Radiocecology
e 354
Table 1.
MATERIALS AND METHODS
the silver salmon,
Noveaber and December 1951
to the rearing
homed
had
orhye hus kisutch which
in
of Washington in Seattle
ty
ersi
Univ
he
0
incubated in screen
O08 ooaened artificially and Methods of irradiat
ghs.
trou
hery
hatc
ion
skets
and larvae were as
cgKs and of handling eggs
fang
, and were
Per cent of
incubation
when
irradiated
at each of 23
Fertilized eggs were irradiated
eyed
e to latestages of development from zygot
y covered by
barel
eggs,
100
to
50
About
ietage.
on a flat screen,
fmater. rested in a single layer
A
collar.
ic
plast
low
a
by
ined
land were conf
ating at
oper
ne
machi
x-ray
py
thera
@ePicker deep
tungsten
aod kilovolt peak and 20 milliamps, with
and
er aluminum
Mtarget and filters of one millimet ately equal
i millimeter copper plus an approxim 100 roentgens
anherent filtration. delivered about
Doses ranged from 12 to 2,400 roentgens,
Sev@incremented by a factor of approximately two.ted
en doses distributed to embrace the anticipa l
Brethal dose-50 were used at each embryologica
Batave.
Eggs were returned to the incubating bas-
Bwere removed once or twice daily and preserved in
calculatedlestimated®
At
150, days
calculated’ estimated
66
80
25
29
224
250)
.295
331]
2373
177
249
471
450
400
600
600
277
26
84
309
300
890
150
400
.413
.493
57
.a7
114
108
268
sou
400
170
350
97
80
252
400
200
120
300
1.18
1.42
350
264
400
400
300
211
400
300
1.66
1.98
6.5
8.4
14.6
17.4
36.5
40.4
48.8
71.6
TT 7
of 39 to 40
Winer minute at a distance to the eggs
Dose rate was determined with a Vicentimeters.
er and
Mtoreen 250-roentgen medium energy chamb
Lethal dose-50 in roentgens
At hatching
.088
.170
fefly as follows.
Beets in the hatchery troughs immediately after iradiation. Dead eggs (at least partially opaque)
radiated at 23 stages of incubation,
50 to 100 eggs per calculation.
p. 229)
escribed by Welander (1954,
Weeter.
Lethal dose-50 of silver salmon ir-
30
50
298
98
586
669
702
757
350
120
800
800
a00
1,200
1,600
1,600
2,400
3,000
3,000
921
1,423
1,871
16
296
93
465
88
635
138
20
115
607
488
874
300
100
400
800
700
800
800
600
700
700
1,000
lca leulated lethal dose-50's.
Lethal dose-50's estimated from graphs.
$formalin.
RESULTS
4
4,000
Figure 1 shows post-irradiation mortality re-
lated to time for each of 23 experiments. The
gtage of development and the percentage of the incubation period attained at the time of irradiation
fare inserted at the upper left in each graph. BeFlow the abscissa the day of x-raying is indicated
‘by an X, and the maximum range of the hatching period, by a solid horizontal line at about 60 days.
fFAfter about 80 days most of the mortalities re-
sMained fairly constant to the end of the observa-
ftion pertod at 150 days, as seen in the last graph
p 23) where this later period is shown for an exam-
ple.
The lethal dose-50's at hatching were calculated for each experiment except numbers 7, 19, and
(23 using the method of Kirber (1931;
p. 481) as
fmodified by Irwin and Cheeseman (1939; p. 574),
rafter adjusting for control mortalities as shown
_pby Finney's (1944; p. 68) use of Abbott's formula.
jLethal dose-50's at 150 days were similarly cal;culated omitting experiments 7 and 19.
The few
# Qless than 0.1 per cent) accidental deaths were
(Simply subtracted from the original totals when
computing percentage mortalities.
-
In order to utilize the data of the experi-
r
T
7
AT HATCHING
7
6
1,000 F
“
i «100+
rT
ra
2
Ww
oO
6
in
=
oO
10
n
T
Ye
'
uu
on
O1,000}F
a
a
<
=
re
ww
a
IO0 Ff
arts omitted in calculating lethal dose-50's, and
7 o serve as a uniform basis for compérison with
we Siher organisms reported in the literature, sub-
_
teueee Cstimates were made from the graphs of
graphs Co psratehing, and from extensions of these
experiment 23 days as exemplified in Figure 1 by
22 vere arbirs
Graphs for experiments 1 through
their exteccceaeily shown to only 80 days, although
F reterence meen to 150 days were available for
tof lethal dosecso 1 gives the resulting evaluations
Foare snown in Figure Sraphs of these relationships
;
Por relatin & tet
or larval) developaene 3s Phe ease
embryP tion. the stage of
the time of Of
irradia:
. development was e
B OMic
p Percentage of developmental period from ferti~
o
"8
10
OF
wt
°
4
I
1
10
100
PER CENT OF INCUBATION WHEN IRRADIATED
Figure 2.
Relationship of lethal dose-50
to per cent of incubation attained at time of
irradiation of eggs of silver salmon,
Upper,
lethal dose=50 at hatching. Lower, lethal dose50 at 150 days.
Circles and solid lines,
calculated lethal dose-50's; crosses and
broken lines, estimated lethal dose-50's from
graphs.
v be
ARE pi
Dor
2