Photo/Illutration Freshwater pearls cultured in Lake Biwako in Shiga Prefecture (Provided by Shiga Prefecture)

Centuries ago, the poet Kakinomoto no Hitomaro likened a pure white pearl resting at the bottom of a lake to his romantic partner.

His poem, “Omi no umi/ shizuku shiratama shirazushite/ koinikeruyoha/ ima koso masare," is contained in “Manyoshu” (Collection of Ten Thousand Leaves), the oldest existing anthology of Japanese “waka” poems compiled in the eighth century.

The “umi” here refers to Lake Biwako in Shiga Prefecture, and the “shiratama,” which literally translates as “white orb,” denotes a pearl.

It amazes me that natural pearls existed in this freshwater lake back then. Perhaps their exquisite luster reminded the poet of his lady love.

According to Masanari Matsuda, 59, a curator at the Lake Biwa Museum, pearl cultivation began in the lake during the Showa Era (1926-1989), and the undertaking succeeded exactly 90 years ago.

During the Taisho Era (1912-1926), the governor of Shiga Prefecture commissioned pearl cultivation to Kokichi Mikimoto, the founder of an upscale pearl and jewelry boutique chain bearing his name.

Through a process of trial and error, Mikimoto’s specialists experimented with various species of bivalve mollusks.

The exported pearls proved popular in the United States, Switzerland and nations of the Middle East. Production topped 6,000 kilograms in 1970.

“Today, most people--even residents of Shiga Prefecture--don’t know that pearls are still being cultivated here,” Matsuda noted.

The industry was hit hard in the 1980s by the poor growth of mother clams and the emergence of Chinese rivals. Local farmers gave up one after another, until production plummeted to a paltry 10 kilograms.

In recent years, however, improved quality of lake water has brought about a slight uptick. The prefecture’s production goal for next fiscal year is 50 kilograms.

“Ikechogai” (Hyriopsis schlegelii), a freshwater pearl mussel, requires three years to mature. It takes another three years for the pearl to form.

Having a luster unlike that of saltwater pearls, some pearls of Lake Biwako appear orange or purple in hue. For their unique sheen and shape, they are dubbed “the moon’s teardrop.”

Strolling around the Lake Biwa Museum, I saw a pearl farm covered with black platforms on the lake’s surface, beneath which I imagined pearl mussels are patiently waiting for the “white orbs” to grow in a submerged netting.

I wondered if those pearls, so admired by Hitomaro, will someday make a comeback.

--The Asahi Shimbun, March 14

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Vox Populi, Vox Dei is a popular daily column that takes up a wide range of topics, including culture, arts and social trends and developments. Written by veteran Asahi Shimbun writers, the column provides useful perspectives on and insights into contemporary Japan and its culture.