Kyushu Island, the third-largest of Japan’s four main islands, is composed of a complex system of volcanic ranges. Mount Aso, one of the world's largest, squats in its centre, and more widespread tectonic activity is evidenced by the hot springs that puncture the island’s mantle throughout. At Kyushu’s edges, crystalline schist drops to the ocean below. The island’s inhabitants have a long working relationship with the sea. Here, a couple carry their fishing rods as they make their way across the craggy coast, as seen from Oshima Bridge, Saikai.
At TASAKI’s pearl farms on the frayed west coast of the island, oysters are raised in floating rafts in the shallow water of the seas of Kujukushima. TASAKI is conducting research into Akoya oysters at the genetic level to produce the strongest oysters. When the young oysters, or “spats”, have grown large enough, they are placed in floating rafts out at sea. The spats are moved to baskets with a wider weave as they grow, allowing too-small spats to slip through the mesh and ensuring only the largest and healthiest remain in the nets.
Pearls were first described in writing by a Chinese historian in 2,206 BCE. Unique among precious gems in that they issue from the sea rather than the bedrock, pearls have accrued a train of symbolic associations and metaphoric parallels. Variously, they are aligned with the moon, the month of June, tears, the goddess Venus, and heaven, in both Christian and Islamic scripture.
John Steinbeck’s 20th-century parable, The Pearl (1947), was inspired by a Mexican folk tale and follows a poor diver who finds an immense pearl of enormous value. The find has a cosmic dimension due to the rarity and plunder involved in wild pearl hunting, in which three tonnes of oysters can be opened and killed to yield one or two gems. As Steinbeck writes, “The pearls were accidents, and the finding of one was luck, a little pat on the back by God or the gods or both.”
Farmed pearls negate the loss of mollusc life and produce pearls of incredible quality. When the oysters have reached full size, technicians add the nucleus to the live oyster that will produce the pearl. Working rapidly, the worker addresses a tray of about 30 oysters, taking each, rapping it on a table so that it opens, and making a small incision in the oyster’s body using a scalpel. A device called an inserter is used to implant the nucleus, as well as a pre-prepared piece of mantle epithelium – a fragment of the oyster’s tissue that secretes a matrix on which calcium carbonate crystals grow – which is also inserted to adhere to the nuclei. A few weeks before, the oysters had been placed in a special basket, where their oxygen intake and feed were limited to gradually slow their activity and put them into a deep sleep. Inserting nuclei into active oysters can shock them and lead to a rapid decline in their bioactivity, resulting in death or expulsion of the nucleus. A chute runs down on the worker’s left-hand side into a bucket of seawater. The farmed pearl still carries its sense of divine significance, being a miracle of organic engineering.
Implanted oysters are laid out in cultivation baskets hung from rope rafts in a gridwork pattern in the okidashi (offshoring) process. In summer, the water temperature can climb higher than 30 degrees Celsius, so the oysters are moved to deeper, colder water at the end of the rainy season, and returned to shallower depths in September.
In December and January, the oysters’ activity level slows as the water temperature cools. This means that the oysters cease to add nacre to the pearl, the organic–inorganic composite material that layers the pearl to produce lustre. During this time, pearls are extracted. Oysters hanging from offshore rope rafts are moved to the extraction site, removed from the net baskets and their pearls taken out individually by hand. The implanted pearl is marked by its uniform sphericality, while natural pearls that may also form are typically smaller and less regular – visible opposite around the oyster’s rim.
These pearls lie waiting in their luminous halls of mother-of-pearl. They will travel across the world to sit on necks and wrists and hang dolorously from earlobes – a fragment of oyster, a drop of the Kujukushima seas, reflecting back the same moon’s watery light, wherever they are. ◉