Securing a safe passage for salmon

IUCN experts are advising the Japanese on the removal of a series of dams that have hampered wild salmon migration in the Shiretoko World Heritage Site.

One of the dams that has been removed on the Shiretoko Peninsula, Japan to help ease the passage of salmon Photo: Wild Salmon Center

In 2005, the Shiretoko Peninsula became Japan’s newest World Heritage Site, recognized for its unique ecosystems formed by the interaction between marine and terrestrial environments.

The Shiretoko Peninsula is located between the Sea of Okhotsk and the Nemuro Strait at the northeastern tip of Hokkaido Island. Twelve species of freshwater fish have been found in the streams of Shiretoko, with six salmonid species naturally reproducing upstream, including chum, pink, masu, and Dolly Varden char. They are an important food source for aquatic and terrestrial species, and also help support a commercial fishery in the region.

The IUCN Salmonid Specialist Group (SSG) was asked to review the World Heritage nomination proposal submitted by Japan in 2005. SSG Chair, Wild Salmon Center (WSC) staff member Dr Pete Rand, joined WSC Programme Manager Brian Caouette on several trips to Hokkaido to inspect progress on the restoration effort. In their review, the SSG highlighted the need to address the impacts of dams within the site to improve the passage of fish.

As a result of the Group’s recommendations, Japanese officials have implemented several restoration projects. Of the 14 streams that have one or more dam structures, 31 (out of 127) structures in five streams were either removed or modified to ease the movement of fish.

Plans for removal had to take into account the high risk of flooding and erosion in the region. Modifications were only made where there would not be a significant risk to human welfare and livelihoods.

“The removal of any dam structure is a major undertaking, and the successful transition of 31 of the dams in Shiretoko is testament to the diligence and hard work of our Japanese partners,” says Dr Rand.

Since the implementation of the projects, SSG member Dr Masahide Kaeriyama has led an effort to monitor the sites. His results show that they have succeeded in restoring the run of salmonids upstream in the Rusha River, one of the most productive salmon rivers on the peninsula. While returns upriver are still relatively low, the restoration work will continue as progress is made to reach an ambitious conservation target in the coming years.

The Salmonid Specialist Group of IUCN’s Species Survival Commission includes as its members fisheries scientists and managers dedicated to protecting and restoring wild salmon throughout their natural range. 

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