The Rise of Eco-Friendly Pearl Farming

A family business in Polynesia shows how raising pearls can benefit marine life.

Kamoka Pearl grows Tahitian pearls in French Polynesia in a way that minimizes environmental impact.

When Josh Humbert inspects his farm, he dives into the clear blue waters of a lagoon, on a picture-perfect island that is fringed with palm trees. Humbert is the manager and owner of Kamoka Pearl, a boutique family business on the French Polynesian atoll of Ahe that is trying to shake up the international pearl market by raising pearls more sustainably.

"It's like another planet," Humbert told National Geographic about Ahe, an atoll that sits just a few feet above sea level, about 300 miles (480 kilometers) northeast of Tahiti in the Tuamotu Archipelago. "There's no dirt, it's just sand and coral, so the bottoms of your bare feet don't even get dirty."

Kamoka Pearl was founded in 1990 by Humbert's father and brother. A year later, halfway through college (where he studied marine biology), Josh Humbert joined the family business, which raises high-quality "Tahitian pearls" for the international jewelry market.

Humbert had spent part of his childhood growing up in French Polynesia with his family, under a roof of palm leaves near the ocean. He returned to Polynesia as an adult, although he moved back to the U.S. three years ago, to Oregon. His father, who is French, stays at the farm year-round. Humbert's mother is American.

How Pearl Farming Works

To raise pearls, Kamoka cultivates a native species of pearl oyster, Pinctada margaritifera. The oysters are placed in baskets or nets to protect them from predators, which include triggerfish, sea turtles, and eagle rays. Made out of plastic, those baskets or nets are hung vertically every three feet (one meter) on horizontal lines that range from 330 yards (300 meters) to 1.3 miles (2 kilometers).

The end of the line is anchored with a concrete block at the bottom of the lagoon, 100 to 200 feet (30 to 60 meters) down, or it is tied to a coral formation on the bottom. Vertical stabilizers are placed along the line, and buoys are interspersed to help hold the oysters at a depth of around 20 feet (6 meters).

The next step involves seeding the oyster to produce a pearl. An oyster makes pearls on its own by secreting nacre, or mother of pearl, around an irritant that gets into its shell. Contrary to popular belief, according to Humbert, that irritant is most often an invading worm that bored in, not a grain of sand.

In the case of Tahitian oysters, the pearls are often colorful—sometimes even black—due to the specific chemistry of the species.

At oyster farms, when the mollusks are large enough, a worker carefully pries open the shell and inserts a small nucleus, or bead, as well as a piece of mantle cut from another pearl oyster. That process is called grafting, and the bit of mantle helps the oyster start laying down nacre, explained Humbert.

Kamoka uses beads that have been cut from the mother of pearl in dead oyster shells, to a size of six to eight millimeters in diameter. Not every bead starts becoming a pearl, but those that do stretch out the oyster tissue around it, forming a small cavity.

To obtain another, larger pearl in the same oyster, farmers often take out the small pearl and replace it with a larger bead. In another two to three years, if all goes well, that bead will get covered with nacre, to form a large, shiny pearl.

After that pearl is harvested, the oyster is usually "sacrificed" because it is unlikely to produce another pearl so shiny. The meat may be consumed locally, although there isn't an international market for the flesh of pearl oyster species. To replace the lost oysters, farmers usually collect spat, or larva, from the lagoon where they work.

In addition to the skilled labor that grafting requires, since 2003 Kamoka has also hired a revolving cast of young people from around the world, who come to work as part of the World Wide Opportunities on Organic Farms (WWOOF) program. Participants receive free room and board, as well as a chance to learn the trade, in exchange for their labor.

"We are kind of the ocean's version of organic farming," said Humbert.