サンプリング用曳航型中層刺網のマイワシ採集能力 Sampling Performance of a Towed Midwater Gillnet for Japanese Sardine Sardinops melanostictus
Sampling for Japanese sardine <i>Sardinops melanostictus</i> was performed offshore of Izu-Oshima, Japan in April 1995 to investigate the sampling performance of a towed midwater gillnet on a research vessel. The towed midwater gillnet (Towed type) and the midwater driftnet (Drift type) of 33, 43mm mesh size were used. The nets were made of monofilament nylon with twine diameter 0.284mm. The Drift type was set at the depth of 30m, hanging on six buoys with ropes. The depth of the Towed type was set in accordance with the depth of sardine shoals located with an echo sounder (50kHz).<br>The Towed type caught about one hundred sardines per operation. The length frequencies of sardines caught by both net types were similar. The sampling performance of the Towed type was similar to the Drift type. Additionally, the Towed type was easier to cast than the Drift type, because the net construction of the Towed type was simpler. It is considered that the Towed type is efficient gear for sampling pelagic fishes on research vessels.
日本水産学会誌 64(3), 412-417, 1998-05-15