Browsing by Subject "Najas graminea"
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Growth performance of Penaeus monodon in lablab, lumut, and digman ponds under various farm practices -
Journal of Aquaculture in the Tropics, 1990 - Taylor & FrancisThe influence of lablab, lumut (filamentous algae), and digmaan (Najas graminea) on the growth of prawns as associates of natural food biomass in brackishwater ponds was investigated. Ponds, each grown with the above macrophytes species and with no supplementary feed used, were selected as sampling areas. Sampling was conducted on a biweekly basis. Results showed that although the specific growth rate of prawns reared in the lablab pond was significantly higher than that of prawns reared in the lumut and digman ponds (p<0.01), absolute values in growth showed otherwise. Prawns reared in the digman pond attained highest growth which was significant (p<0.01). The digman pond was able to support a much higher density and produce a higher growth, coupled with a substantial survival. The digman pond yielded 606 kg of prawns, while the lablab pond yielded 569.5 kg and the lumut pond 305 kg. At value of $ 10 per kg, the rearing of prawns in the digman pond would be more profitable than the other treatments.
Conference poster- In Y Taki, JH Primavera & JA Llobrera (Eds.), Proceedings of the First International Conference on the Culture of Penaeid Prawns/Shrimps, 4-7 December 1984, Iloilo City, Philippines, 1985 - Aquaculture Department, Southeast Asian Fisheries Development CenterRuppia maritima (kusay-kusay, Hiligaynon) and Najas graminea (digman, Hiligaynon) are macrophytes growing in local brackishwater ponds believed to provide food and shelter to prawns and fishes. Their effect on growth and survival of Penaeus monodon juveniles (PL50; carapace length, 4.01 mm; body weight, 0.053 g) were studied in 80-ℓ glass aquaria. The treatments were: (a) a commercial pellet (40% protein); (b) live Ruppia; (c) decaying Ruppia; (d) live Najas; and (e) decaying Najas. The pellet was offered to satiety (approx. 100% of body weight) twice daily. Live Ruppia and Najas were transplanted in the aquaria using pond soil a week prior to the experiment. Decaying Ruppia and Najas were transferred from ponds. Salinity was maintained at 15 ppt and 50% of the water was changed regularly. Highly significant differences (P < 0.01) in mean carapace length (CL) and mean body weight (BW) on the 10th, 20th and 30th days were observed among treatments. Increase in CL was fastest with decaying Najas and slowest in live Ruppia (14% vs. 17% after 30 days). Growth with decaying Ruppia was comparable to pellets on the 10th and 20th days but was faster after 30 days. Body weight on all sampling days was highest in decaying Najas and lowest in live Ruppia. Percentage increases were 122, 273 and 565% on the 10th, 20th and 30th days, respectively, with decaying Najas. Those given live Ruppia registered increases of 11, 67 and 94%, respectively. The rapid growth rate of animals on decaying Najas was compensated negatively by a low survival rate (31%), significantly lower than on live Najas (100%). Other survival percentages were: decaying Ruppia, 59% and pellet, 53%.