Biological parameters of swordfish in the Indian Ocean
used for stock assessment
Growth parameters
• Young, J., and A. Drake. 2004. Age and growth of broadbill swordfish (Xiphias gladius) from Australian waters. Final report for project 2001/014, Fisheries Research Development Corporation, Canberra, Australia. 121 pp.– A preliminary investigation of age and growth
of swordfish, Xiphias gladius, from Western Australian waters using anal fin rays
Growth parameters
• Sampling area
Growth parameters
• Growth parameters (von Bertalanffy)– Female: L = 323.4; K = 0.08148; t0 = -3.413
– Male: L = 260.47 ; K = 0.1096 ; t0 = -3.3808
0
50
100
150
200
250
300
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Age
LJF
L (
cm)
Female
Male
Sex ratio
• Young, J., and A. Drake (2004)
y = 2E-10x5 - 2E-07x4 + 5E-05x3 - 0.0069x2 + 0.5153x - 14.662
Length-Weight relationship
• Ariz. J., A. Delgado de Molina, M. L. Ramos, and J. C. Santana, 2006. Analyses of sex ratio, by length-class and length-weight relationships for several species of Family Xiphiidae (Xiphias gladius, Linnaeus 1758) and Istiophoridae (Istiophorus platypterus, Shaw 1792) and Tetrapturus angustirostris, Tanaka 1915) caught from experimental cruise on Spanish longliners in the South Western Indian Ocean during 2005. The fifth meeting of the Working Party on Billfish (WPB), Indian Ocean Tuna Commission (IOTC), March 27–31, 2006. Colombo, Sri Lanka. IOTC-WPB-06-10, 14 pp.
Length-Weight relationship
• Sampling area
Length-Weight relationship
• Parameters (W = a L b)– L: LJFL– Female: a = 2.413E-06, b = 3.33727– Male: a = 1.351E-06, b = 3.45674– Combined: a = 1.839E-06, b = 3.39209
Sex ratio
• Ariz. J., A. Delgado de Molina, M. L. Ramos, and J. C. Santana (2006).
Sexual maturity
• Poisson, F., and C. Fauvel, 2009. Reproductive dynamics of swordfish (Xiphias gladius) in the southwestern Indian Ocean (Reunion Island). Part 1: oocyte development, sexual maturity and spawning. Aquat. Living Resour., 22: 45-58.
Sexual maturity
• Sampling area
Sexual maturity
• %mature at length– %Mature females =
100[1/(1 + exp(16.2506 − 0.095342 LJFL))]– %Maturemales =
100[1/(1 + exp(10.1758 − 0.084884 LJFL))]
Sexual maturity
• %mature at length
Sex ratio
• Poisson, F., and C. Fauvel (2009).Y = −1.2×10−11 X6−1.2×10−8 X5 + 5 × 10−6 X 4 − 0.
0011 X3 + 0.1355 X2 − 8.3638 X + 209
Age-length key
• The length distribution for each age group is assumed to be normal distributed with mean and SD.
• Mean length and SD for each age group are estimated based on the parameters and data from Young, J., and A. Drake (2004).
2
, 2
( )1exp
2( )2l
l
L L aa l L L
aa
L LdL
Age-length key
• Length distribution for each age group (probability)
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0 15 30 45 60 75 90 105
120
135
150
165
180
195
210
225
240
255
270
285
300
Length (cm)
Pro
ba
bili
ty
A0
A1
A2
A3
A4
A5
A6
A7
A8
A9
A10
A11
A12
A13
A14
A15
Age-length key
• Proportion that a fish with length X assigned to be a age X (age-length key)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 18 36 54 72 90 108 126 144 162 180 198 216 234 252 270 288
Length (cm)
Pro
pro
tion
A0
A1
A2
A3
A4
A5
A6
A7
A8
A9
A10
A11
A12
A13
A14
A15