A threat to the Mongolian grayling | WWF

A threat to the Mongolian grayling



Posted on 08 August 2011
Монгол хадран
© WWF Mongolia

Khar Us Lake is regarded as the wetland with international importance. Thus, it is listed as the Ramsar Convention site in order to reduce and prevent from potential deterioration in the habitats and stopover points of migratory bird species. On other hand, Khar Us Lake is one of the State Special Protected Areas in the country.  However, in recent years an ecological imbalance has become a concern for the internationally important area due to threats. In addition to lowered lakes’ water tables due to climate changes, the pastureland vegetation compositions and yields have reduced because of over-populations of livestock in the lakes’ vicinities.  60 per cent of haymaking in Khovd aimag is supplied from this protected area.

Fish passage of Durgun hydro-power station brings a threat to the Mongolian grayling.  It is said the facility was built according to its approved design. However, high pressure water through a narrow opening does not allow any species of fish to go through.  Distributions and movements of fish species in the interrelated lakes Khar Us, Durgun, Khar, Airag, and Khyargas have fragmented into “west” and “east”.  In fact, the fish passage facility has become “spawning site” for the grayling from Khar and Durgun Lakes.  In the first year after the station was constructed, the species reached the facility, but could not go through because of high pressure water and spawned there. However, the situation has worsened this year. According to the research conducted by Mendsaikhan, Ichthyologist, the Mongolian grayling was about to spawn at the beginning of April. However, the station operators did not timely remove the ice and halt of passage.  They opened it in 10 days later, but almost no any fish was left there.  As the station guard informed, only one or two individuals were seen around. When caught & released fish, there were no any fish individuals with spawns.  It has led to unclear state where the grayling of Durgun and Khar Lakes spawned this year.  If the species spawned somewhere around, it is uncertain how many of them have survived and joined its population. For the grayling that is used to fresh cold water environment in summer time, no one can provide a guarantee that the species will be adapt to the lake water that is above + 20C.
Монгол хадран
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