Diversifi cation of Species for Aquaculture in Guam |
The overall goal of this two-year project was to improve the profitability of Guam's aquaculture industry by diversifying the product mix to reach new local and export markets. During the second year of the project, specific objectives related to that goal were to:
The growth of the aquaculture industry on Guam has declined due to increased competition from imported milkfish. The addition of marine shrimp helped to offset this dilemma somewhat, but the need for a diversity of species remains a priority. Development of techniques for aquaculture of hard corals for the aquarium trade not only will provide a means of economic development for the tropical islands of the Pacific and Caribbean but also will enable the protection of natural resources.
Objective: Develop commercial seedstock production techniques for hard corals.
During the project's second year, the full moon occurred on July 1 and July 31. As a result, some Acroporids released their gametes in early July while others released in early August. This provided two opportunities for experimentation. During the summer spawning events, investigators experimented with modified techniques for mass fertilization and growout of corals and were able to simplify methods substantially. Protocols were developed for culturing coral larvae in 3-gallon plastic tubs, and the amount of labor needed to grow larvae through settlement and metamorphosis was reduced. Simplified methods of calculating appropriate sperm concentration were developed.
During the second year of the project, the crustose coralline alga Hydrolithon reinboldii was found to induce settlement and metamorphosis in a variety of commercially valuable species of corals, particularly Goniastrea retiformis and several species of Acropora. This alga was induced to coat artificial substrate, including 1-inch-diameter Plexiglas discs, through direct contact as well as by distribution in seawater tables with algal thalli. During the second year of the project, colonies of corals cultured during Year One were measured to provide growth rates and survival data. Growth rates of colonies of both P. damicornis and Acropora spp. were found to be non-linear, with larger colonies growing at faster rates. P. damicornis survival was variable, depending on weather conditions. In several experiments, survival through the first month was greater than 85 percent. Due to a seawater system shutdown during a passing typhoon, survival of colonies through the first month in one trial was only 30 percent. This demonstrated the need for dependable seawater flow, an issue that is being addressed by installation of a seawater well above the wash zone to back up the beach-side system that must be dismantled when typhoons pass the coast. Two coral-eating gastropods were found, so the coral was inspected weekly for this predator.
Experiments are being conducted to determine the optimal size for donor colonies from which to harvest coral fragments. Data is being collected on growth rates, repair rates and survival of donors and collected fragments. Investigators made a break-through on increasing the growth rate of corals through juvenile colony fusion. The time to marketable size and an appropriate size for harvesting branches was reduced by half to five months by fusing several small larval recruits. This has valuable implications for the success of the project.
A cooperative agreement between the University of Guam Marine Laboratory and the Guam Aquaculture Development and Training Center, Guam Department of Commerce, allowed scaling up of the production of corals from larvae. In addition, the Guam Department of Agriculture approved permits to produce and sell cultivated corals.
Objective: Develop extension publications and videos to transfer the technology to the aquaculture industry.
Detailed records and photographs of all techniques have been kept for the development of a coral culture manual. Video footage of coral spawning, gamete collection, fertilization and growout have been taken in preparation for the extension video.
Growth rates will continue to be determined for hard corals, and the extension materials will be completed and published.