Marine Forests Recovered from Denudation following Efforts Led by Fishermen Exterminating sea urchin

(7) State of the marine environment

Concerns are growing over the effects of global warming. At the G8 Hokkaido Toyako Summit in 2008, Japan agreed to consider and work towards the adoption of a goal to cut global emissions of greenhouse gases by at least a half of current levels by 2050, under the Framework Convention on Climate Change.

Long-Term Trends in Average Sea Surface Temperatures in Seas off Japan (Annual Average) ( $ ^{\circ} $ C/100 years)

The annual average seawater temperatures in waters around Japan—in Kyushu and Okinawa waters, the central and southern Sea of Japan, and waters south of Japan—are rising at a rate of $ 0.7-1.7^{\circ} $ C every 100 years. This is 1.4 to 3.4 times the rate of annual average sea surface temperature rise of $ 0.5^{\circ} $ C for all seas.

The rise in water temperatures may not be attributed solely to global warming since the waters in question are small in area and thus are prone to be influenced by natural fluctuations. Nevertheless, it is a fact that the rise in sea surface temperatures in waters around Japan exceeds the world average.

Source: “2008 Marine Health Examination—Long-Term Trends in Sea Surface Temperatures (in Seas off Japan),” Japan Meteorological Agency

○ Development of an optimal laver management method was promoted in response to laver color-fading damage.

In March 2008, three vessels collided offshore near Kobe City in an accident that caused one freighter to sink. Ways to remove oil from the ship were studied and educational activities for the prevention of oil pollution accidents were promoted.

O Ways to deal with the sources and disposal of drifting trash and driftwood, including those from overseas, were studied.

The Japanese government finalized the “Guidelines for countermeasures against rocky-shore denudation,” identifying causes of rocky-shore denudation and summarizing concrete countermeasures. Seaweed substrates were installed and underwater plant beds were created. Conservation activities led by fishermen were conducted.

Disappearance of seaweed from rocky-shore denudation (Kuroshio Town, Kochi Prefecture)

Monitoring after sea urchin culling

Recovery from rocky-shore denudation

Source: “Guidelines against rocky-shore denudation,” Kochi Prefecture

☐ Damage was done to fisheries by giant jellyfish which emerged in coastal waters in the Sea of Japan, off the coast of Sanriku, etc. The government took advantage of the relevant funds to conduct surveys and provide information on the emergence of such jellyfish, and implement control measures on the sea.

Feeding damage to clams and fan-mussels by longheaded eagle rays, and damage to fishing equipment and feeding damage to catch, etc., by steller sea lions occurred. Measures were implemented to prevent and mitigate such damage to fisheries.

Damage to fisheries by river cormorants preying on ayu (sweetfish), Japanese dace, etc., became an issue. The “Act on Special Measures for the Prevention of Wildlife Damage” came into effect in February 2008. Measures such as mass repelling and extermination of river cormorants’ nests were implemented, depending on the local situation.

Epidemic prevention technology against ayu (sweetfish) coldwater disease and koi herpesvirus disease were developed.