Thirty-one species and subspecies of fish are of economic importance in Mongolia. In this landlocked country the present annual catch of about 600 t comes mostly from lakes, both freshwater and saline. The estimated commercial fishery potential is 3000 t yr-1, to which should be added an unknown, but probably a fairly substantial subsistence and sport fishery catch. The largest lake, Lake Hovsgol in the Arctic Ocean catchment, has a fishery potential of 200-400 t yr-1. In the past Lake Buyr in the Pacific Ocean catchment, shared by Mongolia and China, had the highest fish production of all Mongolian lakes. However, due to overfishing of the lake as a whole, catches in the Mongolian sector have declined from an average of 537 t yr-1 in the late 1950s, to 40 t yr-1 in the 1996-98 period. Lakes in the endorheic Central Asian Internal Basin have no organised fishery. The current national annual catch of 130 t needs to be substantially increased if the present fish consumption in Mongolia of about 1 kg per person per year is to rise. This could be achieved by improving inputs into the industry and better management. Since 1991 changes to market economy have lead to rapid over-exploitation of fish stocks through private initiatives. Scientific backstopping which would guide fishermen in matters of sustainability and preservation of fish stocks, has been reduced to a minimum. At present Mongolia has no aquaculture, largely due to the extremely harsh continental climate, with annual temperatures ranging from +30oC to -50oC, with long winters and thick ice cover on lakes and rivers. There is a proposal to test in a pilot study the possibility of raising local fish species in hatchery/farm conditions.
Mongolia has over 50,000 km of large rivers suitable for fisheries, and thousands of lakes, the total area of which is about 15,995 km2 (Table 1). More than 3000 lakes are larger than 10 ha, 27 are larger than 5000 ha and 4 are larger than 10,000 ha. The water surface area of lakes represents about 1% of the total area of Mongolia. The total volume of water stored in lakes exceeds 500 km3, of which 380.7 km3 is stored in Lake Hovsgol Nuur(Tserensodnom, 1970) (Fig. 1). The highest number of fish species (43) occurs in water bodies of eastern Mongolia, followed by the water bodies of the Selenga catchment (22 species), and by water bodies in the endorheic Central Asian Internal Basin (8 species). The fish fauna of Mongolia can be separated into three groups according to the above three major drainages.
Water bodies with outlets to the Arctic Ocean are located in northern and northwestern Mongolia. Their catchments cover 20.6% of Mongolia (323,000 km2) and represent 52.1% of the country's aquatic resources. Here belong the catchments of the rivers Shishhid, Selenga and Bulga Gol, with their lakes, and a group of lakes in the Darhat Valley. The drainage area of the Selenga represents close to 90% of the Mongolian Arctic Ocean drainage. It includes the group of Hangayn lakes, with large lakes Hovsgol Nuur (Khubsugul), Dood Nuur (Dood Tsagaan) and Terhiyn Tsagaan (Table 2). Copepoda and Cladocera dominate the zooplankton of these lakes, while diatoms and blue-green algae dominate the phytoplankton. The biomass of zooplankton is in the range of 0.3-33.8 g m-3 in summer, and 0.2-1.52 g m-3 in winter. The rich benthos is represented by many species. The major aquatic plants are pondweed, smartweed, milfoil and duckweed. These lakes are important for commercial fisheries.
Water bodies with outlets toward the Pacific are located in eastern Mongolia and are represented by the River Amur and its tributaries. Here also belong some lakes of the eastern plains without outlets. The region represents 13.5% of the total area of Mongolia and 15.9% of the country's aquatic resources. There are more than 900 lakes in this area. 72% of these lakes are located in catchments of the rivers Onon, Ulz and Halhin Gol. More than 85% of the lakes in this region are smaller than 100 ha. The largest lake is the flow-through freshwater Lake Buyr (615 km2), which has the highest fish production of all Mongolian lakes. The saline Lake Huh, which has no outflow, is of medium size (52.4 km2) and is located at the lowest altitude in Mongolia (560 m).
Copepoda, Cladocera and blue-green algae dominate the plankton. The major aquatic macrophytes are reed and pondweed. Crayfish is common in catchments of the rivers Onon and Balzh. Lakes Buyr and Halhin have the crustacean Leander modestus. The common molluscs are Margarita daurica, Anodonta arcaformis, and Cristata plicata.
Central Asian Internal Basin of Mongolia is the largest of the three regions. It covers 65% of Mongolia and contains 32% of its water resources. It includes the mountain lakes of the Mongolian Altai, water bodies of the Gobi Valley, and some lakes of the Hangayn Mountain plateau. The largest Mongolian lakes are situated in the Gobi Valley, in spite of a very low annual rainfall of only about 100 mm, and a high evaporation rate of 900-1000 mm. This region, bordered in the north by the Mongolian Altai mountains, is endorheic, i.e. it has only internal drainages, not connected to oceans or inland seas. There are three lake complexes within the Great Lakes Valley: the Altai mountain lakes, the Hangayn Plateau lakes, and the Great Lakes.
Altai mountain lakes are situated in valleys of mountain ranges of the Mongolian Altai, Tannu Ola and Hangayn. Of the large lakes Hoton, Horgon, Dayan, Uureg, Achit, Tolbo, Uvs, Hongor-Ulen, all but two are of a flow-through freshwater type. Saline lakes Uvs (20 m deep) and Uureg (27 m deep) are rich in fish.
The Hangayn Plateau lakes are located in the northwest of the Hangayn Plateau, 1700-2000 m above sea level. The largest lakes are Hangayn-Har, Ulaagchnyi-Har, Heh, Oigon, Telmen and Sangiyn Dalai. The first four have fresh water and a maximum depth of 50 m. Rotifers and copepods dominate the zooplankton, with an average annual biomass of
2.8 g m-3. Lake Ulaagchnyi-Har is rich in plankton, but it had no indigenous fish. Three fish species were therefore introduced: northern whitefish, Arctic cisco and Siberian cisco. They have established stocks sufficient to support a fishery. The other lakes are saline and have no outflow. Each of these has its specific plankton, according to the salt concentration.
The complex of Great Lakes includes lakes Hyargas, Ayrag, Har, Har Us and Durgun. The flow-through freshwater lakes Har and Har Us have an average depth of 2-6 m. Hyargas, Durgun and Uureg and some other lakes are saline and have no outflow. Their maximum depth is 80 m. All these lakes have a very similar hydrobiology. Both the freshwater and saline lakes contain fish. Rotifers and copepods dominate zooplankton, the biomass of which ranges from 0.31 to 0.98 g m-3 in summer and from 0.13 to 0.32 g m-3 in winter. Blue-green algae dominate the phytoplankton. Pondweed, yellow water lily and hornwort are the dominant aquatic macrophytes. The fish fauna consists of a small number of species, dominated by the indigenous polymorphic genera Oreoleuciscus and Thymallus. The lakes are rich in waterfowl, muskrat and the Asian beaver.
The lake region of the Gobi basin has over 20 lakes. They are not large and most of them dry up periodically. The largest of these temporary lakes are the saline lakes Boon Tsagaan, Orog Nuur and Ulaan, situated between the Hangayn Plateau and Gobi Altai. All water bodies are shallow (3-5 m depth). Rotifers dominate zooplankton which peaks in July-August. The mean biomass of zooplankton ranges from 1.3 to 2.1 g m-3. Benthic invertebrates are dominated by Phasganophora brevipennis, Diura nanseni, Aeschna affinis, Sympetrum flaveolum, Limnophilus abstrusus and Oecetis ochracea. The lakes are either oligotrophic or mesotrophic. The shallow water of these lakes is relatively warm and rich in aquatic macrophytes, hence it has been proposed to introduce grass carp in them.
For more information on hydrobiology of Mongolian lakes see Dulma (1979). Williams (1991) has reviewed the limnology of Mongolian saline lakes.
Many fish species of Mongolia show great adaptability to a variety of environments. The same species may inhabit both warm and cold waters, fresh and saline, breed in rivers and lakes. In some species this has led to intraspecific differentiation. The highest number of fish species and sub-species (43) inhabits water bodies of eastern Mongolia (43), followed by the catchment of the Selenga (22). Water bodies of the landlocked Central Asian Internal Basin of Mongolia harbour only 8 species. The total number of fish species and subspecies in water bodies of Mongolia is 64. They belong to eleven families: Petromyzonidae (1 species), Acipenseridae (2), Salmonidae (2), Coregonidae (5), Thymallidae (4), Esocidae (2), Cyprinidae (41), Siluridae (1), Gadidae (1), Percidae (1), Cottidae (4).
Mongolian fish fauna forms six distinct faunistic groups. The Arctic group is represented by Salmonidae, Coregonidae and Gadidae. The boreal flatland complex comprises the highest number of species, which belong to Cyprinidae, Esocidae, Cobitidae, Percidae and Cottidae. The boreal submontane group comprises Thymallidae and several genera of the Salmonidae family. The faunistic group of the Asian mountain subregion includes Altai osmans. The old Tertiary complex comprises fish of the pre-glacial era, including Gobio gobio, Pseudaspius leptocephalus, Rhodeus sericeus, Cyprinus carpio haematopterus, Misgurnus anguillicaudatus, Parasilurus asotus. The group of the flatland fish fauna of eastern Mongolia and the immediate vicinity of the Chinese Autonomous Region of Inner Mongolia is most variable and comprises Saurogobio amurensis, Pseudorasbora parva, Erythroculter mongolicus, Hemiculter leuciscus warpachowskii and Hemibarbus maculatus. The fish fauna of eastern Mongolia is related to that of the upper Amur and that of the Lake Dalai Nur basin. Fish fauna of this lake includes two endemic genera, each represented by a single species: Mesocottus haetej and Pseudaspius leptocephalus, and by four endemic species: Esox reicherti, Acipenser schrencki, Coregonus chadary and Hemiculter leuciscus warpachowskii.
The fish fauna in the Shishhid River basin and in the River Hovd (Kobdo) is conspicuous for the absence of Salvelinus. The close similarity of the fish faunas of water bodies in the Darhat Basin, Selenga and Orhon rivers, and water bodies of eastern Siberia is the result of close hydrographic connections and similar climate. The presence of Oreoleuciscus and Thymallus both in the catchment of the River Hovd and in that of the upper Ob suggests that these today separated areas were connected in the past.
The following part deals with the fish species of fisheries importance, their biology and ecology. For more information the reader may wish to also consult Shatunovsky (1983) and Travers (1989).
Arctic lamprey - Lampetra japonica
This uncommon species is present in the eastern Mongolian rivers Barh, Balzh, Hurh and Onon. It prefers sites with stony or sandy bottom, shaded by riparian vegetation. It is not very active during the day, when it is usually attached by its sucker to rocks or submerged wood. The larvae inhabit muddy parts of rivers with slow current, usually being present in old river arms and little embayments. The fish do not migrate over long distances. Arctic lampreys spawn in May/June on stones and coarse sand, in fast current. For spawning the fish gather in groups of ten to forty. The spawning takes place in the dark. Spawning nests are 6-9 cm deep and 22-30 cm long. The mean fecundity is 9000.
In the upper course of rivers Barh and Hurh, Arctic lampreys reach a length of 200 mm, and their larvae reach 130-147 mm before they change into adults, which takes 4-5 years. The fastest growth of larvae takes place during the first year, when they may reach a length of 65 mm. Arctic lampreys feed on small aquatic invertebrates, algae and organic matter contained in detritus.
It has been proposed to enhance lamprey stocks through artificial reproduction and stocking, as many valuable fish species, such as sturgeon, taimen, pike, burbot and perch feed on them. Arctic lamprey has a high quality flesh rich in fat. In Mongolia it is usually prepared as baked fish.
Two species of sturgeon inhabit waters of Mongolia: Amur sturgeon (Acipenser schrencki) and Siberian Baikal sturgeon (Acipenser baeri baicalensis). The former occurs only in some sections of the River Onon, adjacent to Russia. The second species is common in Mongolia in the River Selenga and its tributaries where it reproduces.
Amur sturgeon - Acipenser schrencki
Amur sturgeon is confined to fresh waters. The fish prefers straight stretches of river with sandy or stony bottom. Like other sturgeons, it reaches sexual maturity late, at the age of 11-14 years for females, and 8-10 years for males. It spawns in May/early June at a water temperature of up to 10oC. Fecundity ranges from 27,640 to 433,940. The largest specimen captured in the River Amur had a weight of 56 kg, length of 204 cm and was 38 years old. Amur sturgeon feeds on benthic organisms. It is a highly prized fish, for both its eggs and the flesh. It is rare in the River Onon, which is the only river in which it occurs in Mongolia. It is not fished commercially.
Siberian Baikal sturgeon - Acipenser baeri baicalensis
The River Selenga is the major spawning ground for Baikal sturgeon, which undertakes spawning migrations in this river. In Mongolia it enters rivers Orhon, Tula and Dergen Moron. There are two migrations during the warmer part of the year: one starts in the second half of April at a water temperature of 3-5oC. This migration ends in mid-June. The second migration, which is the major migration of this sturgeon, starts at the end of July and it ends in mid-September. This migration coincides with summer floods in the Selenga. With declining water temperature the migration stops. Sturgeons have often been observed to overwinter in deep pools of the Selenga and its tributaries. In both migration periods the migrants include sexually mature individuals as well as younger fish. Apart from the migrating sturgeon there is a non-migrating sturgeon population in the rivers Orhon and Tula of the Selenga catchment.
Males reach sexual maturity at the age of 15 years when they are 100 cm long and weigh 7 kg. Females become sexually mature when they are about 20 years old (length 130 cm, weight 14 kg). Sexually mature females 26-27 years old, with a body length of 142-144 cm and a weight of 10 kg or more, are caught at the confluence of the rivers Chuluut, Ideriyn and Dergen Moron, which form the head catchment of the Selenga.
In the Selenga drainage the Siberian Baikal sturgeon spawns from the second half of May to early June when the water temperature is between 10 and 15oC. It spawns on rocks, stones and coarse sand. In the Mongolian stretch of the Selenga females produce 70,000-832,000 eggs. Baikal sturgeon are captured when they are 100-130 mm long and weigh 7-13 kg. Some captured fish were 140-150 cm long and up to 35 kg in weight, with the oldest fish being 28 years old (Dashdorzh, 1976). Baikal sturgeon feeds on chironomid larvae, oligochaetes and larvae of caddis flies.
In Mongolia this species is protected, but its protection needs to be better enforced, especially at its wintering sites. More effort should be spent on enhancement of its stocks through regular stocking of juveniles produced in hatchery conditions.
Taimen and lenok are two native salmonid species of Mongolia. Both are important angling fish.
Taimen - Hucho taimen
Taimen inhabits the rivers Shishhid, Selenga and Amur and some of their tributaries. The fish prefers mountain streams and sub-montane rivers with clear, well-oxygenated cold water. It prefers deeper waters near sand banks, close to a confluence. Taimen makes two migrations. In spring it migrates upstream for spawning; for example, in the Darhat Basin it migrates from lakes into the Shishhid, Tengis and some other rivers early in May. In autumn it migrates downstream to lowland river courses and enters lakes. In summer taimen is present in the upper course of the River Herlen, some 200-250 km downstream from its sources (Dashdorzh, 1976). Taimen remains in the upper course of the Herlen until the end of September because of the abundance of food such as minnows and fry of Arctic grayling. The autumn downstream migration usually starts at the end of September and it depends on water temperature and on the presence of fish on which it feeds. A similar lake/river-lake migration takes place between Lake Buyr and the Halhin Gol. The warming up of the lake water in summer drives taimen away, while in winter the fish return back to the lake and are fished.
The piscivorous taimen starts spawning in the second decade of May when water temperature reaches 10oC. The spawning takes place in deep sections of rivers and in lakes. One female produces between 8400 and 53,000 eggs. Taimen is a fast growing fish. Twenty-two to thirty-four years old fish captured in the Shishhid catchment were 120-150 cm long and had a weight of 10-35 kg. The oldest fish captured was 60 year old and weighed 45 kg. In the drainage of the Selenga the largest taimen captured was 180 cm long and weighed 45 kg. In the past, specimens of 160 cm and 40 kg were captured in the River Orhon (Dashdorzh, 1976). For the growth rate of taimen see Table 3.
Thirty-three parasitic organisms have been identified from taimen. The most common are: Tetraonchus huchonis, T. skrjabini, Gyrodactylus taimeni, Basanistes huchonis, B. woskoboinikovi, and Trachelobdella taimeni. In Mongolia, the highest number of parasites are found in taimen from water bodies draining into the Arctic Ocean.
Taimen is a valuable commercial fish species, well appreciated especially by anglers. This is due to the delicate taste of its flesh, its large size, and its fighting behaviour during angling. A special angling licence is now required to capture taimen in Mongolian waters. This is because the numbers of taimen in many water bodies have been declining. In lakes of the Darhat Basin taimen represents 1.5% of the total catch, but in Lake Buyr only 0.1%. Decline in catches has also been recorded for the Mongolian rivers Onon, Herlen, Selenga, Orhon and Tula. Current measures taken to preserve taimen stocks are the imposition of a minimal size at 70 cm, and ban on small mesh-sized nets. Fishing is banned on spawning grounds. Hatchery production of seed for stocking is also being pursued.
Lenok - Brachymystax lenok
Lenok, also called Central Asian trout, is present in all waters of Mongolia except the landlocked Central Asian Internal Basin. Lenok prefers the same water bodies as taimen: rivers with well-oxygenated cold and clear water. Lenok overwinters in Lake Buyr and spends the rest of the year in the River Halkin Gol and its tributaries. In Lake Hovsgol Nuur lenok is most common near the inflows of large rivers into this lake, e.g. the Ih-Hanha, Ih-Horoo, Alag-Tsar, and Uvur-Hachim. Lenok usually occupies waters down to 30 cm depth, but sometimes it frequents the offshore lake areas with depths of 60-80 m.
Lenok spawns from the end of April to the end of May at a water temperature of 5-10oC. Females produce 2200 to 7000 eggs. Lenok growth rates may differ from water body to water body. In water bodies of the Darhat Basin the grown fish range from 400 to 600 mm, with a weight of 1.8 to 3.8 kg. In the River Onon catchment and in Lake Terhiyn Tsagaan eight- to twelve-year-old fish are 22-66 cm long and weigh 250-3200 g. The slowest growth has been recorded in Lake Hovsgol Nuur (Table 4).
Lenok feeds on benthic organisms and on non-commercial fish such as stone loach, minnow and dace.
Twenty-three parasitic organisms have been identified from lenok. These include: Tetranchus grosdevi, T. lenoki, T. rodersi, T. roytmani, T. ergensi, T. sp., and Gyrodactylus lenoki (Ergens, 1971, 1971a).
Lenok is a major commercial fish species, also sought by anglers. Currently, there is little commercial fishing for this species. Lenok dominates fish stocks in the deep lake Hovsgol Nuur, the deepest lake of Mongolia where the yield is 3 kg ha-1. In the past, 24 t were captured annually using beach seines. In summer lenok is dispersed throughout the lake, which makes fishing at that time uneconomic. In lakes of the Darhat Basin lenok represents 5.8% of the total catch. In Lake Buyr the proportion of lenok in catches is negligible.
Five species of coregonids inhabit Mongolian waters. Three of them have been introduced: Arctic cisco, northern whitefish and Siberian cisco. Arctic cisco does well in lakes Hovsgol Nuur and Ulaagchnyi Har. Northern whitefish now reproduces in the lakes of Hangayn and Altai mountains, and Siberian cisco has been introduced in the mountain lakes of Altai.
Siberian whitefish - Coregonus lavaretus pidschian
This is a major fish species in the Darhat Basin. It appears in three forms. The lake form is present in lakes of the Shishhid River catchment, and the lake/river form in Lower Shishhid and Tengis rivers. A dwarf form is also present in these water bodies.
In spring and summer Siberian whitefish prefers warm water areas near river banks and lake shallows rich in food. In mid-August the lake form of Siberian whitefish starts spawning migration from lakes Targan, Harmai and Dund into the River Shargyn Gol. The lake/river form of the River Tengis starts its migration to the lower course of the River Shishhid in early October. The lake form of Siberian whitefish returns to Lake Dood Nuur after spawning in the second half of September. The lake/river form remains in its river-spawning grounds. During winter Siberian whitefish stays in a number of bays of Lake Dood Nuur and close to the inflows of the rivers Upper and Lower Shishhid into the same lake. Siberian whitefish of the River Selenga and its tributaries starts upstream spawning migration in mid-August.
The lake/river form and the lake form spawn at different sites and at different times. The required water temperature for spawning is 10-12oC for the lake form and 4oC or less for the lake/river form. The spawning period lasts from the second half of August to the second decade of October. In the Darhat Basin water bodies females produce between 4956 and 33,372 eggs (Table 5). The average fecundity is similar to that of the Siberian whitefish in Siberian waters. In the River Ob it is 6848-29,429, and in the River Khatanga it is 12,680-21,720 (Moskalenko, 1971). Siberian whitefish matures when 5-7 years old and about 38 cm long. The dwarf form females reach sexual maturity in the third year and males in the second year, at a body length of 17 cm and a weight of 160 g.
The average length of spawning males is 359 mm and of females 382 mm. The average body weight excluding gonads and viscera is 571 g (males) and 687 g (females). The growth rate in Mongolian waters is variable (Table 6). In water bodies with commercial fishery, such as Darhat Basin, older age groups are missing and 3-6 year-old fish dominate the catches, with 60% of the total.
The older Siberian whitefish of rivers and lakes feed mostly on benthic organisms. Plankton is the major source of food for young fish up to two years old. Some 30 species of food organisms have been identified as food items of Siberian whitefish of the Darhat Basin, indicating that Siberian whitefish has a broad feeding adaptability.
The Darhat Siberian whitefish is a major commercial fish. Much of the captured fish is salted and cold-smoked, some are refrigerated. Fish fat is an important by-product of the fish processing.
Extensive management of fish stocks appears to be the best approach to a sustainable fishery for Siberian whitefish. Hatchery-produced fry and fingerlings should be regularly stocked in open waters. When established, such specialised Siberian whitefish hatcheries should take into account two factors: firstly that males produce only a small quantity of milt, secondly, female ovaries remain in the fifth stage of ripeness for only a short time.
Chadary whitefish - Coregonus chadary
In Mongolia this fish appears in the drainage area of the River Onon and its tributaries Barh, Balzh and Hurh. It is especially common in the fast current of the upper river courses. With the declining water temperature in autumn chadary migrates downstream and at the end of autumn or in early winter the larger fish begin to migrate again upstream. In the River Onon catchment chadary matures at a length of 40 cm and a weight of 800-900 g. It spawns in October-November. Fecundity is from 10,348 to 68,000, with an average fecundity of 33,000 (Table 7).
In rivers Onon, Barh and Hurh, some 7 to 10 year-old fish were 308-510 mm long and of a weight of 320-1320 g. Chadary is not a commercial fish, but it is caught by recreational fishermen.
Arctic cisco - Coregonus autumnalis migratorius
In Mongolia, Arctic cisco inhabit the catchment of Lake Hovsgol Nuur where the fish was introduced from Lake Baikal. Fourteen million larvae were released in the northern part of the lake in 1956-1957 and another half a million larvae were released in the southern part in 1980. In the following years the fish was introduced in the deep Lake Ulaagchnyi Har, situated in the Gobi Desert in the Dzavhan aimag (aimag = province). The broodstock from the first releases in 1956-1957 have produced about ten new generations.
Arctic cisco keep to the bottom of lakes Hovsgol Nuur and Ulaagchnyi Har where during summer they inhabit 20-30 m depth. In autumn mature fish start spawning migration into rivers. In Lake Hovsgol Nuur Arctic cisco mature at the age of 7+ years. After returning to lakes, they overwinter in a depth of 20-30 m. The first mature females were recorded in 1975 (body length 340-395 mm, weight 500-752 g). Fecundity of Arctic cisco increases with age, both in the fish introduced in Lake Hovsgol Nuur, and in Lake Baikal, its place of origin (Table 8). In Lake Ulaagchnyi Har the first spawning females produced a much lower number of eggs than females in Lake Baikal. Spawning takes place in September-October. Of the 96 rivers entering Lake Hovsgol Nuur, only two, Ih-Hanka and Alag-Tsar, offer natural spawning grounds for this fish.
The absence of commercial fishery for Arctic cisco in Lake Hovsgol Nuur allowed the fish to establish stocks of a wide range of age groups of up to 20+ years. Arctic cisco populations in lakes Hovsgol Nuur and Har Nuur do not differ from those of Lake Baikal.
The following parasites have been collected from Arctic cisco from Lake Hovsgol Nuur, age groups 6+ to 13+, body length 308-425 mm, weight 640-1200 g: Diphyllobotryum dendriticum, Tetracolyte intermedia, Dermocystidium sp., Cyanthocephalus truncatus, Cystidicola farionis, the last being a major nematode parasite of this fish (Pronin, 1976).
In Lake Hovsgol Nuur Arctic cisco is confined largely to the Hanhin Bay. Even without a commercial fishery for this fish, its stocks are increasing only very slowly. The limiting factors are the unfavourable water level fluctuation in rivers with spawning grounds, limited spawning areas, and freezing of spawning grounds during winter. Its eggs are preyed on by other fish.
There are plans to produce 100 million eggs annually, which would result in a commercial yield of about 25 t of Arctic cisco per year. A hatchery and fish farm are planned for Lake Hovsgol Nuur. They should produce sufficient stocking material of several coregonid species for all those water bodies of Mongolia still lacking in fish. It is expected that Arctic cisco will naturally reproduce in other lakes in Hangayn and Altai mountains. Spawning stocks in lakes Ulaagchnyi Har and Baga Nuur are fish of 1+ to 9+ age groups, with a prevalence of the 4+ to 8+ age groups. Body length of spawners ranges from 360 to 600 mm and weight from 400 to 2900 g (Table 9).
Northern whitefish - Coregonus peled
Owing to its adaptability, northern whitefish can be successfully introduced to a great variety of water bodies. From 1978 onwards it has been introduced in water bodies which have previously lacked any fish. In 1978 twenty-five thousand northern whitefish larvae were released in the Naiman Nuur lake complex in the Ovor-Hangtay aimag, and another fifty thousand in 1979. In 1980-1983 northern whitefish larvae were also released in lakes Ulaagchnyi Har, Baga and Zhaahan on the Hangayn Plateau. The Altai water bodies of the Lake Hongor-Ulen system (Har, Toson, Hongor) in the Bayan-Olgiy aimag, which previously
had very poor fish stocks, were stocked with northern whitefish larvae in mid-May 1981, and several six-months-old fingerlings of up to 50 g were added in summer of the same year. In 1991 and 1996 fish were collected from Lake Ulaagchnyi Har for analysis of their meristic characters. The analysis showed that Coregonus peled and Coregonus autumnalis migratorius have produced hybrids in this lake (Dulmaa et al., 1998).
Northern whitefish have adapted well to the conditions in Mongolian lakes. Early in October the fish begin to migrate to spawning grounds in the littoral and in winter they enter deeper waters. Yearling northern whitefish weigh 25-70 g, and adult fish weigh between 295 and 4500 g, corresponding to a length of 323 and 705 mm, respectively. In the early 1990s the captured northern whitefish ranged from 1+ to 10+ age groups but the major part of the stock consisted of individuals in age groups 1+ to 5+. In its new environment, which has a pronounced continental climate, the fish reach sexual maturity in the second year and some even in year 1+.
The spawning season coincides with the time when ice starts forming on the water surface. It takes place in November-December when the water temperature descends to 1.8-2.5oC and it peaks when the temperature under the ice is between 1.5-1.0oC. Northern whitefish spawn on sand or stones at a depth of 1.5 to 4.0 m. Fecundity increases with the length, weight and age of the fish (Moskalenko, 1971). In Mongolian lakes the fecundity fluctuates between 4400 and 120,000 eggs (Table 10).
The growth rate of northern whitefish depends on water temperature and on the availability of food. The fish grows fast in the Naiman Nuur lake system, and in lakes Ulaagchnyi Har and Baga Nuur. Growth rates of the northern whitefish for Mongolian lakes and water bodies of Siberia are shown in Table 11. Introduced fish grow fast in their new environment due to the ready availability of food there. The initial fast growth period is usually followed by slower growth rates (Popkov, 1980).
In Mongolian water bodies northern whitefish feed all year. Planktonic crustaceans, gammarids, chironomid larvae and molluscs are the major food. The condition coefficient of adult fish is 1.1-1.8. Northern whitefish are now fully adapted to Mongolian lakes where they are now feeding on the formerly unused food. Broodstock fish are now present in all lakes, where they are producing sufficient numbers of offspring for stocking other water bodies of Mongolia, as well as sustaining fisheries. The northern whitefish stocks are still increasing. It has been recommended that commercial fishery targets fish up to three years old, i.e. those which grow fastest. To maintain the stocks at sufficient levels, selected water bodies should be regularly restocked. This should provide sufficiently strong stocks 1-2 years old for the fishery.
Four grayling species occur in Mongolia. Two of them, Mongolian grayling and Kosogol grayling, are endemic.
Mongolian grayling - Thymallus brevirostris
Mongolian grayling is a Tertiary relic. It is present in catchments of the Hovd and Dzavhan rivers and in lakes Hoton, Horgon, Horomdog, Dayan, Tolbo, Hongor-Ulen, Har Us, Har Nuur, Ayrag and Heh Nuur, and in rivers that flow to the Great Lakes Valley. These water bodies are remnants of a huge water body which existed in this area during the Tertiary. They are poor in number of fish species.
In summer Mongolian grayling is present mainly in the mountain rivers and lakes. In mountain lakes, the fish is scattered throughout the water body and at all depths. In autumn, with declining water temperature, it starts migrating from mountain rivers to mountain lakes. In the Hovd catchment the species migrates downstream to overwinter in the deep water layers of Lake Hovd and in lakes Har Us and Har.
Mongolian grayling matures at the age of 5-6 years. Spawning in the major rivers and their tributaries begins in early May at a water temperature of 4-6oC. It takes place late in the evening and early in the morning. Broodstock starts its migration to spawning grounds as soon as the ice begins to break and thaw, sometimes even earlier. It spawns on stony bottoms. Females which spawn for the first time produce about 2000 eggs; their fecundity increases with age. Twelve-year-old females produce up to 18,000 eggs. In the high-mountain lakes Hoton, Horgon and Horomdog where fish grow fast the females have a high fecundity (Table 12).
Mongolian grayling is the largest species of all graylings that occur in Mongolia. In the high-mountain lakes of the country the fish may reach an age of 17 years but in other lakes and in rivers they seldom live longer than 8 to 9 years. The oldest fish are about 700 mm long and weigh up to 4 kg. The maximum body size and weight of the fish in the same age group vary greatly from water body to water body (Table 13). Differences in growth rates and life span are due to the different living conditions, particularly the food supply.
Mongolian grayling is omnivorous, occasionally predatory. It feeds also during the spawning season. The fish can be captured on fly bait. It is a common fish in waters of the Central Asian Internal Basin. In autumn and winter it forms large shoals at the entrance of rivers and streams into lakes.
Sixteen types of parasites have been identified from this fish. Cestodes, trematodes, nematodes and copepodes are the most common parasites. The following parasites have been identified from the fish of the Great Lakes Valley: Diphyllobothrium dendriticum, Proteocephalus thymalli, Salmonicola thymalli, Crepidostomum metoecus, Ichthyocotylurus sp., Diplostomum sp. Six helminths were found on the fish from water bodies of the Altai Mountains: Diphyllobothrium dendriticum, Proteocephalus thymalii, Diplostomum sp., Cotylurus sp., Echinorhynchus borealis, Piscicola geometra.
Mongolian grayling is a valuable fish. Water bodies in the catchment of the River Hovd could yield up to 50 t per year of grown up fish. Once commercial fishery for the Mongolian grayling is started the stocks should be regularly enhanced through stocking hatchery-produced fingerlings.
Arctic grayling - Thymallus arcticus
The omnivorous Arctic grayling is a common fish in Mongolian waters draining into the Arctic Ocean. Its spawning migration usually starts late in April or early May and lasts until mid-May. Spawning grounds are located in the smaller fast-flowing mountain streams. The optimal spawning water temperature is 6-12oC and the preferred spawning substrate is stones or coarse sand. In the lakes of the Darhat Basin mature females have an average body weight of 160 g and produce about 1500 eggs, but in Lake Terhiyn Tsagaan the number of eggs is 5000-10,000.
The size and weight of adults fluctuate within a wide range of 160 to 350 mm, and 250 to 560 g, respectively. The maximum weight recorded for Arctic grayling in Mongolia was 1900 g (length 45.3 cm), for a fish captured from Lake Terhiyn Tsagaan. At present the fish is caught only by sport fishermen but in the past it used to be commercially exploited in the lakes and rivers of the Darhat Basin, where it represented about 1.4% of the total catch. The low catch was the result of this fish species being fished for mainly in winter when it was dispersed. Fishing in autumn and spring, when the grayling congregates in some places, would result in higher catches. This refers not only to Lake Terhiyn Tsagaan, but also Lake Hovsgol Nuur and some other water bodies in the River Selenga catchment.
Kosogol grayling - Thymallus arcticus nigrescens
Kosogol grayling (Kosogol is another name for Lake Hovsgol Nuur) is present only in Lake Hovsgol Nuur and its inflowing rivers. It is a very common fish of the littoral, down to about 25 m depth. In summer (July, August) part of the fish stock consisting mainly of immature fish, remains in the surface layer of the pelagial, while the other part of the fish stock descends down to 60-80 m. Kosogol grayling stocks contain early and late spawning groups. The former spawn from mid-May until mid-June. The spawning takes place in the evening at a water temperature of 6.8-10oC in rivers entering the lake. The late spawners lay the eggs in littoral down to 5 m depth in July-August. The water temperature required for spawning of the late-spawning Kosogol grayling is 7-14oC. Fecundity ranges from 1133 to 4220.
The oldest Kosogol grayling ever recorded in Mongolia was 11 years old and it was captured in Lake Hovsgol Nuur. By the end of the third year both males and females reach a body length of 180-200 mm. Ten-year-old fish are 310-350 mm long. In Lake Hovsgol Nuur Kosogol grayling grows more slowly than graylings in other waters. In their fourth year females weigh 85-100 g and males 58-100 g. Females reach a maximum weight of 330 g when 9-10 years old, but males of the same age weigh much less.
Kosogol grayling is an omnivore, feeding predominantly on plankton. Fifteen parasites have been identified from this fish by Pronin (1976): Chloromyxum thymalli, Microsporidiae gen. sp., Henneguya cerebralis, Protozoa fam., Trichodina sp., Tetraonchus borealis, Cyathocephalus truncatus, Diphyllobotrium dendriticum, Proteocephalus thymalli, Crepidostomum farionis, Diplostomum spathaceum, Cystidicola farionis, Echinorhynchus borealis, Piscicola geometra, and Salmincola thymalli baicalensis. Of these the most common are Tetraonchus borealis, Diphyllobotrium dendriticum and Proteocephalus thymalli.
There is almost no commercial fishery for Kosogol grayling in Lake Hovsgol Nuur. There are plans for enhancing the fish stock through stocking hatchery-produced fingerlings as well as plans to improve the conditions for their natural reproduction. Even with such management, because of the slow growth rate of the fish, the upper limit of the annual catch would not exceed 100 t which would be equivalent to a yield of 2 kg ha-1 yr-1.
Amur grayling - Thymallus arcticus grubei
This grayling occurs in catchments of the following rivers: Onon, Balzh, Barh, Hurh, Eg, Turgen, Kerulen and Halhin Gol. In winter the fish stays in the main channel of rivers and in summer it keeps to the fast current of rapids.
Spawning migration starts in late April or early May when the water temperature is 2.5-10.5oC. The fish spawn in May/June. The maximum fecundity is 3000. In the rivers Barh, Hurh and Turgen 2+ to 7+ year old fish dominate the stocks (Table 14). Fish in the River Turgen have the slowest growth rate.
Amur grayling usually reaches a length of 305 mm and a weight of 320 g. It feeds on benthic organisms. In catchments of the rivers Kerulen, Onon, Balzh and Hurh it is fished by anglers. Current stocks of this species in these rivers appear high enough to allow its commercial exploitation.
Pike - Esox lucius
Pike is a common fish in Mongolian waters where it appears in rivers of the Selenga catchment and in lakes Terhiyn Tsagaan and Ugiy. No pike live in water bodies of the Darhat Basin and in Lake Hovsgol Nuur. During much of the year pike is dispersed. In summer and autumn it forms shoals in the inflows of rivers into lakes. Shoals also form in early spring during the spawning season. Pike do not migrate.
Pike start spawning as soon as the ice is gone, i.e. in mid-April, and they spawn until the second half of May. The water spawning temperature is 3-6oC. The fish prefer to spawn on sand or submerged aquatic plants. In the lower course of the River Selenga pike of 360-900 mm length have a fecundity of 7400-270,560. In Lake Ugiy pike of 7+ years, with a body length of 650-720 mm, have a mean number of eggs of 88,000, and those of 3+ have 23,700 eggs. Pike eggs measure 2.1-3.5 mm across.
Pike seldom exceed 1 m in length. In the River Selenga and in lakes Ugiy and Terhiyn Tsagaan pike grow fast regardless of the presence of other predators, such as taimen, lenok, perch and burbot, with which pike has to compete for food. The weight and length growth parameters of pike in these water bodies are similar to those in other water bodies of eastern Mongolia and China (Table 15).
The fast growth of pike is an indication of favourable conditions in Mongolian water bodies. Pike feed mainly on minnow, dace, roach, perch, crucian carp and stone loach.
Four species of parasites have been identified from pike in Mongolia: Tetraonchus momenteron, Gyrodactylus lucii, Camallanus lacustris and Raphidascaris acus. With the exception of Camallanus lacustris, they are narrowly specialised parasites of the pike (Moravec and Ergens, 1970). Pike is considered to be a useful fish to have as it feeds mainly on fish of no commercial or angling importance, and often on sick fish and those weakened by parasites. The size of fish which pike feeds on ranges from 8 to 45%, but usually 20-30%, of the body length of pike. Smaller pike exert good control over trash fish, therefore one should target preferably the larger and older pike.
In the catchment of the Selenga pike is caught by anglers and commercial fishermen. It is very common in lakes Ugiy and Terhiyn Tsagaan where it represents 25-30% of the total annual fish catch.
Amur pike - Esox reicherti
This pike is present in all water bodies of Mongolia draining toward the Pacific. This includes rivers Onon, Balzh, Barh, Kerulen and Halhin, and lakes Buyr and Bayan. The Amur pike spawning season depends on water temperature. Usually the fish spawn in April/May during the rainy season on flooded floodplains. In Lake Buyr females of a length of 425-920 mm and a weight of 900-5500 g have a fecundity of 30,080 to 131,200, with a mean of 79,210 eggs (Table 16). This is similar to the fecundity of Amur pike from some other lakes and from the River Amur. Mean fecundity of Amur pike is 18 eggs per 1 g of body weight of a female.
In Lake Buyr and in the rivers Degee and Halhin Gol, Amur pike is known to reach 1500 mm and an age of 15-16 years. The usual length of Amur pike captured from Lake Buyr is between 500 and 920 mm, corresponding to a weight of 900 to 5500 g (ages 2+ to 9+) (Table 15).
Amur pike feeds on the same food as Esox lucius. Only one parasitic species - Raphidascaris acus - has so far been recorded from Amur pike in Mongolia (Moravec and Ergens, 1970).
In Lake Buyr Amur pike is an important commercial fish. It represents 25 to 56% of the total in commercial catches. For the period 1974-1977 for the Mongolian sector of Lake Buyr pike represented 24 to 56% of the total catch with catches of 23.7 to 56.2 t yr-1, fished mostly by beach seines. Afterwards, catches of pike declined and during 1978-1990 they were between 13.5 and 33.1 t yr-1
Siberian roach - Rutilus rutilus lacustris
In Mongolia this roach appears both in rivers (Selenga, Orhon, Tula, Bulgan - all in western Mongolia, and in Chuluut, Suman, Eree, Haraa, Ider) and in lakes (Hovsgol, Ugiy, Terhiyn Tsagaan, Dood Nuur in the Darhat Basin). In summer Siberian roach in lakes remains on the littoral and in the inflows of large rivers. In winter it prefers deeper lake water. In Lake Hovsgol Nuur it overwinters at a depth down to 15 m. In spring roach migrates into shallow bays and to rivers entering the lakes. In Mongolian rivers roach prefers the middle and lower courses with slow current, rich in submerged plants.
In Mongolia Siberian roach spawns in rivers in shallow bays with soft vegetation, from the end of May to the first decade of June, at water temperature of 14.5-16oC. In Lake Hovsgol Nuur the fish spawns in June. In Lake Ugiy fecundity ranges from 6500 to 31,350 eggs. Spawning shoals which consist of 3+, 4+ and 5+ year fish, have a mean fecundity of 11,000, 13,500 and 30,000 respectively. The highest fecundity ever recorded was 80,400 from a 14-year-old female from the River Ih Horoo which enters Lake Hovsgol Nuur. Where there is no fishery for Siberian roach, the stocks have a wide spread of age classes. For example, in water bodies of the Lake Hovsgol Nuur catchment the stocks comprise age groups from 0+ to 16+. But in Lake Ugiy which has commercial fishery the stocks include only age classes 2+ to 7+. In this lake fish of 4+ to 6+ are 230-300 mm long and they weigh 150-300 g.
Fourteen different parasites have been identified from this species in Mongolia, none of them species specific. Most of the parasites also commonly occur in other cyprinids (Pronin, 1976).
Siberian roach is presently fished only in Lake Ugiy, where it represents 50-60% (40 t) of the commercial catch. Promising conditions for commercial exploitation of the Siberian roach exist in lakes Terhiyn Tsagaan and Hovsgol Nuur. As this fish does not form shoals, one will have to apply a fishing method which would be efficient in catching dispersed fish. Siberian roach is a common fish in lakes Onholik and Hunt, which are connected, and in delta lakes of the River Ih Horoo. It is possible to capture 20 t of Siberian roach in these lakes in the winter. In the River Selenga one could harvest up to 5 t of this fish. Siberian roach is favoured by anglers.
Altai osman - Oreoleuciscus warpachowskii
Altai osmans are widespread in landlocked water bodies of Central Asian Internal Basin of Mongolia. This Basin has an oval shape, extending from the southeast to the northwest, and it is almost completely surrounded by mountain ranges. Its northeastern boundary is formed by Lake Sangiyn Dalai which separates it from the catchment of the River Selenga. Lake Uvs is the most northern site where Altai osman is found. The Gobi Altai, also called Mongolian Altai, forms the southern and southwestern boundary of the area. It separates the area from the River Irtysh catchment. Altai osmans in Mongolia are limited to the northwestern part of the Central Asian Plateau, at altitudes from 1000 to 2238 m above sea level; outside this area they are present only in the upper catchment of the River Ob, outside Mongolia. The swampy nature of highland streams, which in some places may still connect or in the past connected the two catchments, could possibly have assisted the fish in crossing the divide.
The diversity of conditions in different water bodies populated by Altai osman and the extreme poverty of other fish species probably assisted in the development of a number of morphological and ecological adaptations in Altai osman. In Mongolia, Altai osman appears in three types (Dgebuadze, 1982). The distribution boundaries between these types are often indistinct and some waters may have several types. The morphological and ecological features may also vary with seasons as well as with fish sites.
Altai osman types are interesting examples of non-competitive evolution of a relatively young immigrant. Altai osman is highly adaptable to a variety of conditions. Osman is a lake fish, but it also inhabits rivers with slow current, avoiding the fast current of mountain rivers. It can live in rivers with a wide range of dissolved oxygen concentrations and conductivity. For spawning, osman migrates from saline lakes into freshwater rivers.
The three types of Altai osman are described below.
Oreoleuciscus humilis - small dwarf osman with a slim body and a minimum cover of tiny scales. It reaches a length of 138-200 mm (mean length of 140 mm), and a weight of 7 to 25 g. Dwarf osman matures when 6 years old and about 75 mm long. The brood stock is represented by up to 10 age groups (5+ to 14+). The fish reaches a maximum age of 15 years.
The spawning season extends from late June to August. Fecundity ranges from 670 to 6600 (average 2600) (Table 17). The annual length increment seldom exceeds 10 mm and the annual weight gain is about 7 g. Dwarf osman feeds on zooplankton, insects, larvae of aquatic insects, plant material, and in some lakes, detritus. It is fished by anglers. If exploited commercially it could be used as an ingredient of cattle feed.
Oreoleuciscus potanini - potanini Altai osman, occurs mainly in lakes and in the lower courses of rivers entering lakes. It is a medium-sized fish with a small head. It spawns in July/August, which is a little later than the spawning season of the dwarf osman. The age and size at sexual maturity vary with environmental conditions: for example, in the mountain lake Sangiyn Dalai the first spawning of osman takes place when the fish is 250-300 mm long and 15 years old. In Lake Boon Tsagaan the fish attains sexual maturity when about 200 mm long and 5-6 years old. Its fecundity ranges from 5200 to 52,600 (average 23,600) (Table 17). The maximum length of the fish differs from lake to lake. In Lake Sangiyn Dalai it is 550 mm, in Lake Boon Tsagaan 500 mm, and in lake Tatsin Tsagaan 450 mm. Each stock consists of different age groups. In fish catches age groups range from 4+ to 25+, with a prevalence of 8+ to 10+ years. Potanini Altai osman is an omnivore which easily adapts to any type of food.
Oreoleuciscus pewzowi - bigmouth Altai osman has a long lower jaw and a large head. In summer the fish are scattered, at times forming groups of two to three fish only. For overwintering the fish descend into deep water of lakes. In spring mature fish gather in the lake's littoral or in rivers entering lakes. Males reach sexual maturity at a body length of 200 mm and females at 240 mm, when 8-9 years old.
Bigmouth Altai osman start spawning 1-2 weeks after the disappearance of ice at a water temperature of 7-8oC. In water bodies of the lower course of the River Hovd the spawning takes place at the beginning of May. The spawning period lasts 40-50 days. Of all osman species females of O. pewzowi have the highest fecundity ranging from 27,000 to 342,300 (average 103,99) (Table 17).
Bigmouth osman is the largest in the genus Oreoleuciscus. In saline lakes of the Great Lakes Valley, such as lakes Hyargas, Durgun and Uureg, the fish grow to 1000 mm length, but their usual maximum size is 700-800 mm and they weigh 8 to 10 kg. They are also the oldest of all osmans - reaching over 40 years of age. In some water bodies osmans have a wide range of age classes. Their growth rate is slow, only 10 mm per year, and the annual weight increment is about 70 g.
Bigmouth osman is an omnivore. Where food supply is poor, bigmouth osman feeds on a diversity of food. Plant material is always eaten, but bigmouth osman is also a piscivore and cannibalism is common.
Eighteen different parasites have been identified from Altai osmans. Among them, the following nine have been identified only from the genus Oreoleuciscus: Myxobolus mongolicus, Dactylogyrus oreoleucisci, Gyrodactylus mongolicus, G. oreoleucisci, Rhabdochona humyli, Philometra oreoleucisci, Caryophyllaeides fennica, Allocreadium elongatus, Cappilaria brevispina (Ergens and Dulmaa, 1967).
The flesh of osmans contains many bones, but it is very tasty. Although currently they are not commercially fished, they have a good fishery potential. It is estimated that water bodies of the Great Lakes Valley could yield up to 500 t yr-1 of osman and water bodies in the River Hovd catchment could yield 20 kg ha-1 yr-1.
Amur wild carp - Cyprinus carpio haematopterus
This fish is present in water bodies of eastern Mongolia: in catchments of the rivers Onon, Kerulen and Halhin Gol, and in the lakes Buyr, Bayan and Huh. In the 1960s Amur wild carp colonised the rivers Selenga and Orhon, Lake Ogiy, and the Tula River. In Lake Buyr Amur wild carp normally mature at the age of 3+. The body length of mature females is 320-360 mm, and the body weight is 1 kg. Males reached sexual maturity when 260-280 mm long. In lakes Buyr and Bayan wild carp spawn at 30-70 cm depth, usually from late May to July/August, at water temperatures of 16-20oC. Fecundity ranges from 41,900 to 307,400, with an average of 140,000 eggs.
In the late 1940s the maximum body length of Amur wild carp in commercial catches was 850 mm, and the maximum body weight was 12 kg (Dashdorzh, 1955), but according to the more recent statistics for 1977 and 1986-1988 the maximum body length was 530 mm, corresponding to a weight of 2740 g. The age structure of Amur wild carp in commercial catches from different years varies and depends on the strength of year classes. Fish of 6+ to 10+ age groups dominate the catches.
In Lake Buyr (Mongolia) and Lake Dalai Nur (China) the growth rate of Amur wild carp is much lower than in water bodies situated further north, i.e. in the catchment of the River Amur (Svetovidova, 1960) (Table 18). The low growth rate of Amur wild carp in Lake Buyr is believed to result from the shortage of food organisms, such as chironomid larvae. Hence the fish there feed predominantly on plant material.
Amur wild carp is one of the most valuable commercial fish of eastern Mongolia. In Lake Buyr it has been commercially fished for a long time. During the 1923-1924 winter fishing season 112 t were captured, in 1924-1925 - 310 t, in 1925-1926 - 240 t. In 1954-1955 only 10-20 t were captured, but during 1958-1961 catches ranged from 310 to 400 t yr-1. Presently around 150 t yr-1 of Amur wild carp are captured from Lake Buyr. To further increase catches would require regular stocking of the lake using hatchery-produced fingerlings.
Giebel carp - Carassius auratus gibelio
This is a common fish in water bodies of eastern Mongolia and in the catchment of the Selenga. It dominates the fish stocks in lakes Hovsgol Nuur, Buyr, Bayan, Huh and the River Bulgan Gol in western Mongolia and in most of the shallow lakes surrounded by forests. Many isolated populations, even within the same water body, are present in large lakes and in rivers such as the Onon, Kerulen, Selenga and Orhon.
The fish mature usually when 4 years old, 180 mm long or longer. But in slow-growing giebel carp populations such as those in floodplain lakes of the middle course of the Selenga, mature males are only 111 mm long (weight of 48 g), females 135 mm long (76 g). In all water bodies of Mongolia females represent the major part of giebel carp stocks; for example, in Lake Los males form only about 3% of the total fish present on spawning grounds, and in Lake Gun Nuur 8.5%. Some stocks have a complete absence of males, and gynogenesis was observed after fertilisation of eggs by milt of minnows and by some other cyprinid species.
Giebel carp spawn at a temperature of 14oC or higher. The first mass migration of the fish to their spawning grounds starts in the second half of June and eggs are laid in batches until August. The spawning grounds are located in the littoral or in shallows of lakes. The preferred spawning substrate is soft aquatic vegetation. Spawning takes place after midnight in warm and windless weather. Fecundity ranges between 70,700 and 102,670 in Lake Ugiy, between 32,000 and 195,470 in Lake Buyr, and between 16,000 and 27,780 in the slowly growing fish in lakes of the River Selenga catchment. The first spawners are in the age group 2+.
Giebel carp appears in two forms, which differ from each other in their growth rates, i.e. a fast and a slow growing form. The oldest and heaviest fish, weighing 2520 g and 18-19 years old, was recorded from Lake Huh in eastern Mongolia. In commercial catches from Lake Buyr the body length ranges between 200 and 420 mm, and the weight between 930 and 1250 g. In those from Lake Ugiy the length is between 310 and 380 mm and the weight between 930 and 1400 g. In both lakes age groups 5+ to 7+ dominate in catches. Growth rates vary from one water body to another (Table 19) and even within the same lake. In both lakes giebel carp appears in fast-growing form, while in floodplains of the middle Selenga, and in Lake Dalai Nur (China, Inner Mongolia) the slow-growing form is present.
Giebel carp is an omnivore. More than 30 animal and plant species have been identified from the stomach/gut of fish captured from lakes. The parasite Raphidascaris, many species of Protozoa, especially microsporidia (20 species), and a number of monogeneans and trematodes have been identified from this fish (Moravec and Ergens, 1970).
The easy adaptability of giebel carp to various conditions and its omnivorous character make it possible for this fish to inhabit a variety of water bodies of Mongolia. Giebel carp has been introduced into Lake Huh in eastern Mongolia, and into lakes Ganga, Dagshin and Zegst in the Suhbaatar aimag. Giebel carp represents a major proportion in commercial catches. From 1923 to 1926 giebel carp dominated the fishery with 560-650 t yr -1 of giebel carp captured in winter fishing seasons. This is two to five times more than the catches of Amur wild carp. Later on catches of giebel carp declined: in Lake Buyr in 1955/56 they reached only 87.9 t, in 1957/58 - 101.9 t, in 1959/60 - 114.2 t. More recently, catches increased in Lake Buyr, but there is a need for better management of fish stocks and for regular enhancing of giebel carp fish stocks through releases of hatchery-produced fingerlings. Artificial spawning nests should also be constructed in Lake Buyr to improve the spawning success of this fish. Commercial fishery should target the not yet exploited abundant stocks of giebel carp in lakes Ugiy, Hovsgol Nuur and Terhiyn Tsagaan in the Selenga catchment.
Mongolian redfin - Erythroculter mongolicus
Mongolian redfin is present in the lakes Buyr and Bayan, and in the rivers Orshuun, Halhin Gol, Kerulen, Balzh and Hurhyn Gol, the last three rivers being in the River Onon basin. In Lake Buyr during summer Mongolian redfin stay inshore in areas free of aquatic macrophytes. At the end of spring and in early summer mature redfin form shoals in the lower course of the River Halhin Gol. The fish overwinters in deep waters of lakes.
Some Mongolian redfin reach sexual maturity at the age of 4-5 years but most redfins mature later, at the age of 8-9 years when they are 300 to 500 mm long. Fecundity is 16,200 to 191,600. Spawning takes place in June in flooded terrestrial vegetation of floodplains, with some current and a water temperature of 20-24oC. Males reach sexual maturity earlier than females and they die earlier as well. The number of males on spawning grounds greatly exceeds the number of females.
The largest Mongolian redfin recorded from commercial catches of Lake Buyr was 693 mm long (weight 3500 g), the smallest was 395 mm (weight 809 g). Individuals of a wide range of age groups, from 3+ to 19+, are present on spawning grounds. In Lake Buyr Mongolian redfin is a fast grower, especially when it changes to feeding on larger organisms such as shrimps and fish. The parasitic fauna of this fish includes a large number of monogeneans. Several helminths have also been identified, but there are no parasites typical of predatory fish.
Mongolian redfin is an open water predator in Lake Buyr. In the lake and in the inflowing rivers redfin does not compete for food with other predators.
Flathead asp - Pseudaspius leptocephalus
It is present in the Orshun, Halhin Gol, Onon and Kerulen rivers, and in lakes Buyr and Bayan. Flathead asp generally prefers the main channel of rivers. Unlike the Mongolian redfin, which has a very similar way of life, it prefers cooler water in summer. It reaches sexual maturity at the age of 3+ to 4+ and length of 210-300 mm. Spawning migration starts in late May, and a large-scale spawning starts in the second decade of June and ends in the second decade of July. Fecundity is 1700-48,500. Flathead asp is a predator which feeds on small fish such as gudgeons and minnows.
In Lake Buyr in commercial catches dominate age classes 2+ to 6+ (length 334-620 mm, weight 590-2000 g). Flathead asp represents only 0.9% of the total catch there. In Lake Dalai Nur in China flathead asp in commercial catches range between 190 and 415 mm (weight 80-1060 g).
Lookup - Culter alburnus
Lookup is present in the catchment of Lake Buyr and in the River Halhin Gol, but it prefers lakes. It also inhabits floodplain lakes which are overgrown with aquatic macrophytes and isolated from rivers during the low water level In winter part of the stock returns to feed in the mouths of rivers entering lakes.
Females mature at the age of 3+, and males at 4+ when they are at least 200 mm long. Some fish may already mature at a body length of 139 mm. Lookup spawn in batches, starting in June. The spawning period ends by the end of July. Spawning takes place in mornings in a weak growth of Potamogeton in a depth of 1.4-1.8 m, at a water temperature of 18-25oC. Fecundity ranges from 7680 to 6228.
Commercial catches in Lake Buyr capture fish from 200 to 369 mm, in Lake Dalai Nur 70-370 mm, in Lake Hanka 180-330 mm. In Lake Buyr and River Halhin Gol females reach 251 mm, males 235 mm. Males are smaller than females. The fishery captures age groups from 2+ to 9+, with the bulk of the catch comprising 2+ to 6+ (weight 120-690 g). Lookup is of commercial importance in Lake Buyr. However, nowadays catches of lookup are lumped together with those of skygazer (Erythroculter erythropterus). In the mid-1920s lookup represented about 35% of the total commercial catch from Lake Buyr: during the 1923/1924 winter fishing season the catch was 1610 t, in 1924/1925 - 640 t, and in 1925/1926 - 610 t. Recently, its proportion in commercial catches has been very low, ranging from 0.3 to 6.9% of the total.
Amur barbel - Hemibarbus labeo
Two species of barbel are present in water bodies of eastern Mongolia: Hemibarbus labeo and H. maculatus. The former species is more commercially important than the latter. Amur barbel is present in rivers Onon, Balzh and Halhin Gol and in Lake Buyr. It prefers faster current than H. maculatus and only rarely does it enter lakes.
Amur barbel reaches maturity at the age of 4+, but some males may mature earlier, at the age of 3+. The spawning season extends from late May to June. The broodstock is dominated by fish of 5+ to 7+, with 12+ being the oldest fish captured. The fish spawn in batches onto a substrate of pebbles during the daytime at temperatures of 19-21oC. Fecundity is 10,000 to 120,000. In commercial catches for 1968 Amur barbel from Lake Buyr had a body length of 205-437 mm and a weight of 190 to 1060 g. Recent catches from Lake Buyr contain smaller fish than those currently fished from Lake Dalai Nur in China where the captured fish ranges from 145-295 mm in length and from 90 to 364 g in weight.
Amur barbel is a valuable commercial fish. In Lake Buyr it represents 6% of the total catch.
Buyr sawbelly - Hemiculter leucisculus warpachowskii
Buyr sawbelly inhabits Lake Buyr where it is common both in the open lake and inshore. It reaches sexual maturity in its third year when 93 to 138 mm long. The spawning season starts early in June and continues throughout July. Eggs are laid in batches. The spawning sites, with sandy and stony bottom, are situated along exposed shores of the lake. Fecundity is 6000 to 11,200.
In commercial catches Buyr sawbelly of 167 mm length and 35 g weight dominate. The dominant age groups in catches are 3+ to 6+. The fish feed mainly on the lower crustaceans and algae. Older fish feed on aquatic macrophytes and detritus. It has a medium commercial importance as a small-sized table fish. It could be probably canned.
Siberian dace - Leuciscus leuciscus baicalensis
This species is present in all tributaries of the Selenga River, including the Orhon and Tuul. It also appears in the River Bulgan (Bulgan-gol) in western Mongolia, and in lakes Ugiy and Terhiyn Tsagaan. Siberian dace is very adaptable to a variety of environments. It forms small shoals above sandy and stony bottom, both in fast and slow current of rivers with aquatic macrophytes along the banks. During winter the fish gather at the bottom where they stay active.
Siberian dace reaches sexual maturity at the age of 3-4 years. The spawning season starts at water temperatures of 5-9oC in the last decade of April and continues until the end of May. The fish deposit eggs on terrestrial vegetation of flooded floodplains or sandy bottoms of shallows in rivers. The fecundity of Siberian dace of 104-164 cm length and 25-70 g weight ranges from 1800 to 6800. It increases with age: age classes of 5+ to 8+ have fecundity ranging from 4100 to 13,600.
Siberian dace collected from the River Bulgan Gol were 160-210 mm long, with body weights of 50-120 g; in the River Tula they were 108-197 mm (24-70 g); in the Selenga River 110-215 mm (21-100 g).
In water bodies of the Selenga and Bulgan catchments Siberian dace reaches an age of 10 years, but such old fish are rare. The catches contain mostly 3+ to 8+ age classes. In spite of differences in the character of the western and northern water bodies, in all of them Siberian dace have a similar growth rate (Table 20). This is probably due to the similarity in food supply in all lakes during the summer.
In all water bodies of Mongolia Siberian dace feed in warm shallows of lakes or rivers. In catchments of the Selenga and Tula rivers, Siberian dace feed on insect larvae such as caddis flies and mayflies and on terrestrial insects that fall onto the water surface. Cladocerans, copepods, algae and higher aquatic plants are also important as food. The fish has commercial importance in water bodies of the Selenga catchment but at present the stocks are underfished.
Ide - Leuciscus idus
In Mongolia ide is present in the River Selenga and its tributaries. The southern boundary of its distribution is Lake Ugiy. It is also a very common fish at the confluence of the Hegshin-Orhon River with the main stem of the Orhon River. Here anglers catch ide, taimen, lenok, pike and perch on spoon-bait. In the Selenga catchment ide prefers deep river sections with slow current, well oxygenated water and clay bottom. When feeding ide seeks deep quiet embayments and oxbows, especially where the bottom is overgrown with soft submerged macrophytes. During the first half of July, when water level declines, adults leave lakes to enter rivers where they remain in deep water along steep river banks, but sometimes the fish also visits shallows with stony bottom. The food of ide changes with seasons. In summer and autumn the fish behaves as a typical omnivore.
In Lake Ugiy ide matures at the age of 5+ to 6+. The spawning season starts at the end of April and ends in the second decade of May. The fish spawn on floodplains with flooded terrestrial vegetation, at water temperature of 6 to 8oC. In the Orhon catchment females of 330-350 mm (weight 870-910 g, age 5+ to 6+) have a fecundity of 70,300 to 82,350. Females of age classes 7+ to 9+ (370 mm to 400 mm, 1250 to 1450 g) have a fecundity of 120,400 to 173,600.
In net catches from Lake Ugiy a 5+ to 6+ year ide has a body length of 413-498 mm and a body weight of 1000-1750 g. Fish of age classes 7+ and 8+ have body lengths of 337-526 mm and body weights of 800-2000 g, while those of age class 9+ are 524 mm long and weigh 1950 g. Ide has a high growth rate in the middle courses of rivers Orhon and Selenga due to the presence there of a number of lakes with warm water.
Ide is fished mostly in early spring from ice. Ide stocks consist of a large number of age classes which shows that its stocks are not overfished. However, it is not a common fish, as it represents only 1.6% of the total catch from Lake Ugiy.
Amur ide - Leuciscus waleckii
Amur ide is a very common species in eastern Mongolia where it appears in the catchment of Lake Buyr and in rivers Halhin Gol, Onon and Kerulen and their tributaries. In summer Amur ide keeps to the littoral of river channels and lakes, including floodplain lakes, where it feeds. For winter it returns into the main river channel.
Some specimens may mature already when two years old, but usually maturity is reached at the age of 3 to 4 years. Spawning starts in mid-April and continues until the beginning of May. Eggs are laid on stony or sandy substrate and all eggs are laid at once. The mean fecundity of Amur ide in the River Kerulen is 9020, with a maximum of 22,184 and a minimum of 3940 eggs. Mean fecundity in the River Halhin Gol is 15,413, with a range from 1394 to 39,321.
Fish from 235 to 280 mm with body weights from 199 to 243 g appear in net catches. In the Kerulen catchment the ranges are 222 to 294 mm and 65 to 230 g, this corresponding to age groups 4+ to 7+ (Table 21). There is little difference in the growth rate of Amur ide in different water bodies. Males are slightly smaller than females.
Amur ide prefers to feed on aquatic insect larvae and on flying terrestrial insects. It is a prey fish for a number of piscivorous fish species. Its importance for commercial fishery in Lake Buyr is negligible, but it is a favourite fish of recreational fishermen.
Amur catfish - Parasilurus asotus
Amur catfish is present in water bodies situated from the Onon River in the east to the catchments of rivers Halhin Gol, Nemregiyn Gol and Kerulen in the west. It is also present in lakes Buyr and Bayan. In the late 1960s, Amur catfish entered catchments of Selenga, Orhon and Tula rivers and Lake Ugiy from the Ivano-Arakhlei lakes in Russia.
This species enters the littoral at the end of April - beginning of May, after the ice cover of rivers has melted. It is then captured in large numbers. In summer Amur catfish stay close to shores and river banks and some enter channels connecting rivers with floodplains. They are commonly found among the flooded terrestrial vegetation. In autumn they leave in-shore waters for deeper channels and pools in the main river where they overwinter.
Both males and females mature at the age of 4-5 years when 350-370 mm long. The spawning season starts in late May and ends at the end of July, peaking in mid-June. In the delta of the Halhin Gol the spawning period is shorter, i.e. from the end of May until the end of June. In the evening and at night, at water temperature of 16-18oC, Amur catfish lay eggs in stagnant water on submerged aquatic macrophytes, at a depth of 0.1-0.7 m. In the Halhin Gol delta spawning females are 400-600 mm, males 300-400 mm long. Here the fecundity ranges from 29,470 to 70,850, while in Lake Buyr it is 22,190 to 92,750. In Lake Ugiy in the
Selenga catchment, Amur catfish of 510-740 mm and of 1200-3000 g weight have fecundity of 33,900 to 128,200.
In the Mongolian sector of Lake Buyr the commercial fishery captures catfish of 334-680 mm, with body weights of 360-3650 g. In summer the mean size is 453 mm and the average weight 2835 g. During winter the respective figures are 405 mm and 1600g. In the Tula River and Lake Ugiy catfish reach a body length of 750 mm and a weight of 4.5 kg. Commercial catches from different water bodies of Mongolia contain catfish of 2+ to 9+ age groups, but most of the fish are 3+ to 5+ years old.
Amur catfish is the most common predator of shallow waters. It feeds on all types of fish, and it is important for its regulatory impact on fish such as crucian carp, ide and wild carp. In Mongolia it is an important commercial fish species. In the 1920s, during the winter fishing period, the following quantities were captured: in 1923/1924 - 480 t, in 1924/1925 - 430 t, in 1925/1926 - 370 t. In Lake Buyr, during the 1959-1969 period, the average annual catch was 37.7 t. However, recently catches of Amur catfish from Lake Buyr have declined to approximately 10 t yr-1. In Lake Ugiy Amur catfish represents less than 1% of the total catch.
In Mongolia Amur catfish mature early and live for a maximum of 12 years. In dry years the catfish suffer from the shortage of a suitable spawning substrate, but where such substrate is available, catfish concentrate there in large numbers and are very vulnerable to overfishing. Hence an important management measure is a ban on fishing for catfish during its breeding period.
Burbot - Lota lota
Burbot is present in many water bodies of Mongolia. It gives preference to cold water and in summer it stays in upper catchments of rivers, such as Selenga, Orhon, Tula, Onon, Kerulen and Halhin Gol, as well as in their tributaries. When water cools down in autumn burbot migrates downstream and into lakes, such as Terhiyn Tsagaan and Buyr. In Lake Hovsgol Nuur it is found throughout the lake, down to a depth of approximately 70 m. However, its distribution is uneven, with most fish found along lake shores and down to 30-40 m. When the lake is covered with ice burbot stays in shallower water. During summer burbot feeds less intensively than during other seasons.
In lakes Ugiy and Terhiyn Tsagaan males and females mature when 4 years old. In rivers Selenga and Orhon males mature when 3 years, and females when 4 years old, at a body length of 27-30 cm and 35-40 cm, respectively. In Mongolia burbot spawns in December/January, migrating a short distance upstream. In Lake Hovsgol Nuur it migrates into the mouths of inflowing rivers. Fecundity in Lake Terhiyn Tsagaan ranges from 20,500 to 97,900 (64,000 on average) for the age classes 6+ to 7+, body length of 450 to 550 cm. In the Selenga and Orhon the fecundity is 31,500 to 50,000, and in Lake Hovsgol Nuur 51,000 to 350,000 for age classes 8+ to 13+. For the mean size and weight of these classes see Table 22.
Burbot is a piscivore but it also feeds on benthic organisms. It has a fairly fast growth rate, with some differences among the water bodies. Broodstock females are larger than males of the same age. In Lake Hovsgol Nuur burbot grow slowly. The fastest growth rate has been recorded for burbot in Lake Terhiyn Tsagaan, as a result of a good food supply. In Lake Hovsgol burbot reaches a length of l m and a weight of 6 kg. In Lake Terhyin Tsagaan fish of 53-69 cm weigh 1600-2580 g.
The following parasitofauna has been identified from burbot from Lake Hovsgol Nuur (Pronin, 1976): Myxobolus mulleri, M. pfeifferi, Nosematidae, Trichodinella epizootica f. lotae, Apiosoma sp., Protozoa, Gyrodactylus lotae, Diplostomum baeri, Haplonema hamulatum, Echinorhynchus borealis, and Cystobranchus mammillatus.
Burbot is at present largely underexploited. There are no special fishing methods for this species which is now captured together with other fish. During summer burbot is virtually absent from catches from Lake Buyr. In Lake Hovsgol Nuur about 50 t are captured annually. In the Selenga catchment some burbot are captured by recreational fishermen.
Perch - Perca fluviatilis
Perch is a most common fish species of Mongolia. It is present in catchments draining toward the Arctic Ocean, and in the Bulgan River in the western part of the country. In rivers it prefers quiet embayments, oxbows and slow current. In lakes it is found both in littoral and in the open lake. Perch appears in two forms: a small and slow growing form, which inhabits rivers close to the banks where there is overhanging vegetation, and a large, fast growing form, which occur further offshore in more open and deeper water and in deep pools in rivers, underneath tree snags and rocks. In spring perch come closer to river banks and in autumn they enter deeper water to overwinter. The large form prefers to spend the morning and evening in the littoral, moving into deeper water during the other times of the day. The small form initially keeps to the littoral where it faces poor food supply. When it reaches a length of 10-15 cm and it begins to feed on other fish, it moves into the open water; there its growth rate increases and it soon catches up with the fast-growing form. In Mongolia the largest perch occur in Lake Hovsgol Nuur, reaching over 447 mm in length and over 2 kg in weight, at an age of 23+.
In lakes Ugiy and Terhiyn Tsagaan perch matures when 2-3 years old. In the middle course of the Selenga and in most other water bodies of Siberia, some perch may mature in the 4th year, but the majority mature in the 5th and 6th year. Some perch, as observed in Lake Hovsgol Nuur, may stay immature until the 7th year. For spawning, males and females gather in shoals which are dominated by 2-3 year old fish. The sex ratio in such shoals varies: sexually mature males initially dominate in the shoal; then the ratio of males to females evens out, and later, toward the end of the breeding season, females begin to dominate.
In different water bodies the perch breeding season starts at different times, depending on the water temperature. Usually it starts at the beginning of May and ends by the end of June. Spawning usually starts when water warms up to 3-7oC. Spawning of perch takes place in the littoral of lakes, in bays, oxbows, and often also on river floodplains, usually at 0.5 to 2 m depth, but sometime deeper. Stones, sand, dead submerged vegetation, flooded bushes and reeds, even nets left in water, serve as spawning substrate.
Fecundity of perch increases with body size. In Lake Hunt of the Hovsgol Nuur drainage fecundity reaches 67,200 in an 11+ age group, and in Lake Ugiy a 7+ fish contained 67,700 eggs. Fecundity of the Mongolian perch is higher than that of perch in Siberian water bodies.
In Lake Hovsgol Nuur summer catches contain perch of 3+ to 23+ year classes, with a dominance of those of 4+ to 7+. Fish 15+ and older are seldom captured. In lakes Ugiy and Terhiyn Tsagaan 2+ to 7+ are captured, but 4+ to 5+ dominate. In the Selenga 2+ to 11+ are captured, with 4+ to 7+ dominating the catch. The slowest growth of perch is recorded from Lake Hovsgol Nuur and its inflowing rivers. The reason is the poor productivity of this lake (Kozhova, 1983). In lakes Ugiy and Terhiyn Tsagaan, the Bulgan River and in lakes in the Basin of the Rivers perch grow faster because of the abundance of food. Generally, the growth rate of perch in Mongolia compares with that of perch in the Lake Baikal catchment (Table 23).
Large perch, together with other predatory fish, help to control the stocks of trash fish such as dace, minnow and the small form of perch, hence it has an important stabilising function in the fish community.
The following parasites have been identified from perch in Mongolia: Myxobolus sp., Coconema sp., Trichodina sp., Apiosoma sp., Proteocephalus percae, Diplostomum spathaceum, Cammalanus lacustris, Raphidascaris acus, Echinorhynchus borealis, Psedoechinorhynchus clavula and Piscicola geometra (Moravec and Ergens, 1970; Pronin, 1976).
Perch is commercially fished only in Lake Ugiy, where it represents 12 to 38% of the total fish catch. In other water bodies it is fished by recreational fishermen, who, however, preferably target the fast-growing form. It is expected that in the future perch will become commercially fished in lakes Hovsgol Nuur and Terhiyn Tsagaan. The estimated sustainable catch of perch in Lake Hovsgol Nuur is 50 t yr-1.
The first written source to mention fish captured for food by the people of Mongolia, describing fishing methods, was published in the 13th century. The source is a collection of ancient legends of the Mongols. It mentions fishing gear such as hooks and nets, including large nets made of horse hair considered to be highly efficient. The legends mention methods of fish processing and preservation of fish for winter, and say that no more fish should be caught than can be naturally replaced. This is the first mentioning of the concern for sustainability of fish stocks.
Travellers Wilhelm de Rubruck and Marco Polo reported in the 13th century that big fish, grown in ponds of the khan's nature reserve, were regularly served at the khan's court. The Mongolian "Great Code" of 1640 specified penalties for the theft of fishing gear: "That who steals ... nets for catching birds or fish... shall have his thumb cut off". This is the only mention of laws relating to fisheries from that time, but it shows with sufficient clarity that ancient laws were not forgotten by the "steppe hordes". Fishing has always been an important activity in the life of people who lived in Mongolian forests and around lakes. The Mongolian people still like sitting with a rod on the bank of a river to catch fish. Fishing therefore has a long tradition in Mongolia. Further evidence comes from archaeological finds of wooden fish traps, and pictures of fish on household items, some 4000 years old. Finds include forks made of fish bones, weights for nets, and pictures of fish on stone and copper household utensils (Dulmaa, 1977).
The Mongols' love for nature is expressed in their national emblem which includes depiction of fish. Fish is considered a symbol of alertness and the two fish in the emblem signify man and wife, reason and wisdom.
In the 18th and 19th centuries fish stocks were not exploited by the local people but fishery was organised by foreign traders. The Russian merchant G.I. Posylin organised fishery on Lake Dood Nuur in the Darhat Basin and sold the fish (whitefish, taimen, lenok and Siberian grayling) in northern Siberia. There is also evidence that Russian merchants caught large quantities of fish in the catchment of the River Hovd in Altai (Potanin, 1883).
3.2 Present status of fisheries in Mongolia
Commercial fishery focuses predominantly on large lakes of adequate depth. Lakes with surface area of 10,000 ha or larger represent only 0.6% of the total number of lakes, while lakes smaller than 100 ha are the most numerous (85%) (Sevastyanov et al., 1990). Lakes are present in the northwest, west and east of the country. Most lakes are far from populated centres and with no railway access. For fish yields and annual catches for the late 1970s and the major commercial fish species see Table 24. During those years the minimum annual fish catch from Mongolian waters was 1854 t. Fishery statistics (FAO, 1997) for years 1986-1991 show a decline from 412 t to 100 t. For years 1992-1995 only catch estimates are available, and are given as 120 t to 130 t yr-1.
· Water bodies with outlets to the Arctic Ocean.
In rivers and lakes in this area there are 20 species and sub-species of fish, including the commercially important taimen, lenok, Siberian whitefish, Arctic grauling, burbot, catfish, pike, perch, roach, crucian carp, Amur wild carp, ide and Siberian dace.
Lake Ugiy in the catchment of the Orhon River has had organised fishery since 1938. Fish catches vary considerably: in recent years they have been 50-60 t yr-1. The following fish are captured: roach, perch, pike, ide, Siberian dace, burbot, Amur wild carp and catfish. Fish species distribution in catches has changed over recent years. During 1963-1965 the fishing targeted stocks concentrated in spawning areas. From 1966 some protection of fish stocks was enforced, limiting the fishing to specified periods. This has led to decline in catches and eventually to their stabilisation during the period 1970-1985 (Table 25). This was followed by a considerable decline in fish catches in the following years. A similar decline was observed for lakes Buyr and Dood Nuur. During the period 1993-1998 further decline followed, with the annual catches down to 40 t in the lakes Buyr and Dood Tsagaan, and 20 t in Lake Ugyi. Starting in 1991, changes to market economy in Mongolia led to privatisation of the fishery. Some water bodies, such as lakes Hyargas, Ayrag, Achit, Tolbo and Ulaagchnyi-Har are now intensively fished at a rate of 10-20 t/lake/year. At this rate there is a danger that fish stocks will soon become overexploited.
Darhat Basin is a promising area for fisheries development. Darhat Basin is located in the River Shishhid catchment, which itself is a tributary of the upper Yenisei. The basin has a large network of streams, rivers and lakes with considerable fisheries potential. These are coregonid water bodies. From 1922 to 1943 there was a fisheries cooperative on Lake Dood Nuur, with catches reaching about 100 t yr1. Another fishing company, established in 1943 in the Darhat Basin, is still active. Commercial fishery exists in Hovsgol aimag, which has a number of medium-sized water bodies connected to the rivers Shishhid, Shargin and Hegiyn. In 1956-1976 the total annual catch from these lakes was 120-190 t, of which Siberian whitefish represented 82%, taimen 8.3%, lenok 7.3%, and Arctic grayling 2.4%. The commercial fishery is extensive and the catches vary considerably. In the past most of the fish were harvested when spawning. This was banned by a government law issued in 1971. Still, catches continued to decline, especially those of Arctic grayling. Currently there is a complete ban on fishing for this species in all water bodies of the Darhat Basin.
There is commercial fishery on Lake Hovsgol Nuur, where lenok and Arctic grayling are the most highly prized fish, followed by roach, perch and burbot. Tomilov and Dashdorzh (1965) and Tugarina (1976) estimated the highest sustainable annual catch from this lake to be 200-400 t.
· Water bodies with outlets toward the Pacific Ocean.
These are located in eastern Mongolia. Lake Buyr, shared by Mongolia and China, had in the past an important commercial fishery. It harbours over 40 species of fish, including the commercially valuable Amur wild carp, Amur catfish, Amur pike, taimen, lenok, flathead asp, Chinese carps, crucian carp, ide, Mongolian redfin, Amur barbel, lookup, skygazer, Amur ide and Arctic grayling. Commercial fishery has been practised on this lake for about 50 years but a clear sign of overfishing is evident from the recent decline in fish catches (see above).The most common species in catches are Amur wild carp, Amur pike, Mongolian redfin and Amur. Fish are captured during the spawning period at the beginning of summer which is against the existing fishery regulation, but the regulation is not enforced.
From 1956 to 1964 Lake Buyr was fished by the Chinese. Since then the lake is fished both by Chinese and by Mongolians. In 1954 Amur pike represented 77% of the total catch, lenok 8%, Amur wild carp 5%, Amur catfish 4%, lookup 3%, taimen 2%, Chinese carps 1%. Most fish were 6 years old or older. In the Mongolian part of the lake fish catches reached 500 t yr-1 during 1964-1977, with wild carp representing 59.4%, Amur pike 17.5%, crucian carp 8.5%, Amur catfish 6.9%, Mongolian redfin 4.6%, lookup 2.9%, taimen 2.5%, flathead asp 0.9%, Amur barbel 0.6%, lenok 0.1%. The result of this intensive fishing was that the stocks became younger, which has led to a better utilisation of the naturally available fish food in the lake. In the 1980s the fishing intensity declined, and there was also a change in the proportion of the dominant fish species: Amur pike and Amur carp represented 55% and 21% respectively. At present the lake is again intensively fished on the Chinese side, while there is a low fishing intensity on the Mongolian side. Small-sized Amur wild carp dominate (70%) the catches in Mongolia, and there is no information available on catches on the Chinese side. However, the high dominance of small carp, and the decline in species diversity of fish suggest that the lake is being overfished.
· Central Asian Internal Basin is the largest of the three regions. It covers 65% of Mongolia and contains 32% of its water resources. The following lakes are of interest for commercial fisheries: Hoton, Horgon, Dayan, Tolbo, Achit, Bayan, Heh, Har and Har Us, with 70-80% of all Mongolian stocks of Altai osman and 20-30% of Arctic grayling. Also of importance are lakes Orog, Sangiyn Dalay, Boon Tsagaan, Orog, Durgun, Ayrag and Hyargas in which Altai osman is a major fish species.
There is no organised fishery in water bodies of the Central Asian Internal Basin. From time to time a mobile fishery unit of the forestry and wildlife administration of the Hovd aimag has been fishing Lake Har Us and rivers Hovd and Honoharaih. Since 1980 a fishery unit from the Altai region of the ex-USSR has been fishing lakes Tolbo, Achit and Hongor-Ulen to a level of 50-100 t yr-1, with the major fish captured being Altai osman and Arctic grayling.
Stock assessment surveys on lakes Har, Nogoon and Durgun in the Great Lakes Valley in the Hovd River lowlands provided data for estimates of sustainable catches for other lakes. For Lake Har it is 200 t yr-1, for Lake Nogoon 16 t, for Lake Durgun 230 t. Altai osman would be the dominant fish captured from these lakes. All fish could be captured by a team of just six fishermen. A similar approach has been proposed and is being implemented in some other water bodies of western Mongolia: lakes Boon Tsagaan and Orog in the Great Lakes Valley, and in lakes Telmen, Bayan, Har and a few others on the Hangayn Plateau.
Additional information on fish ecology and fisheries in Mongolia is available in Shatunovsky (1985).
3.3 The future of inland fisheries in Mongolia
The present fishery in inland water bodies of Mongolia is poorly mechanised. Fish is preserved by salting, drying or freezing, both for domestic use and for export. At the same time, Mongolia imports a considerable quantity of fish, including canned fish. With a few exceptions the fish processing personnel have no training, and there is a shortage of qualified technical staff.
Fishery management has focused on expanding fish stocks through introductions of fish species into selected water bodies. Arctic cisco was introduced in Lake Hovsgol Nuur during 1956-1957, and Arctic cisco and northern whitefish were introduced in Lake Naiman Nuur in 1978-1979. In 1980 Arctic cisco was again stocked into Lake Hovsgol Nuur. In 1983 and 1986 northern whitefish were released in Lake Ulaagchnyi Har on the Hangayn Plateau. In May 1981 and in April 1982 northern whitefish and Siberian cisco were released in Hongor-Ulen in the Altai.
Both northern whitefish and Arctic cisco have adapted well to Mongolian lakes. Mature fish reach a weight of 1200 to 4500 g and a length of 248 to 705 mm. In some lakes the northern whitefish has become a very common fish, supporting a fishery and providing seed material for transfer to other lakes.
At present, fish and fish products have only a minor role in the nutrition of the Mongolian people, but their role is increasing. There is potential for greater exploitation of some fish stocks, but this will require better management so as to avoid over-exploitation. The Ministry of Health of Mongolia has recommended that by year 2000 the consumption should reach 1-2 kg of fresh fish and 2-4 kg of fish products per caput per year in the countryside, and 3 to 10 kg of fresh fish and 1 to 14 kg of processed fish (mostly canned) per person in urban centres.
Among the constraints to further development of fisheries are: irregular distribution of lakes and rivers in the country, rivers freezing to the bottom in winter, and harsh winters which do not allow efficient pond culture. It is estimated that 3000 t of fish could be fished annually on a sustainable basis. If the inland fishery is to be a permanent source of fish and employment, it must be kept at a level which allows fish stocks to replenish. The stocks should also be enhanced by regular stocking.
In view of the small fish stocks and their dispersal over large areas of Mongolia, there are no plans to can the fish. Canned fish will continue to be imported. Fresh fish will be supplied according to domestic availability. It is hoped to increase through better management the present very low annual fish catch of about 130 t to 1250 t.
There is a need for better fishing methods and better post-harvest technology and fish processing. Fishing units require better fishing technology and better mobility to improve their efficiency. This includes provision of better fishing boats, tractors, drilling machines for drilling ice for winter fishing from ice, and transport vehicles. Before the introduction of changes to market economy in 1991, programmes existed for the provision of freezing capacity for fish from lakes Buyr, Ugyi, and for the town Hatgal on Lake Hovsgol Nuur. To better preserve fish in summer, more cold stores (using natural ice collected in winter) are needed. This would make it possible to improve summer fish supply to markets and reduce the need for salted fish, a product which is of lesser quality than fish preserved by other methods and for which there is a low demand. Processing by smoking would depend on market demand.
The current level of knowledge of fish stocks in many lakes and rivers of Mongolia is still insufficient to provide a good data base for management decisions. The survey of water bodies concentrating especially on fish of commercial and recreational importance needs to be intensified, and this will require a close collaboration between the Mongolian and international scientists. Hydrobiological, hydrological, chemical and microbiological research should be enhanced through international collaboration, with more work also to be done to improve the knowledge of taxonomy, biology and ecology of aquatic organisms in the individual water bodies of Mongolia. Training of fishery personnel at all levels is also required, especially in fishing methods and post-harvest technology.
For some time fish introductions may still be considered as suitable for selected lakes. Protection of water quality in lakes and rivers will remain among the priorities.
At the beginning of the 1990s Mongolian fisheries management was in the hands of the meat and food production trusts under the Ministry of Agriculture and the Ministry of Light and Food Industries. A reorganisation, if implemented, could lead to the establishment at each ministry of a fishery unit, staffed with specialists, with the objective of providing adequate advise on further development of fisheries in Mongolia.
Mongolian fisheries is poorly staffed, both in management and in technical jobs. This requires urgent attention as the future of Mongolian fisheries will depend heavily on qualified manpower. Attention should be paid especially to education of technical specialists for the projected large-scale fishing in water bodies in which fish are not yet commercially harvested. It is hoped that foreign and international institutions will assist in the education and training of Mongolian specialists.
Drying out of some lakes places further constraint on the development of fisheries in some lakes, especially in the Valley of the Lakes in the Central Asian Basin. The gradual drying up of lakes since 1978 has resulted in a virtual disappearance of lakes Orog and Taitsin Tsagaan. Lake Orog Nuur covers 140 km2 and has an average depth of 3 m when full. This lake completely dried up during 1988-1989 (Dgebuadze, 1995). Lake Taitsin Tsagaan also completely dried out during the same period, and stayed dry for a number of years. Lake Ulan Nuur, the eastern-most lake in Lake Valley, also periodically dries up.
In the mid-1980s, Prihoda and Penaz (1985), in close collaboration with Mongolian experts, reviewed the possibilities for developing aquaculture in Mongolia. It was recommended to improve the existing, and develop new hatchery technologies for selected Mongolian fish species, to be tested on a pilot scale. The low water temperature of Mongolian waters makes culture of common carp uneconomic as it would grow too slowly to achieve marketable size. Production of rainbow trout would require considerable investment in pond construction and water supply to provide the required 3 m depth at which water current would be maintained under ice even at temperatures of -400C. However, the potential for producing selected local fish species in non-drainable deeper ponds might be worth investigating.
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1 There is a variety of names in the Mongolian, Russian and English publications and maps for a single locality. The present text has used English versions as far as available in the current atlases. However, as the original text is translated from Russian, the Editor has transcribed the Russian "kh" as "h" for those names for which no equivalents could be found in English texts and maps. The Editor was not always able to clarify the use of Nuur, Nur, Nor and Tsagaan. As the tables were prepared prior to the editing of the text, they contain a straight transcription from Russian into English. The following list gives some alternatives in brackets:
Aygar (Aigar); Buyr (Buir); Dalai Nur (Dalai Nor, Dalainor); Darhat (Darkhat); Dood Nuur (Dood-tsagaan); Doroo (Durgen); Dzavhan (Zavkhan); Halhin Gol (Khalkhin-gol); Hangayn (Khangain); Har Us (Khar us); Hogorog (Khogorog); Hoh (Khokh): Hongor-Ulen (Khongor-Ulen; Khongor-Olen); Horgon (Khorgon); Hoton (Khoton); Hovd (Kobdo); Hovsgol Nuur (Khubsugul; Kosogol); Hurh (Khurkh); Hyargas (Khyargas); Ih-Hanha (Ikh-Khankha); Orhon (Orkhon); Selenga (Selenge); Shishhid Gol (Shishkhid gol); Terhiyn Tsagaan (Terkhiin-tsagaan, Terhiyn Nuur); Ugiy (Ugii); Ulaagchnyi Har (Ulaagchnii Khar); Yenisei (Yenisey, Enisei).