A science institute in central Japan says it has devised a system to stop eel fraud using cheap DNA testing, as the summer surge in the foodstuff's popularity approaches amid a scarce local catch.

Eel caught locally is much more expensive than imports, due to trade restrictions and the declining numbers available on the market, and in recent years fraud has become a issue. Consumers are rarely able to tell the difference, but advances in DNA testing, which put most of the key technology on a single chip, have made such tests faster and more affordable.

Current DNA sequencing chips incorporate existing technologies such as CMOS sensors, based on the same technology as digital cameras, and prices for sequencing are falling. The cost of sequencing a human-sized genome has fallen into the thousands of dollars since the Human Genome Project was completed in 2003 at a cost of billions.

The slender, snaky fish are often served "kabayaki" style during the summer, cooked in thin slices with a sweet sauce. The traditional dish is thought to help avoid fatigue associated with Japan's hot, humid summer climate, and every year demand surges, increasing the chance of fraud.

"In the past tests had to check each eel individually, which costs 20,000 to 30,000 yen," said Toshihiro Tsuneyoshi, a professor and eel specialist at Shizuoka Institute of Science and Technology, where the test was developed. "This system can drive costs down to 20 or 30 yen per eel."

The Shizuoka Institute of Science and Technology said it can simultaneously test small tissue samples from thousands of eels, greatly reducing the cost and time required for testing. If a non-local eel is found in a batch, more tests will be performed to find the guilty foreigner, but as such cases are currently rare costs should remain low, Tsuneyoshi said. The university used testing equipment from California-based Life Technologies.

He said a similar system can also be used for other pricey foods where consumers can be easily duped, such as pricier cuts of tuna.

For now, concerned connoisseurs will have to rely on tests done by government inspectors, but DNA sequencing capabilities are already starting to appear in pocket-sized devices for other applications.