Creating a Marine Forest - Shimabara Ironworks' Thinned Wood Fishing Reef Project - June 2003

Creating a Marine Forest - Shimabara Ironworks' Thinned Wood Fishing Reef Project - June 2003

Shimabara Ironworks is a company based in Shimabara City, Nagasaki Prefecture, that in recent years has been focusing on research and development of artificial fishing reefs that utilize thinned wood. Normally, fishing reefs are made of concrete or steel, but Shimabara Ironworks' efforts are an innovative project that combines forest resources and marine ecosystem restoration.

Thinned wood fishing reefs are structures designed to improve the habitat for fish and shellfish by utilizing thinned wood generated from the development of mountain forests. Usually, the logged timber is used as building materials or raw materials for paper, but some of it may be discarded. By submerging this unused resource in the sea, thinned wood reefs function as a hiding place and spawning ground for fish.

The first unusual aspect of this technology is that it is a biodegradable reef. While concrete reefs remain in the sea for decades or more, thinned wood reefs decompose naturally after a certain period of time, thus having little impact on the marine environment. The decomposition of wood after its function as a fishing reef also contributes to nutrient cycling in the ocean. In addition, thinning as part of forest management allows for effective use of the resources while maintaining the mountain ecosystem. There is also the possibility of long-term fixation of carbon dioxide, which is normally released into the atmosphere, in the ocean in the form of wood.

Furthermore, wood is softer and more porous than concrete, making it easier for seaweed to attach to it. This is expected to provide spawning grounds for fish and shelter for young fish, thereby promoting ecological diversity. In terms of contribution to the fishing industry, the installation of artificial reefs is expected to increase fish catches and create sustainable fishing grounds in the waters around Shimabara. The impact on local fisheries is also expected to be significant, potentially contributing to the realization of sustainable fisheries.

Shimabara Ironworks is working on this initiative in cooperation with local fishermen, and is also considering offering the technology to other regions. In particular, the technology is expected to be used in areas where fish habitats are deteriorating due to overfishing and climate change. Current research is also underway to develop technology to improve the durability of thinned wood by applying a special treatment to it, in an attempt to improve it so that it will last longer and be more adaptable to more fish species than conventional wooden fishing reefs.

This initiative will create a new cycle of life in Shimabara's sea. As a sustainable technology that links the mountains and the sea, the future development of this project is attracting much attention.