Sea Warming Hits Japan's Fisheries
By Suvendrini Kakuchi
31 January, 2006
Inter Press ServiceTOKYO, Jan 31 (IPS) - Japan, a voracious consumer of marine resources, is now discovering that the drastic depletion of its own fish stocks is linked to the loss of underwater seaweed colonies -- caused, in turn, by rising sea temperatures.
''It's no exaggeration to say that Japan faces a critical situation when describing the rapid decline of marine supply in its domestic waters that is linked to seaweed loss. Tengusa (seaweed) provides food for marine species,'' says Tomohiro Takase, head of the fisheries department at the Hachijojima municipality.
Hachijojima island, situated 300 miles (482 km) south of Tokyo, is now reporting the drastic decline of abalone, a marine resource that fetched high prices and provided a lucrative income for fishermen living on the island.
Takase says regular catches of around 20 tons per year have now dropped to less than one ton, leaving fishermen to face a gloomy future.
''The situation is alarming. Investigations have shown widespread seabed desertification or the surf burnout phenomenon, across Japan. In Hachijojima the loss of tengusa covers most of the waters surrounding the island,'' explained Takase.
Currently, scientists are working on finding the exact cause of seaweed depletion. A project covering Hachojijima, supported by the Tokyo prefecture government and now in its final stages, is expected to identify causes and point to scientific solutions by 2008.
Studies undertaken up to now, Takase says, have discovered that higher underwater temperatures may have led to the death of seaweed. In the past five years, very little tengusa has been harvested in Hachojijima that once had lush algae growth on its sea rocks.
But warming of sea temperatures is only one culprit. Fish and marine species such as sea urchins are voracious eaters of seaweed, which is also an important part of the national diet.
There is also a theory that coastal development has led to the flow of various toxic effluents into the sea, changing the level and contents of nutrients in the shallow waters. Under investigation also is the possibility that higher nitrate concentrations could be distorting the ecosystem and causing algae death.
The fisheries agency has now started providing subsidies to protect the seabed and funds a research project where iron and steel slag and wood chips are buried in coastal areas in Hokkaido to increase levels of ferrous iron that could encourage seaweed growth.
Five years ago, scientists in New Zealand led international research in the remote southern oceans which proved that it was possible to artificially initiate the growth of algae and seaweed by dissolving iron in the sea.
But the thrust of the New Zealand-led Southern Ocean Iron Release Experiment (SOIREE) was on promoting algae growth as a sink for carbon dioxide and other greenhouse gases (GHGs) believed responsible for the global warming phenomenon.
Other means to stop the rapid loss of seaweed beds being explored in Japan includes removal of sea urchins and other creatures that devour the algae. According to the ministry, between 6,000 and 10,000 hectares of seaweed beds have been lost in the past 10 years.
Professor Yoshiaki Masuda, a scientist formerly at Kagoshima University and now working with 'Build A Forest in the Sea', a non-profit organisation, says his investigations have shown that temperatures in some coastal areas have risen by two to three degrees.
The famed women divers of Nagasaki prefecture, southern Japan, now no longer harvest abalone as a livelihood. Here, Masuda is helping local farmers to grow seaweed in a project where seedlings are dropped into the ocean. The project covers 1,600 metres of ocean bed.
''The project is long-term but it is the only way to save Japan's marine life -- regrowing seaweed,'' he said.
Masuda's group has begun working with local fishermen to grow seaweed by conducting workshops to teach how preservation of the ecosystem is important to protect their livelihoods.
Hirohisa Saito, a member of Masuda's group, who calls himself an eco-conscious citizen, says, the import of foreign and cheap seaweed has also contributed to the death of the local market.
''The government ignored the situation by providing the public with cheap seaweed. But that is no solution -- which is why I joined this grassroot movement to restore our marine supply,'' he said.
Konbu, (agar agar)a frilly brown-coloured seaweed, mostly growing on rocks, is used widely in Japan not only as a food but also as an ingredient to make jelly, a highly popular diet food in Japan
Konbu is widely eaten in Japan and valued for its mineral content, which is believed to be anti-carcinogenic. Saito is now working on promoting the seaweed with pharmaceutical companies as a means of getting financial backing to grow the algae in Japanese waters.
''Japan's relentless march towards building a competitive market has been based on using the sea for economic development. Now with the huge loss of marine life, we are discovering the sea is not a free gift,'' Masuda said.
