Arao Tidal Flats are located in Arao City, Kumamoto Prefecture, along the eastern side of the central Ariake Sea. Recognized as an important wetland under the Ramsar Convention, the tidal flats are known for their extensive area, rich biodiversity, and important role in supporting migratory birds and marine life.
The tidal flats cover approximately 1,656 hectares, representing about 40 percent of Japan’s total tidal-flat area according to the original article. Because relatively few rivers flow into this part of the coast, sand and shell fragments carried by tidal currents accumulate along the shoreline. Sandbars have formed near the low-tide line, creating a distinctive coastal landscape.
Compared with many other tidal flats, Arao has a relatively high proportion of sand and shell material and less mud. As a result, the surface is generally less boggy and easier to walk on in suitable conditions. The habitat supports a variety of marine and coastal organisms, including marine worms, shellfish, and small crustaceans.
Arao Tidal Flats are an important stopover and wintering area for migratory birds, particularly shorebirds such as sandpipers and plovers. The birds feed on the abundant organisms living in the tidal sediment and use the wetland as a resting place during their seasonal journeys.
Species recorded in the area include Kentish plovers, Terek sandpipers, and grey plovers. The black-faced spoonbill, a threatened species, is also among the birds associated with the wetland. The Kentish plover is the only bird species that breeds in Arao City and has been selected as the city’s official bird.
In 2008, a spring survey conducted by Japan’s Ministry of the Environment under the Monitoring Sites 1000 shorebird survey recorded 6,492 shorebirds at Arao Tidal Flats. This was the second-highest count nationwide in that survey, demonstrating the site’s importance for migratory birds.
Other threatened or noteworthy species found in the area include the Baikal teal and the Saunders’s gull. Together, these birds underline the importance of conserving the tidal flats and maintaining the habitats on which they depend.
The tidal flats support a rich community of bottom-dwelling organisms. Marine worms and bivalves live in the sediment and feed on abundant organic matter in this environment, which alternates between exposure at low tide and submersion at high tide.
These organisms form an important food source for shorebirds and other wildlife. Their activities also help purify the water, making the tidal-flat ecosystem valuable not only as a habitat but also as part of the natural processes that maintain coastal water quality.
One of the characteristic species of the area is the mud shrimp, known locally as majakku. It is a regional specialty of Arao and is associated with traditional local fishing practices.
The pen shell, another bivalve once abundant in the area, has declined sharply as the coastal environment has changed. Other organisms found on the tidal flats include small crabs such as the fiddler-like chigogani and marine worms such as fusagokai.
The area’s biological diversity reflects the complex relationship between tidal movement, sediment, marine organisms, and the birds that feed on them.
In the past, sandy beaches extended around the Arao tidal-flat area, and Arao’s Second Beach was a popular destination for swimmers. The beach attracted many visitors, and Minami-Arao Station was established in connection with the area’s popularity. Radio broadcasts even provided daily information about beach conditions.
During Japan’s period of rapid economic growth, worsening water quality led to the closure of the bathing beach. Since then, water quality has gradually begun to recover. The area’s history illustrates how coastal environments can be affected by development and pollution, as well as the importance of long-term conservation.
A beautiful pine grove extends for approximately 2.6 kilometers along Arao Coast. The trees form a distinctive landscape beside the sea and provide a scenic area for visitors exploring the shoreline.
Every summer, Arao City also hosts a majakku fishing competition, attracting participants who try their hand at catching the locally prized mud shrimp. The event introduces visitors to a traditional coastal activity and highlights the close relationship between local residents and the tidal-flat environment.
In recent years, declining water quality, red tides, and reductions in marine resources have contributed to falling catches. Local fisheries cooperatives have responded by undertaking restoration projects, including working the tidal-flat sediment and spreading sand to improve the habitat.
Arao City has designated July 3, the date on which the tidal flats were registered under the Ramsar Convention, as Arao Tidal Flats Day. Around this date, the city conducts environmental conservation activities and educational programs to raise awareness of the wetland’s value.
Kumamoto Prefecture also promotes river and coastal cleanup activities through its “Kumamoto Everyone’s River and Sea Development Day” initiative. Residents, fisheries cooperatives, and businesses take part in efforts to help restore and protect the Ariake Sea and Yatsushiro Sea.
These activities reflect the importance of cooperation between local communities, fishing groups, businesses, and public authorities in protecting coastal ecosystems for future generations.
The tidal flats extend across parts of Masunaga, Ichibu, Kuramitsu, and other districts of Arao City, Kumamoto Prefecture. Visitors can also visit the Arao Tidal Flats Waterbird and Wetland Center, located at 20-1 Kuramitsu, Arao City.
The wetland is a place to appreciate the changing coastal scenery and observe the relationship between the tides, birds, and marine life. Because the landscape changes significantly with the tides, visitors should check local conditions before walking onto the flats and follow any conservation guidance provided at the site.
From Minami-Arao Station on the JR Kyushu Kagoshima Main Line, the tidal-flat area is approximately 700 meters away on foot.
By car, it takes approximately 36 minutes to travel about 18 kilometers from the Nankan Interchange on the Kyushu Expressway, using Kumamoto Prefectural Route 29 and National Route 389.
Arao Tidal Flats offer more than an expansive view of the sea. They are a living ecosystem that supports migratory birds, shellfish, crustaceans, and other organisms while contributing to the natural purification of coastal waters.
The site’s history as a former bathing beach, its traditional mud-shrimp fishing, and the continuing efforts to restore and protect the wetland reveal the close connection between nature and the local community. For visitors interested in wildlife, coastal landscapes, and environmental conservation, Arao Tidal Flats provide an opportunity to experience one of Kumamoto’s most important natural environments.