EXPLORATORY EXPERIMENTS IN
GUIDING SALMON FINGERLINGS
BY A NARROW D.C. ELECTRIC FIELD

Marine Biological Laboratory

JUL 18 ib55
WOODS HOLE, MASS.

SPECIAL SCIENTIFIC REPORT-FISHERIES No. 158

UNITED STATES DEPARTMENT OF THE INTERIOR
FISH AND WILDLIFE SERVICE

EXPLANATORY NOTE

The series embodies results of investigations, usually
of restricted scope, intended to ajd or direct management
or utilization practices and as guides for administrative
or legislative action, it is issued in limited quantities for
official use of Federal, State or cooperating agencies and in
processed form for economy and to avoid delay in publication.

United States Department of the Interior, Douglas McKay, Secretary
Fish and Wildlife Service, John L. Farley, Director

EXPLORATORY EXPERIMENTS IN GUIDING
SALMON FINGERLINGS BY A NARROW D. C,
ELECTRIC FIELD

by

Parker S . Trefethen
Fishery Research Biologist

Special Scientific Report: Fisheries No. 158

Washington, D.C.
June 1955

ABSTRACT

The effectiveness of one type of narrow direct -current electrical field in
diverting salmon fingerlings in flowing water was explored experimentally in relation
to (1) the angle of the electrical field relative to the direction of water flow, (2) the
width of the electrical field (distance between rows of electrodes), (3) the spacing
between electrodes, and (4) the diameter of the electrodes . The electrical conditions
were held constant at a voltage gradient of 1 volt/cm . , a pulse frequency of 8 pulses/
sec, and a pulse duration of 40 milliseconds with a square wave form.

It was determined that under the conditions of these experiments the maximum
effectiveness occurred at a 40° angle of electrical field and a 2 -foot width of electrical
field with 1/2 -inch electrodes spaced 12 inches apart. With few exceptions, the 40°
angle of field was not significantly more effective than the 60° angle of field, and the
1/2 -inch diameter electrode was not significantly more effective than the 2 -inch
diameter electrodes . The 2 -foot width of field appeared to be more effective than
the 3 -foot width of field. The results of variation in electrode spacing were greatest
at a 40° angle of electrical field.

CONTENTS

Page

Introduction 1

Methods and materials 1

Experiments 8

Discussion 39

Summary 40

Acknowledgments 41

Literature cited 42

INTRODUCTION

The U.S. Fish and Wildlife Service is engaged in research to develop a method
of electrically guiding or directing downstream -migrating salmon fingerlings into by-
passes away from areas of high mortality. Many fingerlings are injured or killed each
year in spillways and turbines of large dams or are swept into irrigation diversions.
The mechanical screening used at small installations is generally considered im-
practical where huge volumes of water are involved.

This research program includes experiments which range from large-scale
field trials to the seeking of basic information on the electrical characteristics and
energy levels effective in controlling the movements of salmon fingerlings (Collins,
Volz, and Lander, unpublished manuscript) and the relation of these to the electrical
characteristics and energy levels injurious to the fingerlings (Collins, Volz, and
Trefethen, 1954).

The present research, an intermediate step between basic laboratory experi-
ments and full-scale field trials, was designed to test the effectiveness of one type
of a narrow direct current field in diverting salmon fingerlings in flowing water in
relation to the following factors:

(1) The angle of the electrical field relative to the direction of
water flow .

(2) The width of tlie electrical field. (Distance between row of
electrodes) .

(3) The spacing between electrodes.

(4) The diameter of electrodes .

METHODS AND MATERIALS

The experiments were conducted in a large concrete tank 24 feet wide and 30 feet
long, with a maximum depth of 16 inches . A coat of insulating paint was applied to the
inside of the tank to prevent distortion of the electrical field. The water level was
maintained at 9 inches and circulation of the v/ater during the experiments was main-
tained by a recirculating pump. Plywood vanes and a plywood island were used as aids
In Keeping a relatively uniform flow of water through the experimental area which was
approximately 18 feet long and 10 feet wide (fig. 1).

The lower or downstream end of the experimental area was divided by a
plywood vane into two channels with entrances 3 feet and 7 feet wide respectively.
Besides directing the flow of water around the island, the plywood vanes served to
separate the fish that were diverted by the electrical field into the narrow channel
from those that passed through the electrical field into the wide channel. Baffle-type
traps constructed from 1/4-inch-mesh galvanized hardware cloth collected the fish
in the two channels.

The electrical barrier was created by two parallel rows of electrodes suspended
from wires stretched across the experimental area. The parallel wires were adjust-
able at angles at 40°, 60°, and 90° in relation to the long axis of the experimental are4,
the wires could be spaced 2 or 3 feet apart (fig. 2). The distance between these wires
is designated as the width of the electrical field. Electrodes of hollow aluminum tubes
were fastened to each wire by slim -nosed alligator clips at 6, 12, 24, and 36-inch
spacings: they were suspended in the water to within 3/4 inch of the bottom of the tank.
For a comparison, electrodes of 1/2- and 2 -inch outside diameters were used. A
pulsating direct current with a square wave form was supplied to the two rows of
electrodes with the positive row upstream. To eliminate the possibility of a visual
leading effect, two parallel rows of control electrodes suspended from nonconductive
material were placed opposite the rows of electrodes which were electrified; both
sets of electrodes were in the water at the same time. Figure 2 illustrates a typical
arrangement of bor'i test and control electrodes used in the experiments.

Light was supplied by four 500-watt lamps spaced uniformly over the tank. A
variable auto-transform.er controlled the light intensity between 3.4 foot -candles and
less than 1 foot-candle. During the tests the light intensity was reduced in order to
stimulate a downstream movement of the salmon finger lings. Under maximum light
intensity the fish tended to school in the experimental area and any attempt to force
them downstream resulted in startled swimming movements. All changes in intensity
were made very giadually to avoid startling the fish.

A pulsating square -wave direct current was supplied to the barrier with the
following characteristics: pulse frequency 8 pulses per second, pulse duration 40
milliseconds, and voltage gradient 1 volt per centimeter. These electrical character-
istics and energy levels were found to be effective in the preliminary experiments of
Collins, Volz, and Lander (unpublished manuscript) .

The total voltage was measured with a standard RCA WO-56-A oscilloscope;
the voltage gradient was calculated from the total voltage and the distance between
the parallel rows of electrodes. The voltage gradient represents an average value
since the electrical field resulting from the tubular electrodes was not uniform.
The actual voltage gradients were measured with a probe (fig. 3). The lines of
equal potential resulting from one arrangement of electrodes are shown in figure 4.

WATE R

Fig. 2, A plan view of the experimental area with a typical arrangement
of electrodes.

<a

Figure 3. Measuring the electrical field with

special probe. Electrode arrangement
shown includes the following r (l) angle
of electrical field IiO', (2) width of
electrical field 2 feet, (3) spacing
between electrodes 12 inches, {U)
diameter of electrodes 2 inches.

\

^ ' ,

«>

"Z_

TRAP AREA DIVIDER

#.>

^ 1 ' 'Al ^ "i- \ \ III ^

u. Q
o o

-I UJ

■m:

^: — •- '^v

-h

■P

H

irt

O

>

•p

trt

O

vO

-p

h

o

ft

ol

0)

to

s

0)

^

,c^

o

+J

CM H
rH (1)

O iH

A o

CO -rl

W -P
(D o

p r-i

-P

O <H

© O

I

0) (0
H iH <D

^■^^

(D O U
+3 -H 0)
O ^1 rH
0,+' <D

I

Q ^ A3

Pulse frequency and pulse duration were both measured on a special oscilloscope
designed and constructed for laboratory experiments in fish guiding (Volz, unpublished
manuscript).

Water resistance was maintained between 7, 250 ohms/cm. and 10, 000 ohms/
cm. ; it was determined by an industrial Instruments Conductivity Bridge Model RC-IB.
Water temperature varied between 8.0° C. and 16.0° C. and was determined v/ith a
standard mercury thermometer. Water resistance and the temperature were recorded
before each series of tests.

Silver salmon (Oncorhynchuis kisutch) ranging in size from 5.5 cm. to 12 0 cm.
total length, measured from the tip of the snout to the end of the tail, tlie only species
used in these tests, were obtained weekly at the Washington State Fish Hatchery at
Issaquah, Washington, and transported to the laboratory in Seattle where they were
placed in round metal holding tanks. Immediately prior to use they were removed in
small lots of from 150 to 200 fish and placed in a smaller trough near the experimental
area from which they were taken in groups of 60 fish for each test .

Four groups of fish were used each time for each test condition. T'.vo of the
groups of fingerlings (2d and 3d) were released while the electrodes were supplied
with electrical energy and two groups (1st and 4th) v/ere released when tJhe electrical
energy' was not supplied; the 1st and 4th groups of fish were designated as control
groups to ensure that an increase in numbers found in the narrow channel was the
result of the electrical field and not due to the changes in hydraulic patterns created
by the electrodes or leading as the result of a visible barrier.

The fingerlings that were exposed to the electrical current and recovered from
the traps were returned to a second round metal holding tank until all fish on hand had
been exposed once; this procedure was followed to maintain the same condition for all
fish in any series of tests . Since preliminary tests had indicated that conditioning
might influeirce the behavior of fish exposed three or more times to electrical condi-
tions, the fingerlings were exposed only twice; the same handling procedure was
followed in every experiment. The control group of fingerlings, that had not been
exposed to electrical energy, were returned to the original. tank from which they were
taken until they had been exposed to electrical conditions, after which they were
handled as described above.

Prior to release of the fish, the light intensity was subdued to less than 1 foot-
candle and the electrodes were energized. The salmon fingerlings v/ere tlien released
in groups of 60 individuals upstream from the experimental area (fig. 1) equally
divided into the two middle channels. (On the one exception to this procedure, 200
fish were released to investigate the effect with large numbers) . Once the fish were
released the light intensity was reduced to a minimum and the tank remained in almost
total darkness for 5 minutes. At the end of that time, the light intensity was very
slowly increased to a maximum ,

The entrances to the two channels on the downstream end were blocked off with
plastic screens and the electrodes de-energized before a total count of the fish in the
traps was made. Before subsequent tests the experimental area was entirely cleared
of fish by forcing them into the channels at the upstream end.

The results wer? calculated on a percentage basis from the total number of
fingerlings. recovered in both traps and the total number recovered in the narrow
channel. The index of effectiveness is defined as the difference of the percentage of
control fish collected in the narrow channel and the percentage of fish collected in the ■
narrow channel following an electrical test during which the electrodes were energized.

Before a useful comparison between a pair of electrical tests could be made, three
preliminary conditions had to be satisfied: (1) The respective controls had to be uni-
form, (2) The mean percentages of fingerlings recovered in the narrow channel had to
be the same and (3) The electrical tests being compared had to be uniform. While
nonuniformity could result from a response distribution with a large variance,^ the
foregoing restrictions guarantee a uniform experimental technique. All tests of
uniformity and of equal mean percentages were chi-square tests of significance at
the 5-percent level. The results of these tests are shown in tables 1 to 12.

EXPERIMENTS

In exploring the effectiveness of a narrow d.c . field under laboratory conditions,
the electrical characteristics and energy levels were held constant while the following
factors were varied: (1) angle of electrical field in relation to the flowing water; (2)
width of electrical field (distance betv/een rows of electrodes); (3) spacing between
electrodes and (4) diameter of electrodes. These experiments were exploratory in
nature and since the results varied considerably, it was difficult to interpret the data
conclusively. However, the results have been summarized in tables 13 to 18 and
graphically presented in figures 5 to 15.

A maximum effectiveness occurred with a 2 -foot width of electrical field
(fig. 5). This maximum effectiveness occurred at a 40° angle of electrical field
with 1/2 -inch electrodes spaced 12 -inches apart. At the 40° angle and with 1/2-
inch electrodes the 2 -foot width of field was significantly more effective than the 3-
foot width of field. The difference in effectiveness between 2- and 3 -foot fields was
greatest at the closer electrode spacings . As the electrode spacing increased. from
12 to 36 inches there v/as a decrease in the ifference of the effectiveness of the two
widths of field; the effectiveness of the 2-foot width of -field also decreaseci.

At a 60° angle of electrical field with 1/2 -inch electrodes the 2 -foot width of
field appeared to be more effective than the 3 -foot width (fig. 6). The difference
in effectiveness was greatest at a 6- and 36 -inch electrode spacing.

8

^

•H

0)

to

T1

Pl

o

^

fl

•p

0)

c>

^

n)

^

d

•p ;a

EH

H

r^IlM

O

U ^

-P

■P

O

•^

t>

T)

<>-(

H

tJ

(1)

•H

!>Jp.4

+>

"ri

'^

M

O

()

•iH

tH

U

•H

-P

d

o

13

0)

!^

^

O

<M

tN

O

OJ

+^ ;a

to

P

a>

-n

H

•H

r*

<M

()

-p

{)

CO

n

•p

<^^

■^

OJ

OJ

fl)

crt

K

V

• Cm

A rl

<M O CO

O -H 0)

fH (L)

<U P TT !-<

H O H tit

bo 0) Q) (U

q H -H -u

OJ

■a '—

O bO «

f^ c «

-i^ -H .^

o u c>.

(U cd ri,

H P.TI;

O VO
POVO

CM ^ O OJ
vO t— ^£) LP>

- CM h "

iKo

o

5-^

K cd

V

A

l+H

O

O

•H

fH

0)

-P t3

H

U H

hO

(U QJ

l>- t^ :0 t- -

• \0 ir\is\KO

^ d iC-

0)

o to f

vi d oj

•P -H -Cl

o o o

tt) rt G

O

0\

OJ

10

1

O .H

c

fit 4J

o

C

X

P>.05

(Uniform)

X

M

X

X

X

X

X

X

X

X

X

No. Collected
in Narrow
Channel

ITN ON

a\ o

OJ H

CO t-
OJ

O Lr\

OJ rH

rH H

Onvo

H H

on OJ

rH rH

OJ H

OJ ON

vO ro

13
Q)

+i
u

H CQ
O CO

o a

ON 0\

CO VO

-4- LTN

0\(X)

on CO
-4- t-

^ o

vo vo

On rn

^-vo

OOOJ
LTNVO

no m

t— vo

Angle of
Electrical
Field
fde-^rees)

o
4-

o
vo

o

O

o

O

0\

O

o

vo

o

ON

O

o

vo

O
ON

0)

t3 ^~
C t'^ t"

M c JJ

jj -H -C
U o o
(P c' C

H C.-rH

^

VT)

^

OJ

VO
no

11

C W
•H <U

m "O
0) o

p3

+^ ^

0) c

SP4

•rj H

fi ca

o

CO

-p ,«

(0 -P

a; xi
EH r!

^^
O +3

o

CO O
+> Sh

<U n3
K

V

ft

A

O -H

-P TD

H O H

fcO Q) (1)

o

hn

t/)

u

n

fl)

-p

•H

^

o

CI

o

Q)

m

c

H

P.

-H

CO m

-4- LTN

LTNVO

H O
LTNVO

,ONCO

00 CO C^ Lr\

LTN VO t-- Lr\ ^ LTX

O-cJ-
H H

>- ON

CO LTvVO^

o

12

e

LA O

O <M

• -r-l

V ^

ft

+^

o

c

""

g

LA O

O (H

A S

X

w

«

X

X

X

X

X

X

X

X

ft w

(

H

£

5

+

J

t3

c

D

<U

£

J

-P

O

c

n

(U &

r-

H

H O

C

3

H ^1 H

^

O ^^ (U

4- o +

^ -- O

VO OJ

<OcO

OnMD

O VO

t— m

C7N O

On CTn

OO H

-^ LA

c

5

OJ J-

lyi m

OJ CM

-^ oo

CM ro

OJ rn

0>l CM

CA ro

CM rn

c

;

o c ^

S -r-l O

+

:>
-1

£

3

c

)

H

•r

^

'O

£

?

0)

+3

!-

o

C

(U

<(-

:::1^<

4-

O 03

t/

o u

ON on Q

i lAOO

OD OJ

-d- O

Ch ON

LAVO

LA LA

O LA

i-t LA .

^ -d-

03 VO
LAVO

&H

^ U~\ +-

> LA <M

novo

<o t-

LA,;]-

VO vo

LA \T\

LA LA

MD VO

AiVO

o c

c

1

S -H

-^ ^

«H O W

O -H (D

U q;

o c

O

O

o

O

o

O

o

O O

o

CT\

0) +> -a ^

^ vc

ON

^ ^

sO

CK

-* V

^

a\

^ VO

ho Q) 0) (U

C H -H TD

•5 w ^^^

0)

tJ -— ^

o bc to

^ C 4J

+^ -H j:3

vo

CM

-4-

VO

o o o

rH

OJ

en

H ftvH

W CO

1

1

1

1

13

bfl

C

•H

t/1

w

0

fl)

T)

c

C)

n>

^4

^

-P

rs

V

0)

CO

H

+J

N

U)

a)

^

H

V

Q) >

H

O -H

^^
-P H

•rH nJ

•H O
C 0)
P H

M«

O tH
<*H O

M fl
•P +>
to TS
(U tH
6H &

tH -P

o o
o

W Cm
-P I
H OJ

V

A

ft

<u

H
H P^
O 03
O U
EH

(I) 4J
H O
«) 0)

MDCO
OJ OJ

cn PO^ _:f

o

hi

w

u

C

0)

-p

•H

fl

o

V

CJ

0)

0^

c

iH

P<

•H

W

cn

•—'

u
o

f- CO
LTWO

awo OJ iTN

OJ OJ OJ OJ

14

V

/A.

■5 W P^ ■

h- f- CTn m iJ-\ (Tn

ON CTv ro o -a; a')
ir\ Lr\ _ -t u^ t— vo

o ^'■.

rr,

!h C

CI

4-> -H

^

O O

a

0) ff

H P.

•t-^

pq CO

15

bO

C

•iH

m

tn

0

v

T)

a

(J

fl)

J^

^

-p

:*

o

0)

(Q

H

•P

W

CO

0) ^

R

V

c

•^

■P P
o

(U
H

W -a

tW 0)

O -rl

+> H

•H 03

S o

O <)H

<n o

+3 p

CO T)

(U -H

ei >

<^H +»

o o
o

CQ <»H

-P I

(0 d

ft

A

ft

0) &

O ci3

(1) +> -a !h

60 0) 0) (1)
C H -H -O

n

m

to

!h

n

<l)

P

•H

43

o

CJ

c;

a)

C1

r.

H

(-H

•H

W

w

^ — '

o o\ao H

I CO OJ

\-cf lTnmD LPi

\CO 03

o

o

On

16

o

u

•H

<\>

^1

-p

-P

a)

tJ

H

(1)

Cu

H

•H

W

P

(11

(1)

J

Tl

-P

H

<t-l

■p

O

o

^

fl)

■rl

d

•H

U

0)

P^

crt

^

H

(^

+j

01

(1)

o

fl)

w

•H

T)

(h

o

tn

-P

u

-p

V

+J

m

a)

o

(1)

r-l

(1)

H

w

d

(1)

<tH

C)

o

a

^

C)

•p

•H

r)

tM

•r-l

1

o

•H

-p

W

d

Hh

C)

o

•H
-P

w

(rt

+J

H

.^a

h|c

a

CO CM

O tsO

u

1

I -p

CMC
•H tH
to <H

• -t;

bj o

tH U 10

o iH ©

0) -P rc! M

H O r-H tJD

U] 0) (D O

C rH -H -U

M «

M M

^ « Hi

O

^

o

I

o

O O U

<D a a

^

:^ >l

M' M

Hi Hi Hi

M ^ ^ Hi

;^ "^^

K H

v./ v^ «^

t % %

^

K K

M H

»< H

o

o

o

^

o

-4-

17

0) -H

Oj Q

•H

o

f^ 73

■P

(>

U

Fh

(D -P

H

o

W

0)
H

2 w

4i

»\

(ft

n

o

,3

(1)
•H

P4

1

O

•p

Tl

'^

cd

•H

CJ

:o

1-

•H

^H

m

a)
(1)

O
0)

1

i-

H -P

•P

M

o

(1)

u>

«

^

H

«i

-P

•p

(T)

«H

fl)

o

t^

a>

fl) H

1

1

o

•H

-p

•H

^

to

d

<H

o

O

^

-3^

03

^a

,

+> a;

O Tl

C to

-G

O

+5

©
P

.5

M

■>,

N

'^

©

r^J

•H -H

a

m Cm

CO

'H

O

' iZ

©

^v, §

c

^

o
^1
p
o

©

u

5

O bD O

W f.-l

M

K

l^

-<

;

•H C

d c3

i-T

:>J

tu o

M

M

H

•H -H

CO tM

1 +>

•H PI

O Q b

M

K

M

M

fi -H -H

xi

n fM

O

I -P

^

•5

•H C

ti

©

a CO

r-i

P

1

bj CJ

<U

©

Oi

•H -H

•H

q

w ch

tH

3

-rl

H

13

' +2

tii

J

•H rt

O
•rl

o

©

+3 c! Cd

c to o

M

M

!-(

o

a -H -H

■P

t-i

W 'H

O

■p
o

cH

©

.g

©

iH

1 -p

«H

r^i

•dS

O

r-l

•H 'H

^

K

(D

w ch

H

« -P

-a:

©

o

not

sign!
fican

M

K

M

p

.g

0)

as

:^

3

XJ

•H -H

O

W tH

«4

©

"B

' •*£

-P

-P -rj C
O ri C3

X

O

Xi

rt -cJ O

©

o

•H "rl

H

c

m ch

M

•H

t

CM

iH

tl

•H v-i

n ch

X

X

":^

1

Jh H -P

^ -p © ©

*T*

^

<^

*?

4^ O -H ©

1

1

1

1

tj © Cm «H

Oi

cv

CM

Oi

^ ©

O

o o o

vO

J^

■>*

vO

© 05 C

oi

tn

M

n

--^

18

' •!£

•d «^

-p C B

O fcD o

M

«

M

C -H -rl

O

W «H

O

• -ti

s

a

bi) O

^

<D

•H .H

•H

ro Cm

Ch

o

■p

■^

.^•g

g^

o

•H

^ g,g

M

K

M

M

•H a

-p

^1

r! -H ^

-p a

m

-P

w ch

^^-^

CD

0)

0) r-i

rH

1 -P

CrJ <D

CA

Q)

o

d ca
5) o

•H -H

t\

o

a^

O

o

si

0)

W Ch

St

^

1 +»
-p'gS

© -p

«:

t

o & o

•H H

Q

to £h

K

i^

X

n w

•I-

(D (D

o

« -P

T) ^ bp
o -P c

c

5) o

M

•P Cm O

•r-

•H -H

O O cd
<D Pi

4-

CO «H

^•^o

C

a.

• -P

13 O^'Q
<D «J 6

I—

0.

^•dS

X

X

O tlO o

0) U

C(-

fl 'H nH

^ '>-p

■P -Cf o
0) H <B

c

to Ch

,c

o

pq ® H

+■

o

1 4^

•H fa

t.

S

a

•as

:^

X

ffl "ra

0)

•H "H

•H

W «H

tH o

tH

•rl

<1> 1^

H

1 -P

O -P
« 0)

03

O bj O

K

M

M

g^

fn

fl -H -H

•P

w Cm

I'S

^

°c

' +2

So-p

Q)

vQ

•g§

CNJ

tH

:^

O

O

•H -H

(M

w Ch

°5

®

-P

H

P

I -P
O bj o

N

X

01 ffi

c ^ ^

^:3

^o

W Ch

^

1 -P

^

•ds

to o

•H -H

K

::^

QJ

n CH

"Ti

O 0) o

E-t

h -p 0

-p o ,c;

C\J

OJ

«M

c\l

o S u

.^15

1.

1

'

i

M S3>-'

rHJN

Hci

^01

f^lw

O

1.^1

o o o

vO

3

•s^

vO

.^aa

CM

cf^

[X

1 tf

> —

19

0) t:I pt|

•H C

I -P
•H C

a ctf

•H -H

--^

O 'H .rt

H K

N M M K

•P M rj
O tI -r\

-P bO O
O -H -H

j:1 ta cn

t

o o o
<D cJ q

MHlMMlM

K M « M K

M M M M

M M

M W M M

M M

M H «

MM !>< rHlHlHJ

CM rN cNi c^ c^

H Oi {^ Ci OC^

I > I I I I

\0 vO vO Oi OJ -4

o

« Ml ^^

M M M M K

K M

Hi HlHl

« M K M M «

rH (>i C^ Oi C^ C^
I I I I I I

vO sO vO CNJ (V -^

o

^

^20

CO
CO

LjJ

-^

UJ

>

o

UJ
Ll.
Ll.

UJ

X

UJ
Q

60n

50-

40-

30-

U-

O 20-

0-

Width of Electrical Field
^2 Feel
o 3 Fe et

0

12 18 24 30

ELECTRODE SPACING
(Inches)

36

Figure 5.— The effect of electrode spacing in relation to the width of
electrical field using 5-inch electrodes at a 40' angle of
electrical field with a voltage gradient of 1 volt/cm., a
pulse frequency of 8 pulses/sec, a pulse duration cf
40 milliseconds, and a sqviare wave form.

21

if)

UJ

2:

UJ

>

o

UJ

Ll
Ll.
UJ

U-

o

X

UJ
Q

60.

50-

40-

30-

20

10^

Width of Electrical Field

• • Z Fe et

Q o3 Feet

0

6 12 18 24 30
ELECTRODE SPACING
(Inches)

36

Figure 6 — The effect of electrode spacing in relation to the width of
electrical field using j-inch electrodes at a 60'' angle of
electrical field with a voltage gredient of 1 volt/cm., a
pulee frequency of 8 pulses/ sec, a pulse duration of
IfO milliseconds, and a square vave form.

22

When the angle was increased to 90° the 2-foot width of electrical field
appeared to be consistently more effective than the 3 -foot field (fig. 7) . The
maximum difference in effectiveness occurred at an electrode spacing of 24 inches.

The results when 2 -inch electrodes were substituted for 1/2 -inch electrodes
showed a decrease in the difference of effectiveness between the 2- and 3 -foot widths
of electrical field. At a 90° angle of electrical field the 2 -foot width was more
effective than the 3 -foot width of field; the greatest difference occurred at a 24 -inch
electrode spacing (fig. 8) .

The effect of the angle of field is shown in Figures 9 and 10. There appears
to be little difference in the effectiveness of the 40° and 60° angles of field with
two exceptions. One exception occurs at a 12 -inch electrode spacing, 2 -inch electrodes
and a 2 -foot width of electrical field; at tliis point the maximum percentage of finger-
lings was effected. Another exception occurs at a 6 -inch spacing, 2 -inch electrodes
and a 3 -foot width of field; the effectiveness is considerably less than the maximum
effectiveness but a significant difference exists between the 40° and 60° angles of
field. The 90° angle appears to be the least effective of the three angles of field.

At a 40° angle with 1/2 -inch electrodes and a 2 -foot widtli of field the effective-
ness of electrode spacing increased between 6 and 12 inches and decreased to a spacing
of 36 inches (fig. 11). There appeared to be only a slight difference of effectiveness
at the 60* and 90° angles of field. An increase in the width of field to 3 feet and in the
diameter of the electrodes to 2 inches showed a similar result for the same angles
(fig. 12).

There appears to be only a slight difference in effectiveness between 1/2 -inch
and 2-inch diameter electrodes. At a 40° angle of field and a 2-foot width of field
a significant difference exists between the two diameters at a 6 -inch electrode spacing
(fig. 13) . When the width of field was increased to 3 feet, the difference in effective-
ness was greater at a closer electrode spacing (fig. 14). At a 90° angle of field the
difference in effectiveness increases between an electrode spacing of 6 and 24 inches
and decreases at a 36-inch spacing (fig. 15).

Preliminary tests were run under a maximum light intensity to investigate the
effect of light on the effectiveness. In one test the previously described procedure
was followed in which 60 fingerlings were released. At an angle of 40°, electrode
spacing 6 inches, a width of field of 2 feet and with 1/2 -inch electrodes a slight in-
crease occurred. When 200 fingerlings were released the effectiveness was again
increased.

23

o

X

Q

60 1

50-

(D
CO

UJ

z:

UJ

> 40^

»-
o

LU

U-

u.

UJ

30-

20-

10-

Width of Electrical Field

• • Z Fe et

o o3 Fe et

0

6 12 18 24 30

ELECTRODE SPACING
(Inches)

36

Figure 7. — The effect of electrode spacing in relation to the width
of electrical field using j-inch electrodes at a 90° angle
of electrical field with a voltage grsidient of 1 volt/cm.,
a pulse frequency of 8 pulses/sec, a pulse dviration of
kO milliseconds, and a square wave form.

24

CO

en

UJ

LlJ
>

o

UJ

u.

U-
UJ

o

X

LU
Q
2

60n

50-
40-
30-
20-
10-

Width of Electrical Field
• ,2 Feet

-o 3 Fe et

6 12 18 24 30
ELECTRODE SPACING
(Inches)

36

Figure^. --The effect of electrode spacing in relation to the width
of electrical field using 2-inch electrodes at a go'angle
of electrical field with a voltage gradient of 1 volt/cm.,
a pulse frequency of 8 pulses/sec, a pulse duration of
kO mlHiseconds, and a square wave form.

25

60 n

CO

^ 50

UJ

Angle of Electrical Field
— — • 40°

■ 90°

LiJ

> 40-

O
IJJ

u. 30-

UJ

^ 20

o

X

UJ 10"

0

6 12 18 24 30

ELECTRODE SPACING
(Inches)

36

Figure J. — The effect of electrode spacing in relation to the angle
of electrical field using 2-inch electrodes at a width of
electrical field of 2 feet with a voltage gradient of
1 volt/cm., a pulse frequency of 8 piilses/sec, a pulse
duration of kO milliseconds, and a square wave form.

26

CO
CO
LU

>

O

u

Ll
U-
UJ

O

X

LiJ
Q

DU-

Angle of Electrical Field

— — . 40°

50-

►---. 60°

. 90°

40-
30-
20-

p' -5^

10-

'"■''^^^^/^

0-

i 1 1 1 1 1

6 12 18 24 30

ELECTRODE SPACING
(Inches)

36

Figure /£'.— The effect of electrode spacing in relation to the angle
of electrical field using 2-inch electrodes at a width of
electrical field of 3 feet with a voltage gradient of
1 volt/cm., a pulse frequency of 8 pulses/sec, a pulse
duration of 40 milliseconds, and a square wave form.

27

60i

^ 50

UJ

^ 40

o

LJ
U-
Ll.
IJJ

O

X

LU
Q
Z

30-

20-

lO
0

Electrode Spacing

, ^ 6 Inches

, ,12 Inches

^ ♦ 24 Inches

.36 Inches

40 60 90

ANGLE OF ELECTRICAL
FIELD (Degrees)

Figure 11. — The effect of the angle of electrical field in relation
to electrode spacing using |^-inch electrodes at a width
of electrical field of 2 feet with a voltage gradient of
1 volt/cm., a pulse frequency of 8 pulses/sec, a pulse
duration of ^4^0 milliseconds, and a square wave form.

28

CO

(f)

UJ

z:

UJ

>

o

LU
U-
U-
UJ

U-
O

X

LU
Q

60i

50-

40-

30

20

10

0

Electrode Spacing

• • 6 Inches

• •12 Inches

• .24 Inches

• • 36 Inches

40 60 90

ANGLE OF ELECTRICAL
FIELD (Degrees)

Figure 12. — The effect of the angle of electrical field in relation
to electrode spacing tising 2-inch electrodes at a width
ct electrical field of 3 feet with a voltage gradient
of 1 volt/cm., a pulse frequency of 8 pulses/sec, a
pulse duration of kO milliseconds^ and a square wave
form.

29

en

UJ

2:

LlJ
>

O
LU
Ll.
U_

UJ

O
X

u

60n

50-

40-

30-

20-

10-

- 0

Diameter of Electrodes
••---• '4 Inches
2 Inches

12 18 24 30

ELECTRODE SPACING
(Inches)

36

Figure I3. — Effect of electrode spacing in relation to electrode
diameteg using a width of electrical field of 2 feet
at a kO angle of electrical field with a voltage
gradient of 1 volt/cm., a pxiise frequency of 8 pulses/
sec, a pulse duration of 40 niHiseconds, and a square
wave form.

30

60n

cn

^ 50-J

LU

> 40^

o

LiJ

u.

UJ

o

X

Ld
Q
2

30-

20-

10-

Diameter of Electrodes
«. . ^ ^ I/p Inches

^ 2 Inches

^■r'

0-

12 18 24 30

ELECTRODE SPACING
(Inches)

36

Figure l4. —Effect of electrode spacing in relation to electrode
diameter using a width of electrical field of 3 feet
at a kO° angle of electrical field with a voltage
gradient of 1 volt/cm., a pulse frequency of
8 pulses/sec, a pulse duration of kO milliseconds,
and a square wave form.

31

en

LlJ
UJ

>

O

UJ

i±.

IX.

LU

Ll
O

X

Ld
Q
2

60 n

50-
40-
30-
20-
10-
0-

Diameter of Electrode?

♦---■• 4 Inches
m m 2 Incnes

12 18 24 30

ELECTRODE SPACING
(Inches)

36

Figure 15.— Effect of electrode spacing In relation to electrode
diameter using a width of electrical field of 2 feet
at a 90° angle of electrical field with a voltage
gradient of 1 volt/cm., a piolse frequency of
8 pulses/sec, a pulse duration of kO milliseconds,
and a square wave form.

32

55

d oi

o~->.

•H H

+»

;55

&t

a x)

•H H

0)

W "H

M 1^

V

0) vi

> o

•H -H

■P ^1

O -P

(U U

<M 4>

^ <w

«)

O O

(U

Ti

«4

o

-O hp

p

^1

o

4>

0)0

^

A o

■P-*

a aJ

o

+»

^«t

^ Ti

O H

oi 0)

Pt-H

to P»«

o t

^4 -H

■p ^<

O P

0) o

^a

<M

O *-l

O

P

o ja

fl) p

«H X)

<Vh -h

W De

m

H

0)

H

^

(d

B

1

>

^

iH

P

vo

W

irv

VO,

M O

»

0) Cm 0) U)
xJ O V« uj

^

s

o

^

q <M 4j

M W

(U +>

TJ P W

(U ^ "in U

P J» aJ P

o o

vo

r-

o

^

(U ^1 H H

'H M W O

H <d g M

vo
CVJ

C\l

c^

On
CM

o a a p

o a c

a Si o

P

^ -H O O

0)

S^

<iH

0)

i:) P

oo

« ^ <M H

p > oJ aJ
o o o

a> M H -H

vo

ON

ITN

O

H f-i 0) M
r-i aJ q P CO

•

00

h^

H

CM

O C q o p

ro

CO

-*

^

u a 0) (0

^ fl ^ H 4)

Sr».-H O «) -P

• Td

tJ

o e» rt

H

!^ P CM

U

O 5^

•rH

Total
colle
in tr

y

H

3

a

O

o

H

•rH

fM

1

P

V

y

>

4)

•H

d

X tJ

v^

-rf

CM

t—

(U <M 0) (0

Vt

X) O Vl w

O

Oi

ON

00

o

q "(H (u

J-

ITN

CVI

H

j:5

P

M to

•H

0) P

S

id p w

p > a p

o o

ON

VO

00

CO

« M H H

H H <i> o
H a q ^1

P^

ITN
H

CO
CM

CM

o c a p

o 3 c

c ^ o

feT--H o o

^1

u

P

tJ p

0)

p * 3 d

•i-l

o o o

V U r-i -H

\I\

O

O

O

CM

H H 0) J-.

r-l d q P C9

o q a o p

•

•

^

S

^

VO

o a « u3

„ C XI H (U

eS.-H O 4) P

• -O

O (U «

a p Q(

o d

"3 H p hI

S

8

^

VO
CM

P H

H

H

H

H

O O fl

Eh o •r^

4)

t5 -^

O CD

^ (0 U

P t) 43

VO

^

-^

VO

O O O

CM

m

0) d c

H P<-H

^ Q^-* 1

p

o

Ci

n

M

a

H

U

t)

-H CO

P^ P

CO

4)

• P

fl

O P

•H C

P 4)

fl V

a

o w

o

" ■§

<Vh

p 01

w

1

0) 4)

P u

p

o

o

xi <M

fl

O V

CJ ^

01

4>

■p

01

CO

^1 4>

4)

^^

P

H

(u "d

0

u

M p

+i

(d fl

fl

4; 4>

o

-ij^

o

M Vi

o

V

>

S^

4h
+>

P 4)

a
«>

t>

0} xi

K'

bOP

4>

a^

(4

H O

••*

u ^

T)

V B

«)

to a

Xj

fl 4)
■H tl

13

V» P

u

CO

<a

gff

^

x)

in

<H 4)

p

O u

en

M

«>

3^

+>

O «

01

+» ^^

4>

<%

g

^Hl

33

O fi

+> o

a

C tA

O 1

•H CU

+>

OS Xl

H +>

03 "S

a^

« -H

(0 pt4

0)

g-d

> o

•H -H

+» U

O -P

u o

<»-l «

^^

<U «H

o o

«»

1^1

flSi

o

vo «

^ O H

Cl Oj

o

+*

t)D S)

5^

O H

cd «

.K-s:

^•5!

O O

U -H

•p >^

O +»

V O

S^

*H

O Vt

o

+>

y ^

^

V

>

•H

■p

M O

o

t- vo

o>

1) V to

M O qj a

^

i ^

H

^

4J

-d 4->

4> ^ IM

P > <fl

O O

CJ

H CO

t-

H M O O
H a C !^ «

en

t~- CM

O

o d a +> 4J

on

H W

CJ

O a fl tr

„ C! ^ O flj

^

■b'- -H y o -p

V

)h

t)

V

<M

t) +>

m

-P > nj (d
o O o

<U f^ H -H

H »■< « M
H nl C p M
q c a a +»

cy

00 -*

•

H

t~- ir\

t—

u _ rf « m

ir\

LO ^

tn

tP- -H CJ (UP

• X)

O « 03

K -P p.

o ca

H

o o a

•H

(ri O -H

P«<

1

■^

•H

H t5

^

ON VO

•

O

en

H

i ^

CO
OJ

i)

,q Vi hh 4)
H o <y c

^
U

^^

o

if

^>13

Ti

o o

•H

01 ^^ H H

>

H M (U O
H d d h 01

O

CJ o

VO

o c a -p +»

CO

if\ VO

t>l

u a c 03

en

CVJ CVJ

H

„ a ^ o fl)

^•H OOP

u

V

+>

n p

^^^-^

<i-l

o o o

<U V. H -H

^

H VO

CO

OJ r

H l-( « Jh

-H (0 g P to

• •

r

VO

!8 R

ir\

o c a o p

-*

^

(

J ed (u u

„ C ^ H 1)

t

^T-l O 4) p

• TJ

ova

1

5 P PM

o (d

H

D O C5

o

H

3 1

O

E

-t O -H

^ ^

O 60 ta

f~i a u

+» -H J3

o o iJ

tt) oj a

vfl

H CVI

^

H Qt-rt

P"

^ Ws^ i

■

p

71

«

•H U

Ph p

03
(U

s:

•H a

P V

a a>

O 03

"•§

P 03

03

(> V

P U

o

O OJ
«> ,Q

(U "d

03 -p

od C
u V

4) -H

03 Si

bOP

Hi Wl

34

1

V

>

•rl

H->

X O

-*

CO

VO

H

« t) m

•

Xt H-t OJ

^o

(X3

ir\

ITN

Howe

cu

CM

m

H

M

0)

Td -p

m ^ <M

+i > OJ

o o

<U M H H

H ^1 «U O

r-l (d £3 V< 0)

H

O

vo

Ov

o c! a +) +>

fn

cA

^

Lr\

cj a fl CO

cu

OJ

cu

CU

M

d)

Ti -p

t)

-p N rt d
o o o

c>

0) ^1 H -H

Vi

r-l d eJ +J to

»f\

CO

•

Ol

•

o

rn

0 0 3 0 4*

<j\

t-

o

H

o 3 V (0

■^

irv

vo

J?

d ^ H <u

^•H O « -P

• tJ

■d

O « 09

H

S +> Pi

V

u a

•H

33^^

ON

S

O

o

•d

O O C!

EH o -a

H

H

u

•H

1

>H

4)

U

^

^

V

+>

U

X o

CVJ

CU

OV

irv

(u o «a

•

•

o

13 <M ta
q <*-! <w tt)
M o u c

5!

si

?H

f;^

+>

>-i

Td

ti)

tH

tJ +>

Sc

8g^

rH H 4» O

H d d 1^ to

m

o

vo

r^

o a a +> +>

t-^

m

d

vo

u d d to

cy

cu

H

^ d ^ o «

u

9)

xi -P

+>

o o o

0)

V

4) M H -H

Vl

r-l 3 d +» 0)

o d c o +>

irv

cu

tr*

cu

Ol

CO

ir\

^

^

u a <u n

vo

trv

tn

„ d J3 H t)

^•H y «j +>

• tJ

ova

S5 -P Pi

o rt

3d^^

^

H

o

<X5

o o d

H o T-i

^ ^

own

f^ C «

-P -rl J3

vd

cu

^

VO

o o o

H

cu

ro

(u 0) a

H ft-H

W W^^ 1

■p 0

d 4)
o to

-P to
to

V 4)

+> 1^
o

O 4>
«) ^

4-) 3

o "d
to -p

a a

4) 4;
4)

SS'

K

bO-P

5^
H O

S)§

d V

•H ^.

Vi +>

to

V< 4>

o a

u

O o

+> u

g

O

i1

V

Hi OJI

35

(UO

xt o
+> vo

^

d

0)

tH >

O -H

■P

X o

U (U (0

XJ ^-( 01

VO
OJ

81

CVJ

00
CO

O 0) 00

o o q

S

0) CQ
l+H 0}

00 CO

VO

ON
H

OS

^•H o a) +>

O 1) tn
Z +> ft

^
^

o

H

5 3

+»

ft +>

4!

T) ^-^

O U) m

Vi C V

+» -H j:3

o o o

4) ea C

H p,-H

J^

36

^^1

1

<M >

O -H

, P

« O

o\

CM

m

vo

a; (U w

H 0) c

;i

^

m

d

J-l w

0) P

tJ P M

(U <M «

p > CO P

o o

H

ITN

tr-

m

0) l-i H H

•

H ti tt) O

d

t-

H

H

H rt G t.

o a c p

cu

<M

w

cu

O 0 CJ

c ^ o

e^-H o o

u

+>

(U

0)

p

<u

T3 <H rH

lu ^ cd d
p 5 o

<kH

m

O M H -H

o

t-

o

CT\

U f^ V M

•

•

rH aJ C P 01

H a a o p

P^

ii

IfN
CVl

i

O d 0) M

O C ;q H OJ

•H U tt) P

1^

• T)

O (U U)

a p ft

-d

o jy

•H

33^^

o
o

H

i

o

CJ\

P4

o o c

^

O

<u

•H

V. >

^t

o ^

■P

p

CO

H

m

CVJ

O

S a> (0

•

4)

(n

o->

t-

CO

d

Hoc

OO

M

ro

CVl

Im

O

<u +>

^

'O p 01

^

2H

>

4) )h H H

^^S2

00

00

Ox

^

o a a -p

CVl

t^

00

c?>

u ^ a c

w

H

H

H

_ C J3 O

t^-H O U

M

(U

-P

X) P

0)
0)

0) <iH H
P > (0 cd

Vi

o o o

0) ^l H -iH

vo

On

CVJ

vo

W

<-{ u <u u
r^ g q p 01
o q 5 o p

vo

d

vo

c^

ITN

irv

iTk

^

o dun

C ^ H 0)

t^-H O <U P

• TJ

o u n

S; P Pi

o <o

33^^

00

CO

O
H

O
H

^

3

o o c

H O -H

4)

>o '-N

O bO to

M a u

■P -H fl

vo

?i

J-

vo

o o o

OJ

CT)

0) cd c

H P<-H

aq w v^ 1

P

o

c

to

to

a

•H

H

u

0)

bO

•3 n

Ph -p

0>

0)

• +»

fl

o +>

•H fl

31

q (u

•

n

o u

o

" -9

VI

0

•H

+> 01
01

B

0) 0)

-P fn

+>

o

o

xt u

a

a u

(d ^

ca

0)

+»

(d

n

r^ V

4)

o u

-p

<M OS

r-l

(U d

s

01 -p

+>

(d q

fl

(U 4)

o

H a

4J -H

o

u u

4)

v

t»

lt

•ri

+»
o

41

4>

01 XI

^

MP

V

5^

u

H O

• •^

u

T)

S) 3

^

C 4J

M

•H ^1

at

<H -P

o

(0

en

a&

^

•T3

a

Vl 41

+>

o o

m

^

4)

■d.^

■p

+»

4)

O t)

n

-P fH

4)

<:SI

g

^Hl

37

Ol

15

■d

^d

X tt) o

-d «)+>

•»* ON

o

^^

o o

U -H
4> »^
O +>
0) O

O <M
O

U

^

1

0)

^

O -H

+>

H

o

t—

w

X o

•

•

•

4> t) ul

d

m

on

ON'

T3 i*H U3

H

H

W 4> C

M 10

a> -p

ti pro

0) ff-t i)

■P > 03 -P

o o

0) M rH H

t-

00

LTV

OJ

H !h « O

H eg d >^
o d a -p

•

l/^

CTx

o

d

CU

H

CVI

ca

cj a c;

c ^ o

tP--H o o

^1

0)

tJ p

-p

-p > (d (d

(U

o o o

^^

<U Jh rH -H

OD

CO

cy

-*

en

H 1^ »> ^H

r-l ta g +» to
o c a o -p

VO

^

-*

c^

ro

cy

m

o a 0) ta

a S r-i V

l^-H O (U +i

• t:)

O (U w

T)

a: -p p,

H

O ol

<u

33^^

-*

OS

-*

ON

•H

^

d

^

o
H

O O C!

O

B O -H

1

•H

0)

U

'^■< >

■P

O tH

O

■P

V£)

CO

VO

-*

0)

X o

a

1) 0) to

ir\

a\

00

oJ

-d "M w

W

H

H

CVl

o

H 4) C

(-1

XJ

0)

4^

xJ -P

-d

(U li-i

ollect
narrow
nnel a
trol
ts

^

o

t~

H

H

•

•

•

ITN

OS

rn

VO

CJ d C w

H

H

Oi

H

„ C ^ O 4)

tjS--rt CJ O -P

^

4)

T) -P

-P > 3 O

o o o

4) t. H iH
H U 4) t^

r-l a c +> ta

VO

ir\

t~

ITN

•

•

d

ON

H

<o

o c a o -p

-*

ro

^

CO

o a 4) ta

•p

C ^ r-( 4)
^•H O 4J -P

ii)

*H

o 4> n

cv

3 -P ft

33^^

^

o

o o d

Eh o -H

0)

rd -^

O bO n

u a i>

-P -H J3

o o o

>o

^

-Jl-

NO

0) Q] c

CVJ

en

H ft-H

pq «>_•

+>

O

a

CO

g"

•H

H

Vi

0)

bO

5

(ix

• •

a to

o +>

•H ca

+> «

:d^

•

a +»

o d

o

U 0)

4h

•H

+> o«

01 4)

0

9) m

+> ,Q

+>

3

o

M w

a

o

cd 4)

n

4> U

+»

o

(0

U U

0)

o <u

■p

Vi ^

t:) «j

■^

4> 4)

^

a 3

t?

4)

O

u 'd

o

U -P

«

fl

>

4) OJ

•H

■P
O
«>

V

P<

s?

&
S

•H

H 4)

♦•»

M ja

Ti

4) +>

^

bO
d <M

-H O

1

<*-!

O

o i

ca

-p

(0

4-1 (a

+>

O P,

ca

;3

0)

"j tJ

-p

■P «>

v

o o

CQ

+> u

4)

o

g

Hi oil

38

DISCUSSION •

The results of these exploratory experiments generally agree with the results
of other investigators. Lethlean (1^53) noted that he expected better results by in-
creasing the angle of the lines of electrodes in relation to the dam from 30° to 45° .
Biologists of the International Pacific Salmon Fisheries Commission were quite
successful at Cultus Lake (1953) in diverting salm.on fingerlings with an angle of
45° and a 2 -foot width of field.

In the experiments under the laboratory conditions described, a maximum per-
centage was recovered in the narrow channel with the rows of electrodes spaced 2
feet apart. When the v/idth of field was increased to 3 feet the .effectiveness was
reduced and it was observed that many fish experienced difficulty in escaping an area
in the immediate vicinity of a positive electrode. At the same time other fish were
paralyzed in the electrical field and were carried through it by the water current
untii they recovered equilibrium beyond the field. These factors are probably the
cause of much of the scatter in the data resulting from the 3 -foot width of field;
they are possibly the result of the increased power necessary to maintain the average
voltage gradient of 1 volt/cm. McMillan (1928) pointed out that when the distance
between rows of electrodes was increased while maintaining a constant voltage grad-
ient ihe concentration of the voltage gradient at the surface of the electrodes increased.

Tests run under full light intensity resulted in a slight increase of the effective-
ness. A further increase was obtained when large numbers were released under full
light intensity. The results of these preliminary experiments Suggest that group
movement may be an important factor in diverting salmon fingerlings . When large
schools migrate downstream into an electrical field the effectiveness may be hi^er
than when smaller groups come in contact with d.c- barrier. Okada (1929) observed
that a weaker field can restrain the same percentage of fish as a stronger one when
the group was composed of many fish, indicating that group movement was involved in
his experiments.

Since full-scale field trials were scheduled to begin subsequent to the completion
of these laboratory experiments, the experiments were limitfed to three angles, two
diameters of electrodes, a single field, and one arrangement of electrodes. The
experiments were conducted within a range of terriperatures of 8°C,, ,with a maximum
temperature of 16° C . Two test and two control experiments were uSed to investigate
any one set of conditions; each point on the preceding graphs was established with
approximately 100 fish. Hatchery -reared silver salmon ranging in size from 5.5 cm.
to 12.0 cm. were used; this does not include the range of sizes or species that would
be encountered under natural conditions . Another factor to be considered is that wild
fish may be more or less sensitive to an electrical field than?;hatchery -reared fish.
However, the experiments show the relative effectiveness of the various factors exam-
ined in this type of narrow d.c. ireld employed as a diverting barrier.

39

The results of the experiments indicated that with few exceptions the difference
in the effectiveness of the 40° and 60" angles of electrical field were not significant;
this was also true for 1/2 -inch and 2 -inch electrode diameters. There is a question
of whether the size of the experimental area was large enough to allow a valid
comparison of these factors . The effectiveness of the two angles of field and the two
diameters of electrodes should be examined under field conditions. If this lack of
significant difference is verified in the field, a considerable saving can be realized
in the cost of installation and operation by establishing a 60° angle and using 1/2-inch
electrodes. However, it is recognized that the effectiveness of the angle of electrical
field may be a function of water velocity', numbers of fish or species of fish. These
factors should be examined and the relationship to the effectiveness determined.

Since some of the fish experienced difficulty in escaping an area in the vicinity
of the positive electrodes of a single d.c. field, experiments are in progress to exam-
ine the effectiveness of multiple fields of increasing intensity. A pulsating direct
current of a higher intensity is necessary to divert fingerlings than is required for
larger fish. By creating a zone of lov/ intensity upstream the large fish may be diverted
without injury before they reach the zone of higher intensity necessary to divert
fingerlings .

During the experiments it was observed that the fingerlings entered the electrical
field and oriented to the positive electrodes before they were diverted. An investigation
is in progress to explore the effectiveness of a single line of electrodes with an
electrical field of high intensity in an effort to divert the fingerlings before they reach
the barrier. Additional tests are planned to investigate the result when the electrodes
are energized sequentially.

SUJvIMARY

1 . Exploratory experiments v/ere completed under laboratory conditions using .
lines of vertically suspended electrodes with the positive line of electrodes parallel

to and upstream of the negative line of electrodes arid placed at an angle to flowing
water .

2. The electrodes were energized with interrupted direct current of a square
wave form with the following electrical characteristics: (1) a pulse frequency of 8
pulses per second (2) a pulse duration of 40 milliseconds, and (3) an average voltage
gradient of 1 volt per centimeter.

3. Hatchery-reared silver salmon ranging in size from 5.5 cms. to 12.0 cms.
were used in the experiments .

40

4. Tests were run at a minimum level of light intensity to eliminate schooling
and group movements. The technique of manipulating the light intensity stimulated
downstream movement eliminating tJie necessity of startling or forping the fish into
the electrical field.

5 . The most effective results from the laboratory experiments were obtained
at an angle of 40°, a width of field of 2 feet, an electrode spacing of 12 inches with
1/2 -inch diameter electrodes. Under these conditions 68 percent of the fish were
directed to the collecting channel, as compared with only 16 percent in control tests
with power off.

6. Tne 2 -foot width of electrical field appeared to be more effective than the
3 -foot width of field.

7. With a few exceptions the effectiveness of the 40° and 60* angles of electrical
field were not significantly different. The 90° angle of field was least effective.

8. There were few significant differences between 1/2 -inch and 2-inc.h diameter
electrodes.

9. Electrode spacing appeared to be more important at a 40" angle of electrical
field, than at 60° and 90° .

10. Light intensity may increase the percentage diverted through the effect on
schooling behavior and group movement.

ACKNOWLEDGMENTS

Thanks are due Mr. Charles Ellis, Supervisor of Hatcheries for the State of
Washington, for making available the salmon fingerlings used in these experiments.
The cooperation of the personnel of the Waslrngton State Fish Hatchery at Issaquah
is also greatfuUy acknowledged.

Appreciation is expressed for the advice and services of Fishery Research
Biologists Robert H. Lander, Galen H. Maxfield, and Robert R. Morrison, and
electronics technician Donald L, Thorne. Charles Volz was responsible for the
design and operation of the electronic equipment used in the experiments. The
electrical guiding research is under the immediate supervision of Dr. Gerald B.
Collins .

41

LITERATURE CITED

Collins, Gerald B., Charles D. Volz, and Parker S. Trefethen

1954. Mortality of salmon fingeriings exposed to pulsating direct
current. U. S. Fish and Wildlife Service, Fish. Bull.,
No. 92, vol. 56, pp. 61-81.

Lethlean, N. G.

1953 . An investigation into the design and performance of electric
fishscreens and electric fish counters.
Trans. Roy. Soc. Edin. vol. 62, Part II, (13) pp. 505-509.

McMillan, F. O.

1928. Electric fish screen.

Bull. U. S. Bur. Fish., vol. 44, pp. 97-128.

Okada, Mituyo

1929. On the action of electric current on fishes. II. Electro -

phobotaxis of fishes in a group.

Jour. Imp. Fish. Inst. vol. 25 (1) pp. 1-11.

42 82055

MBL WHOl Librnrv - Serials

5 WHSE 01689