Boundaries

The ecoregion includes the watersheds of lakes Balkhash [Balqash Koi], Sasykkol, and Alakol, and their tributaries. In the north, the border goes from west to east across the Kazakhskiy Melkosopochnik Upland [Qazaqtyng Usaqshoqylyghy] to divide the Sarysu River basin (in ecoregion 626) and Nura River system (in ecoregion 602) from the upper headwaters of the northern tributaries (former tributaries) of Lake Balkhash. In the northeast, the border between the Balkash – Alakul ecoregion and Upper Irtysh [603] runs along the Chingistau Range [Shinggystau Zhotasy], and then curves south from the Tarbagatay Range to include the upper Ayaguz River. Further eastward it follows the Tarbagatay Mountains to the Urkashar Range, where it makes a sharp turn to the southwest. The Urkashar, Barlyk and Dzhugarskiy Alatau ranges divide tributaries of lakes Alakol and Balkhash, as well as the drainage areas of lakes Manas Hu (Telli-Nor) and Ebi-Nor (Ebinur Hu) in Duzungaria [623]. The southeastern corner of the ecoregion extends to include the whole Upper Ili River drainage (Kunges River=Kunes He and Tekes River=Tekes He) that lies between the Boro-Horo Range (=Borohoro Shan) in the north and the Narat Range (Narat Shan) in the south. The Zailiyskiy Ala-Tau Range [Ile Ala toosu = Ile Alatauy Zhotasy] and Chu-Iliyskiye Gory Ranges form the divide with Lake Issyk-kul [Issyk Kul = Ysyk-Kol] and the Chu River in the south and southwest.

Topography

The lake basin of Balkhash Hollow – including lakes Balkhash [Balqash Koi], Sasykkol, and Alakol – is enclosed in an extensive intercontinental depression in southern Kazakhstan, situated in the central part of the Asian continent, west of the Dzungarian Gates. It is bounded in the southeast by the Dzungarian Ala Tau, in the east and northeast by the Chingiz Tau and Tarbagatai mountains, in the north by the hills of the Aral-Irtysh watershed, and in the southwest by the submerged ridge of the Chu-Ili watershed.

The catchment area appears to be an extensive basin with lake waters located in the north. The relief of this basin is highly varied. From the southeast, east, northeast, north, and northwest the Balkhash Hollow is surrounded by a continuous arch of mountains and plateaus stretching from the Ala Tau up to Nagornaya, Asia. The lowest ledge of the lake basin, the watershed of Lake Balkhash and the Chu River, is characterized by altitudes of 400 m and more.

The geological structure of the terrain suggests that the Lake Balkhash basin began forming at the end of the Tertiary.

Freshwater habitats

 

Lake Balkhash is a closed lake, with the catchment area in a shape of a hollow formation. Its arid climate has inevitably lead to the salinization of its waters. Moreover, the hollow nature of the basin determines a number of local characteristics of atmospheric circulation, distribution of precipitation, and the flow of river waters into the lake.  The lake currently covers 16,996 km², but, like the Aral Sea, it is shrinking because of the diversion of water from the rivers that feed it. The maximum depth of the lake is 25.6 m, where the mean depth is 5.8 m. The mean depth of the eastern side is 1.7 times greater than that of the western side. The difference between the eastern and the western parts of the lake basin is essential. Fifty-eight percent of the total water surface and 46% of the lake water volume occur in the western part. The mean depth of the eastern part is 1.7 times greater than the western part. The western part of the lake has fresh or slightly salty water (0.5% 1.5%), depending on the secular fluctuation of its water level, whereas the eastern part is characterized by rather high concentrations of dissolved solids (up to 7%). The main reasons for the big difference include the inflow of a huge river into the western part and the impeded exchange of water between the two parts.

The Balkash inland basin drains into Lake Balkash via seven rivers. Chief among these is the Ili River, which brings the majority of the riparian inflow. The Ili is fed from precipitation (largely vernal snowmelt) from the mountains of China’s Xinjiang region.

Lakes Sasykkol and Alakol are freshwater lakes of the Balkhash system that lie in one of the most arid watersheds in the world. The lakes are usually frozen from November through March.

Terrestrial habitats

Lakes of the Balkhash Hollow, as many other lakes of the desert zone, are distinctly associated with the base of mountain ridges. A large part of the watershed lies in the southern and southeastern end of the basin, occupied by the mountain ridges of southeastern Kazakhstan. In the north and northwest, plain, relatively low desert areas occur. The ecoregion also includes semi-desert, steppe, and riparian habitats.

Description of endemic fishes

There are four endemic species in the ecoregion: Balkhash minnow (Lagowskiella poljakowi), Balkhash marinka (Schizothorax argentatus), Severtzov’s loach (Nemacheilus sewerzowi), and Balkhash perch (Perca schrenkii).

Balkhash minnow (Lagowskiella poljakowi) is endemic to the basin. This rare species inhabits the foothill streams of minor tributaries. It has not been reported in lakes Balkhash and Alakol, or in the Ili River itself. The taxonomic status of this minnow is under discussion, and remains unclear.

Another endemic is the Balkhash marinka (Schizothorax argentatus) in the Central-Asian subfamily Schizothoracinae. Prior to the early 1950s it was one of the major fish in Lake Balkhash, Ily River, and the Lake Alakol system. Because of hydroconstruction, overfishing, and exotic fish introduction its number has been sharply reduced. It is no longer found in Lake Balkhash, Alakol lake system, or Ily River. It still remains relatively numerous in many secondary tributaries.

Severtzov’s loach (Nemacheilus sewerzowi) is a rare species, endemic to the Ily basin. Its distribution and number now are not known, and its generic assignment is doubtful.

Balkhash perch (Perca schrenkii) is endemic to the Balkhash and Alakol lakes system. It was a common fish before introductions. Now it is extremely rare in Lake Balhkash, lower Ily River, and many tributaries. Its number has also declined in the Lake Alakol drainage. It almost disappeared in lakes Sasykkol and Koshkarkol soon after the introduction of sander, but it is still being fished in Lake Alakol. Its annual catch was about 300 tons in the 1990‘s. It is still being fished there now, but without specific statistical counting. Individual populations remain in shallow isolated reservoirs; however, there is concern for its status.

Other noteworthy fishes

 Ili marinka (Schizothorax pseudoaksaiensis) is a near-endemic to the ecoregion. In the Balkhash-Ili system it is probably close to extinct. Individual specimens are rarely reported in secondary tributaries of the Ili River. The Tarim [625] populations have not been studied. This species belongs to the Central-Asian subfamily Schizothoracinae.

Scaly osman (Diptychus maculatus) is a near-endemic that is also distributed in the Tarim ecoregion [625]. It inhabits only the mountainous part of the basin, usually at heights greater than 1,000 m above sea level. This species also belongs to the Central-Asian subfamily Schizothoracinae.

Seven River’s minnow (Phoxinus brachyurus) [637] is near-endemic to the Balkhash basin and Liao He [637] ecoregion, and was always distributed only in the tributaries of the Ili River. At present it is very rare.

Spotted thicklip loach (Triplophysa strauchii) is distributed widely across the Balkhash-Ily basin. However, its numbers in many tributaries have declined considerably, and this species has disappeared completely from the Ily River. Nevertheless, in many shallow rivers this species has remained in mass until now. Some authors consider the lake form of the species a distinct subspecies, Triplophysa strauchii ruzskyi, which used to be the most numerous fish in lakes Balkhash and Alakol. In the early 1950s there were successful attempts to test fish for this species in Lake Balkhash. Now it has completely disappeared from Lake Balkhash, and has been drastically reduced in the Alakol lakes. It requires protection.

Gray loach (Triplophysa dorsalis) is widely distributed in the Mountain-Asian region. However, due to the environmental features it is rarely recorded. Its quantity has always been high in some habitats.

Ecological phenomena

The Balkhash District falls into three distinct parts: lakes, large rivers in valleys, and mountain rivers. Each of these habitats is characterized by a particular icthyofaunal composition, which live in sharply contrasting conditions of Lake Balkhash and mountain streams of Tien Shan and Dzungaria. The lake area encompasses Lake Balkhash proper and other lakes. This area is poor in terms of species composition – historically there were only four native species, including Balkhash marinka (Schizothorax argentatus), Ili marinka (S. pseudaksaiensis), Balkhash perch (Perca schrenkii), and spotted thicklip loach (Triplophysa strauchii). The first three species were typical river forms. Their adaptation to deadwater and, even more, to saline water of eastern Lake Balkhash is a recent, secondary phenomenon. The fish species mentioned above evolved an ability to spawn in freshened areas of Eastern Balkhash.

The ichthyofauna of the plain reaches of the Ili River and the lowest reaches of its tributaries comprises six species. Apart from the four lake species, plain thicklip loach (Triplophysa labiata) and Severtsov’s loach (Nemacheilus sewerzowi) live there.

The mountain tributaries of the Ili River and other rivers of the region belong to the mountain-river zone. The icthyofauna is rich and is represented by two species of Phoxinus, Ili marinka, scaly osman (Diptychus maculatus), naked osman (Gymnodiptychus dybowskii), spotted thicklip loach, plain thicklip loach, Severtsov’s loach, gray loach (T. dorsalis), Turkestan catfish (Glyptosternon reticulatum), and Balkhash perch (Perca schrenkii).

Justification for delineation

This ecoregion encompasses the basin of Lake Balkhash and also lakes Sasykkol and Alakol, which once formed part of Lake Balkhash.

Level of taxonomic exploration

Fair