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    Effect of size on spawning of Imbaw, Anodontia edentula (Linnaeus, 1758)
    Cambel, Marianne P. (Division of Biological Sciences, College of Arts and Sciences, University of the Philippines Visayas, 2008-04)
    The effect of shell size to spawning of imbaw, Anodontia edentula was examined. A total of 120 clams with shell length ranging from 34.90 to 68.20 mm were collected. Basing on shell length, 3 class sizes were used to group these clams, namely: < 45 mm, 45-50 mm, and > 50 mm. Thirty-five percent of the clams had shell length of < 45 mm, 21.7% in the range of 45-50 mm, and 43.3% had shell length of > 50 mm. Overall result showed that a high percentage of the clams in the range of 35 to 50 mm responded to spawning induction. Result showed that 41 (98%) of the clams in class size < 45 mm spawned. Twenty-six (100%) of the clams in 45-50 mm spawned and 31 (60%) spawned in class size > 50 mm. A mortality of 2 occurred among the broodstock and had shell lengths of > 50 mm. Among the clams induced to spawn, males predominated in the sample. Only 1 case of hermaphroditism was observed in < 45 mm and no females were observed to spawn. The only immature male in class size < 45 mm has a GSI value of 22.3. The mean GSI value of the 19 immature clams in class size > 50 mm was found to be 23.9 (±7.62).
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    Survival and growth of the sea cucumber Holothuria scabra (Jaeger) juveniles reared at different diets
    Baylon, Basil C. (Division of Biological Sciences, College of Arts and Sciences, University of the Philippines Visayas, 2009-03)
    Sea cucumbers are economically important species, with high demand in local and international markets. Overharvesting due to this high demand causes depletion of wild populations of sea cucumbers. Stock enhancement has been resorted to improve the status of natural populations. This will need the development of rearing technology which includes studies on the effects of different diets on sea cucumber juveniles. In this study, the effects of five diets on growth and survival of sea cucumber Holothuria scabra juveniles were compared. The five treatments used were benthic diatoms (Navicula sp.) alone, combination of benthic diatoms and seaweed (Sargassum sp.) extract, seagrass extract alone, combination of benthic diatoms and seagrass (Thalassia sp.) extract, and commercial shrimp feed. Three replicates were used for each treatment. For every replicate. 10 juveniles with body length 1-2 mm were reared in a 3-L culture container with seawater and no sand substrate. Salinity ranged from 32-35 ppt and the temperature from 26-29°C. It was observed that there was a trend of increasing body weight, body length, and body width of juveniles as weeks of culture progressed. After 7 weeks of culture, best weight gain, increase in body length and body width was achieved in juveniles fed with either benthic diatoms alone or combination diet of benthic diatoms and seaweed extract. There was high survival in all feeding treatments except in H. scabra juveniles fed with commercial shrimp feed. The lowest body weight, length and width and lowest survival were consistently obtained from juveniles given commercial shrimp feed.