Population dynamics and stock assessment of milk shark, Rhizoprionodon acutus (Ruppell, 1837) along Gujarat coast of India

Dash, Swatipriyanka Sen and Chakraborty, S K and Vivekanandan, E and Zacharia, P U and Kizhakudan, Shoba Joe and Jaiswar, A K and Dash, Gyanaranjan and Gohel, Jayashree (2017) Population dynamics and stock assessment of milk shark, Rhizoprionodon acutus (Ruppell, 1837) along Gujarat coast of India. Indian Journal of Geo-Marine Sciences, 46 (5). pp. 936-946.

Text IJMS 46(5) 936-946_Swatipriyanka Sen Dash_Population dynamics and stock assessment of milk shark, Rhizoprionodon acutus (Ruppell, 1837) along Gujarat coast of India.pdf Restricted to Registered users only Download (901kB)

Abstract

Stock assessment of Rhizoprionodon acutus (Ruppell, 1837) was made along with a few biological characteristics in the commercial landings during 2012-2014 from Gujarat waters of India to understand the population dynamics and stock status of the species. L∞, K and t0 estimated were 93.8 cm, 0.32 yr-1 and -1.3 yr, respectively. Total mortality rate (Z), fishing mortality rate (F) and natural mortality rate (M) were estimated as 1.0 yr-1, 0.39 yr-1 and 0.61 yr-1, respectively. Length at capture (Lc50) and length at maturity (Lm50) were estimated as 50 cm and 61 cm respectively, which indicate that most of the sharks are exploited before attaining the sexual maturity. Length-weight relationship showed growth was isometric. The species was a continuous breeder and showed peak recruitment during May. The current exploitation ratio (Ecur) was found to be 0.39, which is lower than E0.1 estimated for the species using Beverton and Holt yield per recruit analysis. Thompson and Bell prediction model showed that the current exploitation is reducing the virgin stock biomass (B0) and spawning stock biomass (SSB) to 55% and 34%, respectively and hence, the exploitation level for the species could be increased by 20% which would increase the yield while maintaining the SSB at a relatively safer 28% level for its sustainability.

Item Type:	Article
Uncontrolled Keywords:	Milk shark; Growth parameters; Spawning stock biomass; Resilient species
Subjects:	Demersal Fisheries > Shark fisheries Marine Fisheries > Stock Assessment
Divisions:	CMFRI-Veraval
Depositing User:	Arun Surendran
Date Deposited:	27 Jul 2017 08:57
Last Modified:	27 Jul 2017 08:57
URI:	http://eprints.cmfri.org.in/id/eprint/12042

Actions (login required)

View Item