Let's save the Hiari Lagoon (Simplified Edition)  
Fukashi Moriya          


Lagoons are very precious natural sewage facilities. The 40 hectare lagoon estuary at the Isumi River Mouth is equivalent to the Activated Sludge Plant for 10,000 persons and is well worth 5 billion yen. For the past half a century, the natural environment here has been changed considerably. While the lumbers and bumboos were brought from the upper Isumi River, sand and mud accumulated along the lagoonbanks, which resulted in decreasing the water regions of the lagoon estuary zone.
It is inevitable to restore the water regions by removing the lumbers, bumboos and accumulated sand/mud so as to revive the lagoon estuary. By resurrection, fishes, shells, shrimps, benthos, infant eels, etc. will be recovered, which will guarantee the wild birds to breed here for the future.

Hiari-Izumiura Beaches along the Pacific Ocean
100 meters apart on the righthand side lies 40 hectare lagoon area.
Overlooking from the Taitomisaki Cape to the south

[Isumi River Mouth Estuary]

The Isumi River Mouth Estuary mainly consists of 5km sea shoreline and the river mouth lagoon area. The Hiari-Izumiura Beaches are facing to the shallow coral seabed. Off the coast of the Taitomisaki Cape, the warm northbound tidal current of "Black Current" flows.
The Isumi River is the largest river in the Boso Peninsula, Chiba Pref. At the river mouth, there lie two lagoons, actually the remnants of the old Isumi River flowbeds. The total inlet spacing is about 40 hectares.

[Southern Boso National Park]

The 170 kilometers coastline of the Boso Peninsula is designated as the Southern Boso National Park in 1956. The 5km shoreline between the Taitomisaki Cape and the O-hara Hachimanmisaki Cape is called as the Hiari-Izumiura Beaches and located at the northern end of the Southern Boso National Park. The beaches are famous for surfing, body-bording, fishing, sea turtle breeding, wild bird nesting, etc. Fishing boats capture Ise-ebi lobsters, sea breams, bonitos, sardines, etc. off the coast of these beaches.
In parallel to the seashore, there lies the 2 lagoons that the local people call as the Hiari Lagoon (southside of the Isumi River) and the Izumiura Lagoon (northside). The water level of the estuary regions changes 1-1.5 meter every day according to the change of level of sea tide. At these lagoons or inlets, we can find various kind of living creatures, including non-marine fishes , shrimps, shells, infant eels, benthos, etc.

"Dokari" High Waves
Along the coast of Taitomisaki Cape
Hokusai learned from Namino-Ihachi
Astonihsed the Impressionists painters
(Photo Courtesy: MET)

[Natural Beauty and Abundant Biosphere]

We can see various kinds of water birds all the year round. Spot-billed ducks, Anas poecilorhyncha, big herons, Egretta alba, green herons, Ardea cinerea, etc. always stay and breed around the lagoon area. There are two colonies (nesting forests) of large-size herons along the Hiari Lagoon. Sternas, Sterna albifrons, migrate to stay in summer to breed their hatchings. In winter, we can see seagals, Larus schistisagus & Larus crassirostris, float on the surface of nearby rivers and sea.
In the seaside area, beautiful green trees of podocarpus are planted as the green hedge. Camellias also sparsely planted among the podocarpus hedge to enjoy flowers. Both of podocarpus and camellias can withstand and bear against salty typhoon winds and fires.

Ihachi's Wave Sculpture at Gyouganji Temple
Hokusai realized Ihachi's genius and ingenious composition

["Dokari" High Waves]

The shoreline of the Hiari-Izumiura Beaches is well known as a good surfing spot. The sea off the Taitomisaki Cape is very shallow (20 meters depth off the coast of 20 kilometers) and riches in rocks, the waves are high and large like in coral reef. The high waves here are very famous among the surfers, being widely-known as "Dokari", which means a big hit or stroke.
The famous sculputor "Namino-Ihachi" in the Edo Era sculptured Nine Waves for the Gyouganji Temple, Isumi Town. After seeing the Ihachi's wave sculpture, Katsushika Hokusai utilized the deformational wave to his famous woodblock print of "Kanagawaoki Namiura". Ihachi's ingenuity can be seen as the fire balls float on the surface of sea. In Buddhism, the fire ball means "Nothing" or "Vacancy", the essence of Buddhahood.

[Geography of the Hiari Lagoon Estuary]

The geography of the Hiari-Izumiura Beaches are shown on the map below. There are the JNR Sotobo Line and the Route 128 Road run in parallel to the seashore. On the sea, 150 meters apart from the seashore, there are 17 wave breaker tetrapods installed, while the O-hara Harbour is located near to the Ohara-Hachimanmisaki Cape. In addition, there are 3 rivers, namely the Isumi River, Ebado River and the Shiota River.

Map of the Hiari-Izumiura Beaches

The traffic is convenient. Riding on a spcial express train from the Tokyo Central Station, you can reach at the O-hara Station within 1 hour and 10 minutes.
The climate of the Sotobo region is very mild and warm in winter. Both of the vegetables and seafood are fresh here. Therefore, many people are removing from other places to live here these days.

[Hiari Lagoon]

The core of river mouth estuary of the Isumi River is the Hiari Lagoon. This lagoon or inlet is actually the remnant of the Isumi River. More than half a century ago, the river mouth lied some 2 kilometers southwards compared to the present one. The estuary area of the Hiari Lagoon is about 25 hectares. Combined with 15 hectares of the Izumigata Lagoon, the total lagoon estuary area results in 40 heactares. Both of the Hiari-Izumiura Beaches and the lagoon estuary regions belong to the Southern Boso National Park, as well as the Bird Sanctuary of Chiba Prefecture.
Various kinds of wild birds breed and stay around the lagoon estuary regions. The sea shoreline is just under the East-Asian Australasian Flyway, therefore many migratory seabirds (Shearwater, Puffinus tenuirostris, etc.) fly over the neighbouring coastline.

[Taitomisaki Cape]

The Taitomisaki Cape lies near the mouth of the Isumi River. Above 63 meters sea level high, there is the lighthouse, originally built in 1950. In 1972, the lighthouse building was receded to westward 100 meters, since the cliff was corroded by the high waves of the Pacific Ocean. The view from the Taitomisaki Cape is excellent. Mt. Fuji can be seen on a windy winter morning (150 km apart). The scent of narcissi, Narcissus tazetta , is very fragrant in early spring (January to March).

The Taitomisaki Cape Lighthouse
Mt.Fuji can be seen in winter
Juveniles hatched from the nest
Haches from Aug. to Nov. here

[Northern Limit for the Loggerheads' Breeding]

Loggerhead sea turtles, Caretta caretta, lay eggs at the Hiari-Izumiuira Beaches. The Boso peninsula is the northern limit for the loggerheads to lay eggs in the Northern Pacific Ocean Zone. On average, the adult female loggerheads land 15-25 times in summer season each year along the 5km beaches here. And they lay eggs 10-15 times annually, of which more than 50% the juveniles can hatch. The characteristics of the sea turtles here are, late landing season arrival (June to September), longer hatching period (90-100 days in a cold summer season), late juvenile hatching season (September to November), etc.
Based upon the recent academic study, the juveniles will come back to Japan as grown-up adults, after spending some 25 years at the habitat in Baja Califorinia, Mexico.


Now is the time to save the Hiari Lagoon. As Rachel Carson wrote in her famous admonitory "Silent Spring", when the birds become extinct, neither human beings nor the living creatures on earth can survive anymore.

Fukashi Moriya
E-Mail: jomonjin@happy.email.ne.jp