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Population dynamics and stock assessment of grey sharpnose shark Rhizoprionodon oligolinx Springer, 1964 (Chondrichthyes: Carcharhinidae) from the north-west coast of India

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Title Population dynamics and stock assessment of grey sharpnose shark Rhizoprionodon oligolinx Springer, 1964 (Chondrichthyes: Carcharhinidae) from the north-west coast of India
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Creator Zacharia,P U
Kizhakudan,Shoba Joe
Akhilesh,K V
Das,Thakur
Dash,Gyanaranjan
Purushottama,G B
 
Subject Grey sharpnose shark, Growth parameters, Length-weight relationship, Maturity, Spawning stock biomass
 
Description Not Available
The life history and exploitation parameters of Rhizoprionodon oligolinx Springer, 1964 were assessed using commercial landing data of 2012-2015 from Mumbai waters of India to understand the population dynamics and stock status of the species. The average annual landing of the species was estimated to be 383 t, which formed about 9.1% of the total shark landings of Maharashtra. L∞, K and t0 estimated were 97.1 cm, 0.47 yr-1 and -0.79 yr respectively. Total mortality (Z), fishing mortality (F) and natural mortality (M) rates were estimated as 2.16 yr-1, 1.48 yr-1 and 0.69 yr-1 respectively. The length at capture (L50), length at female maturity (Lm50) and male maturity (Lm50) were estimated as 49.7, 62.3 and 59.5 cm respectively, which indicated that most of the sharks entered peak phase of exploitation before attaining sexual maturity. Length-weight relationship indicated allometric growth (b>3) for the species. The species was found to be a continuous breeder and showed peak recruitment during April. The current exploitation rate (Ecur) was found to be 0.68, which is lower than Emax estimated for the species using Beverton and Holt yield per recruit analysis. Thompson and Bell prediction model showed that at current exploitation level, the biomass (B) has reduced to 32% of virgin biomass (B0) where as, the spawning stock biomass (SSB) has reduced to 16% of the virgin spawning stock biomass (SSB0). Hence the exploitation level for the species should be reduced by 40% that will ensure the availability of SSB at a relatively safer 30% level to rebuild the stock for long term sustainability of the resource.
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Date 2021-09-17T09:02:41Z
2021-09-17T09:02:41Z
2017
 
Type Article
 
Identifier Not Available
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http://krishi.icar.gov.in/jspui/handle/123456789/64044
 
Language English
 
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Publisher Not Available