A Study of Stock Status and Size at Maturity of Dasyatis Zugei (Pale-Edged Stingray) in Gulf of Mannar (Mannar District)

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dc.contributor.author Gayathry, L.D.
dc.date.accessioned 2021-10-15T05:17:36Z
dc.date.available 2021-10-15T05:17:36Z
dc.date.issued 2014
dc.identifier.other UWU/AQT/14/0003
dc.identifier.uri http://www.erepo.lib.uwu.ac.lk/bitstream/handle/123456789/7287/DAQT%2014%20003-19022021100807.pdf?sequence=1&isAllowed=y
dc.description.abstract Dasyatis zugei is one of the major non-target species caught in the bottom-set crab nets used for catching blue swimming crab (Portunus pelagicus) in Gulf of Mannar. This study aims to determine stock status, the length—weight relationship and size at maturity. In total 1,404 individuals were collected from crab nets in two landing sites; Vankalai and Thalvupadu in Gulf of Mannar during the period of September - November, 2018. Disc Width-WD of all the individuals were measured to the nearest mm, body weight was weighed to the nearest gram and sex was determined. The state of maturity of gonads of females was identified through dissection and macroscopic examination of ovaries. Mean ova diameter significantly varied among females, according to the different maturity stages (P<0.05). Sex ratio in the catch was 1:1.35 (M: F). Disc width of males ranged from 85-260 mm with a mean of 175.43±22.42 and females ranged from 110-220 mm with a mean of 167.27±17.55. The Disc width-weight relationship was analyzed by Simple Linear Regression using log transformed data and it showed Log W = -0.5923 + 2.364 log W D for male and Log W = -3.497 + 2.599 log WD for female. The results show negative allometric growth (b<3) for D. zugei. There was no significant statistical difference (P>0.05) in male and female regression co-efficient. The size at first maturity = was 166.5 mm for female D. zugei. Embryos were found only in females > 160 mm of WD. The maximum fecundity was three embryos per female and the stock status of D. zugei was determined as above limit reference point (Spawning potential ratio as 21%) but not in a state of sustainable utilization. This study reports the first findings on length- weight relationship and size at maturity of D. zugei in Sri Lankan waters. Keywords: Dasyatis zugei, Size at maturity, Stock status, Length-weight relationship, Non-target species en_US
dc.language.iso en en_US
dc.publisher Uva Wellassa University of Sri Lanka en_US
dc.relation.ispartofseries ;UWU/AQT/14/0003
dc.subject Aquatic Resources Technology Degree Programme ( AQT) en_US
dc.title A Study of Stock Status and Size at Maturity of Dasyatis Zugei (Pale-Edged Stingray) in Gulf of Mannar (Mannar District) en_US
dc.title.alternative Research Article – AQT 2014 en_US
dc.type Thesis en_US

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