Study on Monofilament and Multifilament Crab Bottom Gill Net
Crab bottom gill net is very popular small-scale fishing gear in the Gulf of Thailand. The crab caught by this fishing gear is swimming crab Protunus pelagicus (Linnaeus). This type of net usually consists of plane sheet of netting with a weighted ground rope and a buoyant head line. This gill net is normally shot in fleets and is anchored at each with bridles. It can be set across or in line with the tide. This type of net has the advantages that it has a simple structure, which allows relatively easy handling and the catch obtained by this gear commands much higher prices because they are fresher than the catch by trawl they reach the market. However, the crab bottom gill net that is used in the Gulf of Thailand can be divided into two kinds; one is monofilament bottom gill net and the other the multifilament one. It has long been suspectable which one is a more effective bottom gill net to catch a swimming crab or which one is a profitable one. The test of fishing by the monofilament and the multifilament bottom gill nets was carried out in the Gulf of Thailand with M.V. Plalung to compare their catching efficiency. The objectives of the present study can be summarized as follows. 1. Comparison of catch between the monofilament bottom gill net and the multifilament one : 2. Comparison of catch of gill nets with different hang-in ratios. 3. Comparison of catch by the daytime and the night time operations.