The Mainopylgino lake-river system is a valuable sockeye salmon habitat situated on the northeastern coast of the Bering Sea, in Chukotka Territory in the Russian Far East. This region is important in scientific and practical terms because is the spawning ground of Chukotka's largest population of sockeye salmon (Oncorhynchus nerka). For the purposes of creating a system of protected territories to preserve salmonids of the Russian Far East, this sockeye population is important because the ecosystem is close to its natural state and not exposed to major anthropogenic factors except for a well-regulated fishing industry. The entire environment of this shoreline is also in a natural, undamaged state.
The freshwater fish fauna of the Mainopylgino lake-river system consists of 19 species. Of these, one species (sockeye salmon) is caught by commercial and subsistence fishermen, and six species (Dolly Varden char, Arctic char, whitefish, cisco, grayling and pond smelt) by local subsistence fishers. The large population of sockeye salmon in the region is remarkable for its unique biological traits, great size and high fertility. The entire regional economy and society is dependent on healthy sockeye runs.
The renewal of oil and gas prospecting in this territory (and proposed future exploitation of these reserves) is very disturbing. Prospecting can cause irreversible changes of land and sea ecological systems, and damage the region's unique biological production and genetic diversity. That is why it is so important to create a protected territory with the legal status of a federal reserve (zapovednik) to save this unique ecosystem.