Kindai University develops a method to find females faster, cutting production costs significantly

Japan's Kindai University changes sturgeons' sexes to female, could lead to cheaper caviar

JAPAN
Tuesday, August 11, 2020, 15:00 (GMT + 9)

A new technique for sturgeon farming developed by Kindai University could greatly benefit Japan’s fledgling caviar industry.

When it comes to gastronomy, Japan has captured the world’s attention with signatures sake and sushi as well as its bold takes on global favorites like whiskey and caviar.

Wait, what? Caviar? Indeed, after several years on domestic gourmet menus, Japanese caviar had its global coming-out party in Hong Kong in 2017 and is now finding shelf space in Taiwan, Singapore, the United States and Canada.

A pair of young Siberian sturgeon are seen in this image provided by Kindai University.

Even with the eradication of black-market trades from illegal fisheries in the early part of this century, the cost of caviar – made from cured sturgeon eggs – remains an expensive delicacy, even though aquaculture has taken the reins of the global supply chain. This is mainly due to the inordinate amount of time it takes to determine which fish are male and which are female.

Sturgeon farms run up high costs by waiting until their fish are about three years old before opening a section of their stomachs to confirm the color and shape of their reproductive glands. The fish are then stitched back up and returned to their tanks, no worse for the wear.

But a new technique developed by Kindai University could pave the way for cheaper caviar production. In December 2019, the university announced that it had successfully turned a batch of artificially incubated sturgeon into females after administering female hormones.

“In Japan, sturgeon meat is almost never sold and the males, which cannot be used to produce caviar, only increase production costs at sturgeon farms,” associate professor Toshinao Ineno of Kindai University’s Aquaculture Research Institute told the Advocate. “If we can get rid of the males from the beginning and we know for sure that all our fish are female, the cost of determining the sex of the fish can be brought down significantly. Identifying the sex of 1,000 sturgeons requires a team of around five people over 30 days. In addition to labor costs, there is also the cost of feed that’s used while the farmers wait until the fish are three years old.

“We estimate that these costs are around 25 percent of overall production costs, but this can be reduced by making all our fish female,” he added.

Four months after their artificial incubation, 150 juvenile Siberian sturgeons were given feed mixed with the hormone estradiol for about six months before their diet was switched back to regular feed. Several were inspected, and all of them contained egg cells.

“The results are extremely promising,” said Ineno. “As well as producing caviar, an all-female batch of sturgeon is advantageous for other reasons. Sturgeons are big fish to rear, which means that we need more water and bigger rearing facilities. This is a significant hurdle to overcome in mass production and another reason why we started looking into all-female batches.”

“Rearing sturgeon is not without challenges, and it’s difficult to produce a stable amount of caviar,” says Moto-o Sakamoto, president of Japan Caviar Inc., a company in Miyazaki that manufactures and sells caviar across Japan. Photo courtesy of Miyazaki Caviar.

“Rearing sturgeon is not without challenges, and it’s difficult to produce a stable amount of caviar,” says Moto-o Sakamoto, president of Japan Caviar Inc., a company in Miyazaki that manufactures and sells caviar across Japan. Photo courtesy of Miyazaki Caviar.

Kindai University started researching sturgeon in 1995 and began selling its own brand of caviar – Kindai Caviar – in 2008. It’s currently rearing 1,500 sturgeons and plans to produce 45 kg of caviar a year over the next 10 years.

“We want to produce caviar to showcase Kindai’s technology and expertise, not profit from sales,” said Ineno. “In order to export caviar abroad, fish farms and caviar factories must be registered under CITES rules but Kindai isn’t yet registered so our goal is to produce caviar for research and sell it within Japan.”

The university is also investigating the possibility of producing all-female batches in other ways.(continue)

Author: Bonnie Waycott / Global Aquaculture Advocate | Read full story here

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