Experts from the organization "Sakhalin Environment Watch" investigated the causes of the fish kill in the Piltun Bay. They concluded that the fish died because of a lack of oxygen, which was blocked by the ice dam of Exxon Neftegaz Limited. Environmentalists wrote about it on July 9.
In early June 2018 450 tons of dead herring were found in the Sakhalin Piltun Bay, which covered about 40 km of the shoreland. Ecologists researched satellite maps of the bay and sent fish samples for analysis. Expertise in several independent centers showed that the fish did not die from toxic substances and radiation. Environmentalists detected no water pollution. They remembered that the ocean herring is very vulnerable to a lack of oxygen. The state examination decided that the air was blocked by drifting ice, but the researchers contradicted by satellite images of the bay.
Environmentalists found that in the winter of 2017–2018, Exxon employees (a subsidiary of the US Exxon Mobile, Rosneft is another shareholder) repaired their oil pipeline, which runs along the bottom of the bay. For repair, they created an ice dam along the pipeline. At the end of April, no one dismantled the ice, and the herring that was going to spawn in Piltun fell into a trap. One of the Exxon workers anonymously told environmentalists that the gap between the ice and the bottom of the bay was about 40 cm. The researchers also drew attention to the temporary quay, built by the oil workers for their work, it also limited the water exchange between the bay and the sea.
The head of the Sakhalin Environment Watch, Dmitry Lisitsyn, recalled that he organized a public examination of Exxon's facilities in 2008 and 2013, but the conclusions were ignored:
"The story of a fish kill in Piltun Bay in May 2018 is a classic case of a cumulative effect in the environment, when the impact of each individual industrial facility on the nature does not manifest itself clearly, but in conjunction, and in such a fragile ecosystem, leads to severe consequences. If the authorities and oilmen listened to an independent expert community, the mass death of valuable fish resources would surely have been avoided."
Environmentalists are determined to ensure that oil companies are held accountable for harm to nature.
At the end of June, the European Court of Human Rights communicated a complaint from the Sakhalin Environment Watch and other organizations about inclusion in the list of "foreign agents".
Daniil Kuznetsov, «7x7»