Researcher Develops Culturing Techniques for Red Algae
Farmers Gain Better, Redder Abalone Shells
April 16, 2007
Contact: Christina S. Johnson, csjohnson@ucsd.edu, 858-822-5334
MONTEREY HARBOR – California abalone farmers may soon have the tools they need to sell premium live abalone to the lucrative Japanese market, as an ongoing California Sea Grant project has identified basic culturing techniques for growing red algae on site. Red algae are key to the Japanese market because they contain pigments that when fed to abalones turn their shells red.
An employee of the Monterey Abalone Company is ready to take a tending vessel to the prototype seaweed farm. All photos from Thew Suskiewicz, Moss Landing Marine Laboratories.
“Asian markets want red shells for red abalone,” explained lead researcher Mike Graham, a seaweed biologist at Moss Landing Marine Laboratories. Countries selling to the high-end Japanese market – South Africa, Chile and Japan – supplement abalone diet with red algae. Many farms in California, in contrast, feed abalones a diet composed primarily of green or brown algae that is harvested from wild kelp beds, and the result is a dark shell. Red algae need to be cultivated because wild plants tend to be inaccessible to harvesting.
Working in collaboration with the Monterey Abalone Company, Graham has identified two red algae species that so far appear suited to commercial culture – Gracilaria pacifica and Gracilariopsis andersonii; both are hearty, native species that have been successfully grown on polypropylene ropes hung vertically in the water in Monterey Harbor.
Recent experiments, led by Sea Grant Trainee Thew Suskiewicz, have shown that algae growth rates are optimized in Monterey Harbor at a depth range of 3 meters to 3.5 meters. Algae grew 17 centimeters in 2 weeks at this depth range, compared with 3 centimeters in 2 weeks at a half-meter depth. The more
Red algae (Gracilariopsis andersonii ) grown in shallow water is bleached green by sunlight.
than five-fold difference in growth rates likely reflects the fact that algae in deeper water were no longer competing for resources with epiphytes.
In terms of establishing protocols for a commercial algae farm, which is the goal of the project, the next step is to figure out the percentage of an abalone’s diet that needs to contain red algae to color the shell. Graham would also like to determine whether a varied diet that includes red algae can increase abalone growth rates, a pattern that has been observed in farms in Chile and which could offset the costs of rearing algae.
The results of the diet studies, he said, are also needed to determine the number of ropes that need to be put in the harbor to produce sufficient amounts of red algae for the Monterey Abalone Company’s current production level. Once this is all done, Graham will work with Sea Grant Extension director Paul Olin to adapt the results of the study for farms across the state.
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