Browsing Proceedings of the First International Conference on the Culture of Penaeid Prawns/Shrimps by Subject "Food organism"

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    • Ruppia maritima and Najas graminea as natural foods for Penaeus monodon juveniles 

      Gacutan, Rogelio Q.; Primavera, Jurgenne ORCID (Aquaculture Department, Southeast Asian Fisheries Development Center, 1985)
      Ruppia 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%.

    • The use of haptophyceae in rearing experiments on larval Penaeus orientalis 

      Li, M.R.; Bian, B.Z.; Ma, L. (Aquaculture Department, Southeast Asian Fisheries Development Center, 1985)
      The food value of five clones of Haptophyceae, Coccolithus pelagicus, Dicrateria zhanjiangensis, Isochrysis galbana, Tahitian Isochrysis aff. galbana, and Pseudoisochrysis paradoxa were tested for larval Penaeus orientalis. The algae were semi-continuously cultured in 5,000 ml carboys with 4,000 ml of Guillard f/2 medium, under 2,000 lux continuous light and under aeration. The algal density was up to 1 × 107 cell/ml. Rearing experiments were conducted in round tanks with diameter of 45 cm. Algal density was controlled at 1 × 105 cell/ml in the course of the experiments. The larval density was 18 individual/100 ml; water temperature, 21-24°C; pH, 7.5-7.7; and sea water specific gravity, 1.019. The results showed that of five clones used, Tahitian I. aff. galbana and D. zhangjiangensis proved to be the best. It took 9-11 days for nauplius I to develop into mysis I with survival rate of 73.5% and 73.4%, respectively.