by G. Kamilov
Nasimahanum St., passage 1, No. 3, Tashkent 700179, Uzbekistan
and
Zh. U. Urchinov
Khalklar Dustligi 144, Apt. 30, Navoi, 706800 Uzbekistan
All reservoirs in Uzbekistan have been constructed for irrigation. There are 26 irrigation reservoirs at present, with a total surface area of 170 600 ha. Many are the result of damming of rivers, but some were constructed far away from rivers in natural depressions, and are supplied with water by canals connecting them with rivers. The water is distributed through 13 000 km of canals and collected into 12 700 km of drains. Regulation of Uzbekistan rivers has stopped fish migrations and reservoirs have flooded natural spawning and feeding grounds, leading to the decline in riverine fish stocks. Further damage, especially to fry and young fish, has been caused through pumping and diversion of water into irrigation fields. Many floodplain and delta lakes in the lower Amu-Darya have desiccated due to the regulated water flow, irreversible water uptake for irrigation, and the drop in the Aral Sea water level. Under such constraints, fisheries managers have developed a fisheries management plan for each promising water body. Through its implementation it is hoped to increase the current yields by 4-6 times, or even more.
Uzbekistan is a country with a predominantly dry desert climate situated in Central Asia. In the north it is delimited by the Ust-Urt plateau, in the north-east by the sandy desert Kyzylkum, and in the south-east by snow-capped mountain ranges. It is the rainfall and snowfall in the mountains, shared by Kyrgyzstan and Tajikstan, which provides this very dry country with most of its water. According to the information provided by the Gidroproekt Institute, in Uzbekistan 98% of water is now used for agriculture needs, 0.5% for domestic supply, and 1.5% for industrial needs.
Several years ago, Uzbekistan became an independent country and initiated the first steps towards a market economy. This has been reflected in the new approach to the management of water resources. During the years prior to independence, the decision to grow cotton as a highly dominant crop was dictated by the overall policies and needs of the Soviet Union, and this led to the need for maximizing the utilization of water through river regulation. Uzbekistan is rich in natural and artificial water bodies, rivers, lakes, reservoirs, canals and ponds. Uzbekistan has 3 000 km of rivers, 257 000 ha of lakes, and 125 000 ha of reservoirs. The two major rivers passing through Uzbekistan are the Amu-Darya and the Syr-Darya, but there are also three other large rivers, Zarafshan, Surkhan-Darya and Chirchik which supply water to this thirsty country. Since the 1940s many irrigation canals and systems have been constructed, among which the most important are the Amu-Bukhara canal, irrigation canal system in the Hungry Steppe, Karshin Canal, and the canals of the Surkhan-Darya region. All reservoirs of Uzbekistan are constructed for irrigation. The large-scale irrigation system established for cotton production and other crops also includes a number of reservoirs. There are 26 irrigation reservoirs in Uzbekistan (excluding Karakalpakstan) covering 170 600 ha at present. Many are the result of damming of rivers, but some were constructed far away from rivers in natural depressions, and are supplied with water by canals connecting them with rivers. The water is distributed through 13 000 km of canals and collected into 12 700 km of drains (collectors).
The net of irrigation canals is still being expanded, therefore one can expect that the quantity of drainage and ground waters will continue to increase, and that this in turn will result in the formation of still more new storage and seepage water bodies. All types of canals are suitable for fisheries. However, at present, many irrigation canals on the middle and lower Amu-Darya are not utilized for this purpose.
Development of agriculture in the countries of Central Asia led to maximizing the use of the available water resources. This has had a major impact on the Aral Sea. It was a combination of the increased water demand with drought lasting over at least 20 years, which led to a reduced discharge into the Aral Sea through the two major rivers, i.e. Syr-Darya and Amu-Darya. This has led to a gradual desiccation of the sea, to increased salinity and to disappearance of fish. While during the 1950s the capture fishery harvested 35 000 to 40 000 t per year, today the Aral Sea has completely lost its fishery importance. In Uzbekistan now only reservoirs, rivers, natural lakes and lakes receiving drainage water are fished, but there is a growing pond culture fishery as well. New lakes have been created from the drainage water, viz. Arnasai lake system of the Hungry Steppe, Lake Alan in Karshi Steppes, lakes Dengizkul, Shurgak, Karakyr and Tuzgan in the Bukhara region, and some others in Khorezm region and on the lower Amu-Darya River.
Over the last 60 years, on the middle and lower Amu-Darya, over 6 000 km of irrigation canals have been constructed, together with the reservoirs Kelif and Tuyamuyun, and the pumping stations Amu-Bukhara and Karshin, which lift the Amu-Darya water 130 m high to feed Talimardzhan reservoir and Karakul canal and some others.
Regulation of Uzbekistan rivers has led to profound changes in the natural aquatic environment. Dams have stopped fish migrations and reservoirs have flooded natural spawning and feeding grounds. This has lowered the reproduction rate, which in turn, has resulted in a decline in the riverine fish stocks. Consequently, fish catches have declined. The situation has been further aggravated by the often irreversible water uptake for human needs. Not only are large volumes of water diverted for irrigation, industries, cooling of thermal power stations, but the uptakes have diverted most of the young fish onto irrigated fields or into industrial sites. The level of this damage is about the same as that caused to fisheries by dam construction and pollution. The highest demand for irrigation water is during summer when water is rich in young fish. It is estimated that in the irrigation canals of Karakalpakstan alone 5 billion young fish perish annually (Pavlovskaya et al., 1968).
Uzbekistan has a typical continental climate, with large daily and seasonal differences in air temperature. During the coolest month, i.e. January, the precipitation increases with altitude, which means that the distribution of precipitation over the country is not even. Water temperature starts rising from February onwards, with the highest temperatures reached in July-August.
In Uzbekistan, reservoir water level is determined by rainfall and water uptake for irrigation. Lowland reservoirs start filling in March-April, and the filling extends over 40 to 80 days, during which the reservoir fills up. The water level may increase by 5-20 cm per day. The period of filling is followed by a period of summer draining for irrigation, which ends in September, with the end coinciding with the minimum water level in the reservoir. In small mountain and foothill reservoirs, the cycle consists of filling and drawdown periods, which are followed by a period of stabilized water level in autumn.
The hydrological pattern and water chemical composition are conducive for fish in spite of a gradual increase in water salinity with the transition from the foothills to lowlands.
Aquatic macrophytes are an excellent direct food source of fish and aquatic invertebrates. Taubaev (1968) identified 819 species of aquatic and wetland plants from water bodies of Central Asia. Of these, 39 belong to the genus Chara, 62 - mosses, 17 - ferns, and 701 higher flowering plants. Many of these are also present in Uzbekistan. According to their character, 561 species are littoral, 132 - semi- submersed, and 128 submersed species. Deep reservoirs are poor in aquatic macrophytes; shallow reservoirs have more plants, especially in the upper parts of the reservoir.
Zooplankton in the Uzbekistan water bodies is dominated by rotifers, cladocerans and copepods. Benthos differs from water body to water body, and also seasonally. For the numbers and biomass see Tables 1 and 2.
With respect to pollution, phenol and oil product pollution is highest in summer and autumn. Pesticides are generally high and above the permissible levels for fish in almost all water bodies of Uzbekistan.
Uzbekistan lakes have oligotrophic or mesotrophic character, i.e. they have a low to medium productivity.
84 fish species and subspecies have been identified from the Uzbekistan water bodies (Table 3).
The set-up of fish fauna in the reservoirs is largely the result of historical evolution, but lately human activities have substantially changed the fish stocks in some of the water bodies. The development of irrigation systems interconnecting various river basins, and fish species transfer from drainages outside Central Asia have been the two major factors behind the changes.
TABLE 1. Number and biomass of zooplankton in selected reservoirs of the Zarafshan and Kashka-Darya river basins (year 1991)
Water body |
No. (x1000) in m3 |
Biomass g/m3 |
ZARAFSHAN basin |
||
RESERVOIRS Akdarin Karaultepin Kattakurgan Kuyumazar Tudakul Shorkul LAKES Tuzgan Dengizkul |
4.28 124.0 126.5 10.06 18.5-29.8 35.0-160.0
147.5 102.0-251.0 |
2.65 2.2 3.6 4.1 0.3-11.1 0.3-4.6
2.1 3.1-4.8 |
KASHKA-DARYA basin |
||
RESERVOIRS Pachkamar Karabakh 50 Years of UZSSR Yangikurgan Shurabsai Gissarak Lyangar Kamashin Chimkurgan |
81.0-181.0 68.0-240.0 168.0-435.0 57.6-163.0 13.2 80.0-28.0 260.0 505.0 1565.0 |
0.9-2.4 0.1-0.96 4.8-9.6 1.3-2.7 0.82 1.2-11.4 4.0 6.3 2.8 |
TABLE 2. Number and biomass of benthos in selected water bodies of the Syr-Darya and Amu-Darya basins
Water body |
Oligochaeta ind. (mg/m2) |
Chironomidae ind. (mg/m2) |
Total biomass (mg/m2) |
Note |
||
Karkidon reservoir Kurgantep reservoir Sarykamysh lake Akmachit lake Andizhan reservoir Atchapar reservoir Aktepin reservoir Three lakes Uchkyzyl reservoir |
20 8 32 15 11 30 6 8 6 |
150 94 274 200 62 151 24 10 14 |
40 21 60 18 34 18 15 10 13 |
365 231 1 654 300 126 831 60 15 14 |
1 382 856 38 960 1 054 269 1 432 103 91 64 |
Pebbly bottom, in places clay Total drawdown during summer very overgrown with plants, black clay shallow, warms up easily, overgrown mountain lake, very low water temperature 50% overgrown, total drawdown sandy bottom, low water temperature |
TABLE 3. List of fish species of Uzbekistan
Species | Syr - Darya | Zarafshan | Kashka - Darya | Amu-Darya, Surkhan-Darya |
STURGEONS - Acipenseridae | ||||
Spiny sturgeon - Acipenser nudiventris Lov. | LES | - | LES1 | LES |
Stellate sturgeon - Acipenser stellatus Pallas | LES | - | - | LES |
Big Amu-Darya shovelnose - Pseudoscaphirhynchus kaufmanni Bogd. | LES | - | LES1 | LES |
Little Amu-Darya shovelnose - Pseudoscaphirhynchus hermani (Kessler) | LES | - | LES | |
SALMONIDS - Salmonidae | ||||
Aral trout - Salmo trutta aralensis Berg | LES | - | - | LES |
Amu-Darya trout - Salmo trutta oxianus Kessler | LES | - | - | LES |
Issyk-kul trout - Salmo ischan issykogegarkuni Kessler | IES2,3 | - | - | |
Rainbow trout - Oncorhynchus mykiss (Richardson) | IES2 | - | - | - |
Donaldson trout - Salmo olson | IES4 | - | - | - |
WHITEFISH - Coregonidae | ||||
Peled - Coregonus peled (Gmelin) | IES3 | - | - | - |
Least cisco - Coregonus sardinella Val. | IIS3 | - | - | - |
LOACHES - Cobitidae | ||||
Spotted stone loach - Noemacheilus strauchi (Kessler) | IIS | IIS | - | - |
Plain stone loach - Noemacheilus labiatus (Kessler) | IIS | - | - | - |
Grey stone loach - Noemacheilus dorsalis (Kessler) | LNS | - | - | LNS |
Tibetan stone loach - Noemacheilus stoliczkai (Steindachner) | LNS | LNS | LNS | LNS |
Amu-Darya stone loach - Noemacheilus oxianus Kessler | LNS | LNS | LNS | LNS |
Kuschakewitsch loach - Noemacheilus kuschakewitschi Herzenstein | LNS | - | - | - |
Bukhara stone loach - Noemacheilus amudarjensis Rass | LNS | LNS | LNS | LNS |
Khorezm loach - Noemacheilus amudarjensis choresmi Berg | - | - | - | LNS |
Loach - Noemacheilus sp.nov. | LNS6 | - | - | - |
Loach - Noemacheilus malapterurus longicauda (Kessler) | LNS | LNS | LNS | LNS |
Golden spiny loach - Cobitis aurata aralensis (Kessler) | LNS | LNS | LNS | LNS |
SILURIDS - Siluridae | ||||
Wels - Silurus glanis L. | LNS | LNS | LNS | LNS |
CATFISH - Sisoridae | ||||
Turkestan catfish - Glyptosternum reticulatum McClelland | LES | - | - | LNS |
STICKLEBACKS - Gasterosteidae | ||||
Aral stickleback - Pungitius platygaster aralensis (Kessler) | LNS | - | - | LNS |
MOSQUITO FISHES - Poeciliidae | ||||
Mosquitofish - Gambusia affinis Baird et Girard | INS | INS | INS | INS |
SNAKEHEADS - Channidae (Ophiocephalidae) | ||||
Amur snakehead - Channa argus warpachowskii (Berg.) | IIES | - | IIES | IIES |
PIKES - Esocidae | ||||
Northern pike - Esox lucius L. | LES | - | - | LES |
SUCKERS - Catastomidae | ||||
Bigmouth buffalo - Ictiobus cyprinellus (Val.) | IES | - | - | - |
Smallmouth buffalo - Ictiobus bubalus (Rag.) | IES4 | - | - | - |
Black buffalo - Ictiobus niger (Raf.) | IES4 | - | - | - |
CARPS - Cyprinidae | ||||
Aral roach - Rutilus rutilus aralensis Berg | LES | LES | LES | LES |
Bukhara roach - Rutilus rutilus bucharensis g.Nik. | LES | - | - | LES |
Zeravshan dace - Leuciscus lehmani Brandt | LNS | LNS | LNS | LNS |
Syr-Darya dace - Leuciscus squaliusculus (Kessler) | LNS | - | - | - |
Ide - Leuciscus idus oxianus (Kessler) | LNS | - | - | LNS |
Common minnow - Phoxinus phoxinus (L.) | LNS7 | - | - | - |
Rudd - Scardinius erythrophthalmus (L). | LNS | - | - | LNS |
Grass carp - Ctenopharyngodon idella (Valenciennes) | IES | IES | IES | IES |
Black amur - Mylopharyngodon piceus (Rich.) | IES | IES | - | IES |
Pike asp - Aspiolucius esocinus (Kessler) | LES | LES | - | - |
Aral asp - Aspius aspius taeniatus natio ibliodides (Kessler) | LES | LES | LES | LES |
Amur three-lips - Opsariichthys unirostris amurensis | IIS | - | - | - |
Tench - Tinca tinca (L.) | IES | IES | - | - |
Stone morokos - Pseudorasbora parva (Schlegelr) | IIS | IIS | IIS | - |
Gudgeon - Gobio lepidolaemus Kessler | LNS | LNS | LNS | LNS |
Amur false gudgeon - Pseudogobio rivularis (Basil.) | IIS | IIS | IIS | - |
Herat khramulya - Varicorhinus heratensis steindachneri (Kessler) | IES | LES | LES | LES |
Turkestan barbel - Barbus capito conocephalus (Kessler) | LES | LES | LES | LES |
Aral barbel - Barbus brachycephalus (Kessler) | LES | LES | LES | LES |
Marinka (snowtrout) - Schizothorax intermedius McClelland | LES | LES | LES | LES |
Scaled osman - Diptychus maculatus Steindachner | LES | - | - | - |
Osman Severtsova - Diptychus sewerzowi Kessler | LES | - | - | - |
Scaleless osman - Diptychus dybowskii Kessler | LES | - | - | - |
Aral shemaya - Chalcalburnus chalcoides aralensis Berg | LES | LES | LES | LES |
Riffle minnow (bystranka) - Alburnoides bipunctatus eichwaldi (Filippi) | - | LNS | LNS | LNS |
Striped bystranka - Alburnoides taeniatus (Kessler) | LNS | LNS | LNS | LNS |
Tashkent bystranka - Alburnoides oblongus Bulgakov | LNS | - | - | - |
Eastern bream - Abramis brama orientalis Berg | LES | IES | IES | IES |
White amur bream - Parabramis pekinensis (Basilewsky) | IIES | - | - | IIES |
Southwest white-eye - Abramis sapa (Pallas) | LES | LES | LES | LES |
Ostroluchka - Capoetobrama kuschakewitschi (Kessler) | LNS | LNS | LNS | LNS |
Common sawbelly - Hemiculter leucisculus (Basilew.) | IIS | IIS | IIS | IIS |
Korean sawbelly - Hemiculter lucidus (Pub.) | IIS | IIS | IIS | IIS |
Razorfish - Pelecus cultratus (L.) | LES | LES | LES | LES |
Amur bitterling - Rhodeus sericeus (Pallas) | IIS | - | - | IIS |
Goldfish - Carassius auratus gibelio (Bloch) | IES | IES | IES | IES |
Common carp - Cyprinus carpio L. | LES | LES | LES | LES |
- Elopichthys bambusa (Richardson) | IIES5 | - | - | - |
Silver carp - Hypophthalmichthys molitrix (Valenciennes) | IES | IES | IES | IES |
Bighead carp - Aristichthys nobilis Rich. | IES | IES | IES | IES |
PERCHES - Percidae | ||||
Pikeperch - Stizostedion lucioperca (L.) | IES | IES | IES | IES |
Perch - Perca fluviatilis L. | LES | - | - | LES |
Balkhasch perch - Perca schrenki Kessler | IIS | IIS | - | - |
Ruffe - Gymnocephalus cernuus (L.) | LES | - | - | LES |
SLEEPERS - Eleotrididae | ||||
- Micropercops cinctus (Dabry) | IIS | - | - | - |
GOBIES - Gobiidae | ||||
Amur goby - Rhinogobius similis Gill. | IIS | IIS | IIS | IIS |
- Pomatoschistus caucasicus (Kaw.) | IIS | - | - | IIS |
Caspian round goby - Neogobius melanostomus (Pallas) | IIS | - | - | IIS |
Monkey goby - Neogobius fluviatilis (Pallas) | IIS | - | - | IIS |
Tube-nosed goby - Proterorhinus marmoratus (Pallas) | IIS | - | - | IIS |
SCULPINS - Cottidae | ||||
Turkestan sculpin - Cottus spinulosus Kessler | LNS2 | - | - | - |
- Cottus gobio jakartensis Berg | LNS2 | - | - | - |
- Cottus rosalis Berg | LNS | - | - | - |
Total: | 82 | 39 | 36 | 55 |
LES Local economic species 1 Talimardzhan Reservoir
LNS Local non-economic species 2 Chirchik
IES Introduced economic species 3 Charvak Reservoir
INS Introduced non-economic species 4 Pond Fish Farm
IIES Incidentally introduced economic species 5 Fish Farm 'Balykchi'
IIS Incidentally introduced non-economic species 6 Turk Reservoir
7
River Keles
Today, as a result of irrigation needs, the Syr-Darya is connected through irrigation canals with the Sanzar River, and the Sanzar with the Zarafshan. The Zarafshan is connected through the Eski-Angar canal with the Kashka-Darya, and the Kashka-Darya through the Karshin main canal with the Amu-Darya. The Zarafshan is connected with the Amu-Darya through Amu-Bukhara and Amu-Karakul canals (Fig. 1). Connecting various rivers by canals has played an important role in the current fish fauna set-up of the individual water bodies.
The major economically important fish species of Uzbekistan are briefly described here.
Grass carp
(Ctenopharyngodon idella). Its natural distribution is in the rivers of the Far East and China. In 1961 this species was introduced into Uzbekistan in the fish farm Kaglan-Chirchik (now called 'Balykchi'). At the same time the fishery scientists of Uzbekistan released approximately 400 000 one-year old grass silver and bighead carps in the Amu-Darya River. From the Amu-Darya the fish then entered the lower course of the Zarafshan River through Amu-Bukhara and Amu-Karakul canals. Currently grass carp is found in all water bodies associated with the Zarafshan River. From ponds of the fish farm Balykchi the fish escaped into the Syr-Darya. Grass carp is now an important fish of all fish ponds and all lowland reservoirs of Uzbekistan, where it reaches a weight of up to 18 kg. The growth rate of grass carp is shown in Table 4. In ponds, irrigation canals and collectors of drainage water, grass carp is favoured for its efficient conversion of the macrophytes and its ability to prevent the ponds from overgrowing with aquatic plants.TABLE 4. Growth rate of grass carp in the middle reaches of the Amu-Darya
Age |
Age (years), length (cm) |
Number |
||||||
1 |
2 |
3 |
4 |
5 |
6 |
7 |
||
1+ 2+ 3+ 4+ 5+ 6+ 7+ mean increment increment in % |
24.9 25.6 27.1 26.1 23.1 24.2 23.4 24.9 24.9 100 |
47.0 47.7 45.3 45.9 42.6 43.9 45.4 20.5 82 |
67.2 61.9 61.1 59.3 58.6 61.6 16.2 35.8 |
73.0 75.1 71.9 72.5 73.1 11.5 18.7 |
86.5 83.2 81.8 83.8 10.7 14.6 |
88.7 89.9 89.9 5.5 6.1 |
95.8 95.8 6.5 7.2 |
1 12 18 20 11 4 5 |
Aral asp
(Aspius aspius). This piscivore is present naturally in the Amu-Darya and Syr-Darya. Through irrigation canals from the Amu-Darya it has spread into the Zarafshan and Kashka-Darya rivers. The length/age relationship for a diversity of water bodies of Central Asia is given in Table 5. In the Amu-Darya the fish reaches a maximum size of 6 kg and length of 85 cm.TABLE 5. Body length of the Aral pike asp in selected water bodies of Central Asia
Water body |
Age (years), length (cm) |
|||||||
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
|
Water bodies of the middle reach and the left bank of
the Amu-Darya (author's data) Lake Akchatau (Syr-Darya basin) (Gladkov, 1934) Lake Arnasai (Kamilov,1973) Lake Balkhash Tulikul lakes (Dukravets, 1976) Kapchagai reservoir (Baimbetov et al., 1975) Farkhad reservoir (Maksunov, 1961) Uchkyzyl reservoir (Amanov, 1963) Uchkyzyl reservoir (author's data) |
12.6 10.9
-
31.2 12.0
7.8
10.5
11.1
13.0 |
21.2 17.5
22.7
40.1 19.7
14.8
17.4
19.4
19.2 |
28.4 24.7
31.8
46.2 26.1
24.1
23.4
26.2
27.0 |
34.3 31.0
-
- 31.8
32.0
29.4
-
34.0 |
38.7 35.7
-
- -
36.8
40.6
37.3
45.6 |
44.1 37.7
-
- -
48.4
43.0
-
- |
47.5 -
-
- -
53.3
-
-
- |
49.8 -
-
- -
-
-
-
- |
Turkestan barbel
(Barbus brachycephalus), an economically important omnivore, is found in the Amu-Darya, Syr-Darya, Zarafshan and Kashka-Darya rivers and many water bodies connected with them. In Ferghana Valley and the Surkhan-Darya District this fish is present in all reservoirs, lakes and canals. In the Khorezm District it is a very common fish of lakes, canals and water bodies, resulting from drainage water. In large reservoirs it undergoes seasonally local migrations. The growth rate for a number of water bodies is shown in Table 6.TABLE 6. Growth rate of Turkestan barbel in Uzbekistan water bodies
Length (cm), Weight (g) |
Age (years) |
Number |
|||||
1 |
2 |
3 |
4 |
5 |
6 |
||
KATTAKURGAN (reservoir) |
|||||||
cm g |
12.2 44 |
23.1 160 |
26.0 250 |
34.4 320 |
39.2 776 |
47.8 1470 |
193 |
KUYUMAZAR (reservoir) |
|||||||
cm g |
- - |
24.8 192 |
31.0 425 |
39.2 840 |
44.3 1080 |
46.5 1225 |
161 |
TUDAKUL (reservoir) |
|||||||
cm g |
- - |
22.5 167 |
32.5 436 |
36.1 611 |
41.5 950 |
44.3 1280 |
133 |
CHIMKURGAN (reservoir) |
|||||||
cm g |
- - |
20.0 105 |
22.4 250 |
28.0 700 |
38.2 1200 |
48.0 1600 |
64 |
ULLISHORKUL (lake) |
|||||||
cm g |
13.4 62 |
20.1 142 |
28.5 300 |
34.2 520 |
38.6 713 |
46.2 1478 |
128 |
ABULKUL (lake) |
|||||||
cm g |
14.5 65 |
22.2 160 |
28.0 400 |
35.0 730 |
42.0 1120 |
46.0 1885 |
80 |
Goldfish
(Carassius auratus), an omnivore, was introduced in 1951 from the Moscow area in ponds of the Tashkent district. In 1952 it spawned there and in June 1952 the fingerlings were transferred into the Kattakurgan reservoir. From there the species entered the lower reach of the Zarafshan River through a connecting canal. In the following years the species was also introduced into reservoirs Uchkyzyl and Yuzhnosurkhan; in both of them the fish stocks are now well established. The species is of economic importance and is now very common in all water bodies of Central Asia. Its growth rate is shown inTable 7.
Common carp
(Cyprinus carpio) (wild form) is a widespread species present in most water bodies of the Syr-Darya, Amu-Darya, Zarafshan and Kashka-Darya catchments. The growth rate seems to differ from water body to water body (Table 8).TABLE 7. Growth rate of goldfish in water bodies of the lower Zarafshan
Length (cm) Weight (g) |
Age (years) |
Number |
||||
1 |
2 |
3 |
4 |
5 |
||
TUDAKUL (reservoir)1/ |
||||||
cm g |
13.7 74.0 |
21.0 268.6 |
23.7 430.0 |
- - |
- - |
74 |
KUYUMAZAR (reservoir)1/ |
||||||
cm g |
12.5 60.1 |
20.1 170.0 |
23.2 380.0 |
- - |
- - |
30 |
SHORKUL (reservoir)1/ |
||||||
cm g |
17.4 117.0 |
19.8 160.0 |
21.5 272.0 |
24.0 390.0 |
- - |
87 |
DENGIZKUL (lake)1/ |
||||||
cm g |
- - |
19.4 344.0 |
22.2 458.0 |
24.3 540.0 |
- - |
55 |
SHURGAK (lake)1/ |
||||||
cm g |
15.7 120.0 |
18.4 172.0 |
20.5 258.0 |
23.9 382.0 |
25.8 640.0 |
82 |
TUZGAN (lake)1/ |
||||||
cm g |
14.8 100.0 |
18.0 138.0 |
21.7 270.0 |
23.4 365.0 |
25.8 456.0 |
128 |
KARAKIR (lake)1/ |
||||||
cm g |
13.7 103.0 |
20.8 249.0 |
23.6 374.0 |
25.6 447.0 |
- - |
80 |
KHADZHIKUL (lake)2/ |
||||||
cm g |
- - |
11.2 30.0 |
13.0 50.0 |
20.0 170.0 |
- - |
|
ULLISHORKUL (lake)2/ |
||||||
cm g |
- - |
- - |
18.0 220 |
25.0 280 |
- - |
|
BESHARYK (fish farm) |
||||||
cm g |
- - |
11.1 43 |
14.4 74 |
17.8 195 |
- - |
1/
Abdullaev and Urchinov, 19892/
Khakberdiev, 1983TABLE 8. Growth rate of common carp (wild form) in water bodies of the Zarafshan and Kashka-Darya basins
Water body |
Age (years), length (cm) |
|||||||||
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
9 |
10 |
|
ZARAFSHAN BASIN |
||||||||||
Kuyumazar reservoir Kattakurgan reservoir Lake Tuzgan Karaultepin reservoir Shorkul reservoir Lake Dengizkul |
11.4 11.1 12.8 8.2 10.2 - |
22.2 24.2 24.1 20.5 20.8 17.1 |
30.5 31.8 33.1 38.5 31.7 30.7 |
39.3 38.0 42.7 - 42.4 41.3 |
47.5 - 51.3 - 50.8 52.2 |
52.7 - 58.0 - 59.3 59.6 |
57.8 - 59.8 - 62.0 63.1 |
61.0 - - - 64.0 74.8 |
- - - - - 84.4 |
- - - - - 87.0 |
KASHKA-DARYA BASIN |
||||||||||
Talimardzhan reservoir Chimkurgan reservoir 50 Years of UZSSR reservoir Yangikurgan reservoir Kamashin reservoir Pachkamar reservoir |
15.7 13.0 13.5 12.6 11.7 13.4 |
27.0 20.6 26.2 22.0 22.1 20.6 |
37.7 28.8 48.4 27.4 28.3 28.5 |
47.7 - 55.0 - 35.5 34.7 |
56.4 - - - - - |
62.8 - - - - - |
67.4 - - - - - |
70.7 - - - - - |
74.8 - - - - - |
80.9 - - - - - |
Silver carp
(Hypophthalmichthys molitrix) and bighead carp (Aristichthys nobilis) were introduced into Uzbekistan after 1960 and they are successfully grown in fish farms, but also stocked in lakes and reservoirs. Their abundance in some water bodies depends on the stocking density. Silver carp is a fast-growing species which in the Syr-Darya river may reach a weight over 20 kg. It is now self-propagating in some rivers and the early juveniles are found in large numbers in August and September in collectors, canals, lakes and in ricefields. Growth rates for the individual Uzbekistan water bodies are given in Table 9.TABLE 9. Growth rate of silver carp in the middle course of the Syr-Darya
Parameter |
Age (years) |
||||||||
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
9 |
|
Length (cm) Weight (kg) Number |
34.0 0.72 18 |
45.6 1.6 12 |
64.0 4.2 4 |
73.4 7.7 22 |
84.5 9.9 56 |
86.5 12.2 30 |
93.2 16.6 8 |
96.7 18.6 8 |
103.0 21.8 4 |
Pikeperch
(Stizostedion lucioperca) is a common fish in the deltas of the Syr-Darya and Amu-Darya. From the Amu-Darya it has spread into the Zarafshan and Kashka-Darya catchments through the Karshi and Amu-Bukhara canals. In 1963 it was transferred from the lower Ural River into Kairakkum and Dergez reservoirs. From the latter reservoir it entered the Surkhan-Darya and Yuzhno-Surkhan reservoirs through canals (Kamilov 1973). In Chardarin reservoir (on the middle Syr-Darya) pike perch was introduced in 1983 from the Ural River. From this reservoir the species then spread into the system of Arnasai lakes, Lake Andara and Lake Tuzgan. Its growth rate for individual water bodies is given in Table 10.The investigated water bodies also harboured the following rare and threatened fish: spiny sturgeon (Acipenser nudiventris), little Amu-Darya shovelnose (Pseudoscaphirhynchus hermani), big Amu-Darya shovelnose (P. kaufmanni), and Syr-Darya shovelnose (P. fedtschenkoi). Amu-Darya shovelnose was not found by the author anymore and is probably extinct in water bodies of Uzbekistan. Spiny sturgeon and big Amu-Darya shovelnose are present only in irrigation reservoirs of the lower Zarafshan, Kashka-Darya and in Khorezm district, but are absent from lakes. One specimen of Syr-Darya shovelnose was captured in 1986 from the lower course of the Keles River (Syr-Darya catchment). Aral asp was present in Talimardzhan reservoir during the first years after its formation when it was commercially fished. At present it is a rare fish of irrigation reservoirs of the Khorezm district, and of the lower Syr-Darya, Zarafshan and Kashka-Darya.
Pike asp (Aspiolucius esocinus), osman (Diptychus gymnogaster), ostroluchka (Capoetobrama kuschakewitschi) and Turkestan catfish (Glyptosternum reticulatum) also became rare. The first three species are now proposed for inclusion in the red book of Uzbekistan.
The most common commercial fish are now roaches (Rutilus rutilus aralensis), razorfish (Pelecus cultratus), and Aral shemaya (Chalcalburnus chalcoides aralensis).
TABLE 10. Growth rate of pikeperch in selected water bodies of Uzbekistan
Water body |
Age (years) |
Note |
||||||
1 |
2 |
3 |
4 |
5 |
6 |
7 |
||
Aral Sea Amu-Darya River Lake East Arnasai Lake Aidar Lake Tuzgan Kairakkum reservoir Yuzhnosurkhan reservoir Yuzhnosurkhan reservoir Talimardzhan reservoir |
12.1 - 21.7 20.2 21.9 17.8 22.5 25.3 17.3 |
21.9 16.0 30.3 30.3 31.4 30.8 35.5 35.0 28.8 |
30.3 28.0 38.4 37.1 39.3 40.8 43.4 43.0 38.3 |
38.3 32.0 46.5 46.9 46.4 49.7 51.7 50.0 44.1 |
44.4 - 52.1 56.2 48.6 56.2 59.7 55.0 48.6 |
51.0 - 59.1 - 53.9 - - - 51.6 |
56.9 - 69.0 - 61.4 - - - - |
Ermakhanov et al., 1974 Sagitov, 1983 Amanov et al., 1990 Amanov et al., 1990 Amanov et al., 1990 Fedorov, 1972 Amanov, 1985 author author |
During the last 30 years irrigation needs have dominated the use of water resources without regard to the cost of such measures to other users and environment.
Although the Government of Uzbekistan gives the highest priority to the use of water for irrigated agriculture, the Government has lately focused on the problems caused to fisheries by irrigation. Virtually all rivers are now regulated especially in foothills and lowlands with intensive agriculture and industries. Rivers have been polluted by industrial waste waters and agriculture runoff and as a result their fisheries importance has been declining. On the positive side, the human interference with water resources has resulted in an increase in reservoir water surface area. While the total water surface area increased, the number of lakes in Uzbekistan slightly declined.
In the Khorezm district of the Amu-Darya basin major changes in water area redistribution have resulted from the formation of water storage lakes as a result of the accumulation of drainage and wash water in depressions.
In the Syr-Darya basin, a number of lakes in the delta of the river as well as on its floodplains have partially desiccated or completely disappeared (Nikitin, 1987). On the other hand, several lakes formed in Ferghana Valley and outside it, e.g. Arnasai, Tuzgan and Aidara. In 1970 the water level in these lakes started declining, but the decline has recently stopped, and the surface area in the lower Zarafshan water bodies has been increasing.
The current situation is presented in Tables 11-13.
Khorezm region, which covers 47 000 km2, is an oasis situated on the left bank of the lower Amu-Darya. In the south and southwest it is bordered by the sands of the Karakum desert. The Amu-Darya River in Khorezm region has a strong current and is turbid. During floods the river often spills over the banks and forms a wide floodplain. The water of Amu-Darya in Khorezm region is diverted into a system of canals with a total length of 900 km. The length of collector canals totals 215 km. Northern collectors join collector Daryalyk and this in turn brings the drainage water into another large collector, which then joins with the drainage waters from the Khorezm and Tashauz regions and discharges water into the Sarykamysh depression.
A total of 36 fish species are known for the Khorezm region. Grass carp, silver carp, common carp, Turkestan barbel, roach, rudd are found among macrophytes and above hard substrates, such as sand, at the riprap of dams, in canals and collectors. Clay or clay-sandy bottoms have gudgeon, ostroluchka, goldfish, and above sand and usually in current are found riffle minnows and Amur stone loach. Close to riprap of dams are also found juveniles of Aral asp, pikeperch and silver carp, and during the spawning period also grass carp, silver carp and Aral asp. Many fish species and their juveniles (common carp, Aral asp, rudd, Aral roach, crucian carp, mosquito fish, barbel, shemaya, riffle minnow) are found in spring and summer in the littoral of lakes and reservoirs. After spawning the adults retreat into deeper water.
TABLE 11. Grouping of Uzbekistan water bodies1/
Group |
Max. surface area (ha) |
Number |
Lakes |
||
1 2 3 |
up to 100 ha 101-500 ha more than 500 ha |
all town and village water bodies, more than 30 13 10 |
Reservoirs |
||
1 2 3 |
up to 100 ha 101-1000 ha more than 1000 ha |
4 10 13 |
1/ without Karakalpakstan
TABLE 12. Uzbekistan lakes of groups 2 and 3
Group 2 |
Surface area (ha) |
Group 3 |
Surface area (ha) |
Amu-Darya basin Khodzhalikul Dongizuldi Uzunsuv Khassakul Kurvanakul Yumalandi Shorkul Koldavkul Chagil Daryalan system Zeikul system Ishakbarat Korpkul Balykkirilgan and Tuzlak Total |
120 150 150 100 150 120 130 60 300 350 470 250 215 190 2 850 |
Syr-Darya basin Sarykamysh Arnasai system Zarafshan basin Dengizkul Tuzgan Shurgak Karakir Amu-Darya basin Kaladzhik system Tazakul Abulkul Ullishorkul Pamidin system Total |
900 17 750 25 000 6 000 2 000 12 000 1 500 2 000 900 2 200 800 71 455 |
Grand Total 74 305 ha |
TABLE 13. Grouping of Uzbekistan reservoirs by size and river basin
Group 1 |
Surface area (ha) |
Group 2 |
Surface area (ha) |
Group 3 |
Surface area (ha) |
Kashka-Darya basin Lyangar Karabag Yangikurgan Shurabsai Total |
70 75 70 38 253 |
Syr-Darya basin Kassansai Karkidon Akhangaran Zarafshan basin Karaultepin Kashka-Darya basin Gissarak Kamashin 50 years of UZSSR Surkhan-Darya Degrez Uchkyzyl Total |
800 950 810
750
410 450 250
230 1 000 5 650 |
Syr-Darya basin Andizhan Tuyabuguz Charvak Zarafshan basin Akdarin Kattakurgan Kuyumazar Tudakul Shorkul Kashka-Darya basin Pachkamar Chimkurgan Talimardzhan Surkhan-Darya basin Yuzhnosurkhan Amu-Darya basin Tuyamuyun Total |
460 000 2 070 4 010
8 450 10 000 1 624 17 500 1 700
1 240 4 550 7 735
6 500
64 000 589 379 |
Running waters of the Khorezm region are inhabited by the rheofilic fish Amu-Darya stone loach, Aral barbel, shovelnose, Aral asp, razorfish, pikeperch. Those with preference for still waters are Aral bream, crucian carp, gobies, rudd, white-eye, pike, roach, ide. The majority of commercial fish species mature in the second or third year (bream, wels, common carp, white-eye, roach, crucian carp, razorfish), and the low-value Turkestan gudgeon, striped bystranka, spiny bitterling, golden spiny loach, stone morokos which lay eggs during the first and second year. Aral asp and Turkestan barbel mature at the age of 4-6 years. Mature males are usually smaller than mature females.
Spawning of the riverine fish takes place during spring and summer. Asp, roach, pikeperch and white-eye spawn over a period of one week to one month, with the whole batch of eggs being released at once. The spawning period of the other species (serial spawners) may extend over 2-3 months.
Starting in mid-April large quantities of fish larvae and some juvenile pikeperch - up to 1.5 million within 24 hours - enter irrigation canals (Table 14). The larvae and juveniles are carried by the current. In May small pikeperch dominate in irrigation uptakes, but the number of fish is lower than in April. On average 200 000 juveniles and larvae enter the irrigation system every 24 hours through the two canals, starting from the pumping station. It is estimated that in May the pumping station lifts 27 million cubic metres of water from the Syr-Darya, and with it 4.5 to 5 million juvenile fish which end on irrigated fields (Table 14). During June-August the bulk of fish pumped into the canals are juveniles, but there are still some fish larvae as well.
TABLE 14. Juvenile fish incidentally pumped out from the Syr-Darya with irrigation water
Time |
Water volume pumped (m3) |
Quantity of juveniles in m3 |
Quantity of juveniles entering irrigation system |
Percent |
Last decade of April | 9 417 600 |
1.5 - 1.6 |
14 to 15 million |
63.6 |
May | 26 956 800 |
0.17-0.19 |
4.5 to 5.0 million |
21.3 |
June | 31 363 200 |
0.09-0.1 |
2.9-3.2 million |
13.1 |
July | 31 872 960 |
0.0105-0.0115 |
340 000-360 000 |
1.5 |
August | 28 571 400 |
0.0025-0.0035 |
90 000-100 000 |
0.5 |
TOTAL | 128 181 960 |
21.8-23.6 million |
100.0 |
In spring, when river water is murky and there is a strong current, the young fish cannot orientate visually and cannot resist the current and therefore enter the pumps. In summer the juveniles are bigger and more capable of resisting the current and in the less turbid water they can avoid the pumps.
Aquatic macrophytes represent a major problem for irrigation canals. This problem has been handled in the Karakum Canal by introducing grass carp. This canal, which branches off the Amu-Darya River, and its lateral lakes, has in the past experienced growth of aquatic plants on a large scale. To sort out the problem, grass carp was introduced in 1958 and released in large numbers in 1960 and 1961. By the mid-1960s, large-scale natural reproduction of grass carp took place and within a few years most of the aquatic macrophytes disappeared. Some problems, however, remained. Selective feeding of the grass carp led to succession in macrophytes, with Myriophyllum spicatum being replaced by Ranunculus, which is considered toxic to grass carp. Charyev (1984) who summarized the experience with the introduced Chinese carps into the Karakum Canal, emphasized the need to protect the higher aquatic vegetation, particularly in cases where macrophytes represent spawning substrate for other fish, such as common carp. The combination of three Chinese carps, viz. grass, silver and bighead, has been considered very suitable for maintaining good water quality, and at the same time the three carp species constitute 75 to 80 percent of the total catch from the canal and its associated water bodies.
Grass carp and silver carp stocks in reservoirs, lakes and irrigation canals depend on a number of variables, such as predatory fish, size of fingerlings of Chinese carps used for stocking, and the character of the water body itself. Good results are obtained if 2-year-old fish are stocked but hydrological parameters such as width, depth, transect of the canal, current velocity in it are also of importance and determine what size of fish to be stocked and when. The density of stocking grass carp will depend on the quantity of aquatic plants present in the irrigation system. Large canals should be stocked with 2-3 year old carps, small canals and collectors with 1-2 year-old. Large canals should be stocked in autumn, small canals and collectors in early spring. During the first year after stocking there is usually little effect on aquatic plants, but results become clearly visible during the second and third years.
Irrigation of the Hungry Steppe soils required construction of many collector canals, of a total length of over 1 000 km. The function of these canals was to collect the residual water from irrigated fields. The water entering collectors from fields has an elevated salinity and this encourages the growth of aquatic plants. Small collectors will overgrow with aquatic plants already during the first year. The first to appear are usually submersed filamentous algae, Potamogeton pectinatus and P. crispus, Zanichellia sp. and in some canals also Naias maritima and Ruppia maritima. Later on sixty percent of these are replaced by the reeds Phragmites communis and Typha angustifolia.
Much of the drainage and collector water is reused. This leads to a gradual increase in water salinity and to salinization of irrigated land. From the annual volume of 19 to 21 km3 of drainage water in the Amu-Darya river basin, 9.7 km3 is returned back to the river. Over the last 30 years water salinity in the lower Amu-Darya has increased to 3 g/l. Such salinity causes problems both in the irrigated fields and in water bodies receiving drainage water.
The lower Amu-Darya lakes and lakes in the Khorezm region of Uzbekistan are fed by drainage and ground water. The lakes of the Khorezm oasis are of three types: those fed by the Amu-Darya water through irrigation systems; those which do not receive the Amu-Darya water but are connected through collectors with other lakes, and those which partially or completely dry out during summer. The chemical composition of water differs. Water salinity ranges from 1 044 to 3 040 mg/l. Those floodplain lakes situated many kilometres from a river, with river water reaching them only in autumn and winter, experience a drop in water levels in spring and summer. This may be accompanied by an increase in water salinity, which negatively affects especially the young of common carp and bream. The pH in floodplain lakes ranges from 7.2 to 8.2, dissolved oxygen concentration from 8.2 to 17.7 mg/l, which corresponds to 90.6 to 198.4 % saturation. In several lakes (Abulkul, Khodzhakulgan and Tokizchokur) the dissolved oxygen concentration at the bottom declines to only 55% saturation in summer. The lakes' ionic composition is dominated by sodium chlorides. They are rich in plyto- and zooplankton. Mysids and freshwater prawns entered the lakes from the Amu-Darya and Syr-Darya and are also consumed by most fish species.
Floodplain lakes of the Amu-Darya in Uzbekistan still have good spawning and feeding conditions for the local fish. At present some 50 species of fish are found in these lakes, and 20 species are of economic importance. While common carp, pike and wels are heavily fished, the low-value species such as roach, dwarf common carp, goldfish, and perch are neglected. As a result, stocks of low-value fish are high. Fish yields in lakes average about 15 kg/ha. Currently, attention is being paid to increasing the fish production of Lake Tuzgan (Dzhizak region) and Ulli-Sharkul (Khorezm region), which cover some 32 000 ha. Management measures proposed are stocking of mysids and introduction of gammarids from the River Don delta and from Mingechaur reservoir. Another proposed measure is to develop combined fish stocks of common, grass and silver carps.
Enhancement of lake and reservoir fish production has become a priority with the collapse of the Aral Sea fishery. In the Khorezm region, situated in the Amu-Darya delta and one of the oldest agricultural areas in the world, there are more than 100 water bodies suitable for fisheries. Since 1974 Khorezm Fish Farm, with 900 ha of ponds, has been producing 2 600 - 2 900 kg/ha of fish. The total fish pond harvest is about 20 000 t/y. The pond area will be expanded to 1 500 ha. Fisheries managers hope also to harvest a total of 5 000 t from open waters of this region. and there are plans to convert lakes with low fish production into managed fish-producing water bodies.
Of the 80 species listed for Uzbekistan reservoirs, twenty have economic importance. A fishery exists on seven reservoirs. The catches change from year to year. In 1970 the total catch from reservoirs was 328.8 t, in 1975-1979 it ranged between 100 and 200t. Reservoir fisheries management has focused on the following:
- introduction of new fish species and fish food organisms
- management of spawning sites, fish protection, improvement of the efficiency of fishing methods
- intensification of fish production in separated or isolated parts of reservoirs
- fish production in the littoral zone
- pond and cage culture.
Reservoirs Kattakurgan, Kuyumazar, Tudakul and Chimkurgan, which have low or no stocks of introduced fish, have also very low yields. Common carp, which forms 15 to 20% of all fish stocks, is the most important economic fish species.
Reservoirs in the semi-desert or desert areas, viz. Farkhad, Kairakkum, Kattakurgan, Kuyumazar, Tudakul, Chimkurgan and Uchkyzyl have a relatively low primary and secondary production and therefore poor fish food resources. In spite of that, the introduced Chinese carps which feed on macrophytes and plankton, became well established in some of these reservoirs (e.g. Chimkurgan). This shows that such reservoirs have good fisheries potential, and that the estimate of natural fish food production should not be based on standing crop but on turnover rate, which, due to the high water temperature and insulation is believed to be high. There is a need for fundamental studies on the primary and secondary productivity of reservoirs, as well as on biology and fish dynamics, both for the native and introduced fish species.
During the 1950s to 1980s the following fish species were released in Uzbekistan reservoirs: goldfish, Aral bream, pikeperch, silver carp, grass carp, bighead carp and some other species of fishery importance. Together with them, 15 species of low-value fish were also incidentally introduced. While the first group of fish was becoming established, the fish of the second group, due to their high adaptability to new conditions, quickly spread though the water bodies of Uzbekistan. As a result, the original fish fauna composition has changed considerably. Some valuable fish species such as khramulya, Turkestan barbel and shemaya, as well as the less valuable Zarafshan dace, ostroluchka, gudgeon, riffle minnow have become rare.
The proposed management measures include stocking of Chinese carps, establishment of artificial spawning substrates, and expanding closed seasons and closed areas. Regular stocking of the common carp and Chinese carps should increase the reservoir fish yield to 40-50 kg/ha, resulting in an annual reservoir fish catch of 1 600 to 2 000 t of fish.
Establishment of reservoirs has had a positive impact on the growth rate of the wild form of common carp. In the Amu-Darya reservoirs Uchkyzyl, Dagrez, Yuzhnosurkhan and Chimkurgan a two year-old common carp ranges between 14.9 and 16.8 cm length, while in the rivers Kafirchirgan, Surkhan-Darya and Amu-Darya (region Termez-Aivaj) the length is only 10.5-12.1 cm. A four-year old carp in Surkhan-Darya and Amu-Darya is 21.3-22.3 cm long, in reservoirs 25.3-28.1 cm. The fast growth rate in reservoirs is noticeable and this is surprising as the carp there feeds on plant detritus. In reservoirs, common carp faces the problem of finding suitable spawning sites, as a rapid drop in water level due to irrigation demands is common. As a result, fertilized eggs of carp, bream, crucian carp and wels usually die. Nevertheless a large fishery development potential exists in Uzbekistan reservoirs and can be realized by regular stocking of hatchery-raised fingerlings. Further intensification is possible through developing semi-intensive fish culture in cages, which could be made largely independent of reservoir water level fluctuation. Induced breeding could be practised on fish other than Chinese carps, such as Turkestan bream and Aral asp, khramulya and snowtrout which require river currents and are migratory. Both conditions are no longer available to them.
Current fish yields of Uzbekistan reservoirs range between 7 and 30 kg/ha and this is considered to be low. At present any increase in catch is achieved through an increase in fishing pressure.
Lakes, as well as reservoirs, have major importance for fish and fisheries. Due to the high silt load, turbidity and fast current, as well as rapid changes in discharge rates, the rivers Zarafshan, Surkhan-Darya and Kashka-Darya have little fishery importance. In summer Kashka-Darya completely dries out while Surkhan-Darya and Zarafshan carry only a small amount of water.
Factors that determine the current low fish production of Uzbekistan reservoirs and other water bodies are still not clear enough to allow formulation of sound management strategies for a steady increase in fish yields. It is probable that each reservoir and lake may require a specific approach. The management measures need to address protection of the existing fishery resources, especially of the riverine fish of the Syr-Darya, Amu-Darya and Zarafshan, current levels of fishing pressure, ways of increasing fish stocks in the individual reservoirs and floodplain lakes. Special attention needs to be paid to small lakes and the potential for converting them into semi-intensive well managed fisheries bodies.
Formation of reservoirs has caused major changes in the riverine fish stocks, and fish species requiring water current (rheophilic fish) have gradually declined. Only those species of backwaters continue to be common. Each reservoir has developed its specific features, determined especially by its morphometry and altitude in which it is situated. Lowland reservoirs, due to their shallowness and water temperatures, have become normally more productive than those situated higher upstream.
Table 15 shows that the highest number of economically important fish species is present in the Syr-Darya basin, followed by Amu-Darya, Zarafshan and Kashka-Darya. Sixteen economic species (equal to 19.2% of the total) have been introduced into the Syr-Darya. In the Zarafshan, the introduced fish species of economic importance represent 20.5%.
In 21 water bodies out of 28 (Table 16), the number of fish species of economic importance in reservoirs and lakes of the four river basins of Uzbekistan range between 44 and 76%. The number of predators ranges from 0 to 5, with a mean predator/non-predator ratio of 8:1 for the total of 28 water bodies.
While lakes have been fished for many years, fishing in reservoirs started with their formation, i.e. largely during the second half of this century. Fishing rights are given to fishing companies and can change from year to year. This contributes to the poor quality of statistical data. This can be seen from the difference between the two sets of data available for some water bodies and collected by two different fishing companies (Tables 17 and 18). Information on catches of individual fish species is not available. Lowland reservoirs usually contain more commercial fish species than foothill and mountain reservoirs and lakes.
The major commercial fish are common carp, Aral white-eye (Abramis sapa), silver carp, bighead carp, pikeperch, grass carp, pike asp, Aral barbel, goldfish and wels. The formation of fish stocks in new reservoirs was influenced by management including introduction of exotic fish species and their food organisms, and by stocking (Table 15). The management has yielded variable results. During the first years the new reservoirs contained less fish than later on when fish started immigrating into reservoirs through the new canals connecting them with other rivers, and more fish species were introduced and stocked. The final result is that the fish fauna in each reservoir has a different set-up, as can be seen for example from the number of predatory and non-predatory fish (Table 16). Nevertheless, the water bodies of Uzbekistan represent an important fish production base. It is well understood that this resource needs to be rationally exploited and managed and that irrigation reservoirs and water bodies resulting from irrigation practices can be further developed for fisheries to maximize the benefits. This includes the production of fish of high quality for which there is a great demand.
TABLE 15. Fish species composition by river basin (Uzbekistan)
Syr-Darya |
Zarafshan |
Kashka-Darya |
Amu-Darya |
|||||
No. |
% |
No. |
% |
No. |
% |
No. |
% |
|
Local commercial species Local non-commercial species Introduced commercial species Local trash fish Accidentally introduced commercial fish Accidentally introduced non-commercial fish Introduced non-commercial fish Total |
24 18 16 17 3 16 1 83 |
28.9 7.2 19.2 20.5 3.6 19.2 1.2 100 |
12 1 8 10 - 7 1 39 |
30.7 2.6 20.5 26.0 - 17.9 2.6 100 |
12 1 5 10 2 5 1 36 |
33.3 2.8 13.9 27.8 5.6 13.9 2.8 100 |
21 4 6 13 2 8 1 55 |
38.2 7.3 10.9 23.6 3.6 14.5 1.8 100 |
TABLE 16. Fish species composition in the individual water bodies of Uzbekistan
Water body |
Total No. of species |
Non-predators |
Predators |
Economically important |
Economically non-important |
||
No. |
% |
No. |
% |
||||
SYR-DARYA basin |
|||||||
Reservoirs: Charvak Tuyabuguz Turk Andizhan Lakes: Arnasai system Sarykamysh |
15 25 4 9
21 23 |
12 21 4 9
16 18 |
3 4 - -
5 5 |
7 13 2 3
14 13 |
47 52 50 33
67 57 |
8 12 2 6
7 10 |
53 48 50 67
33 43 |
ZARAFSHAN basin | |||||||
Reservoirs: Akdarin Karaultepin Kattakurgan Kuyumazar Tudakul Shorkul Lakes: Tuzgan Dengizkul Karakir |
15 9 14 24 24 17
24 23 12 |
13 9 13 22 21 15
21 20 12 |
2 - 1 2 3 2
3 3 - |
7 4 9 16 18 13
18 15 9 |
47 44.4 64 67 75 76
75 65 75 |
8 5 5 8 6 4
6 8 3 |
53 55.6 36 33 25 24
25 35 25 |
KASHKA-DARYA basin | |||||||
Reservoirs: Pachkamar Lyangar Gissarak Shurabsai Yangikurgan 50 years of UZSSR Karabag Kamashin Chimkurgan Talimardzhan |
13 8 6 8 4 8 5 15 20 29 |
13 8 6 8 4 7 5 14 18 24 |
- - - - - 1 - 1 2 5 |
4 3 2 2 3 4 2 8 10 20 |
30 37.5 39 25 75 50 40 53 50 69 |
9 5 4 6 1 4 3 7 10 9 |
70 62.5 67 75 25 50 60 47 50 31 |
SURKHAN-DARYA basin | |||||||
Reservoirs: Degrez Yuzhnosurkhan Uchkyzyl |
17 23 20 |
16 21 18 |
1 2 2 |
7 13 9 |
41 56.5 45 |
10 10 11 |
59 43.5 55 |
TABLE 17. Fish catches (tons) from selected reservoirs of Uzbekistan (Source: fishing company Uzryba)
Reservoir |
Year |
||||
1987 |
1988 |
1989 |
1990 |
1991 |
|
Andizhan Charvak Kattakurgan Tudakul Shorkul Chimkurgan Talimardzhan Yuzhnosurkhan Uchkyzyl Tuyamuyun |
- 8.0 22.8 238.0 42.0 31.0 14.0 15.3 1.0 66.4 |
- 10.0 - 370.7 111.4 27.3 11.3 25.8 1.1 98.1 |
8.0 8.0 184.0 547.0 115.8 60.9 33.9 20.2 3.1 63.1 |
8.0 8.8 16.6 533.1 85.3 72.6 30.1 70.6 - 45.3 |
5.0 8.7 44.0 540.0 63.1 50.4 23.3 - - 3.4 |
TABLE 18. Fish catches (tons) from water bodies of Uzbekistan (Source: fishing company Uzbekrybvoda)
Water body |
Year |
|||||
1987 |
1988 |
1989 |
1990 |
1991 |
1992 |
|
Andizhan reservoir Charvak reservoir Syr-Darya river Arnasai lakes Tuzgan lake Dengizkul lake Karakir lake Dzhizak reservoir Karaultepin reservoir Kattakurgan reservoir Tudakul reservoir Shorkul reservoir Chimkurgan reservoir Talimardzhan reservoir Uchkyzyl reservoir Yuzhnosurkhan reservoir |
- 8.0 - - - - - - 142.8 - 238.0 - 31.0 14.0 0.6 15.3 |
- 10.03 - - - - - - 22.8 - 374.0 - 27.3 11.3 0.7 25.8 |
7.77 8.09 - - - - - - 184.0 - 547.0 44.0 61.8 33.8 3.1 20.2 |
1.84 8.20 37.5 2 558.4 - 258.1 12.3 137.0 16.6 235.1 533.0 - 72.5 24.8 - 70.5 |
0.56 8.04 24.1 1 959.0 1.5 - - 40.1 - - - - 64.3 9.5 - - |
- 4.3 8.1 1 141.4 4.1 117.2 5.3 1.2 1.6 - 492.0 55.1 31.1 3.2 - 30.9 |
During 1990-1993 the fishery was targeting predominantly wild stocks. There still exists a number of water bodies which are not fished, and for others there are no reliable fish catch statistics which would allow us to obtain a better picture on fish species and fish stock densities, and to estimate the sustainable fish production of such water bodies. An estimate of the total fish production from all inland water bodies of Uzbekistan, as given in Table 19, is based on fishery statistics of two fishing companies (Uzryba and Uzbekrybvoda), on information provided by the Government Control Unit of the Government Commission for Nature and on fisheries literature. The statistics show a gradual increase in fish catches over the period 1981-1991. During the first three years, the collapse of the Aral Sea fishery contributed to the decline in fish catches between 1982 and 1983 but afterwards the catches have maintained a range between approximately 7 000 and 8 000 t, with the exception of 1990, when less than 6 000 t was captured. Fish came mostly from lakes, which yielded ten times more fish in 1991 than reservoirs. River fish catch has widely fluctuated, with little fish captured in 1991. At present it is difficult to speculate on the reasons behind this sudden collapse in riverine fisheries.
TABLE 19. Fish catches (tons) - Uzbekistan
Year |
Total |
Lakes |
Reservoirs |
Rivers |
Aral Sea |
1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 |
5 572.7 8 434.0 6 915.3 6 977.9 8 139.2 8 114.6 7 127.8 8 184.8 7 095.5 5 768.2 6 906.0 |
4 318.7 6 878.3 6 150.1 6 274.9 7 299.2 6 716.1 6 493.1 7 060.7 5 101.2 4 699.3 6 267.6 |
236.3 222.4 381.9 415.1 520.3 681.5 396.0 554.9 1 074.0 772.9 612.0 |
174.4 573.3 330.3 187.9 319.7 716.9 238.7 569.2 920.3 296.0 26.4 |
843.3 760.0 53.0 - - - - - - - - |
It is believed that there is much scope for increasing the low fish catches from reservoirs, if suitable management measures are applied. Today's low fish production is considered to be the result of several factors:
(i) existing fish food resources such as aquatic plants, plankton and benthos, are not fully utilized due to the absence or low stocks of species feeding on them, or they may be consumed predominantly by low value or trash fish
(ii) there is a shortage or absence of suitable spawning and nursery sites in reservoirs for fish species of economic importance
(iii) there is a high mortality of juveniles largely as a result of the absence of fish protecting devices on canal intakes; and
(iv) in some reservoirs economically important fish species are absent.
The fishery managers need to target the above problems either individually or in totality, if better results are to be achieved.
Specific fishery management measures for each river basin have been proposed with the objective of optimizing the yields. For Ferghana Valley water bodies, the following mix of species are recommended: (i) those reproducing under the existing conditions (Group 1), i.e. snowtrout (Schizothorax intermedius), Barbus capito, wels, Aral asp, (ii) those to be stocked annually (Group 2), i.e. Coregonus peled, silver carp (as phytoplankton feeder), and common carp (benthos feeder).
For the water bodies of the Zarafshan basin. Group 1: white eye (Barbus capito), Herat khramulya (Varicorhynchus heratensis), goldfish. Group 2: common carp, silver carp, grass carp, Aral asp and pikeperch (the last two are piscivore).
For the first and second group of reservoirs (see Table 11) of the Kashka-Darya basin.
Group 1: snowtrout. Group 2: silver carp, common carp, grass carp and pikeperch.
For reservoirs of the Surkhan-Darya basin. Group 1: white eye (Barbus capito), khramulya, pike perch and wels. Group 2: bighead, common carp.
For all lowland and some foothill reservoirs the species of major economic importance are: common carp, (Barbus capito), khramulya. In some years conditions for their reproduction are very poor and without stocking the production would be extremely low. There is enough potential in the existing fish hatcheries to produce a sufficient amount of stocking material. A better organization of commercial and recreational fisheries would also result in higher yields. It is believed that if appropriate management measures are introduced, 4 to 6 times higher yields, i.e. 30 to 40 kg/ha could be achieved.
Abdullaev, M.A., 1969. Biological basis of national reservoir fisheries in the desert zone of Uzbekistan (river basins of the Bukhara and Kashka-Darya regions). Ph.D. thesis, Tashkent
Abdullaev, M.A. and D.U. Urchinov, 1989. Commercial fish in waterbodies of the lower Zarafshan. Publ. FAN AN Uz SSR, Tashkent
Abdullaev, M.A. and D.U. Urchinov, 1989. Economically important fish in water bodies of the lower Zarafshan River. Pub. FAN, Tashkent
Amanov, A.A., 1963. Ichthyofauna of the waterbodies of the Surkhan-Darya River Basin. Doctor's Diss., Frunze
Amanov. A.A., 1985. Fish ecology of water bodies in the south of Uzbekistan and neighbouring republics. Pub. FAN, Tashkent
Baimbetov, A.A. et al., 1975. Taxonomy and biology of pikeperch from Kapchagay Reservoir. Biol.Nauki, Alma-Ata, Kaz GU, Vol. 9
Berg, L.S., 1948-9. Freshwater fish of the USSR and neighbouring countries
Charyev, R., 1984. Some consequences of the introduction and acclimatization of grass carp, Ctenopharyngodon idella (Cyprinidae) in the Kara Kum Canal. J.Ichthyol. 24(3):1-8 (in English)
Dukravets, G.M., 1976. Ichthyofauna of Tilikul lakes. Abstract in: Biological basis of fisheries of Central Asia and Kazakhstan. Balkhash.
Gladkov, N.A., 1934. Fisheries research of lakes Kamyshlybash. Tr.Aral.otd.Inst.Ryb.Khoz., Vol.3.
Kamilov, G.K., 1973. Reservoir fish of Uzbekistan. Publ. FAN, Tashkent.
Khakberdiev, B., 1983. Fish in reservoirs of the Khorezm District. Publ. FAN AN Uz SSR.
Lindberg, G.U., 1955. Quaternary in the light of biogeographic evidence. Publ. AN SSSR, Moscow-Leningrad.
Maksunov, V.A., 1961. Biomorphology of fish of Farkhad Reservoir. Tr.Inst.Zool.Parasit. AN Taj. SSR, vol. 23
Nikitin, A.M., 1987. Lakes of Central Asia. Publ. Gidrometeoizdat, Leningrad
Nikolsky, G.V., 1949. Fish of the Aral Sea, MOIP.
Nikolsky, G.V., 1956. Fish of the Amur Basin. Publ. AN SSSR.
Taubaev, T., 1958. Overgrowing of irrigation canals in Khorezm District, Central Asia. In: Canals of USSR; Publ.Nauchnaya mysl, Kiev.
(The references, as given by the authors, could not be checked against originals. Any errors are regretted)