Title Development of a large-sized dredge 'Beni-Zuwai Type 1'for deep sea bottom sampling
Authers Taro HIROSE, Ikuko YOSHO, Shigeru SHIRAI, Takashi MINAMI and Kodo NIU
Keywords deep sea, sampling gear, dredge, Beni-zuwai crab Chionoecetes japonicus
Citation Bull. Fish. Res. Agen. supplement No. 17, 69-82, 2006
A large-sized dredge ‘Beni-Zuwai Type 1 (BZ-1)' was designed for sampling mainly in sea bottom deeper than 1000m. The width and height of the BZ-1 were 8.2 and 1m, respectively. Its weight was 1150kg (890kg in water). Sea trial was conducted at a depth of 500-2000m. The BZ-1 was towed at the speed of 2 knots for 15 minutes with a single warp which was shorter than that required for an otter trawl. For example, for trawling at 2000m depth the warp length and the total operating time was 2720m and about 2 hours, respectively. The catch ability of the BZ-1 was compared with that of an otter trawl. The BZ-1 collected large individuals of many species as well as the otter trawl, and small individuals which were not caught by the otter trawl. Catch number and weight per swept area of the BZ-1 were more than those of the otter trawl. From these results, the BZ-1 was an effective sampling gear in deep sea.
URI http://www.fra.affrc.go.jp/bulletin/bull/bull17/hirose.pdf