MANUAL ON SEAWEED CULTURE 2. POND CULTURE OF CAULERPA AND 3. POND CULTURE OF GRACILARIA

Several species and varieties of Caulerpa may be utilized as food in the form of fresh vegetables. These are mainly produced through gathering of natural stocks. Only C. lentillifera is commercially cultivated in ponds in the Philippines. The culture of this species started in the early 1950s in the island of Mactan, province of Cebu, Central Visayas. The accidental introduction of C. lentillifera with some other seaweed species to fishponds as fish food initiated its formal cultivation. The high demand for this alga in the local markets in metropolitan Cebu was a major factor contributing to the success of its commercial production. The species is preferred because of its delicate, light taste, soft and succulent texture. It is also a fast growing species.

The pond culture of C. lentillifera was started by a fishfarmer in 1952 utilizing his fishponds with milkfish and shrimp. At the beginning, Caulerpa was a secondary crop to fish and shrimp but later, because of the marginal production of fish and shrimp compared to the high production of Caulerpa, the farmer shifted to Caulerpa as his major crop and milkfish and shrimp became secondary crops. Interviews made among farmers revealed that some 400 hectares of ponds are presently used for the culture of Caulerpa. Although the commercial culture of Caulerpa in ponds started more than two decades ago, it has not been successfully transferred to other parts of the Philippines as yet, with the exception of the pond and open reef culture in Calatagan, Batangas, introduced by the author in early 1980s, so that the bulk of the fresh supply of Caulerpa in Metro Manila and some bigger towns in Central Luzon still comes from Mactan, Cebu. Although local consumption statistics are not available, it is probably safe to assume that several tons of Caulerpa are transported to Metro Manila from Mactan, Cebu every month. This seaweed is always available in the local markets any day of the week. The statistics of the Bureau of Fisheries and Aquatic Resources showed that in 1982 some 827 tons of Caulerpa were exported to Japan and Denmark in fresh, brine-cured and salted form.

The present cultivation utilizes the traditional brackishwater ponds. However, results of recent studies (Trono, 1987) have shown that water management is a primary factor in the productivity of Caulerpa, the culture of which would require a flowthrough system to facilitate water exchange. Thus, some modification of the traditional ponds such as the introduction of water control gates have to be made. Unlike pond culture of fish where water exchange is relatively infrequent (e.g., once a week or a fortnight) pond culture of Caulerpa requires more frequent water exchange in order to maintain the necessary level of nutrients required for growth and development. Some of the more progressive farmers in Mactan had through experiences, learned the importance of proper water management and achieved higher production through the introduction of some form of a flow-through system by providing both entry and exit gates for each pond compartment.