7119 ‎(2)‎

• UCREFRP Catalog Number: 7119
• Author: Emery, L.
• Title: Physiological effects of electrofishing.
• USFW Year: 1984.
• USFW - Doc Type: February 3-4, 1984.
• Copyright Material: NO

the first few days. It appears that the first 2 or 3 days„after shocking is a critical
period that determines whether a fish will survive, Holding and confining fish for obser-
vation after shocking, as well as handling. can also affect the mortality rates of electro-
fished fish.
100
se
v
50
N
0
days after shock
Figure 9. Delayed mortality observed i:n threesp%ne sti:ckleh.acks
electroshocked with ac and do currents (adapted-from
DeMont 1971).
L
Comparison of the Effects of ac and do Shocking of Fish
rol
S5)
(n_175)
(n= 845 )
Some differences in the effects of shocking fish with ac, dc, and pulsed do currents were
discussed earlier. These included higher oxygen consumption, longer recovery period and
higher numbers of fish suffering from delayed mortality when shocked with ac current.
Taylor et al. (1957) found quite a difference in the rates of mortality for rainbow trout
subjected to three different currents. Ac current killed a greater percentage of fish than
•any other method (Table 4).
Table 4. Fish mortality rates (Taylor et al. 1957).
Form of Power Number of Number of Percent
fish shocked fish killed mortality
DC
Pulsed DC 91
1641 0
5 0

60 cycle AC
46
2 0.3
4.2
Spencer (1967) observed more damaged vertebraes in bluegills subjected to various ac cur-
rents than for those shocked with dc. Those percentages for damage ranged from 12.2 for
230 V ac to 1.5~ for those shocked with do currents (.Table 5).
CAL-NEVA WILDLIFE TRANSACTIONS 1984
69
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