A new study has found that climate change is significantly contributing to the decline of Japanese chum salmon, as warming oceans and changing marine conditions reduce the availability of suitable habitats for the species.
The research, conducted by scientists at Hokkaido University, highlights how environmental changes in the North Pacific over the past 25 years have disrupted the natural migratory patterns and survival of chum salmon, known locally in Japan as “shirozake.”
Once a major part of domestic seafood consumption in Japan, chum salmon populations have seen a noticeable drop in recent decades. Today, much of the salmon consumed in the country is imported from nations such as Chile and Norway, reflecting the declining local supply.
The study analysed environmental and marine data collected between 1998 and 2022 to track changes in suitable habitats for the species. Researchers found that rising ocean temperatures, declining zooplankton populations a key food source and increasingly frequent marine heatwaves have all contributed to habitat loss.
According to the findings, suitable habitats for chum salmon have not only shrunk but also shifted geographically. The fish are now moving northward in search of cooler waters, extending toward regions such as the Chukchi Sea, while losing ground in traditional areas like the Gulf of Alaska. This phenomenon, known as a “poleward shift,” is a clear indicator of how climate change is reshaping marine ecosystems.
Scientists warn that this large-scale habitat loss is closely linked to the declining population of Japanese chum salmon. Marine ecosystems are particularly sensitive to climate change, and even small increases in temperature can disrupt food chains, breeding cycles, and migration routes.
The study also raises concerns about the effectiveness of current conservation efforts. Despite extensive hatchery programmes aimed at boosting salmon numbers, researchers say these measures may not be enough to counter the broader environmental changes driven by global warming.
Experts stress that tracking these habitat shifts is critical for developing effective conservation strategies. As ocean conditions continue to evolve, fisheries management systems will need to adapt quickly to protect vulnerable species like chum salmon.
The findings underline a broader global trend, where climate change is increasingly altering species distribution and threatening biodiversity. Scientists caution that without urgent action to address rising temperatures and protect marine ecosystems, the long-term survival of species like Japanese chum salmon could remain at risk.