Characteristics of ichthyofauna reservoirs of the Gydansky peninsula

The Gydansky peninsula, located in the north-east of Western Siberia, is studiedbadly from the ichthyologic point of view. At the same time, the activization of such formsof economic action here as prospecting and extracting oil and gas, urbanization andfishery cause deterioration of conditions of fish habitats and reduction of their specificvariety and number.The hydrographic network of the peninsula is well-developed and presented by dozensof small rivers and numerous shallow lakes of thermokarstic origin. The greatest riversof the peninsula are the Tanama (length 520 km) and the Yuribei (400 km). The largestlakes have relict-sea genesis and are running and incorporate through rivers with seawaters. The maximum depths in these lakes reach 25-42 m, up to 50-60% of the area oflake bottoms are occupied by sandy and uliginous-sandy deposits, unproductive in thehydrobiological relation. In the hydrochemical relation waters of rivers and lakes of thepeninsula are low-mineral (150-200 mg/L), with small maintenance of biogene elements.The maximum temperature of water in rivers of the peninsula does not exceed 20С, inthe surface layer of lakes it goes up to 12-15 С. Many lakes of thermokarstic genesisfreeze through to the bottom in winter.Extreme conditions of habitation cause low level of development of seaweeds and hydrocolesnonvertebrata in the rivers and lakes of the peninsula and, as a result of this, aforage reserve of fish. For example, the biomass zoobentos in lakes of thermokarstic andrelict-sea genesis makes 0,5-1,5 g/m2 during the summer period, in inundated lakes -3,0-3,5 g/m2. Considering all abiotic and biotic characteristics, rivers and lakes of thepeninsula are oligotrophic.In rivers and lakes of the peninsula live 22 species and subspecies of fish, with the speciesnumber domination (8) of Coregonidae family, the most adapted to the conditions inSubarctic region of Siberia. Four species of fishes of this family: Coregonus lavaretus (Linnaeus,1758), C. nasus (Pallas, 1776), C. peled (Gmelin, 1789) and C. sardinella Valenciennes,1848, make the basis of fishery. The appreciable specific weight in fishing is occupiedby Lota lota (Linnaeus, 1758) (Lotidae family). Other species of fish of the peninsulaare either small or rare. Judging by the data of fishery statistics, the efficiency of rivers andlakes of this region of Western Siberia is low and makes 2-3 kg of fish per hectare. Howeverthe uniqueness of ichthyocenosis and gidrobiocenosis of waters of the peninsula causethe necessity of their studying and protection.

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