Growth Performance and Survivorship of Sea Urchin (Tripneustes Gratilla) in Grow-Out Culture

Abstract

This study was conducted in Nalvo, Sta. Maria, Ilocos Sur from November 2000 to June 2001. It primarily aimed to assess the growth performance and survivorship of sea urchin (T. gratilla) in grow-out culture. In particular, it sought to assess the growth performance of sea urchins in terms of test diameter, test height, and body weight. It further aimed to monitor the percentage survivorship of sea urchins in cages. Two cages made of polyethylene plastic screen (lm x 2m x .75m) were set up in the reef flat at a depth of about two meters. Each cage was stocked with 100 juvenile sea urchins (2-3 cm in diameter). Prior to stocking, the average test diameter, test height, and body weight of the initial sea urchin stock were recorded. For the seven-month culture, the sea urchins were fed with Sargassum spp. twice a week. Growth performance of the sea urchins in terms of increases in the above-mentioned parameters was recorded once a month. The average growth rate and percentage survivorship of the sea urchins on the first four months of culture and the last three months of the study period were also monitored and compared. Results showed that on the average, sea urchins in cages have high growth rate and percentage survivorship. However, findings of the study revealed that the growth rate and percentage survivorship of sea urchins are higher on the first four months than the last three months of the culture period. From the results of the study, it is evident that grow-out culture of sea urchin, T. gratilla, is a coastal management tool which contributes to
the recovery of the depleted population of this resource. Further, this management practice could be an alternative source of livelihood, particularly in coastal communities.