Sea of changing tides 1993-2007 Wakayama Kinan Aomori Off Oma Seto Inland Sea

Sea of changing tides 1993-2007 Wakayama Kinan Aomori Off Oma Seto Inland Sea

In the mid-200s, the seas around Japan were quietly changing their appearance. The Japan Meteorological Agency has newly analyzed ship observation data over the past hundred years and found that annual mean sea surface temperatures around Japan have been rising over a wide area, with a particularly marked increase in the central Sea of Japan, and a large increase from autumn to winter. This was a change that overshadowed seasonal cycles, nutrient supply, and even fish migration. In terms of climate policy, it was also a time when international trading of greenhouse gas emission credits expanded and the market became even more real. The sea on the ground and the global system were heating up at the same time. fileciteturn3file0L23-L33 fileciteturn3file0 L51-L62 fileciteturn5file1L60-L68

In the Kinan region of Wakayama Prefecture, the change was first seen in the face of catches. The water temperature at a depth of 100 meters was in the 15°C range until 1993, but reached the 16°C range in 1995 and the 17°C range in 2002 and thereafter, indicating a shift in the tides with a decrease in chub mackerel and an increase in sesame mackerel. In 2005, 80% of the mackerel catch was accounted for by sesame mackerel, bringing to light the reality of regions that were forced to review their unit prices and fishing methods. fileciteturn4file0L13-L27

Looking further north, around Aomori Prefecture, especially in the Tsugaru Straits, the growth of kelp has deteriorated, and rocky shore scorch with no seaweed on the seafloor can be seen. Even off the coast of Oma, as the cold currents recede and warm currents increase, kelp, which has high economic value, has declined, dealing a blow to the local fishing industry. The slightest tilt in the tug-of-war between cold and warm currents is enough to collapse the foundation of seaweed beds and rewrite the way sea urchins, abalone, and even fish live. It is a scene where the memory of the cold sea is slowly fading away. fileciteturn4file0L42-L63

The Seto Inland Sea has also recorded a winter red tide, which was previously rare. The warming trend, combined with stagnant seawater and unbalanced nutrients, causes plankton outbreaks even in winter. The results bounce back as losses in the aquaculture industry, and pose a need to reorient the rudder of local ocean development. fileciteturn4file1L28-L36

In response to these changes, Japan at that time was trying to respond with both technology and institutions. Based on the Law for the Promotion of Nature Restoration, the Ministry of Land, Infrastructure, Transport and Tourism and local governments expanded efforts to restore the connection between the sea and land by restoring wetlands in rivers and ports, restoring riverside forests through meander repair, and restoring tidal flats in Mikawa Bay through effective use of dredged sediments. In the development of cities and harbors, design based on consideration for the ecosystem has been introduced, and urban development that incorporates resource recycling and the use of renewable energy has begun to become the "norm. fileciteturn3file1L17-L25 L35-L41 fileciteturn3file2L21-L33

Adaptation techniques were also sprouting in the northern seas. In Hachinohe City, Aomori Prefecture, an attempt is underway to transport waste heat from waste incineration in special containers and use it to heat seawater at nearby abalone farms. This is an ingenious way to ensure stable temperatures while reducing fuel costs and supporting production in the ever-changing sea. If the temperature of the sea changes, human hands can adjust the temperature to protect the livelihood. Technology became a tool to accompany the time of the sea. fileciteturn5file0L4-L13

Between 1993 and 2007, Japan's oceans slowly shifted their seasonal phases, posing new questions for coastal life. Observation and analysis outlined the changes, institutions provided direction, and on-site technology filled in the gaps. Living in the complex ocean where the Kuroshio and Oyashio meet, we stand in an age when we are finally beginning to put into words the meaning of these subtle fluctuations. fileciteturn3file0L23-L33 fileciteturn3file0 L51-L62