Assessment of some demographic trends of Spadenose shark (<em>Scoliodon laticaudus</em>) of the Bay of Bengal, Bangladesh

Abstract

1986-1995Present study featuring the assessment of demographical trends of Scoliodon laticaudus that were analyzed on the basis of monthly length frequency data from the Bay of Bengal, Bangladesh from July 2014 to June 2015. Total length (TL) range of the collected 1520 specimens were 26 to 70 cm and weight (W) 329 to 2758 g. The relationship of length and weight was W = 0.3409L2.1137, R2 = 0.9987). The von Bertalanffy growth model parameters were L∞ = 73.75 cm and K = 0.30 yr-1, hypothetical age at zero length of t0 = - 0.3922 years and goodness of the fit of Rn = 0.112. The natural mortality rate at average annual water surface temperature of 220C was 0.5651 yr-1. The total mortality was 1.31 yr-1 while fishing mortality was 0.745 yr-1 and the current exploitation ratio 0.57. The Beverton-Holt yield per recruit model was done by FiSAT-II in which when tc was 1 the Fmax was estimated at 0.95 yr-1 and F0.1 was 0.8 yr-1. Current age at the first capture was approximately 1 year, Fcurrent = 0.745 yr-1 which is smaller than F0.1 indicating the current stock of S. laticaudus of Bangladesh is in safer state but more work is needed for the sustainable management of this fishery resource

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