Kết quả nghiên cứu thử nghiệm cửa thoát ghẹ non cho nghề lồng bẫy ghẹ hình trụ tròn trong bể thí nghiệm

Abstract

    Marine resources in general and crab resources are on a declining tendency, along with increased fishing of immature crabs. Therefore, it is necessary to take appropriate measures to reduce the fishing of immature crabs and illegal crab sizes to increase the number of legal crabs size. One of the measures considered is to install vents on the round-pillar crab trap. In Hai Phong, We tested the shape, location, and size of the vents in the experimental tank. Research results show that in the experimental vent shapes (including square, rectangle, and circle), the square gives the best results to escape immature crabs; in 05 locations to place the vent (including the lower slope panel of corner and center, the side panel upper and bottom, and the top panel), the side panel bottom position for the best immature crab escape rate; Through testing the square vent with size 55×55mm, it was shown that individual crabs with CW50% = 92.65 mm, coefficient SR = 19.08, frequency individual crabs with CW> 120mm did not escape from the trap, while all crabs with CW< 70mm escaped from the trap; The 50×50mm square vent shows that the individual crabs with CW50% = 88.57 mm, the coeffi cient SR = 19.5, the frequency of crabs with CW>110mm while being trapped. Some individual crabs with CW<70mm were still trapped in the trap.