The samplings were taken with the WP-2 closing net (sampling area: 0.255 m2, mesh size: 200 µm) and the WP-2 modified net (sampling area: 0.196 m2, mesh size: 45 µm) . The type of tows was vertical. The WP-2 closing net, has mesh size 200?m and net mouth diameter 57cm. The tow speed was 1m/s and the filtered water volume was estimated by the net mouth surface and the towing distance. The WP-2 modified net, has mesh size 45?m and net mouth diameter 50cm. The tow speed was 0.5m/s and the filtered water volume was estimated by the net mouth surface and the towing distance. Sampling volume was estimated by the net mouth surface and the towing distance.