Flow distribution on a simple separator device for trawling, TREND

Fuwa, Shigeru; Nakamura, Junya; Ebata, Keigo; Kumazawa, Taisei; Hirayama, Mamoru

doi:10.1111/j.0919-9268.2003.00742.x

Cited by 8 publications

(3 citation statements)

References 15 publications

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“…Further experiments are required, perhaps by using stereo high‐speed camera systems, to quantify maneuverability of fish penetrating the mesh. Experiments should also investigate body shape 17,26,27 and water flow 28 caused by cod end pulsing.…”

Section: Discussionmentioning

confidence: 99%

Herding and escaping responses of juvenile roundfish to square mesh window in a trawl cod end

Kim

Wardle

2008

Fisheries Sci

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The movements of juvenile roundfish, mainly haddock Melanogrammus aeglefinus and whiting Merlangius merlangus, reacting to a square mesh window in the cod end of a bottom trawl were observed during fishing experiments in the North Sea. Two typical behavioral responses of roundfish are described as the herding response and the escaping response, which were analyzed from video recordings by time sequences of the movement parameters. It was found that most of the actively escaping fish approached the square mesh window at right angles by swimming straight ahead with very little change in direction, while most of the herded fish approached the net at obtuse angles and retreated by sharp turning. The herding and escaping responses showed significant difference when characterized by frequency distributions of swimming speed and angular velocity, and both responses showed large and irregular variations in swimming movement parameters like the panic erratic responses. It is concluded that an escaping or herding response to the square mesh window could be decided by an interaction between the predictable parameters that describe the stimuli of net and angular changes of fish response, such as approaching angle, turning angle and angular velocity.

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Section: Discussionmentioning

confidence: 99%

Herding and escaping responses of juvenile roundfish to square mesh window in a trawl cod end

Kim

Wardle

2008

Fisheries Sci

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“…Since the flow distribution determined in the flume tank is not constant at the measured positions, the values found during these experiments were converted to the ratio of the flow speed with a blank condition at the same point using the equation reported by Fuwa 11,12 …”

Section: Methodsmentioning

confidence: 99%

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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“…Application of the square mesh is compulsory for the trawl codends in the Baltic cod fishing (Anonymous 2005). Fuwa et al (2003) give an example of the rectangular meshes facilitating escape of the flattened body shape fish from the fishing gear.…”

Section: Introductionmentioning

confidence: 99%

Equations describing changes of shape along the flatfish body length and their importance for sustainable and responsible fisheries

Balejko¹,

Miler²,

Nowakowski³

2007

Acta Icth et Piscat

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Equations describing changes of shape along the flatfish body length and their importance for sustainable and responsible fisheries. Acta Ichthyol. Piscat. 37 (2): 113-116. Background. The purpose of this study was to identify mathematical equations describing changes in a flatfish body shape along its longitudinal axis. The initial function for the description of a cross-section contour is the ellipse equation including a factor deforming the symmetry with respect to one of axes. Such equations may find their use in fisheries engineering and food-fish processing. Materials and Methods. The morphometric examination of the fish raw material was carried out in order to check whether the proposed function meets expectations and draws a curve. The model fish species used was flounder, Platichthys flesus (L.). Results. The mathematical equation describing changes in a cross-section contour of flatfish body shape along its longitudinal axis. The high value of correlation coefficients (r > 0.99) showed that a hypothetical curve matches experiment results quite well. The equation describing the shape of a flatfish body cross-section contour can be defined by means of the ellipse equation including a factor deforming the symmetry with regard to one of its axes. The function represented by equation (8) draws a curve that follows the contour of the fish cross-section. Conclusion. The shape of flounder, defined in the presently reported study may have importance for sustainable and responsible fisheries, helping to design more selective fishing gear. It can also be used in food-fish engineering for designing more effective fish-processing machinery.

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Flow distribution on a simple separator device for trawling, TREND

Cited by 8 publications

References 15 publications

Herding and escaping responses of juvenile roundfish to square mesh window in a trawl cod end

Herding and escaping responses of juvenile roundfish to square mesh window in a trawl cod end

Fundamental study on the flow speed distribution around small traps

Equations describing changes of shape along the flatfish body length and their importance for sustainable and responsible fisheries

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