July 29, 2022

Fishermen’s Forest links land and sea resources



Members of fisheries cooperatives and forestry associations, along with local children, participate in tree-planting in the mountains. | COURTESY: MUTSU CITY

Minerals from lush mountain forests find their way into rivers and then flow into the sea. In recent years, a group of fishermen in the Aomori city of Mutsu have been trying to sustain this healthy cycle linking land and sea resources by planting trees in their neighboring mountains. They call their project Fishermen’s Forest.

Mutsu, in the northernmost part of Honshu, has been known for its sea cucumbers and abundant fisheries since the Edo Period (1603–1868). These days, scallop farming is also popular. It was about 20 years ago that a group of local fishermen began a program of tree-planting in the area. Central to that group was Shigeru Nihonyanagi, of the Mutsu City Wakinozawa Agricultural Promotion Corp.

“Scallops feed on phytoplankton, and the minerals supplied to the sea are the main determinant in how good they taste once harvested. Around 80% of the area of Mutsu is forested, and as the leaves fall to the ground and rot they are returned to the soil. Rainwater and snowmelt seep into the ground and then the water finds its way back into the sea via rivers. Rich in organic substances and minerals, this water is ultimately the source food for the scallops,” Nihonyanagi explained.

The city of Mutsu in Aomori Prefecture is located on the northernmost part of Honshu. Surrounded by the sea on all sides, it is blessed with rich marine resources such as scallops. | COURTESY: MUTSU CITY

In order to produce nutrient-rich humus that provides minerals for scallops, broad-leaved forests are preferable to coniferous forests. However, during the period of Japan’s high economic growth from the late 1950s to the 1970s, a large number of sugi (cryptomeria) trees, which are easy to use as building material, were planted all over Japan. The coniferous sugi trees grow rapidly, but this makes it hard for other plants to thrive alongside them. Since that time, the seawater has lacked minerals and, with expanded scallop farming also contributing to the problem, scallops became smaller in size. The tree-planting work began in response to this problem.

“It takes a long time to create a forest. The tree-planting that started about 20 years ago was temporarily abandoned, but with seawater temperatures rising recently due to global warming, we are seeing a big impact on the scallops,” Nihonyanagi said. “So it became clear that long-term planning to ensure the supply of minerals from the upper reaches of the mountains was essential, and we restarted the tree-planting in 2018.”

In recent years, there has also been a movement to make compost using the small shellfish that stick to fishing nets when pulling up scallops from the sea, and then use that compost as fertilizer when planting the forests.

The method of aquaculture used in Mutsu is to grow scallops in underwater nets and haul them up once they have grown. | COURTESY: MUTSU CITY

“Once something has been landed in the boats, we’re prohibited from returning it to the sea again. But it wasn’t easy to dispose of that residue, with the cost of incineration being significant,” Nihonyanagi said. “We succeeded in composting the residue by mixing it with livestock manure, and now even farmers are using it.”

In this way, a system for helping the circulation of resources between the mountains and the sea has been created. So how does Nihonyanagi, who has been involved in this work for many years, intend to pass it on to the next generation?

“The trees are all planted at one time every year, and the program is run by the local fishery cooperative and also forestry association, and local children get involved too. The chairman of the fishery cooperative was working on this for 20 years,” he said. “But now the head of the young fishermen’s group within the cooperative is participating too, and so the knowledge is being passed on to the next generation. We humans need to keep doing whatever we can to maintain these rich natural resources.”







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