Hokkaido's Rausu Town, Home to Shiretoko World Natural Heritage, Undertakes Underwater Debris Cleanup Project to Protect Rich Seas

Rausu Town in Hokkaido (Location: Rausu-cho, Menashi-gun, Hokkaido; Mayor: Minoru Minatoya), as a municipality encompassing the Shiretoko World Natural Heritage site, has been continuously engaging in initiatives to walk alongside nature, issuing the "Rausu Town Nature Positive Declaration" in March 2026.

In FY2025, utilizing the "Hometown Support H Program," a donation project by Air Water Hokkaido Inc., and with donations from Air Water Life Solution Inc., an underwater debris cleanup project was implemented.

Background and Purpose of the Project

In the seas of Shiretoko, a wide variety of creatures live through a food web based on the blessings brought by drift ice. When it was registered as a World Natural Heritage site, the richness of its sea was highly evaluated.

This project aims to protect the marine environment of Rausu, a World Heritage site, by recovering underwater fishing nets and other items inevitably washed away due to stormy weather and drift ice. It also aims for continuous efforts by turning the recovery of fishing nets into diving tours. Abandoned fishing nets in the sea cause ghost fishing (where organisms unintentionally get entangled in nets and die, rather than for fishing purposes), which has become a worldwide problem.

Shiretoko Diving Planning Ltd., the only diving operator in the town, has been steadily engaging in underwater debris cleanup as volunteers since around 2013, utilizing time between business operations. Leveraging the past track record of Shiretoko Diving Planning, this project was undertaken through collaboration and cooperation between the company and Rausu Town.

Project Implementation Results

The recovery work was conducted from June to November 2025. Three divers went underwater, confirmed the debris situation, and manually recovered it. Additionally, the recovery of large debris was carried out with the cooperation of patrol boats from the Rausu Fisheries Cooperative Association. Furthermore, guests participating in diving tours from within and outside Hokkaido (8 people in total) also assisted with the recovery work.

A total of 16 recovery operations were conducted, retrieving 1,276 kg of debris. The majority was fishery-related debris such as fishing nets and ropes, with a small amount of cans and bulky waste. Creatures found entangled in the fishing nets included sea urchins, crabs, and gunnels, many of which had died. It was also confirmed that birds diving to eat the fish entangled in the nets had become caught themselves and drowned.

Table: Underwater Debris Recovery Results
Location | Recovery Amount | Main Debris
Matsunori Fishing Port | 934 kg | Gillnets, ropes, household waste
Chienbetsu Fishing Port | 257 kg | Gillnets, ropes
Rusa River Mouth | 35 kg | Gillnets, ropes
Seseki | 25 kg | Ropes
Aidomari Fishing Port | 25 kg | Gillnets, ropes

Image: Recovery work of Ezo rockfish entangled in a fishing net
Image: Recovery with the cooperation of Rausu Fisheries Cooperative Association

Comment from Shiretoko Diving Planning Ltd.

The seas around Shiretoko, including the Nemuro Strait, receive the blessings of drift ice and are home to various organisms. Because the annual water temperature variation is large, exceeding 20 degrees Celsius, many species appear in rotation, and both the fishing and tourism industries benefit from this. Additionally, there is a return to the land through the upstream migration of chum and pink salmon, creating an environment where the sea and land are deeply connected.

Our company has previously cooperated with Rausu Town, the Rausu Fisheries Cooperative Association, the Ministry of the Environment, and others to conduct underwater environment preservation activities. Unlike on land, the underwater environment is rarely seen by people and thus less likely to be noticed. However, an increase in underwater debris affects the growth of seaweed and causes fish to suffer from ghost traps, indirectly affecting humans as well. Seeing such situations during the project this time, we reaffirmed the importance of maintaining the environment.

Given this situation, when we had general divers participate in the work in 2025, we received comments such as, "Seeing underwater debris that we don't usually see changed our awareness of environmental issues," and "We want to do similar work again." Receiving this, we hope to have even more people help in the future and fully enjoy the wonderful underwater world of Shiretoko.

Future Plans

Rausu Town and Shiretoko Diving Planning Ltd. will continue activities to protect the rich sea. We welcome inquiries from anyone interested in this activity or who can cooperate in some way.

Inquiries Regarding This Matter

Rausu Town Office, Planning and Finance Division
TEL: 0153-87-2114 MAIL: kikaku.r@rausu-town.jp
Location: 100-83 Sakaecho, Rausu-cho, Menashi-gun, Hokkaido