Browsing by Author "Lakmal, J.A.S."

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    Comparative Study on Growth Performance and Profitability of Shrimp Farming Industry in Sri Lanka: Native Penaeus monodon vs. Imported Specific Pathogen Free
    (Uva Wellassa University of Sri Lanka, 2020) Priyadarshana, S.D.A.M.; Athula, J.A.; Ranathunga, R.M.N.P.K.; Lakmal, J.A.S.; Adikari, A.M.L.W.
    Until 2018, Penaeus monodon was the main commercial-scale cultured shrimp species in Sri Lanka and the seed production industry depended on wild-caught native broodstock. Due to the high prevalence of White Spot Disease among the wild-collected brood shrimps, the farming industry has been affected by post larvae shortage and disease outbreaks. As a solution, National Aquaculture Development Authority has decided in 2016 to introduce Specific Pathogen Free (SPF) broodstock to the industry imported from Thailand and they are planning to encourage the SPF shrimp farming in the country. Therefore, this study was focused to compare the growth performance and profitability of farming these two varieties. During the period of 21st March 2019 to 28th February 2020, 14 ponds for each variety were selected from the Ambakandawila area in Puttalam District for the study. Data collection was initiated after the 8th week of the stocking and continued up to the harvest. Specific Growth Rate (SGR), Survival Rate (SR), Average Daily Gain (ADG) of the body weight, Feed Conversion Ratio (FCR), total cost, revenue, and net profit were calculated. SGR was recorded as 2.51 ± 0.1 & 2.13 ± 0.06 and ADG of the body weight was recorded as 0.31 ± 0.02 & 0.23 ± 0.01 g day-1 for SPF and native shrimp varieties respectively. SR was recorded as 70.1 ± 3.4% & 69.9 ± 3.2% and FCR was recorded as 1.51 ± 0.04 and 1.54 ± 0.07 for SPF and native shrimp varieties respectively. It recorded 1,482,311.62 ± 50,687.49 and 1,087,716.21 ± 72,449.54 LKR acre-1 as the total cost of the farming of SPF and native shrimp varieties respectively. Total revenue was recorded as 1,783,733 ± 102,197 and 1,535,122 ± 162,199 LKR acre-1 and estimated net profit was calculated as 301,421 ± 105,412 and 447,406 ± 101,576 LKR acre-1 for SPF and native shrimp culture systems respectively. Although the SGR, SR, ADG, FCR are better in SPF shrimps than native shrimps, profitability mainly depends on the total cost. Keywords: SPF Penaeus monodon, Shrimp farming, Growth performance, Profitability
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    Development of Quality Assessment Guideline for Litopenaeus Vannamei (Whiteleg Shrimp) Post Larvae
    (Uva Wellassa University of Sri Lanka, 2020) Premarathna, N.M.C.N.; Athula, J.A.; Soyza, W.A.D.; Lakmal, J.A.S.
    Penaeus monodon is the main brackish water aquaculture species in Sri Lanka which targets the production for the export market. Litopenaeus vannamei (Penaeus vannamei) was introduced in 2018 as a new species expecting a rapid increase in production in the country. As a management strategy implemented by the National Aquaculture Development Authority (NAQDA), the assessment of post larvae quality is a compulsory requirement to obtain a better harvest via better growth without disease infections. Quality assessment of the P. monodon is based on 10 criteria and a minimum of 80% marks are required to get the approval for stocking. Up to now, the same assessment method has been used for P. vannamei, and due to some morphological and anatomical deviations; it did not totally comply with the new species. Hence, this study aimed to develop a post larvae quality assessment guideline for Litopenaeus vannamei with a score allocation procedure for each quality assessment criterion. The characteristics of different post-larvae stages (PL 1 - PL 30) from three different culture cycles of Litopenaeus vannamei were evaluated under each criterion and performed microscopically and morphologically. The microscopic observations were Monodon baculoviruses and Baculovirus penaeid, condition of hepatopancreas and gut content, necrosis and deformities, epibiont fouling, muscle opaqueness, and gut to muscle ratio of post larvae. The average body length, rostral spines, and size variation of each PL stage were the morphological observations measured to apply as standard values. The obtained values for post larvae of P. vannamei differed from the values of P. monodon. This study reveals the incompatibility of using the same assessment method for both shrimp species. Revision of marks allocation procedure, validation of the quality assessment method, and introduction as a new guideline will contribute to the future development of the Litopenaeus vannamei farming industry in Sri Lanka. Keywords: Litopenaeus vannamei, Post larvae quality, Quality assessment guideline, Shrimp farming