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Biological parameters of swordfish in the Indian Ocean used for stock assessment.

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Presentation on theme: "Biological parameters of swordfish in the Indian Ocean used for stock assessment."— Presentation transcript:

1 Biological parameters of swordfish in the Indian Ocean used for stock assessment

2 Growth parameters Young, J., and A. Drake 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

3 Growth parameters Sampling area

4 Growth parameters Growth parameters (von Bertalanffy) –Female: L  = 323.4; K = ; t 0 = –Male: L  = ; K = ; t 0 =

5 Sex ratio Young, J., and A. Drake (2004) y = 2E-10x5 - 2E-07x4 + 5E-05x x x

6 Length-Weight relationship Ariz. J., A. Delgado de Molina, M. L. Ramos, and J. C. Santana, 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 The fifth meeting of the Working Party on Billfish (WPB), Indian Ocean Tuna Commission (IOTC), March 27–31, Colombo, Sri Lanka. IOTC-WPB-06-10, 14 pp.

7 Length-Weight relationship Sampling area

8 Length-Weight relationship Parameters (W = a  L b ) –L: LJFL –Female: a = 2.413E-06, b = –Male: a = 1.351E-06, b = –Combined: a = 1.839E-06, b =

9 Sex ratio Ariz. J., A. Delgado de Molina, M. L. Ramos, and J. C. Santana (2006).

10 Sexual maturity Poisson, F., and C. Fauvel, 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:

11 Sexual maturity Sampling area

12 Sexual maturity %mature at length –%Mature females = 100[1/(1 + exp( − LJFL))] –%Maturemales = 100[1/(1 + exp( − LJFL))]

13 Sexual maturity %mature at length

14 Sex ratio Poisson, F., and C. Fauvel (2009). Y = −1.2×10 −11 X 6 −1.2×10 −8 X × 10 −6 X 4 − X X 2 − X + 209

15 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).

16 Age-length key Length distribution for each age group (probability)

17 Age-length key Proportion that a fish with length X assigned to be a age X (age-length key)


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