This article reviews the fish fauna of Lake Baikal, the world's deepest and largest lake in volume. The nucleus of the fish fauna of Lake Baikal is a unique complex of endemic cottoid fishes (56% of the total number of species and 41% of the total number of genera) and endemic species and subspecies of the coregonid and thymallid families. Abundance and composition of the fish fauna have changed during the 20th Century in each of the three main parts of the lake: north, central and south. Historical and present environmental conditions, such as main habitats, water quality and anthropogenic impacts, are discussed. Key objectives of fishery management on Lake Baikal include: (i) protection of fishes, especially commercial species, during periods of preparation for spawning, on spawning runs and in spawning areas; (ii) progressive restriction of the industrial fisheries and rapid expansion of sports and recreational fisheries; (iii) reallocation of priorities in the artificial breeding of fishes to restore the natural population structure of Omul and to restore the abundance of other valuable species that are important for sport fishing; (iv) prevention of the introduction into the Baikal basin of any new non-indigenous fish species; (v) conservation of habitats used by different ecological groups of fishes.
Addition of Lake Baikal to the World Heritage List necessitates a critical review of human activities on the shores of the lake and development of new environmental management strategies. This review describes changes in the fish community of the lake, resulting from human activities, and analyses the status of fisheries in Lake Baikal. For several hundred years human impacts on this ecosystem were mainly expressed in the intensification of fisheries. Only since the mid-20th Century has the pace of industrial development increased in the lake basin, leading to a significant increase in adverse impacts on the ecosystem of Lake Baikal, including the fish stocks. The authors review the actions taken in recent decades to prevent these effects primarily on the fishes, evaluate their effectiveness, and outline the future prospects for fisheries development.
A brief physical-geographical review of Lake Baikal
Lake Baikal is by volume (23,015 km3) and by depth (over 1630 m) the earth's largest freshwater body (Ravens et al., 2000). It holds about 20% of world freshwater reserves, and, at the same time, is an important Russian inland fishery region. Lake Baikal is located in Eastern Siberia at 454 meters above sea level and fills the biggest central depression among a series of tectonic breaks of the Baikal Rift zone. The lake is 636 km long and 25 to 80 (averaging 48) km wide with a water surface area of 31,500 km2, a catchment area of 540,000 km2, a shoreline length of 1800 km, a mean depth of 731 m and a maximum depth of 1631 m (Efimov, 1970).
The lake bed consists of three depressions (Figure 1). The most ancient is the southern depression with the maximum depth, by different sources, of 1394–1432 m; the maximum depth of the middle depression reaches, by different sources, 1632–1642 m; the most recently formed and shallow northern depression is 889 m deep. More than 300 rivers and small streams flow into the lake; the biggest one is the River Selenga which accounts for about half of river inflow (some 30 km3). Other big tributaries are the River Verkhnyaya Angara (640 km long) with an annual inflow of 9.42 km3, and River Barguzin (700 km long) with an annual influx of 3.54 km3. A single river, the Angara, flows out of the lake. Water level has a seasonal fluctuation within limits of 1.4–2.7 m with the minimum level observed in April and the maximum in September. The water's mineral content is less than 100 mg l−1 and the calcium content is less than 15 mg l−1. One of the unique features of Lake Baikal is the high concentration of oxygen in the water at all depths. Oxygen saturation varies from 75 (at the bottom) to 115%. Transparency by Secchi disk is 5–8 m in summer and 30–40 m in winter (Domysheva, 2009).
The thermal regime of the lake is harsh and only exposed to seasonal fluctuations in the surface 200–250 metres. In summer, the temperatures of the surface water layer are 14–16ºC, at 10 metres 10–12ºC, and in some shallow bays surface values may reach 20–24ºC. There are two periods of the temperature stratification – direct in summer and inverse in winter. Also, there are two periods of homothermy, in spring (May–June) and in autumn (October–November), when the water temperature of the surface 0−250 m water layer equals to about 4ºC. Below those depths, there is a permanently stratified deep water mass with temperature throughout the year equaling to 3.1–3.8ºC (Shimaraev et al., 1993; Ravens et al., 2000). The lake is covered with ice from January–February until early June. Maximum ice thickness ranges from 0.6–0.8 to 1.2–1.5 m. Bottom sediments vary in different parts of the lake from stony-pebble and sandy bottoms in the shore zone to silty sand, silt, and clay in the deeper zones. Sediment accumulation is 4.2 cm per 1000 years (Efimov, 1970; Domysheva, 2009). The recent state of hydrology of Lake Baikal was reviewed by Shimarev and Domysheva (2012).
Review of fish fauna composition and history
Ecology, taxonomic contents, and endemism
Lake Baikal Lake has a unique and rich endemic flora and fauna. Specialists predict there could be as many as 3500 animal species and 1500 plant species (Timoshkin, 2001). The most diverse are infusorians (350 free-living and parasitic species), flatworms (more than 290 species), rotifers (more than 200 species), oligochaetes (more than 200 species), and crustaceans (more than 690 species). The Chironomidae contain more than 120 species, mollusks (gastropods and bivalves) more than 180 species, and fishes 61 species. Besides a great number of endemic species, there are also some endemic genera and families.
In its structure and characteristics, the Baikal ecosystem is similar to oceanic ecosystems with the following characteristic features:
The presence of a pelagic community with low taxonomic diversity and high productivity. The most abundant and productive (0.25–0.64 g m−3) species of mesoplankton is a small endemic crustacean Epischura baicalensis Sars, 1900. The main species of macroplankton (up to 3 g m−3) is an endemic pelagic amphipod Macrohectopus branickii (Dybowski, 1874). The pelagic endemic fish community consisting of five or six pelagic and benthopelagic species is discussed below;
The presence in slope zones of a macroplankton community, that possesses a very high biological productivity, analogous to the upwelling zone in the ocean rich in nutrients;
The benthic community is characterized by high species diversity and high productivity (up to 30 g m−2 y−1 in the open littoral zone and up to 80 g m−2 y−1 in the bays). Key species of the benthic community are oligochaetes, mollusks, amphipods, and chironomids;
The presence of the fresh water fauna at a great depth (more than 100 m) analogous to that known only in oceans and seas; and,
The terminal species in the food chain is an endemic Baikal Seal Pusa sibirica (Gmelin, 1788), the world's only completely freshwater seal with a population size between 70,000 and 120,000.
Areas with a depth up to 20 m (only about 5% of the total lake area) are the main fishing zones adjacent to the mouths of main rivers such as Selenga, Verkhnyaya Angara, Kichera, Barguzin or located in bays, relatively larger (Barguzin Bay, Chivyrkuy Bay, Maloye Morye [Small Sea] Strait) or smaller, so-called sors (North Baikal Sor, Proval Sor, Posolskiy Sor, Dubininskiy Sor). A scheme of zoogeographic regions was proposed by Taliev (1955) for Lake Baikal with the lake divided into two main bathymetric zones, the shallow zone of 0–400 m depth and the deep zone (400 m down to the maximum depth). The shallow zone is subdivided into the northern part and the central-southern part with nine open water districts within both, and shallow isolated areas (sors) neighboring river mouths. The deep zone is subdivided into north-central and southern parts. Based on modern data on fish distribution in the lake, the scheme has been modified and no subdivisions are accepted now as it was shown that there are no distributional barriers for most deep-lake species (Matveyev and Samusenok, 2006).
There have been a number of fundamental investigations of the taxonomy and ecology of Baikal fishes (Taliev, 1955; Skryabin, 1969, 1979; Smirnov and Shumilov, 1974; Tugarina, 1981; Sideleva, 1982, 1994, 2003; Matveyev et al., 2008). The Baikal fish fauna includes 61 species and subspecies (Sideleva, 1994, 1998, 2001, 2003; Knizhin et al., 2004; Matveyev and Samusenok, 2006; Matveyev et al., 2008) from 15 families; a list of taxa is given in Table 1.
Significant differences of the fish fauna of Lake Baikal from those in adjacent basins is the reason for establishing it as a separate zoogeographic subregion belonging to the Holarctic Region (Berg, 1909). The nucleus of the fish fauna of Lake Baikal is a unique complex of endemic cottoid fishes (56% of the total number of species and 41% of the total number of genera).
Using the species endemism and distributions in the lake, three groups of fishes can be distinguished. The first group comprises endemic species of the families Cottidae, Comephoridae and Abyssocottidae (the latter two families are considered to be within Cottidae by some authors) (34 species from 12 genera) which are widely distributed at all depths all over Lake Baikal. The second group was defined as a ‘Baikal-Siberian complex’ by Vereshchagin (1935) and consists of five fishes endemic at the species or subspecies level: Baikal Sturgeon Acipenser baerii baicalensis Nikolski, 1896; Baikal Omul, or just Omul Coregonus migratorius migratorius Georgi, 1775; Baikal Lake Whitefish C. pidschian baicalensis Dybowski, 1874; Black Baikal Grayling Thymallus baicalensis Dybowski, 1874; and White Baikal Grayling T. brevipinnis Svetovidov, 1935. The third group is a complex of non-endemic ‘common Siberian’ species inhabiting the lake's littoral zone and mouths of rivers, which consists of 16 indigenous species and 6 introduced species. Many species from this third group are very rare or occasional in the lake (Table 1).
Fishes of the ‘Baikal-Siberian complex’ inhabit the lake up to depths of 250–300 m; however their maximum abundance occurs at depths of 20–50 m. The same zone is also inhabited by several species of the ‘endemic Baikal complex’ and of the ‘common Siberian complex’. The latter group is represented there by so-called ‘Baikal forms’ specialized for inhabiting the Baikal littoral zone and having increased growth rate (Kozhov and Misharin, 1958; Kartushin, 1958). A few of the non-indigenous species – Peled Coregonus peled Gmelin, 1789, Amur Catfish Parasilurus asotus Linnaeus, 1758, and Amur Sleeper Percottus glenii Dybowski 1877, are also established there. The Baikal littoral zone is an area of interaction between ‘endemic Baikal complex’ and ‘common Siberian complex’ and is a transit zone for energy and nutrient exchange to and from the deep zone. At the same time, the littoral zone is of great significance for fishery as it is inhabited by valuable species and, thus, is the main zone of traditional fishing.
Species abundances and the composition of the fish fauna in each of the three main parts of the lake have undergone considerable changes during the 20th Century (Table 1). According to our 20-year-long investigations and literature (Taliev, 1955; Bazikalova and Vilisova, 1959; Ustyuzhanina, 1971), the fish composition of the Baikal littoral zone and the slope zone up to the depth of 200–300 m consists, at present, of 46 species and subspecies inhabiting it permanently or sporadically.
Species that mainly inhabit the littoral zone are as follows (in decreasing order with regard to their biomass and abundance): Sand Sculpin Leocottus kesslerii (Dybowski, 1874), Stone Sculpin Paracottus knerii (Dybowski, 1874), Black Baikal Grayling Thymallus baicalensis (Dybowski, 1874), Baikal Omul C. migratorius migratorius (Georgi, 1775), Bighead Sculpin Batrachocottus baicalensis (Dybowski, 1874), White Baikal Grayling Thymallus brevipinnis Svetovidov, 1935, Baikal Lake Whitefish C. pidschian baicalensis Dybowski, 1874, and Siberian Whitefish C. pidschian (Gmelin, 1788). In the sublittoral zone the main species are Baikal Omul and Yellowfin Baikal Sculpin Cottocomephorus grewingkii (Dybowski, 1874) and other cottoid species are also present.
Depths of more than 300 m are inhabited by only endemic cottoid fishes. This is a very specific autochthonous lineage that evolved in the lake itself (Mamontov, 2001). At depths of more than 1000 m, there are only six species, and at the maximum depth only four species occur: Cottinella boulengeri (Berg, 1906), Neocottus werestschagini Taliev, 1935, Abyssocottus gibbosus Berg, 1906 and Abyssocottus korotneffi Berg, 1906 (Sideleva, 1994, 1998, 2003).
The pelagic ichthyocenosis is more productive, though composed by a limited number of species: two pelagic viviparous cottoid species (Big Oilfish Comephorus baicalensis [Pallas, 1776]) and Small Oilfish Comephorus dybowski Korotneff, 1905) and three benthopelagic fishes (Yellowfin Baikal Sculpin, Longfin Baikal Sculpin (Cottocomephorus inermis [Jakovlev, 1890]), and Baikal Omul. The biomass of Big Oilfish was estimated by our observations as 73,300–112,000 tonnes (t); Small Oilfish 61,500–103,000 t, Yellowfin Baikal Sculpin 5000 t, Longfin Baikal Sculpin 3000 t, and Omul 23,000–30,000 t.
Endemic species are absent from shallow bays and sors where the most abundant species are cyprinids, in particular Roach Rutilus rutilus (Linnaeus, 1758), and also Perch Perca fluviatilis Linnaeus, 1758 and Pike Esox lucius Linnaeus, 1758.
History of the fish fauna formation
The formation of the unique present-day fish fauna in Lake Baikal is the result of a long evolution and adaptation to the diversity of existing biotopes. Prior to the existence of the modern Baikal there were several pre-historic water bodies. Their shape and number changed through time (reviewed by Timoshkin, 2001). The first lakes appeared between 25–30 and 60–70 million years ago. The most ancient (Oligocene–Miocene) deepwater lake appeared first in the South Baikal depression and it was inhabited by diatoms, sponges, and mollusks that were closely related or identical to the present Baikal species. The most ‘recent’ part is North Baikal which appeared only some 6 million years ago. The process of mountain uplift started around Baikal only 3.5 million years ago. This orogenesis led to significant water level fluctuation in the lake and changes of its drainage pattern. It is considered that Lake Baikal was subsequently connected with three great Siberian drainage basins: Lena, Yenissey and Amur (Korzhuyev, 1977). In general, the border of the Arctic and Pacific Ocean watersheds were displaced to the south. At that time, in whole Siberia, and particularly in the Baikal Basin, the warm-water Tertiary ichthyofauna became extinct and was replaced by a complex of cold-water species of Arctic and Boreal origin. The only species that has persisted from the Tertiary period up to present is the Baikal subspecies of Siberian Sturgeon. Cold-water species such as Taimen Hucho taimen (Pallas, 1773) and Lenok Brachymystax lenok (Pallas, 1773) probably appeared in Lake Baikal as late as the Pliocene; the most probable time of the appearance of Burbot Lota lota (Linnaeus, 1758), graylings and whitefishes is Pliocene–Pleistocene.
The most uncertain timing is that of the penetration of the ancestors of modern cottoids and formation of their diversity in the Baikal Lake. Berg (1922) and Sideleva (1994) hypothesized that the Baikal cottoids are ancient autochthonous forms. Another theory was proposed by Dorogostayskiy (1923) and worked out in details by Taliev (1955). It emphasizes the evolutionary youth of the endemic cottoid fishes and their rapid speciation in the lake. New genetic and molecular data (Kirilchik et al., 1995) support the latter hypothesis confirming the age of cottoid diversification as recently as about 2 million years only (Timoshkin, 2001).
Fishery and fish-farming
Fishing in Lake Baikal has had a long history beginning in the 17th Century. The primary objects of the commercial fishery were Baikal Sturgeon and Omul. The first fishing regulations appearing at the end of 19th Century limited net fishing of Omul in the pre-spawning period; these regulations had very little effect. At the beginning of the 19th Century, the sturgeon catch was as high as 200 t in some years, and declined to only 10 t in the 1920s (Egorov, 1961, 1985). Omul catches decreased during the same period from 8000 t to 1500–2000 t (Popov, 1958) but stabilized at levels of 5000–6000 t in 1930s. During the Second World War, Omul catches increased to 8000–9000 t due to increased fishing activity. During that period, the catches of other fishes also increased, and fishing of Baikal cottoid fishes began. In 1945 to 1955, Omul catch was 4000–5000 t, but by the early 1960s fell to 1700 t. In 1969–1975, Omul fishing was banned, but the Omul stock did not recover and its main population characteristics continued to deteriorate. The restrictive measures led to increased fishing of other valuable fish species, in the first place, salmonids, whitefishes, and Burbot, during their pre-spawning and spawning periods at mouths of rivers. Such practices quickly destroyed the fishery stocks of these species and from mid-1980s on they did not play any significant role in the fishing industry. At present, the most important commercial fish species are still Omul, as well as Black Baikal Grayling, Pike, Roach, Burbot, Perch, and some cyprinids that are rare or sporadic in the lake but caught in lower reaches of rivers. In recent years, introduced Amur Catfish and Bream Abramis brama (Linnaeus, 1758) have appeared in commercial catches in small amounts. Commercial fishing for the following species is forbidden: Baikal Sturgeon, Taimen, Lenok, White Baikal Grayling, and whitefishes. These species are included in Red Book data at various administrative levels.
The total official catch fluctuates from 2700 to 3450 t, of which up to 65–70% is Omul. Another 20–25% is Roach. The total catch of all other species does not exceed several tens of tonnes. Expert estimates of illegal catches, at the same time, are put at about 700 t.
Hatchery activities are in place for Baikal Sturgeon, Omul, Baikal Lake Whitefish, Black Baikal Grayling and White Baikal Grayling. There are three still functioning fish farms located on a tributary to Posolskiy Sor (Bol'sherechenskiy hatchery farm), on River Selenga (Selenginskiy hatchery farm), and River Barguzin (Barguzinskiy hatchery farm) (Figure 1). The main species that is artificially reared is Omul. In 1920s, K. N. Panteleyev first experimented with keeping breeders in cages, artificial spawning and egg incubation at a fish farm in Ulan-Ude; since then, number of individuals released increased to 120 million in 1930s and 2.53 billions in 1998 (50% of this being produced at Bol'sherechenskiy, 43% at Selenginskiy and 7% at Barguzinskiy hatchery). In the 2000s, the average number of fry released was 1.26 billions per year. Artificial spawning of Baikal Sturgeon was started in the middle 1980s when a dramatic decline of this species occurred. It is based at the experimental hatchery station on River Selenga (Selenginskiy), the main spawning river for sturgeon in the Baikal basin. From 1996 to 2002, 4.36 million sturgeon fingerlings were released into the lake. Artificial rearing of Baikal whitefishes and White Baikal Grayling was also begun at the Selenga hatchery. It is still in the experimental stages and the releases are only 15 million whitefishes and 250,000 Grayling per year.
State of environment: Main habitats, water quality and anthropogenic changes
During the second half of the 20th Century, the pace of economic development activities in the basin of Lake Baikal grew dramatically. In the early 1960s, habitats of many Baikal aquatic organisms were seriously impacted by the rise in the water level (about 1 m) and changes in the natural seasonal fluctuations due to construction of the Irkutsk Hydroelectric Power Station on the Angara River, 70 km downstream from its outflow from the lake. Based on this source of cheap power, an industrial area was developed (the Irkutsk-Cheremhovsky Industrial Region), which then became a source of significant pollution from aluminum, pulp and paper and chemical industries, as well as from further power plants that burn solid fuels. However, because of regional topography and prevailing wind directions, contamination from the industrial region have had less impact than that from industrial enterprises located in the Baikal Depression proper. The greatest negative impacts have arisen from the air emissions of sulfur dioxide, nitrogen oxides, sulfur-and hydrocarbon, methyl mercaptan, formaldehyde, and phenol. The biggest source of air pollution of the environment located directly on the shores of Lake Baikal is the Baikal Pulp and Paper Mill (BPPM). The total annual emissions of air pollutants from stationary and mobile sources at Baikalsk, where the plant is located, are 8100 t (2100 t of solid substances, 2000 t of sulfur dioxide, 200 t of carbon monoxide, 2000 t of nitrogen oxides). In 1990s, the release of specific substances (dimethyl sulfide, methyl mercaptan, hydrogen sulfide, chlorine, etc.) decreased by 10–15% (State Report on Environmental Conditions in Irkutsk Province in 1998, 2000). In general, since then a clear trend toward reducing atmospheric emissions of pollutants has been seen in the region. The most prominent sources of liquid sewage are the major pulp and paper production plants in the south of Lake Baikal and in the lower reaches of the Selenga River. For example, in 1998, dumping partially-treated waste water from sewage treatment plants at BPPM amounted to 33.7 106.m3, and the lake received 146 t of lignin, 12 t of nitrates, 4215 t of sulfates, and 1596 t of chlorides. As with air pollution in recent years, there has been a significant reduction of liquid pollutants as a result of equipment upgrades at treatment facilities.
Increased coastal erosion caused by the higher water level on Lake Baikal, necessitated large-scale bank protection works at the south-east coast where the Trans-Siberian Railway passes. These measures had negative impacts on the coastal spawning sites of Baikal Yellowfin Sculpin. Also, beginning in the mid-1970s, the Baikal ecosystem was strongly negatively impacted by the construction of the Baikal-Amur Railway close to the shore of the northern part of the lake, due to large-scaled straightening of the shoreline, deforestation, timber floating, and a sharp rise in water freight transport with concomitant release of oil products into the lake. The population growth was associated with increased illegal harvesting of valuable fish species to levels thought to be as great as the official (legal) catch.
All these categories of human activity had the greatest impact on biota of the littoral zone, where the highest number of endemic species occurs, especially at the higher levels of the food chain in the ecosystem of Lake Baikal – the fish and seal populations. For example, one of the consequences of the lake water level increase was a drastic drop in numbers of Baikal Yellowfin Sculpin, an important part in the Baikal food chain and an important food source of Omul, a species that had long been a dominant component of the fish fauna and the fishery in Lake Baikal. Due to the rise in water level, spawning sites of Baikal Yellowfin Sculpin were placed beyond the favored surf zone. In addition, southern lake shores along the Trans-Siberian Railway were reinforced with solid concrete constructions, and local people started collecting Yellowfin eggs for consumption. The joint impact of these factors led to the disappearance of several generations of Baikal Yellowfin Sculpin. As a result, yellowfin catches decreases in 1970s to 10 t comparing to 1400 t in the 1950s. By the middle 1980s, the numbers of yellowfin sculpins had decreased dramatically—by a factor of 300 (Matveyev et al., 2008). In turn, this caused a decline of Omul numbers of at least two times and of its biological characteristics as well because Baikal Yellowfin Sculpin was the main food item for Omul. In Omul diet, Yellowfin contributed up to 38% in the 1950s, 12% at the end of the 1960s, and only 0.2% in the 1970s (Toporkov, 1987). Beginning in the 1980s, there was some evidence of improvements in the biological characteristics of the stocks with increasing of numbers of eggs laid and of Yellowfin young-of-the-year in the upper water layers. It appears that the Yellowfin stock is slowly coming out of the depression state that began at the end of 1960s. In the late 1980s, the contribution of Yellowfin increased in the Omul diet. Omul again became more abundant in the southern part of Baikal where it had been only occasionally caught in the 1970s. In 1995–2004, concentrations of foraging Omul become comparable to those in the 1950s, and Baikal Yellowfin Sculpin young-of-the-year comprised up to 30%–90% of Omul's ration by mass.
Management of the Baikal fishing industry is now implemented by three independent organizations: (1) Baikal Basin Department on Protection, Reproduction of Fish Resources and Fishery Regulation (Federal State Institution FGU “Baikalrybvod”) whose main duties are protection, regulation of fishing and inspection of biological resources use; (2) East-Siberian Scientific-Production Center of Fishery (FGUP “Vostsibrybcenter”) which assesses the size of fish stocks, develops fishery forecasts (i.e. the total allowable catch, TAC) and provides research support for fishery industry and fish farming; (3) Union of Fishing Organisations (ZAO “Baikalrybhoz”) that performs fishing and processing of fishes and Baikal Seal.
These organisations were part of the Ministry of Fisheries of the RSFSR and the USSR. Currently, the coordinating role is provided by the Scientific Fishery Council affiliated at FGU “Baykalrybvod,” which draws representatives from these organisations and a number of research institutions. The membership of the Council is approved by the Main Department on Protection, Reproduction of Fish Resources and Fishery Regulation (“Glavrybvod”) of the Committee on Fisheries of Russian Federation.
General coordination of scientific research and consultations regarding strategic decisions on the use of Baikal biological resources were previously implemented by East-Siberian Branch of Ichthyological Commission of the Ministry Fisheries of the USSR (now the Interdepartmental Ichthyological Commission of Russian Academy of Science, Ministry of Agriculture, and State Fishery Committee). However, the activities of the Commission have not been effective in recent years.
Fishing in Lake Baikal is governed by the Russian Federation Law “Protection of Lake Baikal,” which was adopted in May 1999. The State Resolution “On peculiarities of protection and harvesting of endemic water animals and gathering of endemic water plants in Lake Baikal” (No. 67, 28 January 2002) is also in effect. Annual TACs are adopted on the base of a scientific forecast developed by the “Vostsibrybcenter” using the State's ecological expertise. Recreational fishing is licensed; the licenses are distributed by the local fishery authorities. Data from “Vostsibrybcenter” shows that, for example, in 2003, the total recreational fishing catch was 170 t, including 115 t of Omul, 17 t of Roach, 12 t of Perch, and 10 t of Siberian Dace. To ensure of the sustainability of the fisheries, a special law of the Government of the Russian Federation (No. 234, 26 March 2001) established allowable limits of the water level fluctuations in Lake Baikal of 1 m between 457 and 456 m (according to the Pacific System of Elevations). In 2011, for example, the water level was at 456.28 m (Pacific system).
The main direction of work to maintain and restore the fish stocks of Lake Baikal was to maximize the Omul fishery. This fisheries management strategy has had both positive and negative consequences. Persistent decreases in Omul commercial catches in the first half of the 20th Century became the main driving force for the intensification of efforts to create technologies for artificial reproduction. The main idea was to maintain a high abundance of natural spawning populations through contracted hatcheries at all spawning rivers. Hatcheries on tributaries of Posolskiy Sor, Chivyrkuy Bay, Maloye Morye Strait, Selenga and Barguzin rivers were built while that on the Angara was only planned. The size of the Omul populations in the Chivyrkuyskiy Bay and the Maloye Morye was small and could not provide enough breeders to sustain the hatcheries; so, those hatcheries were closed. Similar situations were repeated at the Selenginskiy and Barguzinskiy fish farms. As a result only half of their facilities are used for re-stocking population of the rivers where they are located. Other parts of their facilities are used to incubate eggs from the Posolskiy Sor population. Hence, the Posolskiy Sor Omul became the main reared population though the fingerlings are released, in part, into the lake areas non-native for this population. The Posolskiy Sor Omul is a benthic deepwater dweller inhabiting mainly depths from 200 to 400 m. Thus, re-stocking of this population has been ineffective as it cannot be fished at those depths. As a result, there is now an imbalance in size of the different Omul populations and the reproductive state of their spawning stocks.
Another direction for “improvement” of commercial fish stocks was the introduction of new exotic species as it had been thought that native fishes did not use all the food resources of the lake. Introduction of new species, mainly of commercial value, began in the early 1930s. Up to 1970s, introductions were made without any effort to account for specific features of the Baikal fish communities or the Baikal ecosystem in general, and without any long-term predictions. Altogether, thirty fish species were proposed for introduction, and sixteen were introduced (Mamontov, 2001). Most of these introductions failed. Only five non-native fish species (Peled, Amur Carp, Amur Catfish, Bream and Amur Sleeper) became established; all of them are caught periodically in the lake. The Amur Carp stock reached a commercially valuable level up to the end of the 1970s, though later its catches declined to a level so that official records are not kept. Although the present numbers of Peled, Bream, and Amur Catfish are also very low, these fishes are still included in the TACs for Lake Baikal.
Amur Sleeper was unintentionally introduced along with Amur Carp into a lake in the Selenga river drainage. From there it expanded its range rapidly and became established in a number of waterbodies of the Baikal basin including Lake Baikal. At present, Amur Sleeper inhabits the delta of River Selenga, all shallow-water bays along the lake eastern coast, coastal areas of the southern part of the lake, and some locations along the western coast. In some locations at the eastern coast its abundance, in 1990s, reached 75–90 specimens per m2 (Pronin et al., 1998), and it became a competitor of native shallow water fishes, especially roach and dace (Litvinov and Gorman, 1996). At the same time, Amur Sleeper became a common part of the food diet of Pike, Perch, sometimes White Baikal Grayling, and piscivorous birds. In recent years, a marked downward trend in the number of Amur Sleeper and a reduction of its distribution in the lake has been recorded. As to deep water habitats in Baikal, little is known.
Modes of fishing, fishing gear, protective measures, and hatchery activity were mainly focused on Omul. The young of other species of fishes, similar in size to Omul, were caught alongside Omul with no special consideration of additional pressures on populations of these species. The long-term depression of species other than Omul has given rise to the viewpoint that those species have no commercial value in the lake (Mamontov, 1996). Thus, Omul fishing in Lake Baikal has acquired the characteristics of a monoculture.
Nature protection and conservation
The present state of fisheries and fish stocks described above has arisen from the negative impacts of economic activity in the Baikal basin. In the 1980s, these changes become obvious to all those involved in research on the Baikal ecosystem. This situation made necessary specific efforts to make improvements. In the late 1980s and early 1990s due to the political changes occurring in Russia, a movement formed to protect Lake Baikal, which brought together scientists and a wide range of the general public. As a result, Lake Baikal was added to the UNESCO list of World Heritage sites in 1996. This act along with ratification by Russia of the Convention on Biodiversity became the basis for the “Strategy on Biodiversity Conservation in the Baikal Lake ecosystem” which was supported by the World Bank. A full range of activities to preserve the Baikal ecosystem was elaborated in the sub-programme “Protection of the Lake Baikal and Baikal Natural Territory” of the National Programme “Ecology and Natural Resources of Russia (2002–2010), which was approved by the Government of Russian Federation in 2001.
According to the national law “On Protection of Lake Baikal,” the Baikal natural territory is selected with an area of 30.7 million hectares. This area is subdivided into the following zones: (1) The Central zone that includes Lake Baikal, all its islands and adjacent protected areas, where the main protective activity is conservation of rare and endemic species and their habitats; (2) the Buffer zone that overlaps the whole Baikal basin (except the lake proper, or the Central zone) in the Russian Federation, where the main tasks here are protection and regulation of the traditional uses of the natural resources (grassland farming and fishing), elimination of timber logging, and reduction of other industrial impacts; (3) the Zone of Atmosphere influence that includes the territory out of the Baikal basin within the range of 200 km from the lake towards the west and the north-west from the lake encompassing those areas where some industrial plants are located that could have negative impacts on the Baikal ecosystem, where the main tasks are to minimize influences of the hydro-construction on the water level in Baikal, decrease the air pollution from industrial plants, and prevent negative impacts from the planned industrial activities (e.g. the construction of the power transmission lines to other countries). At present, the new legislation has been passed framing these basic strategies, but implementation has been very slow.
There are also some special protected areas in the Central zone. There are three state nature reserves (Barguzinskiy, Baikalskiy, Baikalo-Lenskiy), two national parks (Pribaikalskiy, Zabaikalskiy), and also four wildlife sanctuaries. All are located on the shores of the Baikal, but aquatic areas are not included in any of them. All special protected areas currently only serve to protect terrestrial ecosystems around the lake.
Fishing has been the traditional focus of management on Lake Baikal and its modernization needs to be considered as part of the economic development plans for the Baikal region.
However, it is clear that besides the development priorities for Lake Baikal uses such as increased tourism and recreation, or as a source of hydropower and drinking water, fisheries are becoming less significant. Traditionally extensive fishing methods, their low efficiency, large-scale poaching, along with the prospects for the reorientation of economic activities in the Central zone of the Baikal Natural Territory in accordance with the principles of the Convention “On the Global Natural and Cultural Heritage,” make it necessary to implement several urgent actions including the reorganization of fisheries and measures to improve the lake's ecosystem.
Reorganization of fisheries proposals include: (1) changes in fishing strategy aimed at managing the intensity of fishing instead of catch volume limitations; (2) more effective security measures on the part of fishing and local authorities; (3) optimization of the technology and scale of artificial propagation of Omul and other valuable fish species. Today's excessive emphasis on artificial reproduction of Omul does not provide the necessary economic and environmental benefits while, at the same time, significantly altering the natural structure of Omul populations and their ecological relationships in the lake. It appears that preserving or expanding artificial reproduction, aimed at maximizing the catch on the one hand, and maintaining the natural population structure of Omul on the other hand, is compatible. It is necessary to limit the scale of artificial Omul reproduction to levels sufficient to maintain the rate of natural reproduction, and to significantly extend the capacity of hatcheries for other valuable fish rearing, in particular, of Baikal Sturgeon, Taimen, Lenok, whitefishes, and graylings. Such measures will not only restore the natural structure of fish communities, but will provide an opportunity to greatly intensify sport fishing. There is evidence, that recreational fishing as part of the tourism industry can have a greater economic impact than traditional fishing.
Any introduction of non-indigenous fish species to the basin of Lake Baikal is entirely forbidden at present, and a prohibition of incubation of eggs of non-native species in Baikal hatcheries has been recommended.
Protection of the environment should be considered as another important activity. The priorities in this area include: (1) stabilization of the lake level regime and its seasonal variation within the limits that are close to natural regime; (2) relocation of enterprises now operating directly on the shores of Lake Baikal; (3) reduction of the negative impacts coming from industrial, agricultural and household pollution in the basin; (4) in the future, complete elimination of pollution loads into the lake; (5) reduction of the impacts of construction and upgrading of shore facilities and transport routes, of which some level of development is inevitable.