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Last modified
7/14/2009 5:02:31 PM
Creation date
5/20/2009 10:53:53 AM
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UCREFRP
UCREFRP Catalog Number
7792
Author
Kolz, A. L.
Title
In-water Electrical Measurements for Evaluating Electrofishing Systems.
USFW Year
1993.
USFW - Doc Type
\
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20 BIOLOGICAL REPoRT 11 <br />102 <br />4 <br />10' Vertical plates - 0.32 cm thick x 122 cm wide ; <br />? 100 <br />E - 45.7-cm immersion. <br />910-1 <br />?? E 5.2 cm immersion <br />y pi-245.7 <br />cm immereiori <br />4 <br />0)0+ 10-2 <br />" Ea -16.2-cm immersiol <br />510-1 <br />7 <br />10-4 <br />50 100 <br />Distance (centimeters) <br />50 <br />45 <br />40 <br />35 <br />E <br />PM <br />m <br />0 <br />9 <br />30 <br />25 <br />20 <br />15 <br />10 <br />150 200 <br /> <br />Sphere immersion depth = 40 cm <br />Profile depth + - 2, 5, and 10 cm <br />•-20 cm <br />o - 40 cm <br />x-80 an <br />20 40 60 80 <br />Distance (centimeters) <br />tical gradient, it would be necessary to redesign <br />the probe with additional sensors located in the <br />vertical plane. Actually, electronic circuits could <br />be developed to add the horizontal and vertical <br />components and display the resultant magnitude <br />of voltage gradient. <br />The electrofishing literature often describes <br />the electroshock phenomenon by referring to the <br />head-to-tail voltage (Edwards and Higgins 1973; <br />Reynolds 1983; Jesien and Hocutt 1990; Zalewski <br />and Cowx 1990). Since undisturbed fish are nor- <br />100 <br />Fig. 23. Profiles of voltage gradient (E) <br />and the squared value of voltage gra- <br />dient (E) for two vertical plates meas- <br />ured along a transect normal to their <br />surface. <br />Fig. 24. Voltage profiles measured at six <br />depths in the water on a common ver- <br />tical plane to demonstrate the vertical <br />components of voltage gradient for a <br />27.7-cm-diameter sphere. <br />mally oriented horizontally in the water, it be- <br />comes easy to think of the horizontal component <br />of voltage gradient as the head-to-tail voltage. <br />However, fish rarely remain horizontal when sub- <br />jected to an electrical shock, and all electrofishing <br />systems produce electric fields with horizontal <br />and vertical components of voltage gradient. In <br />practice, the spatial direction and magnitude of <br />the gradient vector must be considered to change <br />continuously throughout the electric field. It be- <br />comes necessary to carefully differentiate as to
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