7114 ‎(2)‎

• UCREFRP Catalog Number: 7114
• Author: Shentyakova, L. F., et al.
• Title: Effect of an Alternating Electric Current on Fishes and Aquatic Invertebrates
• USFW Year: 1970
• USFW - Doc Type: Journal of Ichthyology
• Copyright Material: YES

experiments were carried out. The experi-
ments were performed with fertilized perch
aDd white bream eggs and larvae and with two-
month-old blue bream and roach larvae. An
eqyal number of eggs (or larvae) was taken for
the experiment and for the control from ferti-
lized eggs or larvae kept in a large glass
crystal pan. The experimental material was
placed in a rectangular plastic container. In
this container the eggs (or larvae) were sub-
jected to the effect of a uniform ac to electric
field of known strength for 5 sec, The experi-
mental material was subjected to the effect of
an electric current in water with an electric
conductivity of 1. 5. 10-4 ohm -1 ,cm-l. The
experimental and control batches of eggs (or
larvae) were then placed in Petri dishes in
which the subsequent development of the eggs
ami larvae took place. The water in the dishes
was changed twice a day for fresh water taken
from the reservoir. Systematic observations,
the results of whic h were recorded in a log of
observations, were made on the state of the
eggs and the larvae in the experiment and the
control. The temperature regime was stable
(18-21"C). The rate of development of the
eggs in the experiment and in the control was
factually the same. No monstrosities were
discovered. Data on the survival of perch
eggs are set out in Table 3.

~
~

The eggs of spring-spawning fishes are
known to he most sensitive to the effect of dif-
ferent environmental factors in the stage of
formation of the embryo. The experiments
with perch eggs were carried out at this stage
in development. In the course of egg develop-
ment the greatest natural wastage in the ex-
periment and in the control occurred in the
main during the period of transjtion from the
embryonic to the larval development stage,
i. e., at the time fo resorption of the yolk sac

and the commencement of transition to active
feeding. The data of 29 experiments with perch
eggs exposed to an ac electric field of different
strength (E) are set out in Table 3. These data
show that the survival of developing eggs follow-
ing the action of alternating current on them was
no lower in the experiments than in the control.

After the hatching of the perch prolarvae in
large crystal pans a series of experiments was
carried out to clarify the survival of perch pro-
larvae and larvae following their exposure to an
alternating current of different strength E and
current density cr (Table 4).

It is evident from the data in Table 4 that the
survival of the prolarvae and larvae was prac-
tically the same in the experiment and in the
control.

We also investigated the survival of white
bream eggs and prolarvae and of 2-month-old
roach and blue bream fingerlings taken from
pond No.2.

The data in Table 5 show that the survival of
eggs, prolarvae and Wlderyearlings in the ex-
periments was no lower than in the control even
when the electric field strength was high (E =
= (3-5) vfcm), more than 10 times the possible
electric field strength of the electrified trawl.

In all the experiments described above with
eggs and larvae the period of exposure to the
ac electric field was constant (5 sec); all that
was varied was the electric field strength (E)
and the current density (cr).

The effect of exposure of white bream larvae
to an electric field was verified in experiment
No. 18. Three groups of white bream larvae
6.6 mm (50 in each group) were taken for this

Table4

Survival of perch prolarvae and larvae at different stages of de-
velopment after their exposure for 5 sec to a uniform ac elec-
tric field, %

'Otj No. of .... Survival
prolarvae Dectric
8 E Development stage of or larvae parameters on 7th day
-1: larvae wheD exposed to
. ~ to the current in the
1:1>. in the in the E, a;;~1 in the
.:;~ con- uel experl-
exper. trol v/cm /cm2 ment contrOl
8 After hatching 15 17 5.0 0.625 94 53.3 60 0
20 20 15.0 1.870 280 52.9 65.0
9 1 day after hatching 23 t9 5.0 0.625 94 13.0 79.0
16 22 15.0 1.870 280 8\\.0 64..~)
20 20 25.0 3.120 468 94.0 0
10 2 d:ays after hatching 20 20 5.0 0.625 94 85.0 60.lt
> 20 21 25.0 3.120 468 60.0 BO.!)
11 Same 19 20 5.0 0.625 94 94.7 if,,!
After transition to 21 23 25.0 3.120 468 100 lOll
12 25 25 24.0 3.00 4511 60.0 44.0
active feeding
13 Same 25 25 15.0 I. 870 2~0 100 92.0
25 25 25.0 3.120 468 \00 100
14 Age 17 days 12 12 25.( 3.120 468 100 83.0

368

Table 5

Survival of white bream eggs and prolarvae and blue bream and
roach underyearlings after their exposure to an alternating cur-
rent for 5 sec %

, .
o~ No. of eggs Dectric fSUrvival, %
8E Developmentstage at the or la:rvae parameters
_.~ time of exposure to the
i~ in the in the
<:un'eDt experi... Ue!J v E, ':-P'fc",2 after Oct.
"'~ ment control v/cm 1 1
mo,
15 Embryo fonn ed 100 - 10.0 1.250 188
17 8
(egg) 100 - 15.0 1.870 280 44 t4
\00 - 25.0 3.120 468 71 II
16 2 days after hatching - 100 - - - 37 5
25 - 10.0 1.250 188 36 -
(prolarval 25 - 15.0 I. 870 280 44 -
25 - 25.0 3.120 468 24 -
- 25 - - - 28 -
20 Underyearling blue brea.m and roach at aD age of 2 months on July 19, 1968
Roach } 20a { 10 - 40 5.0 750 90 70
Blue bream 15 - 40 5.0 750 73 64
Roach } 06 - 30
Blue bream 20a 3.75 562 100 67
Roach f - 30 3 75 562 89 88
Control - 17 - - - 100 82
Blue bream - 8 - - - 88 0

purpose. The first group of larvae was sub-
jected to the effect of an ac electric field for
which the voltage in the dish electrodes was
Vel = 2~ v (E=. 2.? vfcm, cr = 375 /.l ampfcm2)
for 1 mm, ThiS field strength induced a state
of ~hock in the larvae. The second group of
white bream larvae was subjected to a similar
current effect for 5 min. The third group was
not subjected to the effect of an electric cur-
rent (control), The experimental and control
groups were placed in different aquaria in which
they were kept under identical conditions Ob
servations on the survival of the larvae ';ere -
made for all three groups, which were fed
equal portions of plankton. All the white
bream larvae in the control aquarium died
with 8 days. The survival of the larvae which
had been exposed to the action of the current
for 1 min was 20 %, and the survival of the
larvae which had been acted upon by the cur-
rent for 5 min was 22%. By November 1 four
white bream ....ere surviving from the firs't ex-
periment (exposure 1 minI and 6 from the
second experiment (exposure 5 min), There
was practically no size difference between
these larvae and larvae from the control ex-
periment No. 15.

We also investigated the effect of alternat-
ing current on Dactylog}Tus parasites in roach
and blue bream young.

Experiment No. 20 (Table 5). These
groups each containing 25 were selected from
a mixture of roach and blue bream fingerlings
(Table 5, experiment No. 20). Before com-
mencement of the experiment infection by
Dactylog}Tus was uniform In all the fishes,
One group of fishes (9 roach, 16 blue bream)
was exposed to an electric field with a strength
in the dish electrodes of 30 v (exposure 5 sec)

.",

and the second (10 roach, 15 blue bream) was
exposed to 40 v. The control batch was not
exposed to an electric current.

All three groups of fishes were examined
25 days later and it was found that no changes
had occurred in the infection of the fingerlings
by Dactylogyrus in the experiment in which
current strength was 30 v. In the second ex-
perimental group in which current strength was
40 v no Dactylogyrus were found on the gills of
the finger lings. There were no changes in
infestation by Dactylogyrus in the control group
of fingerlings.

The Effect of Alternating Current on the
Glycemia Level of the Fishes

The effect of an electric current on the
glycemia level of the roach was investigated in
the Laboratory of the Physiology of Fishes
Experiments were carried out on 71 fishe;in
October 1968. Before the experiment the fishes
w~re kept for 10 days in running water aquaria
Without food to eliminate the effect of alimentary
hyperglycemia. Water temperature in the
experimental aquaria was 10.:1: I"C. A field
strength (E) of 0.3 vfcm was used. Blood for
analysis was taken immediately after cessation
of the action of the cUrP.!!ut, which lasted for
12 sec.

. The glyc~mia level was 86.3:t 12, 7 mg";'
In the experimental fishes and 59.7.:1: 6. 3 mg%
m the control fishes. Student's test was 1 81
i. e., the differences' between the experim~nt '
and the control were significant (p > O. 1) and
78, 2 % ?f ~he experimental fishes had a glycemia
level wlthm normal limits (normal 52.7.:1: 4.32
~g%); hyperglycemia was found in 21.8% of the
fishes. .

369