Sea urchin gonads, or "roe," are considered delicacies in Europe, Japan and Asia. Known as "uni," urchin roe can demand a high price. Unfortunately, stocks in many coastal waters have become seriously over-fished, and the harvesting practice known as dredging negatively impacts the sea urchin's ecosystem. Aquaculture of the more popular species of sea urchin may be the answer to meeting consumer demand without depleting the ocean. However, the science of "echiniculture" is still in its infancy, and it can take several years, from egg to urchin, to produce a viable harvest.
Instructions
Nursery
1. Place larvae in a small nursery tank, approximately one larva per milliliter of saltwater. Provide water circulation at approximately 20rpm. Avoid bubbling air, as bubbles seem to damage larval spines.
2. Three days after hatching, begin to feed the tank with single-celled algae. Feed only as much as they will eat in 24 hours (approximately 3,000 algae per milliliter of seawater).
3. Perform a 10 percent water change daily, carefully siphoning out uneaten food and dead larvae.
4. Move larvae to larger tank, approximately one larva per 10 milliliters of saltwater, after 10 to 15 days and continue to feed well and perform daily water changes until larvae are full grown at three to four weeks.
5. Move grown larvae to a well-established aquarium with biological and/or mechanical filtration and mature bacterium in the substrate to induce metamorphosis. The process of metamorphosis takes about five days.
6. Feed small sea urchins a phytoplankton diet. Substrate-dwelling diatoms work best. After approximately one year, the juvenile urchin will be large enough to accept adult food.
Grow-Out Phase
7. Place sea urchins in large, well-filtered tanks with corrugated sides for climbing or in a landlocked saltwater pond. Do not overcrowd.
8. Feed them a high-protein, sinking, pelleted food supplemented by sea kelp.
9. In six years or more, when an urchin reaches sexual maturity, it will produce roe every six to 12 weeks. However, the urchin must be cracked open and killed to harvest the roe.
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