Behavior of Puffer Lagosephalus and the Fishing Mechanism of the Pot Trap.

Hirayama, Mamoru; Fuwa, Shigeru; Ishizaki, Munechika; Imai, Takehiko

doi:10.2331/suisan.65.419

Cited by 6 publications

(6 citation statements)

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“…The diameter of the outer funnel is 180 mm and the entrance ring frame was interconnected with 22 wires of 180 cm long and 1 mm in diameter. This trap is commonly used to catch puffer fish 10–14 …”

Section: Methodsmentioning

confidence: 99%

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Fundamental studies on the hydrodynamic resistance of small pot traps

2004

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The hydrodynamic resistance of small pot traps has been conducted in order to establish some basic information. The specific objectives of the study was to measure the hydrodynamic force and estimate the critical setting condition for traps. Five types of traps with different materials were used in the experiment: a netted semi-cylinder shape, a wire semi-cylinder shape, a heart shape, a box shape, and a cylinder shape. The hydrodynamic force of each trap was measured in a flume tank. Flow speeds in the flume tank were 0.1, 0.2, 0.3, 0.4, and 0.5 m/s. Attack angles for this study were 0, 15, 30, 45, 60, 75, and 90 degrees. At an attack angle of 0 degrees the main axis of the trap was parallel to the water flow and at 90 degrees it was vertical. The values of the hydrodynamic drag coefficient varied with traps: netted semi-cylinder shape, 2.75-5.96; wire semi-cylinder shape, 2.81-4.49; heart shape, 2.77-3.66; box shape, 2.39-2.97; and for cylinder shape, 3.57-3.67. The flow speed (0.5 m/s) was effective to set the netted semi-cylinder, wire semi-cylinder, box, and cylinder shaped traps. The same flow speed applied to the heart-shaped trap was only effective to a maximum of 30 degrees attack angles and below.

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Section: Methodsmentioning

confidence: 99%

“…This trap is commonly used to catch puffer fish. [10][11][12][13][14] The heart-shaped trap ( Fig. 1c) was constructed completely from bamboo strips.…”

Section: Experimental Materialsmentioning

confidence: 99%

Fundamental studies on the hydrodynamic resistance of small pot traps

2004

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“…Equation 8 gives the relationship between solidity ratio and unit projected area (equations 3,7). Finally, the solidity was given as the average (S 0 A) of the unit projected area:…”

Section: Discussionmentioning

confidence: 99%

“…The diameter of the outer funnel was 180 mm and the entrance ring frame was made of 22 wires 180 mm long and 1 mm diameter. This trap is commonly used to catch puffer fish in Kagoshima Prefecture 5–9 …”

Section: Methodsmentioning

confidence: 99%

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Fundamental study on the flow speed distribution around small traps

et al. 2005

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This study measured the flow speed distribution using actual small traps to investigate the effects of their materials and shapes by analyzing the characteristics of the water flow patterns around them. Five types of trap (netted semi-cylinder shaped, wire semi-cylinder shaped, heart shaped, box shaped, and a cylinder shaped traps) constructed from different materials were used in the experiment. The flow speed distribution around each trap was measured in a flume tank. Flow speeds in the flume tank were 0.1, 0.2, 0.3, and 0.4 m/s. The webbing of the traps was different in shape and had various diameters of twine. The diameters of twine ranged from 0.55 to 1.00 mm. The relationship between the solidity ratio of the twine and flow distribution of the traps was also analyzed. For the netted semi-cylinder shaped and cylinder shaped traps, the area of reduced flow speed extended along the downstream area and its width slightly increased with distance from the trap's entrance. The heart shaped trap is shown to have the largest solidity ratio and this resulted in a high reduction of the flow speed downstream from the trap.KEY WORDS: flow ratio, flow speed distribution, solidity ratio, trap.

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