Sea urchins' grow-out culture worthy of investment

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Notwithstanding its globular, spiny appearance, sea urchins (Tripneustes gratilla) have proven to be a lucrative shellfish industry worldwide. However, the high economic value of sea urchins prompted its depletion due to overexploitation. With this concern, the Bureau of Agriculture Research (BAR) included in the 7th Agriculture and Fisheries Technology Forum and Product Exhibition, a featured seminar that discussed a BAR-funded project that is looking into the problems, solutions, and future of the sea urchin industry in the Philippines and its status for commercialization.

The seminar was delivered by project leader, Ms. Amanda S. Galang, a senior aquaculturist of Bureau of Fisheries and Aquatic Resources – Regional Fisheries Office I (BFAR-RFO I) in San Fernando, La Union. In her presentation, she said that the country is not spared the problem pertaining to unregulated harvesting of sea urchins. One of the solutions that they have come up with is the practice of grow-out culture.

Locally, known as ‘maritang-tang’ in the Ilocos region, ‘kuden-kuden’ in Pangasinan and ‘tuyom’ in the Visayas, the initial grow-out culture of sea urchins was undertaken in sea pens at Brgy. Nalvo, Ilocos Sur in 1998. Since then, BFAR-RFO 1 has been vigorously promoting the cage culture of sea urchins.

Grow-out culture simply means that the sea urchins are collected and raised to marketable size in bamboo pens installed on the reef flat. The grow-out cages are regarded as ‘mini-reproductive reserves’. Grow-out culture effectively protects seedstock species (juvenile sea urchins) from natural predators, increases survivorship to reproductive maturity and enhances recovery of depleted natural population. As observed upon the introduction of grow-out culture, with the increase of sea urchin in the area, there has been a remarkable growth also of other species such as sea cucumbers, indicating that the practice may also be contributing to the survival of other vulnerable animal life nearby.

For those who want to engage in sea urchin grow-out culture in cages, some general considerations need to be heeded before starting. First, avoid building cages in area with very low salinity because this is stressful for sea urchins and may result in mass mortality. Second, cages should be ideally situated in a sheltered area where wild T. gratilla are naturally found. Third, avoid areas prone to ‘kulaba’ or water poison. Fourth, stock the cages with fresh Sargassum (brown algae) regularly even if some food still remains. This is to ensure that urchins feed at maximum rates and consequently grow fast and develop large gonads. Finally, for beginners, the UP-MSI recommends to start with about 3-4 grow-out cages, each with approximately 1000 – 5000 seedstock species (about 25-500 individuals per square meter).

When harvesting, keep in mind that bigger urchins command a better price. Thus, it is stressed that only the biggest urchins should be harvested.

Production of sea urchins under grow-out culture promotes resource conservation for it prevents further depletion of sea urchins and, at the same time, provides an alternative source of livelihood to the community. Sea urchins fishery is a good livelihood because there is always a demand for the roe or gonads (the edible part of urchins) and is a high value product in the local and foreign markets. In the international market, Japan is the world’s largest importer and consumer of roe (or uni in Japan). It is noted that during year 2000, roe was the most expensive marine product in the Tokyo central wholesale market. It is also considered a premium marine food delicacy in Korea, Greece, France, and New Zealand. In the domestic market, roe is considered a delicacy and is sold to specialty restaurants. The live sea urchin is sold at P60.00 – P70.00 per kilogram while the fresh chilled sea urchin roe fetches P1000.00 – P1200.00 per kilogram.

Aside being a food source, the shells of sea urchins can be used as fertilizer and as raw material for novelty items like candleholders.

Ms. Galang remarked that there are still issues that need immediate attention and long-term solutions such as the proper cage design and size, inadequate supply of juveniles at the start of project, sustainable harvest of sargassum, and poaching. Further interventions are therefore needed by the industry. (Diana Rose A. de Leon/DA-BAR)

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