In French Polynesia, an Ancient Conservation Model Is Helping Revive Fisheries

The global ocean faces grave and increasingly intense threats from damaging human activity, including overfishing, pollution, and acidification. To address these challenges the scientific community and a growing number of world leaders point to the need to highly protect at least 30% of each marine habitat to allow them to regenerate and continue to provide the critical ecological benefits, such as oxygen and climate regulation, that support all life on the planet.

Rāhui, a traditional Polynesian conservation practice, offers some promising lessons for restoring ocean health. Rāhui involves banning access to a space, or prohibiting the taking of a natural resource, to promote regeneration for the benefit of an entire community. Historically, throughout the Polynesian triangle—the area between New Zealand, Hawaii, and Easter Island—the practice played a key role in the sustainable resouce management of nature.

Communities would set a rāhui, for example, in part of a lagoon, or throughout a bay or coconut grove, or even for certain species of birds or taro for a certain amount of time. Historically, these periods, which ranged in duration, allowed habitats to regenerate, species to develop to optimal harvesting size, or for popultions to grow beyond typical harvesting levels in anticipation of periods of scarcity or for celebratory events.

The main reason for imposing a rāhui was often political or religious, to assert the authority of a chief over the community. But the emergence of this concept may have also been because of a perceived need by the community to conserve and sustainably use their ecosystems in the face of limited food resources amid realtively high population densities.

Following the arrival of western Europeans in Polynesia, the practice of rāhui gradually disappeared. In the space of a few years, some islands lost up to 80% of their human population, mainly due to diseases transmitted by foreign arrivals. Rāhui, like all traditional practices, has also suffered from cultural erasure caused by Westernization, loss of communal ways of life, and less reliance on natural resources with increased imports. But despite this, rāhui survived as part of the local cultures and traditions.

In the 1980s, on the island of Rapa in the Austral Islands, the arrival of freezers led to the overfishing of coastal fish, as the local fishers began storing their catch for sale off the island. Local leadership responded by creating a rāhui to protect the main bay of the island, on the ancestral model. In an effort to mirror its success in restoring fish populations, the rāhui revival has spread throughout French Polynesia, and many municipalities have gradually re-established protection zones in their lagoons, including Teahupoo, Teva I Uta, Tautira in Tahiti, Ua Huka in the Marquesas Islands, and Tubuai in the Australs.

These recent rāhuis are hybrids: managed by the community while also benefiting from the legal and government protection under environmental or fishing regulations. French Polynesia’s Department of Marine and Mining Resources has also taken up the concept to ensure the protection of certain species of fish, mollusks, and crustaceans by regulating the minimum catch size for these species, and this legal recognition provides an enforcement mechanism.

Because rāhui is firmly rooted in traditional Polynesian culture, most locals understand and accept the practice, which gives it a significant advantage over other modern conservation tools such as marine protected areas and maritime spatial management plans. In fact, a recent survey showed that 90% of the population of French Polynesia wishes to establish a rāhui in each community.

Thanks to these high levels of acceptance and compliance, many recent scientific studies demonstrate significant resulting ecological benefits from rāhuis. The University of Hawaii observed a considerable effect from Rapa's rāhui, with about twice as many fish in the safeguarded area as in the nearby unprotected waters. Ecological monitoring by the Centre for Island Research and Environmental Observatory (CRIOBE), a French research laboratory based in French Polynesia that’s focused on the study of coral reef ecosystems, showed a significant increase in the biomass and quantities of commercially important fish inside the Teahupoo rāhui.

Momentum on rāhui continues to grow. During the One Ocean Summit in February in Brest, France, French Polynesian President Édouard Fritch announced plans to create a 500,000-square-kilometer (193,000 square miles) protection zone called Rāhui Nui, or literally “great rāhui.” This announcement follows a campaign started in 2014 by elected officials from the Austral Islands and supported by the Pew Bertarelli Ocean Legacy Project seeking the creation of a large rāhui in the waters of their archipelago.

As Tuanainai Narii, mayor of Rapa, said, “The creation of a great rāhui for the whole archipelago is vital. It would protect the resources of our island for our people and for future generations. After establishing our coastal rāhui in Rapa, everyone saw its benefits. It makes perfect sense for us to extend this rāhui out to sea.”

Long ago, Polynesians overcame challenges similar to those now facing the entire planet. The knowledge they passed down provides a sophisticated and proven blueprint for the protection, sustainable management, and equitable sharing of marine resources and offers a marine protection model that leaders around the world could follow to benefit people and nature.

Jérôme Petit is a senior manager and Donatien Tanret is an officer with the Pew Bertarelli Ocean Legacy Project.