Best use of Isahaya Bay

In November 2006, fishermen from Nagasaki, Saga, Fukuoka and Kumamoto prefectures around Ariake Sea filed a lawsuit, demanding removal of the dike in Isahaya Bay in Nagasaki Prefecture or at least the opening of the dike’s gates. They said dike construction had caused their fish catch to dwindle.

The dike was constructed far inside the bay, whose mouth opens to Ariake Sea. The dike’s gates were closed in 1997 to reclaim land for agriculture and create a freshwater pond. The land reclamation project was completed in November 2007. At a cost of ¥253.3 billion, it created 672 hectares of agricultural land and a fresh water pond of 2,600 hectares.

In June 2008, the Saga District Court ruled in favor of the plaintiffs, ordering the government to open the gates north and south of the 7-km-long dike for five years.

On Monday the Fukuoka High Court upheld the earlier ruling, ordering the government to open the dike for five years after three years’ preparatory work of building an alternative disaster prevention facility.

In April a government panel had proposed opening the dike’s gates to study the impact of the dike’s construction on the environment. The ruling apparently had an effect. The farm ministry has decided to open the gates but in a different manner from the ruling.

The high court ruled that the closing of the gates violated the plaintiffs’ right to engage in fishing. It said there is a strong possibility that the closing of the dike’s gates caused a decrease both in the tidal range and in the speed of sea currents, which led to a reduction in the amount of oxygen in sea water, thus affecting fish catch near the mouth of Isahaya Bay. It called for opening the gates for five years since a new method to protect the local fisheries may be found.

Farmers in the Isahaya Bay area fear damage from salt. But the ruling said the government has not proved that such damage will occur. The government is urged to proceed with opening the gates while taking necessary steps to prevent possible salt damage to farmland.