ネットの目詰りが濾水計による濾水量測定に与える影響

概要

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This paper deals with the effect of net clogging on measurement for filtered water volume with a flowmeter placed at the center of a net frame. Experiments were carried out using a sampler which had two cyclinder-corn nets: one with fine mesh (0.100×0.100mm, F-net), the other with coarse mesh (0.140×0.170mm, C-net), with a ratio of mesh aperture to mouth area of 10. The sampler was towed horizontally 151 times at a speed of about 1.25m/s for 7 min. In most of the tows, the distances which the C-net flowmeter travels (Lc) and which the F-net flowmeter travels (LF) almose reached the expected value (525m). However, on some of the tows, LF was much shorter than the expected value and LF/Lc was under 0.9. On these tows, the settling volume caught with the F-net was over 100ml and the number of fish eggs caught with the F-net per 25m3 (DF), calculated with the filtered water volume estimated from the revolution of the flowmeter's impeller, tended to be a little more than the number of fish eggs caught with the C-net per 25m3 (Dc). The correlation between DF and Dc are indicated by a regression line of DF=1.128 Dc. This suggests that net clogging has an effect on measurement with a flowmeter for filtered water volume.
日本水産學會の論文