Sep 26 (NHK) - Data show that rising sea temperatures around Japan have significantly affected the country's fishing industry.
Catches of saury, squid and other sea creatures have been substantially falling in recent years.
According to the Japan Meteorological Agency, the sea surface temperatures have risen by more than one degree Celsius over roughly a century through 2018.
The rate is higher than the global average over the same period.
The Japan Fisheries and Education Agency says a change of just one degree can be enough to force some species to leave their traditional fishing grounds.
One example is Pacific saury, which Japanese eat in autumn. The fish live in the Northern Pacific and start moving south from off Hokkaido to Ibaraki in August, when sea temperatures in the areas are around 10 to 15 degrees.
The arrival of the fish creates a saury season for fishers in coastal regions. But their catches have been falling in recent years.
The agency compared data for 2009, a good catch year, and 2016, when the catch was poor.
In 2016, the temperature off eastern Hokkaido in late August rose close to 20 degrees. That month, Hokkaido had a saury catch of 4,300 tons -- down10 percent from 2009.
In October 2016, Miyagi Prefecture, to the south, had a catch of 12,000 tons -- barely half that of 2009.
Rising sea temperatures may also be affecting the season for Japanese squid in the Sea of Japan.
In the 1980s, fishers in the Hokuriku region on the Sea of Japan caught squid between May and October. But since around 2000, the season has been shorter -- from May to June.
The agency says a recent rise in sea temperatures off the coast of Hokuriku may have kept squid away.
Fukui Prefecture in Hokuriku has seen its annual squid catch fall from around 2,000 to 4,000 tons through the 1990s to just over 1,000 tons in the 2000s. Last year, Fukui's annual catch was down to 165 tons.
Hideaki Kidokoro of the agency says growing competition from foreign fishing ships as well as a decline in squid stocks may also be blamed for the falling catch.
But he says fish and other sea creatures tend to look for water temperatures favorable to their survival.
He warns that a further rise in sea temperatures could have a wide range of effects on Japanese eating habits.
