September 14, 2010


Japan's Toyama Bay: Working to Restore the Links between Forests, Rivers, and the Sea

Keywords: Newsletter 

JFS Newsletter No.96 (August 2010)
"Initiatives and Achievements of Local Governments in Japan" (No. 30)

Toyama Bay, a "Natural Fish Tank"

Toyama Bay is a large bay on the east side of the Noto Peninsula, which projects into the Sea of Japan in west-central Japan. Known for its wide variety of fish, Toyama Bay has been dubbed "a natural fish tank," because throughout the year many kinds of kitokito-no fish (meaning "very fresh" in Toyama's local dialect) are caught and then unloaded from ships at bustling fishing ports along the coast of the bay, such as Uozu, Shinminato, and Himi.

The coastal shelf in Toyama Bay is small, and the sea floor drops sharply a short distance from the land, with the deepest parts of the bay being more than 1,200 meters deep. Into the surface seawater of the bay, warm-water fish species are carried by the warm Tsushima current, while in the deep seawater at a depth of over 300 meters coldwater fish species live in the much cooler waters of the Japan Sea (deep seawater) at a temperature of around two degrees Celsius. Thus, Toyama Bay has an environment where both warm- and cold-water marine life can exist, and thus it is a treasure trove of marine resources.

Seventy percent of the total fish catch is comprised of migratory warm- water fish such as tuna and yellowtail, while the rest includes many kinds of deep-water fish and shellfish such as sweet shrimp, benizuwai crab, Japanese ivory shell, firefly squid, and white shrimp. Rare firefly squid and white shrimp are particularly valuable marine resources that are rarely found in areas other than Toyama Bay. Every spring, a large number of the tiny squids come to the coast from waters more than 200 meters deep for spawning. The mysterious pale blue light emitted by the squids in the night sea when they are caught is a common spring sight in Toyama Bay.

Over 400 years ago, a coastal fishery mainly using fixed nets was developed by fishers in Toyama Bay. This type of fixed-net fishery is a fishing method that takes advantage of the typical fish behavior of swimming around obstacles. Fishers select places where fish often pass, considering the season and undersea topography, then set their nets and wait until fish come into the net. In contrast to methods by which whole populations are caught in one swoop, the fixed net fishery has advantages such as not damaging fish and not overly depleting fish populations. Thus, this method is regarded worldwide as a sustainable fishing method that preserves marine resources.

Abnormal Changes in Toyama Bay

Recently, however, unprecedented incidents have been observed in Toyama Bay, which has long been called the sea of fertility. The best time to fish for firefly squid was usually April to May, but now the squids gather along the coast earlier than before. In some years, the squid-fishing season ends by March to April. Furthermore, moon jellyfish, which usually appeared in late summer, can now be start to appear in the spring, causing great harm to the local fishery, because a large amount of them caught in fixed nets damage the nets and reduce the commercial value of other fish. Another problem is the stormy current called "kyucho," a coastal current that strengthens suddenly. Recently, it has occurred more frequently and caused loosening and damage to fixed nets.

Moreover, the biggest concern of coastal areas is the ongoing phenomenon of shrinking in the size of beds of large seaweed and algae species (tangle, sargassum, etc.) that grow in coastal reef rock, to be replaced by calcareous seaweed (shell-like white and hard seaweed), which leads to the equivalent of "desertification" of the sea. Although the causes of this phenomenon, called "isoyake" in Japanese, have not yet been confirmed, possible causes include rising water temperatures due to changes in ocean currents, shortage of nutrients needed for seaweed to grow, and damage to seaweed caused by seaweed-eating species like sea urchins.

This phenomenon is spreading in coastal areas throughout Japan, including Toyama Bay. Seaweed and algae beds serve as spawning grounds, as well as feeding and hiding grounds for young fish; thus, the decline of algae beds has a great impact on the yield of coastal fisheries. Algae beds contribute not only to preserving biodiversity but also to other various environmental benefits, such as purifying water and inhibiting coastal erosion. Therefore, immediate actions against this phenomenon are required.

Collaboration between Fishers and Foresters

"What is happening in the mountains?" asked Hiroyuki Hamazumi, who belongs to the Japan Fisheries Cooperative of Uozu (JF Uozu), when he found the ocean looked obviously different from that of the past and began to worry about mountain conditions. Just above Toyama Bay, the Tateyama mountain range rises steeply to about 3,000 meters, and many rivers flow from there into the bay. It has long been understood that these carry rich nutrients from the mountains, creating favorable feeding grounds and helping various kinds of fish to thrive.

About ten years ago, on the upper reaches of the Jinzu River that flows into Toyama Bay, Hamazumi observed plantation forests that were left without being thinned or managed for many years. This was due to the fact that the Japanese forestry industry has continued to face a variety of problems, such as low timber prices, an aging generation of foresters, and a shortage of successors in forestry. These factors have consequently increased the prevalence of poorly maintained mountain forests. Previously, the relationship between foresters and fishers was not very harmonious, but he says that after witnessing the terrible forest conditions he came to better understand the situation of the foresters. Since then, members of JF Uozu have gradually deepened their ties with foresters through, for example, participation in tree-planting activities arranged by neighboring forestry associations.

Then, however, fuel prices skyrocketed, threatening the survival of the fisheries industry. In July 2008, as many as 200,000 fishing boats suspended operations nationwide. JF Uozu was also forced to follow suit, thinking that suspending operations would be better than consuming fuel to go offshore. They then began to consider whether it would be possible to restore fishing grounds during the suspension of fishing, by using the support of the Japanese Fisheries Agency under its energy saving promotion project (rotation system of suspending fishing activities).

JF Uozu then received a suggestion from the Agriculture, Forestry and Fisheries Section of the city of Uozu to build artificial fish reefs made in part from trimmed cedar wood. Helped by the fact that JF Uozu had steadily built ties with neighboring forestry associations through its participation in tree-planting activities, negotiations quickly reached an agreement, and on August 1, 2008, construction of the artificial fish reefs began. The building block they used was a one-meter cube, weighing about one ton, made using a steel frame and filled with concrete in the lower part, which serves as a weight, with oyster shells in the middle and trimmed wood in the upper part.

Coastal fishers took turns to make the artificial fish reefs while fishing was suspended. Fishers, typically unaccustomed to mountain work, went into the mountains in Muroda, around Uozu, cut down about 120 trees to thin the forest, and then hauled them out by themselves under the guidance of the foresters. They constructed a total of ten artificial fish reefs at the Kyoden Port using the resulting timber, and these were carried about 100 meters offshore by boat and placed in shallow waters two to six meters deep. According to the people involved, this process took about 40 days from start to finish.

In September 2009, about one year after the artificial fish reefs were placed in the water, shipworms and other organisms were found attached to the wood, and small fish were gathering and eating them. Furthermore, shrimps, crabs, lugworms, and other creatures were living between the shells. The approach in which fishers themselves cut trees to thin the forest, haul them out, and construct fish reefs is rare in Japan, so the work of JF Uozu was recognized at the "2010 Stop Climate Change -- One Village, One Action at a Time" convention, where they represented Toyama Prefecture, and won the Judges' Special Award (Award for Connecting the Forest and the Sea).

JFS Articles about the initiatives selected at the "Stop Climate Change -- One Village, One Action at a Time" convention

Students Become "Marine Rescue Party"

Recent studies have found that decreased iron ion concentrations in seawater are one cause of the isoyake phenomenon, as iron ions are an essential element for the growth of phytoplankton and seaweed. Iron ions, bonded with humic substances (fulvic acid and humic acid) contained in humic soil in forests, are typically be supplied in abundance by rivers to the sea. However, the supply of iron ions to the sea has reportedly dropped due to forest decline and other reasons.

In order to demonstrate that iron ions induce the growth of seaweed, JF Uozu began planning activities to scatter balls made from iron powder in the sea. These are made by melting the iron powder contained in disposable body warmers using citric acid, infiltrating it into diatomaceous soil, and then rolling up the soil into balls. On May 13, 2010, JF Uozu staff members took iron powder out of the disposable body warmers collected by local elementary school students and made about 200 iron balls by hand, working with local children. The balls were thrown into the sea from the pier at the Kyoden Port so that the children can periodically observe them. The children, calling themselves the "Marine Rescue Party," say they are looking forward to seeing restoration of the bountiful sea.

Forests, rivers, and the sea are connected to each other and they each play a vital role in the natural cycles. Our predecessors fully understood this mechanism intuitively. Modern generations, however, seem to have left this knowledge behind somewhere along the way. It is important for people to realize that we too are part of natural cycles. We have destroyed forests, rivers and the sea, so we are also responsible for restoring them. It can be said that the efforts in Toyama Bay, though they may appear to be a small step, have created new knowledge to help us leave our precious resources for future generations.

Written by Ichie Tsunoda