Environment Aomori Prefecture Tsugaru Strait and Oma Offshore - Seagrass Depletion and Seaweed Shifts, 2000s

Environment Aomori Prefecture Tsugaru Strait and Oma Offshore - Seagrass Depletion and Seaweed Shifts, 2000s

The Tsugaru Strait and offshore Oma in Aomori Prefecture have long been known as a rich fishing ground where cold and warm currents intersect. In the 2000s, however, rising seawater temperatures during the winter months caused a marked deterioration in the growth of kelp, which had previously grown stably, and the phenomenon of "isoyaki," in which little or no seaweed grows on the seafloor, became pronounced. Especially along the coast of the Tsugaru Straits, the seaweed beds that were once the foundation of the kelp fishery have shrunk, and local fishermen have suffered a serious blow.

A similar shift in vegetation has been reported off the coast of Oma, where cold current seaweeds are decreasing and warm current seaweeds are predominant. This is not just a simple change in seaweed species, but also directly affects the habitat environment of high-value-added marine resources such as sea urchins and abalone, and has attracted attention as a problem that affects the entire fishing economy.

In the late 1990s and early 2000s, the Intergovernmental Panel on Climate Change (IPCC) report highlighted the risks of global warming, and in Japan, the Fisheries Agency and the Ministry of the Environment were investigating and warning about the effects of rising water temperatures on fishery resources. In Japan, the Fisheries Agency and the Ministry of the Environment were investigating and warning of rising water temperatures and their impact on fishery resources. The changes in the Tsugaru Straits and off the coast of Oma were treated as symbolic examples of how "even the northern seas are not immune to the effects of global warming" in the context of such global trends.

In terms of related technologies, "seaweed bed creation technology" to artificially regenerate seaweed beds, the use of substrate blocks installed on the seafloor to promote the growth of seaweed, and seafloor cultivation technology to improve seawater circulation, were introduced. These were attempts made in collaboration with local fisheries research institutes and fishery cooperatives, and attracted attention as experimental attempts to stop rocky shores from burning. In addition, the trend of fishermen themselves participating in seaweed bed preservation activities, transplanting seaweed seeds and seedlings, and conducting monitoring surveys was also spreading.

In other words, the isobake phenomenon off the coast of Oma in the Tsugaru Straits was a frontline example of the local impact of climate change, and the very process by which local communities sought "how to coexist with environmental change. As the conventional image of a rich cold-water fishing ground was shaken, the local community began to search for new forms of fishing as a measure to adapt to global warming.