Photo/IllutrationArtificially developed elvers for farming tests (Provided by the Japan Fisheries Research and Education Agency)

With dwindling catches of young eels threatening a summer delicacy in Japan, a complete cycle of culturing eels in captivity is nearing a commercial application that could help keep the pricey fish on the dinner table.

In the cycle, juvenile eels artificially developed from eggs are being distributed to private fish farmers. The announcement came on July 18 amid dwindling catches of young eels, also known as elvers.

In the complete farming cycle, elvers are first raised to adult eels so they can lay eggs. Larvae artificially hatched from the eggs are called leptocephali and then grown to elvers again.

The Fisheries Research Agency, the predecessor of the Japan Fisheries Research and Education Agency (FRA), in 2010 accomplished the complete cycle of culturing eels for the first time in the world.

Artificial incubation is currently carried out at the Research Center for Self-Sustained Eel Culture of the FRA’s National Research Institute of Aquaculture in Kagoshima Prefecture, resulting in an improved hatch rate and enabling 1,500 larvae to be produced annually.

The most difficult process under the method is raising larvae to elvers, so the biggest challenge is improving their survival rate during the process.

To put the technology to commercial use, it is also important whether artificially developed elvers can be raised to adulthood in farming pools just as in ordinary culturing methods where caught juvenile eels are raised in pools.

As the research center does not have a farming pool itself, it decided to distribute a total of 300 elvers to two private farming companies.

The elvers will be raised in their farming pools under different conditions until they grow enough to be shipped, so that researchers can examine whether the usual one-and-a-half-year culturing period will be the same for artificially hatched eels and whether unexpected problems will be reported.

“Through the commercial farmers’ pool cultivation processes, we will see what kind of challenges remain in connection with eels’ food, the farming environment and other factors,” said Keisuke Yamano, 54, director of the center.