“This was not a trivial task,” says Dr. Stephen Watts, professor in the Department of Biology at the University of Alabama at Birmingham (UAB), who teamed up for five months with Dr. Addison Lawrence, director of the Texas A&M Shrimp Mariculture Facility to determine the composition of diets necessary for the proper growth of juvenile, sub-adult, and adult sea urchins. “Our primary concern was the same concern that everyone has for cultured species: nutrition. What do we feed them?”
Background: The team formulated 44 different diets based on the knowledge of commercial diets for other invertebrates and sea urchin feeding ecology. Feeding over 800 urchins individually, and working 12-hour days, seven days a week, researchers have developed semi-purified and purified dry feeds that promote high rates of growth and survivorship of sea urchins in the laboratory at levels that exceed field populations.
Significance: Their results lay the groundwork for boosting the feasibility of building a land-based aquaculture system for Tripneustes ventricosus and other edible sea urchins which are a major component of marine environments found throughout the world’s oceans. The promise of sea urchin farming would not only help to alleviate the over-fished sea urchin population and bolster the seafood industry, but has important biomedical applications and the ability for global economic impact.
“Sea urchin farming in the U.S. is at or near commercial feasibility to supplement the declining fishery,” says Watts. “Enhanced production and export can help limit our increasing agricultural trade deficit. We have several major corporations interested in working with us.”
Since sea urchins are also of major economic importance in many other regions of the world, interest in their management, as well as the ability to grow them, has increased greatly in recent years. In 2001, the United States shipped nearly $86 million in sea urchin roe (known as “Uni” in the sushi industry) to Japan. That number is down from a high of $174 million in the mid-1990s, due to the falling numbers of sea urchins in U.S. coastal waters. Even the large northeast coast fishery has declined by 90% in the last 10 years.
“Despite the fact that a large variety of species of sea urchins are fished worldwide, the Gulf of Mexico is the last major body of water in the U.S. that does not have a developed sea urchin fishery, yet has several species that have culture potential.”
Next Steps: By the end of the two-year project, the researchers hope that their continued development of semi-purified and purified diets will have greatly increased the likelihood of successful culture for a number of urchin species, with important implications for many U.S. and global industries.
* This project will help NOAA accomplish its performance objective to increase the number of fish stocks managed at sustainable levels.