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The American state of California is famous for its agriculture. Now, scientists are working to make California a world leader in the production of caviar. Caviar is made from the eggs of the large fish called sturgeon. Caviar is a popular and very costly food in many parts of the world.

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The University of California at Davis reports that California is already the world's leading producer of white sturgeon. It says the state's success is partly the result of work by one of its professors.

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Serge Doroshov (surge DOOR-uh-shof) joined the university's animal science department twenty-five years ago. He and his team showed that it is possible to speed up the rate at which sturgeon develop sexually. To do this, they successfully changed the environment where the fish develop. They also used hormones to influence the production of eggs and male reproductive fluid.

Sturgeon and their ancestors are thought to have lived as long ago as two-hundred-million years. That is long before the appearance of most modern fish. Sturgeon have long, thin bodies covered with a series of bony plates. The head is also well protected with these hard structures.

Sturgeon can live for more than one-hundred years. Some weigh more than four-hundred-fifty kilograms. However, the fish develop slowly. Females in the wild are not able to reproduce until they are fifteen to twenty-five years old.

Most sturgeon move from salt water into inland waterways when they are ready to reproduce. However, some live permanently in fresh waters.

Sturgeon were once common in North America. However, too much fishing, building projects and pollution have greatly reduced their number. Today, Iran and Russia produce most of the world's caviar from sturgeon. The most valuable caviar comes from a kind of sturgeon called beluga (ba-LOO-ga).

Professor Doroshov showed that sturgeon could be raised in small bodies of water and large containers. He also showed that the fish will eat food not found in their natural environment. He and other scientists are now attempting to grow bigger, longer-living sturgeon that produce large amounts of caviar.

Professor Doroshov has also helped develop methods to raise other kinds of fish.

This VOA Special English AGRICULTURE REPORT was written by George Grow.