Japan and Bahrain will jointly study pearl oysters in the Persian Gulf in a bid to revive the region's pearl tradition, which has not thrived since the early 20th century, Japanese researchers said Tuesday.

Starting in mid-May, the Japanese researchers, including some from the government-linked Fisheries Research Agency, will examine up to 30,000 "akoya" pearl oysters and other species taken from 10 to 25 meters beneath the surface about 30 to 40 km off Bahrain, they said.

The Bahrain government will fund the study into the factors behind a recent dropoff in natural pearls. Suspected culprits include deteriorating water quality triggered by the island nation's economic development and depredation by rays.