Environment Isofossilization and Seaweed Change in the Offshore of Oma, Tsugaru Strait, Aomori Prefecture - Marine Environment in the Early 2000s

Environment Isofossilization and Seaweed Change in the Offshore of Oma, Tsugaru Strait, Aomori Prefecture - Marine Environment in the Early 2000s

Around the Tsugaru Straits in Aomori Prefecture, the growth of kelp has deteriorated significantly due to rising sea water temperatures in winter, and the "iso-yaki" phenomenon, in which seaweed does not grow on the seafloor, has become increasingly serious. Similarly, off the coast of Oma, the traditional cold current seaweeds were decreasing and warm current seaweeds were gaining strength, and the impact on the local fishing industry was a major concern. The Tsugaru Straits, where the Kuroshio and Oyashio currents intersect, has long been known as a rich fishing ground, but changes in water temperatures associated with global warming have shaken its foundation.

As background at the time, in the early 2000s, the Intergovernmental Panel on Climate Change (IPCC) issued a series of reports, and interest in the impact of global climate change on marine ecosystems was growing. In Japan, "isoyaki" (rock scorching) has been observed over a wide area from Hokkaido to Kyushu, and has been drawing attention as an environmental problem that causes a decrease in fishery resources and devastation of coastal landscapes. In Aomori Prefecture in particular, seaweed resources such as kelp and wakame seaweed are deeply connected to the local economy and food culture, and their decline was not merely a natural change, but a problem directly related to the survival of the local community.

In response to this situation, researchers and government officials sought countermeasures. They included "seaweed bed creation," in which seaweed is artificially planted, measures to promote its growth by supplying nutrients, and activities to exterminate sea urchins, which cause feeding damage. In addition, the concept of "from forest to sea," in which the supply of nutrients is balanced through the preservation of forests in the watershed in order to improve the environment for seaweed growth, has spread, and an environmental policy that integrates the watershed and the sea area has been formulated.

Fishermen were changing their mindset from traditional resource-dependent fisheries to environmentally friendly fisheries. The area off the coast of Oma is famous for tuna fishing, but the decline of seaweed deprives fish of spawning grounds and hiding places for young fish, which in the long run can affect tuna resources. Environmental conservation in the region is therefore now recognized as an essential foundation for protecting fisheries and livelihoods. The problem of isobake off the coast of Oma in the Tsugaru Strait, Aomori Prefecture, is a microcosm of the "climate change and local resources" that Japanese society faced in the 2000s, and it became a symbolic example of how to reexamine the connection between nature and human life.