by
T. Petr
27 McLeod Street, Toowoomba Qld 4350, Australia
Following the request of the Fourth Session of the Indo-Pacific Fisheries Commission (IPFC) Working Party on Inland Fisheries, Kathmandu, Nepal, 8-14 September 1988, the Secretariat initiated the collation of information on coldwater fish stocks and fishery resources in Asia. The areas and countries of attention were: Himalayas (Bhutan, Nepal, northern states of India within the Himalayas), Western Ghats (India), Karakoram-Hindu Kush (Pakistan, Afghanistan), Pamir (Tajikistan), Tien Shan (Kyrgyzstan, Kazakhstan), Altai (Kazakhstan, Mongolia, China), high altitude areas of Mongolia and those of western China (provinces of Qinghai and Xinjiang [Uighur Autonomous Region] and Xizang [Tibet Autonomous Region]) and Caucasus (Armenia, Georgia, Azerbaijan) (Fig. 1).
Some areas include mixed zones inhabited by both warm and coldwater fish species, for example floodplain lakes of Kashmir (India) and low altitude reservoirs in India at the foothills of the Himalayas, receiving cool waters from mountain rivers. The reservoirs may be subjected to hot summers, which warm up the surface water layers while maintaining a cool water underflow. In rivers of the southern slopes of the Himalayas in India, Nepal and Bhutan, two zones are distinguished: the rhithron, characterised by lower water temperature, high concentration of dissolved oxygen, fast current and turbulent water, and the downstream situated potamon, with higher water temperature, lower dissolved oxygen content, and lower current velocity. While the fish fauna of the rhithron is stenothermic, as represented by the cyprinid schizothoracines and the introduced brown trout, the fish fauna of the second zone is eurythermic or warm-stenothermic. There is no firm separation of these two zones. Large numbers of stenothermic schizothoracines migrate to the potamon zone during winter to avoid extremely low water temperatures higher upstream. On the other hand, some species of potamon enter the rhithron for spawning.
The areas covered by the papers in this document belong to two major zoogeographical complexes: the Palaearctic and the Oriental regions. Fish fauna of high mountain lakes of Pamir and Tien Shan have historical connections with the fish fauna of the high altitude watersheds of Afghanistan, Pakistan, India and Nepal. The fauna is dominated by the cyprinid subfamily Schizothoracini, which is mainly Central Asiatic in distribution, although a few species are present also along the southern face of the Himalayas. The fish fauna of Afghanistan, including water bodies at lower altitudes, has an almost equal mix of Palaearctic and Oriental fish species (Coad, 1981). On the northern boundary of the Asiatic mountain massifs, the fish fauna of rivers draining the Altai mountains belongs to the Palaearctic region; the rivers eventually enter the Ob, which then enters the Arctic Ocean. These waters are dominated by salmonids. Geographical barriers virtually prevent mixing of this fish fauna with that south of it. In Lake Balkhash the ichthyofauna had no contact with the neighbouring faunas of the river Ob basin in the north and the Ponto-Caspian basin in the west and the south. Lake Balkhash was colonised by fish such as marinka (Schizothorax argentatus), perch (Perca fluviatilis) and stone loach (Noemacheilus spp) from the river system of Tien Shan. As no major predatory fish were present among the indigenous species,
when fish were introduced here from catchments of the Caspian, Aral, Ob and Amur, the newcomers dealt with the indigenous fish very rapidly.
The Central Asiatic rivers Amu Darya, Syr Darya and their tributaries, and rivers ending in terminal lakes or disappearing in desert, belong to the Ponto-Caspian complex. Each of the Central Asiatic rivers has typical coldwater fish species. Turdakov (1963) provided a detailed account of fish stocks by zone for these rivers. For the coldwater montane zone he listed 13 species for the rivers Amu Darya, Syr Darya, Chu and Talas, and rivers of the Issyk-kul catchment. These comprise salmonids (1 species), schizothoracines (8), cobitids (3), and sisorids (1). He noted that typical coldwater species predominate at altitudes of 1200-2000 m. Below, and especially above this zone the number of coldwater species declines.
For Western China 190 fish species are listed, most of which belong to the Central-Asia Plateau Complex. The Qinghai-Xizang Plateau includes 112 native species, Xinjiang has 90 species. Introductions in these areas increased the number by 17 and 18 species, respectively. The fauna of the Qinghai-Xizang Plateau is broadly like that of Xinjiang. The native species are a relict of mass extinction in the Quarternary, when uplift of the Himalayas transformed the prevailing low-altitude tropical or sub-tropical conditions to the present cold, high altitude climate. In the large saline Lake Qinghai the fish stocks are highly dominated by naked carp (Gymnocypris przewalskii, Schizothoracini), which until recently, supported a considerable fishing industry. Presently, the stocks are overfished.
The Western Ghats in southwestern India formed at about the same geological time as the Himalayas. In the past they were probably continuous with the Eastern Himalaya, and it is suggested that this was the likely migratory route along which the coldwater fish entered the Ghats. Today, due to the relatively low altitude and the latitude, mahseer Tor khudree is the only indigenous fish of fishery importance with coldwater affinity.
In the Caucasus, Lake Sevan in Armenia was famous in the past for the presence of the salmonid Sevan trout (Salmo ischchan), but the extreme water level manipulation has led to this species almost disappearing. Its successful translocation into Lake Issyk-kul in Kyrgyzstan, although having negative consequences for the indigenous Issyk-kul fish fauna, probably saved this fish from extinction. Introduced pelagic whitefish (Coregonus lavaretus) then became the major commercial fish replacing Sevan trout and Sevan khramulya (Varicorhinus capoeta).
High altitude rivers and streams mostly have a low fish production and hence no importance for fisheries, except at subsistence level. Fishery management of rivers and streams has concentrated on introductions of fish for recreational and sport fishery, with mainly brown trout being stocked. In some streams this exotic fish has established self-sustaining populations. In the Western Ghats, rainbow trout has also been successful in some streams with the same result, but in other mountainous areas of Asia where conditions are suitable, rainbow trout is cultured. Common carp is another exotic which has been widely introduced, and is now stocked regularly in a variety of cold waters, such as Tarbela Reservoir on the Indus River in Pakistan, high altitude lakes in the Western Ghats, and the high altitude (2000 m) ricefields of Arunachal Pradesh in India. Production of marketable size trout on fish farms is still low, as the final product is too costly for wider consumption. The best results with farm production of market-size trout have been achieved in northern Pakistan and in Kashmir (India).
Mountain rivers of Tien Shan and Pamir have largely unexploited fish stocks, as they are poor in species and numbers. Many of such streams and rivers remain a welcome reserve of indigenous fish. Only a few introductions of exotics have been done. The introduction of rainbow trout in some Tien Shan lakes initially resulted in spectacular growth rates, but within several generations the growth rate slowed down, fecundity of females declined, and eventually cannibalism took place. Coregonids (six species) introduced into lakes in northeastern Kazakhstan with the purpose of increasing commercial catches also showed a decline in growth rates in response to the depletion of food supplies.
Multispecies introductions took place especially in water bodies of Kazakhstan. For many years the fish faunas of Lake Balkhash, its major tributary Ili River and Kapchagay Reservoir, situated on the Ili, have been manipulated by introductions and commercial fisheries. The result is that the indigenous fish species now form a meaningless proportion in total fish catches (Petr and Mitrofanov, 1998). In addition, the manipulation of fish fauna in Lake Balkhash, despite scientifically coordinated efforts over many years, has not led to any significant increase in fish landings.
Damming of the Chu River in Kyrgyzstan provided new habitat for reservoir fish and resulted in higher fish production than in the wild river. On the other hand, diversion of water for irrigation reduced the river's flow downstream where it fed a series of lakes in the desert. As a result, these lakes, formerly rich in fish, are now largely desiccated. The profit from the reservoirs just makes up for losses from the lakes. Damming of the Himalayan rivers in India has flooded many spawning grounds of schizothoracines and mahseers (Tor spp) in Pakistan and India, or made it impossible for them to reach spawning grounds.
Culture of coldwater fish is still used largely to produce fingerlings for stocking rivers, lakes and reservoirs - predominantly for sport and recreational fishermen. Until recently, only trout and common carp were produced for stocking. There has been considerable progress in hatchery breeding of mahseer carp (especially Tor khudree and Tor putitora), and less so with schizothoracines, which has led to a slow increase in the number of releases of fingerlings into some waters of India and Nepal draining the southern Himalayas and Western Ghats. In Tien Shan waters, lenok (Brachymystax lenok) can be induce-spawned in hatcheries, but its eggs are still collected from the wild to produce fingerlings in some hatcheries of Kazakhstan. Also in Kazakhstan, marinka (Schizothorax argentatus) and Arctic grayling (Thymallus arcticus) are suitable for hatchery production and coldwater aquaculture, with the first species tolerating saline waters.
In Mongolian waters a number of species have been declining and it is thought that only hatchery production of seed for enhancement of their stocks in natural waters will help them recover. This concerns especially sturgeon (Acipenser baeri baicalensis), the salmonid Hucho taimen, Arctic cisco (Coregonus autumnalis migratorius) and Mongolian grayling (Thymallus brevirostris). However, fish culture and hence any hatchery production in Mongolia are heavily constrained by very cold winters.
Two species of fish have been found suitable for enhancing fish stocks in high altitude lakes of Caucasus: khramulya (Varicorhinus capoeta), and the coldwater Lake Paravan common carp.
The individual papers in this document suggest a number of ways of improving fish stocks and preventing disappearance or possible extinction of some species in cool and cold waters of mountainous regions of Asia. There is general agreement, that protection of catchments should be high on the list of priorities, as well as protecting good water quality through prevention of pollution, from both point and non-point sources. A further priority is the need for enforcement of fishery laws and regulations, which should assist in the preservation of the most threatened fish species. Often stocks of indigenous species can be saved or replenished only with the help of regular stocking of hatchery produced fingerlings. For many such species hatchery production technologies are either unavailable or need to be refined to produce viable fingerlings for releases on a regular basis. Shortage of specialist manpower is often a hindrance to speeding up the development of such technologies.
Coad, D. 1981. Fishes of Afghanistan, an annotated check-list. Publications in Zoology, No. 14. National Museum of Canada, Ottawa. 26pp.
Petr, T. and V.P. Mitrofanov. 1998. The impact on fish stocks of river regulation in Central Asia and Kazakhstan. Lakes & Reservoirs: Research and Management 3: 143-164.
Turdakov, F.A. 1963. Fish of Kirgizia. Academy of Sciences of the Kirgiz SSR. Frunze. 282 pp. (In Russian).
