The sea is too clean for the fish! 

Efforts to clean up the sea have caused an adverse reaction giving the fishing Industries in Hyogo, Okayama, and Oita Prefectures along the Setonai Seaboard a major headache.  The irony being that the sea is too clean for the fish to thrive.

An analysis of the sea water by researchers found the natural levels of Nitrogen and phosphorous in the salt content of the sea water needed for the nutritional growth of healthy plankton have diminished to the point that it has effected the natural eco system 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.

■ Fishing profits have shown substantial decline. 

A reporter at Yomiuri Shinbun spoke with a 38-year-old fisherman in the fishing town of Izumisano Harbor near the 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.

10 years ago he got 70,000-80,000 yen (US $880-$1150) per catch,  today his profit won’t exceed 20,000 ($255).  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 Fishing’s statistics show the fishery catches after peaking to 460 thousand tons in 1982, dropped consistently on a yearly basis till in 2010 they only reached 175 thousand tons.  Compared to in the 1980’s, 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.  Mr. 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.

■ A decrease of natural nitrogen by 60%

Fishermen say the reason for this decline in their catch is that the sea water has become too clean for the fish to survive due to lack of sustenance.  The director of the Agricultural and Fisheries Technological center, Mr. Handa, says 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 sea water in the seventies. Industrial waste water was strictly regulated as well as the building and maintenance of new water pipe systems.  This remedy set into place in the seventies set the stage for the disappearance of fish in the Setonai sea by 2001.  The sea waters natural source of nitrogen and phosphorous started to be depleted.

As a result, a liter of Setonai sea water 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  is in direct correlation with waste water regulation.

The seaweed industry has also been effected – 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