UC research on caviar production helps protect endangered fish in the Caspian Sea

Even before dinosaurs roamed the planet, wild sturgeons swam in the rivers and lakes of the Earth's northern hemisphere. However, when humans realized the delicacy female sturgeons produce within their ovaries - sweet, nutty tasting glossy black eggs known as "caviar" - sturgeon numbers began a steady decline.

That decline may now finally stop. UC scientists, working with industry cooperators, have discovered how to meet the demand for high-quality caviar from sturgeon farmed in America, relieving pressure on wild fish that have been aggressively harvested for centuries half a world away.

Traditionally, most of the world's caviar has come from the Caspian Sea, the largest inland body of water in the world, bordering Iran and four former Soviet nations, including Russia. Pollution, over fishing and poaching have severely depleted the number of sturgeon in the Caspian Sea. An international treaty protects beluga sturgeon, the Caspian Sea native species that produces the most highly prized caviar, in much the same way as ivory and turtle oil. All countries that are participants in the international treaty require an export permit. However, poachers have maintained a significant illegal beluga caviar trade.

Consumers can help protect Caspian Sea fish by selecting the eco-friendly domestically farmed caviar made available by nearly three decades of UC research. The first recorded attempts at artificial propagation of sturgeon were made in 1870 in Russia. In North America, programs to artificially propagate surgeon made some progress between 1875 and 1912, but by 1920, serious interest was abandoned.

"Earlier, fisheries scientists couldn't solve the problem of getting the fertilized eggs to hatch in significant numbers," said Fred Conte, UC Cooperative Extension aquaculture extension specialist based at UC Davis. "In nature, sturgeon eggs stick to rocks in the river bottom, where fresh water flows over the eggs. In order to successfully hatch eggs in the hatchery, the eggs must be mixed by hand in a suspension of fresh water and river silt."

This and other sturgeon technology came to the United States with Russian scientist Serge Doroshov, who left the Soviet Union via Cuba and Rome, and joined the faculty at UC Davis in 1977. In 1979, a grant from the U.S. Fish and Wildlife Service to UC researchers led to a resurgence of sturgeon research in the United States.

"The fact that Serge came with this technology kicked off the sturgeon farming program in the U.S.," Conte said.
Scientists faced another natural hurdle in domestic caviar production. In California, the industry is raising native white sturgeons, which mature slowly. It takes about 17 years before females are ready to breed for the first time. In their natural habitat, sturgeons may spawn only three to four times, but can live well over 100 years.

The keys to hastening reproduction and development of caviar, they found, was water temperature and nutrition.

"Sturgeons are cold-blooded animals," Conte said. "When the fish are raised in warmer water, their growth and reproductive processes are accelerated. By carefully monitoring and regulating the water temperature, as well as providing a high quality diet, we can get sturgeon to spawn in seven to nine years."

UC Davis scientists, unable to find the natural trigger for spawning, have also learned that injection of an artificial hormone or a hormone from another species spurs the development of sturgeon eggs.

Conte said the University provided the initial research and training to the domestic sturgeon industry, but that many advancements in domestic sturgeon farming were the result of the close partnership that developed between the industry and UC scientists. California producers raised more than 14,500 pounds of white sturgeon caviar in 2003, valued at $3 million.

Future goals of industry and UC research will be improvement of the caviar in terms of taste, texture and shelf life - changes that may increase the value of domestic caviar. Currently, a one-ounce jar of Sterling-brand white sturgeon caviar, produced by the Stolt Sea Farm in Sacramento, is $38. An ounce of beluga caviar fetches $90 an ounce.
"Caviar is like fine wine," Conte said. "The true connoisseur knows beluga has been the preferred caviar for hundreds of years. However, the beluga mystique is driving the demise of beluga sturgeon in the Caspian Sea. Unless we stop the over-exploitation of beluga sturgeon, it will be a thing of the past."

(July 2004)

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