Canadian Journal of Fisheries and Aquatic Sciences



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Figure S2


Fig. S2: Annual abundance and standard deviation of Atlantic bluefin tuna (Thunnus thynnus) in the Gulf of Lions, estimated from aerial surveys.


Figure S3


Fig. S3: Relationship between tuna age and length (left) and weight (right), as modelled by the Dynamic Energy Budget model for Atlantic bluefin tuna (Thunnus thynnus). For comparison, the growth curve used by ICCAT (International Commission for the Conservation of Atlantic Tunas) is also plotted (red line).


Figure S4




Fig. S4 Age-length keys of anchovy (Engraulis encrasicolus), sardine (Sardina pilchardus) and sprat (Sprattus sprattus) calculated from the small pelagic survey data over the period 2008 to 2013. For sprat (n=100, years = 2013) a linear model was used, where L(t) is the expected length at age t. For sardine (n=4744, years = 2009-2014) and anchovy (n=4412, years = 2009-2014) seasonal variability was accounted for using Somers’ model (Somers 1988), with , where L is the model asymptote for average length, K is as measure of the exponential rate of approach to asymptotic length, t0 is the theoretical age at which the average length would be zero, C is the amplitude of the growth oscillation and ts is the inflexion point.

Table S1


Table S1. Biological parameter values of major prey species found in the stomach contents of juvenile Atlantic bluefin tuna (Thunnus thynnus). The ranges of energetic densities were taken from literature (see Appendix 1: Energetic density). Lengths of sardine, anchovy and sprat were calculated using the linear relationship between otolith (oto) length and individual (ind) fish length (), and their body mass was obtained by converting these lengths using an annual length weight key (). Direct length measurements were not needed for mackerel and squid, and otolith lengths or beak lower rostral lengths (LRL) were directly converted to weight (). All relationships were calculated from the small pelagic survey biological data. Parameter estimates and relationships were always significant. We specified the number of data points (N) on which the relationships were based and the range of values for which it was specified.

Energetic density (kJ/g wet weight)

Sardine

Anchovy

Sprat

Mackerel

Squid

4.00-14.40

2.67-12.81

3.7-12.40

6.00-10.30

5.01-6.46






R2

a

b

N

range

range

Sardine

0.86

0.46

0.14

50

1.6 - 2.9

9.3 - 17.5

Anchovy

0.78

0.62

0.18

53

1.9 - 3.8

8.6 - 3.8

Sprat

0.24

0.98

0.06

47

1.2 - 1.8

0.9 - 11.1









c

d

N

range

range

Mackerel




0.88

3.09

36

7.2 - 36.2

2.0 - 3.1

Squid




7.07

2.24

61

3.0 - 215.2

0.9 - 4.2






year

e

f

N

range

range

Sardine

2011

4.40*10-3

3.2

229

1.7 - 45.0

6.5 - 18.0




2012

2.29*10-3

3.47

220

2.0 - 46.0

6.5 - 17.0




2013

4.09*10-3

3.24

216

2.5 - 27.0

7.5 - 15.0

Anchovy

2011

2.97*10-3

3.29

195

3.0 - 22.5

8.5 - 15.0




2012

4.76*10-3

2.1

168

4.0 - 22.0

8.5 - 15.0




2013

4.10*10-3

3.18

126

2.0 - 22.0

8.0 - 15.0

Sprat

2011

6.50*10-3

3.03

139

1.7 - 13.0

6.5 - 18.0




2012

5.19*10-3

3.15

171

2.0 - 15.0

7.0 - 11.5




2013

6.61*10-3

3.03

153

1.0 - 10.8

6.0 - 11.5


Table S2


Table S2 Dynamic equations of the non-standard Dynamic Energy Budget model developed and validated for Pacific bluefin tuna (Thunnes orientalis, Jusup et al. 2011) and reparameterised for Atlantic bluefin tuna (T. thynnus) for use in this study. t denotes time and T temperature. Processes are usually defined in terms of energy and are thus measured in J.

State and auxiliary variables

Symbol

Definition

unit

E(t)

Amount of energy in reserve tissue




J

V(t)

Volume of structural tissue




cm3

L(t)

Structural volumetric length




cm

EH(t)

Level of maturity




J

ER(t)

Status of the reproductive buffer




J

E0

Initial energy reserve of an egg




J

Energy fluxes

Metabolic process

Energy flux




Assimilation (A)



Utilization (C)



Somatic maintenance (S)



Growth (G)



Dynamics of state variables, reproduction state

State variable

Dynamic equation




Energy in reserve



Structural length



Maturity (H) level



Auxiliary functions

Auxiliary functions

Functional form




Shape correction function



Efficiency of internal heat production



Arrhenius equation



Shape factor




Table S3


Table S3 Dynamic Energy Budget parameters for Atlantic bluefin tuna (Thunnus thynnus) and their values.

Symbol

Definition

Value

Unit

Basic DEB parameters

{ṗAm}

Maximum surface-area-specific assimilation rate

124.8

J cm-2 d-1

[EG]

Volume-specific cost of structure

7163

J cm-3



Energy conductance

0.09542

cm d-1

[ṗM]

Volume-specific somatic maintenance rate

5.149

J cm-3 d-1

{ṗT}

Surface-area-specific somatic maintenance rate

1877

J cm-2 d-1

J

Maturity maintenance rate coefficient

1.362

10-2 d-1

κ

Fraction of mobilized reserve allocated to soma

0.8222

 

EbH

Maturity at birth (b)

0.2253

J

EpH

Maturity at puberty (P)

2.937

107J

Other DEB parameters

EjH

Maturity at the end of the larval stage

2566

J

E2H

Half-saturation maturity

7050

J

EyH

Maturity at the end of the early juvenile phase

1.629

106 J

TA

Arrhenius temperature

6398

K

δ1M

Shape factor in the larval stage

0.1475

 

δ2M

Shape factor in the adult stage

0.2531

 


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