(-) 



(+) 



(A) 30- CM. SPACING, PARALLEL 



(8) 30- CM. SPACING, PARALLEL 



e e 



--© g e e 



(-) 



(+) 



(C) 61 - CM. SPACING, STAGGERED 



(D) 91 - CM. SPACING, STAGGERED 



(-) 



( + ) 



9 9 g e e & 



--« e e ©-- 



--e g e G-- 



J v 



(-) 



(+) 



(E) 61 - CM. SPACING, PARALLEL 



(F) 91 - CM. SPACING, PARALLEL 



Figure 2. — Electrode arrays used in experiments 



4. Voltage gradient. 



5. Effectiveness of three sets of electrical 

 conditions including two pulse shapes when 

 combined with the above factors. 



The electrical field was in the center of the 

 experimental area and was generated through 

 two rows of hollow aluminum electrodes, 

 each 5 cm. in outside diameter and 30 cm. 

 long. The electrodes were suspended in the 

 water from two parallel wires secured to 

 insulators and strung at right angles across 

 the experimental channel. They were attached 

 to these wires by two lengths of No. 14 copper 

 insulated wire soldered into an alligator clip 

 at one end and fastened at the other end by 

 bolts through holes drilled in the electrodes. 

 The electrodes hung in the water to an ap- 

 proximate depth of 15 cm. (i.e., to about 3 cm. 

 above the bottom) and were spaced 30, 61, or 

 91 cm. apart in parallel or staggered arrays 

 (fig. 2 and table 1). 



Table 1. — Description of electrode arrays 

 used in exploratory and systematic tests 

 for blocking adult northern squawfish 



