A trousers-type framed midwater trawl for simultaneous sampling of plankton and micronekton: Size selectivity of minnow netting for euphausiids
2008
Fujimori, Y.(Hokkaido Univ., Hakodate (Japan)) | Yamashita, Y. | Abe, M. | Itaya, K. | Mukai, T.
A trousers-type framed midwater trawl (T-FMT) was developed for the simultaneous sampling of plankton and micronekton, which allows the use of two kinds of mesh sizes at the same time. This paper describes the performance of T-FMT in the survey of plankton and micronekton. In addition, the estimation of size selectivity for these small creatures was conducted by using the SELECT analysis expanded for a sub-sample from the trousers trawl experiment. The experiments for plankton and juvenile walleye pollock were conducted offshore of Usujiri, Hokkaido. Three kinds of codends were prepared : two moji-nets with mesh sizes of 1.7mm (M17) and 3.1mm (M31) , respectively, and a plankton mesh with a mesh size of 526 microm (PL). A pair of codends, M17 vs. PL and M17 vs. M31, was tested for sampling plankton and juvenile walleye pollock, respectively.
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