Fig. S1. Photographs of partially migratory masu salmon (Oncorhynchus masou). (a) A
pair of migrants in the breeding season. (b) Male residents and a female migrant in the
breeding season. The insets illustrate wounded residents. (c) An outmigrating smolt (i.e.,
potential migrant) characterized by silvery body and black margin on the dorsal fin.
(a)
(b)
(c)
1
Fig. S2. Two typical trajectories of the number of fry aged 0+ years (thin lines),
outmigrating smolts (dashed lines), and returning migrants (thick lines) of masu salmon
from simulations of the stochastic, life cycle model, (a) T = 6 °C and (b) T = 10 °C.
2
Table S1. Masu salmon life history and temperature data of 22 Japanese rivers (updated from Morita & Nagasawa, 2010). (a) Breeding
season sampling, (b) outmigrating season and corresponding adult sampling. Numbers of fish are in parentheses.
(a) Breeding season sampling
Temperature (°C)
River
Ichannai R.
(Masuhoro R.)
Sanru R.
(Teshio R.)
Sampling
date
Sept 2007
Sept 2008
Tokotan R.
Sept 2007
Kobechanai R.
Sept 2007
Hutagoe R.
Sept 2008
Ohtsukushinai
R.
Sept 2008
Isomatsu R.
Sept 2007
Tomari R.
Sept 2007
Ohno R.
Oct 2008
Hase R.
Sept 2007
Kurumigahara
R. (Jintsu R.)
Oct 2007
Togi R.
Sept 2007
Kugami R.
Oct 2010
Location
45°25´N,
141°55´E
44°26´N,
142°45´E
43°40´N,
141°21´E
42°45´N,
140°09´E
41°34´N,
140°00´E
41°26´N,
140°04´E
41°06´N,
140°21´E
40°21´N,
140°02´E
38°19´N,
138°28´E
37°43´N,
139°19´E
36°35´N,
137°17´E
37°11´N,
136°47´E
35°35´N,
134°23´E
Fork length ± S.D. (mm)
Male parr
maturity
rate at age
0+ (%)
Density
(m-2)
Mean (late
May to
early Sept)
Late
May
Age 0+
parr
Age 1+
parr
Age 2+
parr
10.9
7.2
66±8 (164)
91±10 (35)
117±12 (8)
1 (77)
0.428
11.5
8.1
65±13 (267)
113±12 (4)
155±42 (2)
3 (122)
0.944
13.8
7.2
67±10 (178)
106±17 (43)
152±2 (2)
1 (98)
0.666
13.9
9.5
92±10 (168)
140±25 (17)
199±15 (6)
22 (82)
0.145
15.7
11.4
100±12 (109)
234±5 (3)
69 (52)
0.117
15.9
11.6
98±16 (92)
238±40 (3)
51 (51)
0.203
14.0
11.7
84±14 (88)
128±16 (21)
169±21 (4)
41 (39)
0.109
13.9
10.4
94±13 (76)
154±24 (27)
237 (1)
35 (40)
0.106
17.8
14.0
92±17 (155)
180 (1)
55 (77)
0.693
16.1
12.9
89±10 (186)
132±16 (26)
65 (92)
0.204
17.1
13.7
98±11 (68)
148±12 (9)
219 (1)
65 (43)
0.086
13.4
13.3
100±14 (18)
117±22 (31)
188 (1)
71 (7)
0.072
18.7
13.8
112±14 (33)
155±15 (6)
90 (10)
0.026
3
Age 3+
parr
185 (1)
291 (1)
(b) Outmigration season and corresponding adult sampling
Temperature (°C)
River
Shimonaefutoro
R.
″
Sampling
date
June 2011
June 2011
Furreppu R.
June 2011
″
June/July
2012
May/June
2011
May/June
2011
Tokotan R.
45°24´N,
142°03´E
Mean (late
Early
June to next
May
early May)
Age 1+
smolt
Age 2+
smolt
6.2
109±7 (38)
131±9 (11)
5.2
Age 3+
smolt
July 2012
Nairo R.
Moshosanbetsu
R.
Location
Proportion of age
≥2+ smolt (%)
Fork length ± S.D. (mm)
Koitoi R.
(Shoro R.)
May 2011
Betsubetsu R.
May/June
2011
Mokun-nui R.
May 2011
Yamazaki R.
May 2011
Rubeshibetsu R.
May 2011
Adults
(age 2+/3+)
Sex ratio
(%male)
Smolts
22 (49)
373±26 (12)
45°23´N,
141°03´E
44°45´N,
142°46´E
47%
42 (12)
42%
6.2
5.3
126±7 (6)
147±6 (3)
33 (9)
44%
5.5
4.0
111±8 (24)
124±10 (10)
29 (34)
41%
386±49 (45)
44°32´N,
141°46´E
43°40´N,
141°21´E
42°59´N,
144°09´E
42°35´N,
141°25´E
42°25´N,
140°19´E
42°19´N,
140°17´E
42°12´N,
143°20´E
Adults
7.7
4.6
126±8 (45)
7.1
4.8
117±10 (51)
7.4
6.5
7.7
38 (45)
31%
0 (45)
49%
131±11 (17) 152 (1)
26 (69)
41%
110±9 (26)
129±7 (10)
28 (36)
25%
7.7
131±10 (65)
135±4 (2)
3 (67)
24%
8.2
7.1
126±11 (23)
0 (23)
4%
8.3
7.2
131±15 (26)
4 (27)
22%
7.9
6.9
138±15 (33)
0 (33)
33%
4
158 (1)