492 
graph A (Fig. 5) is known only to be between 
7 and 8. If the true average current values 
were 7.5 amperes for graph A, 5.0 amperes 
for graph B, and 2.5 amperes for graph C, 
then the peak current in all cases would be 
10.0 amperes. 
Decreasing the on- (pulse) period results 
in a more pronounced electrotactic effect at a 
lower amperage and also represents a saving 
in power. It is quite possible that further de- 
creases in the on-time would result in equal 
electrotactic effects and a still greater saving 
in power. 
The success of electrofishing in the open 
sea will depend mainly on the ability to make 
still more efficient use of available power. 
This- is necessary because generators must be 
able to produce sufficient power, yet be of a 
size that will permit installation in a fishing 
boat. 
The use of large amounts of electrical pow- 
er presents a constant element of danger to 
personnel unless proper precautions are taken. 
Safety regulations must be strictly observed 
both in the laboratory and in the field. 
CONCLUSIONS 
1. Interrupted direct current is more desirable 
for electrofishing purposes than uninter- 
rupted current because of the increased 
electrotactic and electronarcotic effects on 
the fish. 
2. The use of interrupted current in electro- 
fishing represents a considerable saving in 
power over the use of uninterrupted current. 
3. The pulse length of interrupted current can 
be decreased, at least to some extent, with- 
out sacrificing any effectiveness. This re- 
sults in further power savings. 
PACIFIC SCIENCE, Vol. VII, October, 1953 
4. The peak current value reached during a 
pulse may be the important consideration 
in causing the response desired in electro- 
fishing. 
5. With interrupted direct current, fish can 
be attracted to the positive pole and im- 
mobilized without being killed or injured. 
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