Preliminary Study on the Polyculture of Sea Urchin (Tripneustes gratilla) and Sea Cucumber (Actinopyga spp.) in Concrete Tank

Abstract

This experimental study was undertaken to assess the growth performance and monitor the survivorship of sea urchin (Tripneustes gratilla) and sea cucumber (Actinopyga spp.) polycultured in tank. It was conducted at the UNP-Marine Resources Development Center in Nalvo, Sta. Maria, Ilocos Sur from October 2005 to February 2006. Two hundred (200) juvenile sea urchins and two hundred (200) juvenile sea cucumbers collected from the wild were stocked in a 10-ton capacity concrete tankfilled with 4-ton sea water and provided with enough aeration. These were fed with Sargassum spp (aragan) twice a week. Cleaning ofthe tank as well as regular water change was also done. The initial average body weight (g), test diameter (cm), and test height (cm) of sea urchins as well as the initial average body weight (g) of sea cucumbers were recorded. To monitor the growth performance of the experimental
organisms, the monthly increases in the aforementioned parameters were monitored and recorded. In addition, the final number of stocks lef afer the four-month culture periods were also recorded and the percentage (%) survivorship were computed. Results on the  growth performance of sea urchins showed that the highest increase in weight of 29.02g (74.83% growth increment) was observed on the second month of culture period while the lowest increase of 8.73g (02.88%) was observed during the third month. In terms of mean monthly increase in test diameter, the highest mean increase of 1.22cm (38.73%) was observed during the first month; while the lowest mean was observed during the last month with 0.10cm (1.69%). Data on the mean monthly increase in test height showed that the highest mean monthly increase of0.82 cm (43.62%) was recorded during the first month, while the lowest mean was noted during the fourth month with 0.09cm (2.49%). On the other hand, data on the growth performance of sea cucumber revealed that the mean monthly increase in body weight (g) and growth increment (%6) of sea cucumbers was highest (12.02g or 39.18%) during the first month while the lowest (3.17g or 6.09%) was recorded during the fourth month of culture period. Resultsfurthershowed that the percentage survivorship ofsea urchin and sea cucumber after four-month culture period were 98% and 100%, respectively. From the above findings, it was concluded that there is a high growth performance and survivorship of sea urchin and sea cucumber polycultured in tank. Considering the high performance and survivorship of these organisms, this activity is recommended as a management tool for these echinoderms. It isfurther recommended that similar study using higher stocking density for sea urchin and sea cucumber should be undertaken to fully maximize the culture area. A comparative study on the monoculture and polyculture of these echinoderms both in grow-out and in tanks should be undertaken so as to have a more comprehensive analysis of data. Furthermore, since sea cucumbers are known as substrate feeders, the tank should be overlaid with sand as its substrate. Production technologies such as sea urchin and sea cucumber hatchery should be developed in the province to have an access for juveniles needed for culture.