Efforts to clean up the sea have caused an adverse reaction giving the fishing industries in Hyogo, Okayama and Oita prefectures along the Setonai inland seaboard a major headache. The irony being that the sea is too clean for the fish to thrive.
An analysis of the seawater by researchers found the natural levels of nitrogen and phosphorous in the salt content of the water needed for the nutritional growth of healthy plankton have diminished to the point that it has affected the natural ecosystem of the sea. Without enough plankton, the major nutrition for many small sea animals, the whole food chain is disrupted to the point of great loss to the fishing industry.
A reporter at Yomiuri Shimbun spoke with a 38-year-old fisherman in the fishing town of Izumisano near Kansai International Airport after he returned from eight hours of trawl net fishing in the Setonai sea. His face reflected the critical state of his current situation. That day he fished for the usual flatfish and prawns but the numbers in both fish and profit were too low.
Ten years ago he got 70,000-80,000 yen per catch. Today his profit won’t exceed 20,000. With gasoline prices so high, this barely covers the running cost of the boat and there is hardly no profit left over.
The Ministry of Agriculture, Forestry and Fisheries' statistics show that fishery catches after peaking to 460,000 tons in 1982, dropped consistently on a yearly basis until in 2010, when they only reached 175,000 tons. Compared to the 1980s, flatfish catches have decreased by half, small fish catches are 1/6th of what they were, while clam type catches dropped drastically to 1/190th of what they were.
Most fishermen put off repairing boat parts and replacing engine parts, and have to go out to work extra hours at night on part-time jobs to make ends meet. Noboru Matsubayashi, the chairman of one of the major unions of the fishing industry for Osaka, laments that the fishing industry cannot survive at this rate.
Decrease of natural nitrogen by 60%
Fishermen say the reason for this decline in their catch is that the seawater has become too clean for the fish to survive due to lack of sustenance. A spokesman for the Agricultural and Fisheries Technological center said that the depletion of the nutritive value of the salt water is due to the lack of natural nitrogen in the seawater salt.
During the industrial boom era of Japan, laws had to be passed to avoid water contamination from pollution. Still, there was damage from the red tides caused by contaminated seawater in the 1970s. Industrial waste water was strictly regulated as well as the building and maintenance of new water pipe systems. This remedy set the stage for the disappearance of fish in the Setonai sea by 2001. The seawater's natural source of nitrogen and phosphorous started to be depleted.
As a result, a liter of Setonai seawater from 1983 had a nitrogen level of 0.34 mils per gram compared to a liter of water last year with only a 0.14 mils per gram nitrogen level. The visibility of the water in Osaka Bay has increased from an average of 3 meters visibility to 6 meters visibility.
One thing can be said for sure: the diminishing catches of the fishing industry are in direct correlation with waste water regulation.
The seaweed industry has also been affected – especially the seaweed cultivation farms as seaweed absorbs nitrogen from the salt water. Discoloration of seaweed harvests turn the harvests into a sickly yellow color. Another victim of this unsettling phenomenon.
Source: Yomiuri Eco News© RocketNews24