The Lower Amur Mountain Valley Ecoregion was delineated by WWF as a representative ecoregion in the boreal zone due to its importance as breeding and stopover habitat for migratory waterfowl on the East Asian-Australasian Flyway. The Amgun River is the richest salmon river in the entire Russian Far East.
The Lower Amur is the most important habitat for all species of salmon and sturgeon in the Amur-Heilong basin, and still holds the richest freshwater fishery in the basin. The Lower Amur is the most critical habitat for the surviving population of kaluga sturgeon.
The large inter-tidal zone of the Okhotsk Sea coast is an important habitat for wading birds while shallow bays provide some of the last feeding grounds for gray whales (Eschrichtius gibbosus).
The wide floodplain valley of the Amur-Heilong and its tributaries has many oxbows and lakes where the river is braided in many smaller streams forming thousands of islands. Surrounding grasslands and narrow strips of floodplain forests provide good shelter and foraging habitat for mammals. Many relics of the Tertiary Period and southern aquatic species that reach the wetlands of the Middle Amur-Heilong River are absent in this downstream reach. Another peculiarity is the relative abundance of large (ox-bow) lakes that are seasonally connected to the Amur-Heilong (Kizi, Hummi, Udyl, Orel, and Evoron Lakes). These provide important habitat for nesting and migrating waterfowl and spawning fish.
Main threats include overfishing, poaching, and pollution from upstream and from industries of the city of Komsomolsk-on-Amur. Logging in upstream reaches of tributaries also degrades this ecosystem.
Lake Udyl, the only designated Ramsar site in the ecoregion, is protected as a national (federal) game reserve (zakaznik). Other lakes are equally important for biodiversity conservation but have not been nominated for Ramsar listing. There are no protected areas at Amur Estuary or other important coastal wetlands (Uda River Mouth, Schastya Bay). Komsomolsky Zapovednik protects a small area of biodiverse wetlands near the Gorin River mouth. In general, wetlands of this ecoregion have been minimally protected in nature reserves. Less than 1% of the lower Amur floodplain is preserved in protected areas.
Various sources reported in 2000-01 that large maturing Kaluga sturgeon (age over 13 years, length over 180 cm, and weight at least 50 kg) numbered at least 60,000 fish with a total biomass of 5.5 thousand tons (at an average weight of 90 kg). During recent years a rapid decline in abundance has been reported. By some estimates, existing levels of official catch and poaching could represent up to 95% of the spawning population annually. At this rate, the number of mature fish in 2010 could be one tenth that of 2000. The main causes for decline are the same as for Amur sturgeon – licensed fishing in China and poaching in Russia. In China the Amur-Heilong population of Kaluga and Amur sturgeon is the main source of fry for farming sturgeon for meat in southern regions. Water pollution is almost certainly negatively affecting kaluga sturgeon reproduction, both the chronic levels of toxic compounds and the acute concentrations caused by accidental and intentional discharges in 2005 and 2006.
The trend in the kaluga sturgeon population may be the best demonstration of the impossibility of protecting Amur-Heilong biodiversity through unilateral efforts. Unless an effective joint Russia-China program of sturgeon conservation is implemented in the near future the commercial fisheries (legal or not) are doomed and the species might face extinction.
Lower Amur. Photo by P.Sharov