SBIR-STTR Award

Hawaii has several species of edible marine limpets called Opihi. They are endemic to the Hawaiian Islands and are a highly prized delicacy served at special occasions. The natural populations have been drastically reduced by overfishing, and a once thriving commercial fishery has all but vanished. Royal Hawaiian Sea Farms proposes to develop mass spawning and settling techniques, the first steps necessary to realize large land based aquaculture of Opihi. Phase I research will evaluate four methods to stimulate spawning and four techniques to induce settling and metamorphosis. Because the reproductive biology of Opihi is very similar to abalone, proven commercial abalone hatchery techniques should be applicable to Opihi Simulation of natural lunar, tidal, and seasonal reproductive cues will make captive spawning on a large scale possible, and the added effect of W irradiation and serotonin injections, so successful with other mollusks, will likely result in increased efficiency. Opihi require substrates with biofilms to settle. Various types of natural biofilms from different water sources, as well as some produced from laboratory diatom monocultures will be tested as settling inducers along with some promising chemical inducers, such as GABA and elevated potassium levels.

Anticipated Results:
We anticipate one or more of the procedures to stimulate synchronous spawning and settlement will be effective at a level which will allow the year round production of commercial quantities of Opihi spat. These techniques will lead to the development of cost effective grow-out methods developed during subsequent Phase II research. The local market demand for Opihi is sufficiently large to support a significant aquaculture industry, and it is likely an export market to Japan could be developed. This new aquaculture opportunity would assist in the diversification and economic development of rural Hawaii and possibly a stock enhancement program.

During Phase I, reliable large scale techniques were developed for spawning, larval rearing, and settling of all three commercial species of Hawaiian limpets (opihi). Several types of substrate/biofilm complexes can be produced that elicit mass settling and good early growth and survival. Preliminary nursery and growout trials show that juveniles and adults can be reared to harvest size in a matter of months using on-land aquaculture systems. The next step in Phase II is to further develop the nursery and growout techniques to improve survival and overall growth rates. This will be done by manipulating the culture environments to provide: adequate water movement to aerate their gills, a proper algal diet, and an adequate amount of biological grazing to prevent overgrowth of the spat. High pressure spraying will provide necessary flushing. Variation in tank design, fertilization, light intensity and wavelength and controlled seeding of biofilms will produce different diets. Biofilm maintenance will be provided by the grazing of other mollusks, and other adult opihi. The feasibility of ocean ranching and stock enhancement will be tested by introduction of competent larvae and juveniles to the coastline. Feasibility of producing "opihi pearls" will also be addressed.Applications:Given the encouraging results of Phase I, we expect to develop a financially feasible technology for commercially producing at least one species of opihi in an on-land culture system and possibly more using ocean ranching. This would provide product for an already existing strong but under-supplied market, and stimulate growth of a new aquaculture industry in Hawaii, providing employment in economically depressed rural areas. This research will also provide the framework for stock enhancement programs. The possibility of producing a unique, high priced product such as pearls could greatly increase the commercial viability of opihi farming.