Satoumi in an Okinawan Coral Reef System

2012•08•15 Shinichiro Kakuma Okinawa Prefectural Government, Masahito Kamimura World Wide Fund for Nature

From north to south, the long coastline of Japan cultivates diverse local lifestyles reflecting unique geographic conditions. People live in harmony with the sea by combining their traditional wisdom with scientific knowledge. These coastal areas, where the sea and human beings are intimately connected, are called “satoumi”. This article and video brief are part of a series exploring several variations of satoumi, or can be watched as one 74-minute film.

♦ ♦

Satoumi is defined as marine and coastal landscapes that have been formed and maintained by prolonged interaction between humans and ecosystems. The essential elements of the Okinawan approach to satoumi include “commons” and “local rules”. The former refers to resources that are shared and used by local people. The latter refers to resource use regulations that are autonomously determined by local communities.

Okinawa’s satoumi is also characterized by ino — shallow, calm waters located between the offshore coral reefs where the waves break, and the shore. Since ancient times, the professional fishers have collected their catch in the outer seas, while village residents relied on the fishery resources of the ino inside the reefs as commons and have led a semi-agrarian, semi-fishing reliant lifestyle. This commons-type usage is practised even today, particularly in the outer Okinawan islands. Such is the case in the Shiraho Lagoon on Ishigaki Island in Okinawa’s Yaeyama district.

On the other hand, as many sedentary resources are subject to common fishery rights, members of Fishing Cooperative Associations (FCAs) have the right, in principle, to harvest or capture them. This has greatly complicated the relationship between traditional customs regarding the ino and the fishery rights system.

Legal and management aspects must therefore be considered, in addition to technical issues, for the enhancement of productivity and biodiversity in the ino. For this reason, the local people, who are the most closely involved with the ino, must create local rules and observe them.

Threats to the ecosystem

Some of the anthropogenic influences of greatest impact on the coral reef ecosystems include increased soil runoff, excessive input of nutrients and chemical substances, land reclamation, dredging, illegal harvesting of coral, fisheries, aquaculture, and excessive tourism.

Powerful natural influences include typhoons, massive coral bleaching, predation damage by crown-of-thorns starfish and shellfish, and diseases. Coral bleaching and an increase in the magnitude of typhoons are associated with climate change, and it is also possible that crown-of-thorns starfish outbreaks and the spread of diseases are the indirect impact of human activities.

So-called red soil pollution (akatsuchi osen) is a grave environmental problem in the region. Massive runoff of the red-coloured soil found on Okinawa, Ishigaki and Iriomote Islands has increased due to coastal development, among other reasons including a lack of regulations until 1995 when Okinawa Prefecture instituted the Red Soil Runoff Prevention Ordinance. The red soil does not contain toxic components but damage results from the sheer quantities that flow into coastal waters, silting over the reefs. Even small quantities are sufficient to stress the coral, which secretes mucus in response.

Clouding of seawater by red soil adversely affects the photosynthesis of zooxanthellae, an alga that has a symbiotic relationship with the coral. Furthermore, coral larvae cannot settle to the ocean floor if they are covered in red soil sediment. Red soil pollution affects not only coral, but it also has a direct impact on fisheries and aquaculture.

Another issue is that the growth of Acropora corals was found to be poor in marine areas where there were high concentrations of nutrients. Coral reef ecosystems have adapted to nutrient-poor environments, so the influx of excessive land-based nutrients is a serious problem. Although the direct effects of the nutrient influx on coral reefs are not fully understood, high nutrient conditions are known to favour phytoplankton development, which clouds the water, and the excessive nutrients result in increased macroalgae growth as well. As algae and coral compete with one another, the fast-growing algae propagate, and the coral reefs go into decline.

The growth of the livestock industry in Okinawa increased nutrient loading from the effluent of cattle, pig and other stock farms. In 2004, The Law on Promoting Proper Management and Use of Livestock Excreta was amended to prohibit the open-air storage of manure. Farmers are now obliged to lay down concrete to prevent feces and manure from percolating underground, and to cover such material with a roof or tarpaulin. Enforcement now includes fines of up to ¥500,000 (US$6375).

Deterioration of the coral reefs in Yaeyama district continues, however. Not only did the area suffer from the extensive coral bleaching that occurred worldwide in 1998, it experienced more coral bleaching in 2007 on a scale that surpassed the 1998 levels, with reports that approximately half the coral had died.

Damage caused by major typhoons, the runoff of red soil and excessive nutrients from terrestrial areas also had a significant impact. The predation of corals by crown-of-thorns starfish has recently become the greatest threat.

Catches of several coral reef fish species have decreased by half in the last 15 years, according to Itaru Ota Toshihiro and colleagues in “The State of Fisheries Resources in the Coastal Areas of the Yaeyama Islands” (2007). Catch per unit effort (CPUE) has also fallen and fish resources have diminished. Although over-fishing is probably the main cause, coral reef degradation is also thought to be responsible. For this reason, there is a pressing need for fishery resource management, including in the form of Marine Protected Areas.

While “passive” measures, such as curtailing excessive nutrient input from terrestrial areas and imposing catch limits, are strategic pillars of conservation efforts, they do not suffice, even in the case where a consensus can be built for their significant expansion.

The case of Shiraho village

The village of Shiraho looks out over a 12 km stretch of coral reef. The ino within this reef is a central element of the local community’s culture and livelihood. Local inhabitants consume a wide variety of fishery resources from the ino waters, and festivals and religious rituals are part of what could be described as a coral reef cultural-sphere lifestyle that is intimately connected to the sea.

The historically semi-agrarian, semi-fishing, subsistence lifestyle of the villagers traditionally had a light environmental footprint and the natural environment was sufficiently resilient. Human use of nature’s resources here, therefore, did not significantly infringe on the biodiversity of the reef. Inasmuch as the coastal seas were common village property since the time of the Ryukyu Kingdom (15th to 19th century), and as the local community there developed an intimate and sustainable relationship with the sea, this could well be called satoumi.

The relationship between the people of the village and the sea has weakened, however, due to the modernization that took place after the end of World War II, the reversion of Okinawa to Japan (1972) and the recent assimilation of Okinawa into mainland Japanese culture.

The increased runoff of red soil from construction sites and the influx of household effluents into the sea have increased the burden on the environment from human presence on the island. In environmental monitoring surveys conducted over the 10 years since the World Wide Fund for Nature Japan Coral Reef Conservation and Research Centre was established in the village, fixed monitoring points on Shiraho Reef have revealed that the amount of coral has significantly decreased. For example at one WWF monitoring point the coral coverage decreased from 27.4% (2003) to 6.4% (2008), an impact resulting in decreased biodiversity of the Shiraho ino, once known as “the bountiful seas” (sakana waku umi).

The community’s response

As a response, in 2006, a charter establishing seven basic policies for village development was created at a general meeting of community members held at the Shiraho Community Centre. As one of its basic policies, the Charter advocates “protecting our coral reef environment, which is one of the best in the world, and leading lives that are based on nature”. The entire community has started working to conserve biodiversity and to sustainably manage the resources of the sea directly in front of the village.

This Charter was enacted because it had become difficult to maintain village norms and pass down culture on the strength of oral tradition alone. In addition to passing on traditional culture to the next generation, the Charter also represents a basic stance vis-à-vis local rules. The local community in Shiraho thus positioned itself to maintain and manage the satoumi within the sphere of its regional autonomy, and is using these approaches as a platform for “cultural transmission” and “learning experiences”.

The Shiraho Conservation Council for Bountiful Seas (SCCBS), plays a central role in coral reef conservation and resource regeneration activities conducted by the local community. The coral reefs of Shiraho are viewed as commons. Thus, in addition to fishers and tour guides, residents of the villages, including agricultural and livestock farmers, participate and cooperate in actions to invigorate the region through the conservation and sustainable use of the reef.

The Council has been active since it was established in 2005, and in 2006 developed the “Self-Determined Rules for Coral Reef Tour Guides” and “Dear Visitors to Shiraho…” (a collection of instructions on tourism etiquette). The Council also worked to restore Shiraho’s traditional ishihimi. Ishihimi (stone tidal weirs) are the infrastructure of an ancient fishing method where rocks are piled up in walls on the shore or in shallow areas of the coral reef in order to use the tides to catch fish. Replaced by more efficient net fishing techniques, this method had almost sunk into obscurity.

Recently, however, the technique has been reconsidered for its value for environmental education and interest to tourists, and thus a movement has emerged to revive this method. Ishihimi do not merely function as infrastructure; they also enhance biodiversity as the crevices of the piled up rocks create habitats for a variety of organisms. The algae that grow densely on the rocks attract sea life that feeds on it, which in turn causes fish species to increase in the area. A study conducted by WWF Japan confirmed that in the ishihimi areas, shellfish and fish species have increased. For example, Mollusca increased from 18 species to about 45 species in the first 2 years following ishihimi construction.

The Council also launched a program in 2007 for planting shell flower (getto, a species of ginger; Alpinia speciosa) around fields as a means of preventing red soil from flowing into the sea. A local women’s group has since developed a new product made from this getto. The product, named “sarmin”, is a floral water spray for room fragrance. This project is expected to increase farmers’ participation in community-led conservation and part of the proceeds will be used for coral reef conservation in Shiraho.

In 2009, the Council embarked on a stock enhancement project, restocking 7,000 giant clam juveniles cultured in a hatchery. A survey conducted one year later revealed that the average survival rate was 43 percent, indicating that the project could be considered a successful first attempt. The aim of restocking the clams is not to harvest them, but to increase the resources of the surrounding area while also providing a new attraction for snorkeling ecotourists. The clams will be protected and nurtured for approximately four years, so that they will spawn. This is one example of increasing productivity through human interaction.

The Shiraho community has plans to set up a nonprofit organization that will focus on sustainable coral reef management for improving the livelihoods in Shiraho community as well as ecotourism development. The organization will be staffed by local young coordinators. SCCBS is also developing a new lecture programme about coral reefs with a member of the fishery cooperative.

Future perspectives

Stone fishing weirs are found outside Japan, including in Taiwan, South Korea, the Philippines, France, Spain and Micronesia. Reflecting this, the World Ishihimi Summit was held in Shiraho in October 2010. There is wide consensus that coral reef ecosystem conservation is vital for many coastal communities around the world, and is a critical aspect of global marine biodiversity preservation as well. There is, however, considerable debate on the best way to achieve this, with one view being that natural wilderness environments, should be protected from all human impact for the protection of biodiversity.

In many cases, this would deprive local communities of essential ecosystem services and, often, of their very livelihood, and would therefore not be a realistic policy option. It is thus essential to enhance the knowledge base available to conservationists and coastal managers in charge of managing biodiversity; and to balance the conservation and the sustainable use of the resources in such areas where human interaction with the ecosystem must remain significant for the foreseeable future.

The satoumi experiences such as those discussed here, although still works in progress, illustrate a number of good practices for managing biodiversity in reef ecosystems under significant anthropogenic influence. It is hoped that they may be of use for the management of similar ecosystems around the world.


This article is an abbreviated version of the paper: Kakuma S. and M. Kamimura. 2011. “Okinawa: Effective conservation practices from satoumi in a coral reef ecosystem” in Biological and Cultural Diversity in Coastal Communities: Exploring the Potential of Satoumi for Implementing the Ecosystem Approach in the Japanese Archipelago. Secretariat of the Convention on Biological Diversity Technical Series No. 61. 86-93.

Creative Commons License
Satoumi in an Okinawan coral reef system by Shinichiro Kakuma is licensed under a Creative Commons Attribution-NoDerivs 3.0 Unported License.


Shinichiro Kakuma

Vice DirectorOkinawa Prefectural Government

Shinichiro Kakuma is Vice Director of the Fisheries Extension Center, Okinawa Prefectural Government. He graduated from the Tokyo University of Fisheries and holds a Ph.D. from the Tokyo Institute of Technology. His current research interests are satoumi, Marine Protected Areas and fisheries co-management.