Nearly 90 percent of fishermen who mainly make their living off the Ariake Sea think the Isahaya Bay land reclamation project is the cause of their poor catch, according to a survey by a fishermen’s association.
The survey of 161 fishermen showed that 89 percent of the respondents believe the government project to fill in part of the bay to create farmland and a reservoir has led to the poor sea harvest in recent years, the association told a symposium in Tokyo over the weekend.
The 700-strong association includes fishermen in Fukuoka, Saga, Nagasaki and Kumamoto prefectures.
Asked to give multiple replies on what they think are the reasons behind the dwindling fish catch, 144 of the pollees pointed to the Isahaya Bay project.
The contentious government project includes a 7-km-long dike whose floodgates were closed in 1997 to keep out seawater while land reclamation work went ahead.
Isahaya Bay is part of the Ariake Sea, a nearly landlocked body of water encircled by Nagasaki, Kumamoto, Saga and Fukuoka prefectures.
The survey also found that 34 percent of the respondents blamed the reduced fish catch on the movable dam built across the Chikugo River, which flows into the Ariake Sea, and 20 percent faulted the acid used by seaweed growers to prevent algae from sticking to cultured nori.
According to the group’s catch indicator, the volume has declined since the dike gates were closed in 1997.
The index for the average catch was around 133 in the 1980s against the base of 100 for 1997. Between 1990 and 1996, it had fallen to around 110. Since 1998, the index has fallen to around 62.
Many respondents also said the speed of the currents, which is believed to have affected water quality, subsided between 1997 and 1999. On average, they said, the speed fell by around 25 percent from previous years.
The Kyushu Agricultural Administration Office said it plans to compile a report soon that maintains that closing the floodgates affects only the currents of Isahaya Bay and has little impact on the Ariake Sea.
However, the report will not offer conclusions on the relationship between the closing of the dike and the reddening of the waters, as well as the decline in living creatures such as clams, saying further research is necessary.
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