental hauls were conducted off the north-west coast of Hagi during May, 1997. A two-level seine, the reported remodeled net used in November, 1996, was used but a square-mesh separator was attached to the mouth of the upper level instead of the lower level. We compared the former seine (the November Lower Grid) and the latter (the May Upper Grid). The measurement of the height of the net mouse and fish and the method of assessing the separation efficiencies were the same as before. A total of nearly 8,500 individuals were caught. Twelve species were chosen that were dominant in number. Separation efficiencies defined as the proportion of the catch number of the upper codend versus the lower codend are discussed for these 12 staple species. Although 57 % of the catch passed through the separator, the separation efficiencies by body length were not found. The square-mesh separator attached to the mouse of the Danish seine seemed to act as a guide net within the set-net.