NEW DATA ON FISH COREGONUS PELED (GMELIN,1788) IN SOME WATERBODIES OF MONGOLIA

Abstract

In connection with the planned establishment of a coregonid fishery and the construction of a specialized hatchery in the area of Western Mongolia was organized with the task of studying some parts of the reproduction biology of Coregonus peled population inhabiting Lake Ulaagchnii Khar Nuur (Zavhan aimag). This species was introduced into this Mongolian lake, originally lacking any fish stock, in 1980 -1982. The samples of 11230 fish examined was collected during 1993 -1999, 2005-2011 and consisted partly of the fish originating from imported and introduced larvae and partly of the individuals belonging about 25th generating , already born in the lake studied. Most of parameters studied, such as absolute size, weight, the population dynamics, reproduction biology, of food analyses, and fatnes observed to the during vegetation period (November – December and first half of January), when the minimum daily waters temperature drops to 40centigrade or less. The sex ratio is fairly balanced if the total material from all fishings is considered. During this period of peak-spawning females predominate. The average individual standard length of spawners was 400 mm in males and 420 mm in females, the average weight 700 g in males and 900 g in females. Nevertheless, all parameters under study tend slightly to deteriorate in the course of time, which is obviously a result of the gradually increasing population density and of decreasing quantity of food available in the lake. In Khuisiin Naiman Nuur (Uburchangajskij ajmag) sexually mature at the age of 2 + , exceptionally already at the age of 1 + , at the minimum total length of 323 mm and minimum weight 295 g. Gonadosomatic index of mature females ranged 9.0 to 25.0 %, mean absolute fecundity averaged 58.060 eggs.