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SUPPLEMENTARY MATERIAL 3
Relationships between vulnerability to decline, life history traits and relative fishing
mortality rates
We examined the relationships among our three metrics of vulnerability to decline, the life
history traits and the relative fishing mortality rates using bivariate plots and Pearson’s
correlation coefficients (Figure 1). We assessed whether populations with certain life histories
have been preferentially targeted with high fishing intensities by examining the span of variation
in the life history traits and relative fishing mortality against the three metrics of vulnerability to
decline. Scombrid populations with slower growth rates, greater longevities and later age-atmaturity, appear to have declined in adult biomass more rapidly (measured by the annual rate of
declines) and to a greater extent (measured by total extent of declines). We find time-related
traits such as growth rate, longevity and age-at-maturity are moderately correlated with the rate
and extent of decline in adult biomass in scombrid populations (absolute value of the Pearson’s
correlation coefficient [r] ranging from 0.41 to 0.55) (Figure 1 G,H,J,K,M,N). We find sizerelated traits such as maximum body size and length-at-maturity are uncorrelated and are poor
predictors of the rate and extent of decline in adult biomass in scombrid populations (Figure1
A,B,D,E, absolute value of r ranging from =0.05-0.25). Moreover, scombrid populations that are
currently overfished tend to be longer-lived, mature later and have slower growth rates than
populations that are not currently overfished (Figure 1 I,L,O). There are no clear patterns
between the exploitation status of the populations and the size-related traits of maximum body
size and length-at-maturity (Figure 1 C,F). Finally, we also find that scombrid populations that
are overfished were exposed to higher relative fishing mortality rates, during their period of
exploitation than populations that are not currently overfished (Figure1 R). The relative fishing
mortality rate in scombrid populations is weakly positively correlated with rate and extent of
decline in biomass (r=0.28-0.35), such that populations that have been exposed to higher relative
fishing mortality rates, on average, have tended to decline in adult biomass faster and to a greater
extent (Figure 1 P-Q).
The relative fishing mortality rate (Faverage/FMSY ) is weakly correlated with growth rate (r=-0.29,
Figure, 2B) and uncorrelated with maximum body size (r=0.11) (Figure2A-B). This suggests
scombrid populations with specific life history traits have not been preferentially targeted with
high fishing intensities. Instead, we find scombrid species irrespective of their maximum body
size and growth rates have been exposed to a range of average relative fishing mortality rates
within their period of exploitation. The wide exposures to fishing intensities and wide span of
life history variation across scombrid populations allows testing for the combine effect of
exposure and life histories in determining population declines and current exploitation status.
Furthermore, we find that FMSY is highly correlated with the time-related trait of growth rate
(r=0.71, Figure 2D) and moderately correlated with the length-related trait of maximum body
size (r=-0.53, Figure 2C).
43
FIGURES
Rate of decline
Extent of decline
A
C
Not overfished
●
●
●
●
●
●
●
● ●
●
2.4
●
●
●
●
●
●
●
●
0.7
40
100
160
●
r=−0.25
220
280 340
100
80
60
●
●
●
●
●
●
●
●●
●
●
●
0.7
●
●
●
●
●
●
●
25
55
r=−0.11
85
115
100
80
●
100
●
●
●
●
●
●
r=0.5
10
14
20 24
Extent of decline
Rate of decline
●
●
●
●
●
● ●
●
●
60
55
85
●
●
●
●
●
●
●
r=−0.51
●
●
●
●
●
●
0.7
●
0.08
0.23
0.38
25
● ●
●
●
●
●
2.4
●
●
●
●
●
●
●
●
●
●
0.7
●
1
r=0.41
3
5
10
15
20
7
9
●
●
● ●
●
●
●
●
●●
● ● ●
●
●
●
0.23
2.4
●
●
●
●
●
●
●
●
●
0.38
r=−0.53
●
●
●
0.7
●
0.2
0.4
0.7
r=0.35
0.9
●
B/Bmsy>1
1.2 1.4 1.71.9
Relative fishing mortality (Faverage/Fmsy)
20
25 30 35 40
●
●
●●
●
●●
●●
●●
●
0.53 0.68
●
●
● ●
●
●
●
● ●
0.08
0.23
0.38
0.53 0.68
Growth rate (1/y)
●
●
●
●
●
●
●
●
●
●
●
●
60
●
●
●
B/Bmsy>1
●●
B/Bmsy<1
●
1
●●
● ● ●●
●
●
●
●
●
20
●
●
●
●
●
●
●
r=0.5
3
5
7
9
11
1
3
5
7
9
11
Age at maturity (y)
R
100
80
60
15
O
100
80
Extent of decline
●
●
●
●
●
10
Age at maturity (y)
●
●
● ●
●●
●
Maximum age (y)
Q
●
●
●
Age at maturity (y)
●
5
●
0.08
11
115 145 175205
L
B/Bmsy<1
40
●
●
●
●
25 30 35 40
20
P
9.2
7.5
5.8
4.1
●● ●
●
B/Bmsy>1
Growth rate (1/y)
●
85
r=0.55
40
0.53 0.68
●
● ●
●
●
100
80
Extent of decline
●
●
●
55
B/Bmsy<1
20
60
●
Length at maturity (cm)
N
●
●
●
●
●
Growth rate (1/y)
●
●
●
●
40
M
9.2
7.5
5.8
4.1
●
115 145 175 205
●
●
5
Extent of decline
●●
●
●
●●●
●●
●●
●●
●●
●
●
Maximum age (y)
●
●
220 280 340
r=0.13
K
●
160
I
●
30 34 40
●
●●
●
●
Maximum age (y)
●
B/Bmsy>1
B/Bmsy<1
20
J
9.2
7.5
5.8
4.1
100
●
100
80
●
● ●
4
Rate of decline
40
Length at maturity (cm)
●
●
●
●
Maximum length (cm)
●
●
25
●
●
0.7
Rate of decline
280 340
H
2.4
Rate of decline
220
●●
●● ●
●
●
40
145 175 205
●
●
●
r=−0.05
F
Length at maturity (cm)
45
46
47
48
49
50
51
52
53
160
●
●
60
G
9.2
7.5
5.8
4.1
●
●
B/Bmsy<1
20
●
● ●●
● ●
Overfished
●
Maximum length (cm)
Extent of decline
Rate of decline
●
●
●
●
●
40
●
●
●●
B/Bmsy>1
●
E
2.4
44
●
● ●
● ●
●
Maximum length (cm)
2.4
●
●
●
●
●
40
D
9.2
7.5
5.8
4.1
Exploitation status
B
Extent of decline
Rate of decline
9.2
7.5
5.8
4.1
●
●
●
●
●
●
●
●●
●
B/Bmsy>1
●
●
●
●
B/Bmsy<1
●
0.2
0.4
● ●●
●
●
20
●
●
●
●
40
●
●
●
●
0.7
●
●
●
●
●
●
● ●
●●
r=0.28
0.9
1.2 1.4 1.71.9
Relative fishing mortality (Faverage/Fmsy)
0.2
0.4
0.7
0.9
1.21.4 1.71.9
Relative fishing mortality (Faverage/Fmsy)
Figure 1
Relationships between three measures of vulnerability (columns) and each of the predictor
variables (rows) in scombrid populations. The three measures of vulnerability are: average
annual rate of decline in adult biomass over time (% decline per year), total extent of decline in
adult biomass within the whole period of exploitation (total % decline), and current exploitation
status of the populations (whether the populations are overfished [B/BMSY <1] or not [B/BMSY
>1]). The predictor variables include five life history traits and the relative fishing mortality rate.
Pearson’s correlation coefficients (r) and lowess smooth lines with 95% confidence intervals are
shown to highlight the main patterns.
A
B
●
r=0.11
●
Maximum size (cm)
280
220
●
●
●●
● ●
160
●
●
●
100
●
●
0.68
●
●
●
Growth rate (1/year)
340
r=−0.29
●
0.53
●
● ●
0.38
●
●
●
●
●
●
●
●
0.23
●
●
● ●
●
●
0.2
0.4
0.7
0.9
1.2 1.4
●
0.08
●
●
●
40
1.7 1.9
0.2
0.4
Relative fishing mortality (Faverage/Fmsy)
220
●
r=−0.53
●
●
●
●
●● ●
●
●
160
●
●
●
●
100
●
1.2 1.4
1.7 1.9
●
40
0.24
Fmsy
0.44
0.64
0.84
●
0.53
●
0.38
●
●
0.23
●
●
●
●
● ●
●
●
●
●
●
●
●
●
0.08
●
●
●
r=0.71
0.68
●
0.04
0.9
D
Growth rate (1/year)
Maximum size (cm)
C
340
280
0.7
Relative fishing mortality (Faverage/Fmsy)
0.04
0.24
0.44
0.64
Fmsy
Figure 2
Relationships between life history traits and relative fishing mortality rates (Faverage/FMSY)
and FMSY in scombrid populations. (A-B) Correlations between maximum size and Von
Bertalanffy growth rate and the relative fishing mortality (Faverage/FMSY), which is
calculated as the ratio between the average fishing mortality rate experienced by each
population within their period of exploitation and the fishing mortality predicted to
provide the maximum sustainable yield (FMSY). (C-D) Correlations between maximum
body size and somatic growth rate and the fishing mortality predicted to supply
maximum sustainable yield (FMSY). Pearson’s correlation coefficients (r) and lowess
smooth lines with 95% confidence intervals are shown to highlight the main patterns.
0.84
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Relationships between vulnerability to decline, life history traits and