7130

• UCREFRP Catalog Number: 7130
• Author: Adams, W. J., D. J. Behmer and W. O. Weingarten
• Title: Recovery of Shocked Common Shiner,
• USFW Year: 1972
• Copyright Material: YES

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SHORT :rAPERS AND NOTES

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TOTAL LENGTH (MILLIMETERS)

FIGURE I.-Relation between recovery time mea.
sured in seconds, and total length of common shiners.

Halsband (1%7) and Patten and Gillespie
(1966) have reported that fish which are
fatigued, exhausted, or sick do not react well
to electric current. The fish were placed in
the tank one or two at a time and current was
applied for a specified length of time. The
position of the fish relative to the cathode or
anode was not taken into consideration, the
only requirement being that the fish were
located directly between the electrodes. The
length of time the fish were subjected to the
current was controlled by a manually operated
key in the electrical circuit. The data collected

are restricted by the fact that the length of the
recovery time was only measured up to 120
seconds. Fish which required longer than
120 seconds were given a recovery time of 120
seconds. These fish frequently died.

EFFECTS OF ELECTRICITY

'- Initial results showed that longer fish have
a longer recovery period (Fig. 1). Indirectly,
this supports the data reported by Halsband
(1%7), Lamarque (1967), and Holzer (1932),
I that voltage drop per unit length of fish or the
potential difference between head and tail
determines the amount of electrical energy to
which the fish is actually exposed. In order to'
minimize this variance due to length, common
shiners of approximately the same size (rang-
ing from 65-85 mm) were used in all subse-
quent experiments.
Preliminary experiments (Table 1) showed
that a wide variety of results were obtained
when either voltage, current, or time were
varied, other faCtors being constant. This
illustrates the difficulty of singling out any
one factor such as valtage or current as affect-
ing recovery time of shocked fish. Electrical
energy would take into consideration all of
the above variables since E = foTei dT where

E is the energy in joules, e is the voltage in
volts, i is the current in amperes, and T is the
time in seconds. If the voltage and current
are constant, then the energy E is simply the
product of the voltage, current, and time (E =
e X i X T). But it is necessary to know the
energy flow through the fish, which is difficult
to determine because it depends not only on
the conductivity of the fish's flesh, but also on
the conductivity of the water. The voltage
drop across the body of a fish differs between

TABLE I.-Average recovery time from galvanonarcosis of common shiners subject to varying electrical pa-
rameters

CUITent Voltage Time Energy
(milliamps) ( volts) . ( seconds) (joules)
214 1145 10 310
214 ]62 10 132
]340 14.5 10 492
147 145 10 68
214 62 110 132
214 62 ]25 331
1 Variable factor in the pair of experiments.

1

Range
( seconds)

Average
recovery
time
( seconds)

0-120
0-8

0-120
0-61
0-8
0-.'5.5

48.7
1.46

41.6
9.13
1.46
13.6

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