Effect of bubbles on the count accuracy of seedlings fry sucked with the vacuum pump
1993
Chen, H.(Tokyo Univ. of Fisheries (Japan)) | Yada, S. | Sakai, H.
When the fry's numbers were counted with the suction counting system, a number of bubbles occurred. This paper describes the relation between the diameter of bubble and the light ray's power passed through the bubble. The smallest diameter of bubble detected with the light sensor was measured. In the case of the sensor's sensitivity was adjusted to the limit which the bubble could not be detected, the count accuracy of the fry sucked with the vacuum pump was also measured. The attenuation of the light ray's power passed through the bubble was theoretically analyzed. The results are as follows. l. When the diameter of bubble was big, the light ray's power passed through the bubble reduced. 2. Theoretically, in the case of neglecting the light ray's power attenuated by the air, the power passed through a bubble's center was reduced by 4%. 3. The smallest diameter of bubble which caused the calculation errors was equal to the smallest diameter which can be detected with the sensor. 4. When the sensor's sensitivity adjusted to below 9.7 microW, and the diameter of bubble is smaller than 4.6 mm, the bubble was undetected. When the ratio of fish height and measuring pipe's inner diameter is bigger than 0.6, all fry passing through the pipe was successfully counted.
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