Sandimirov S.S. Catalogue of lakes in the Russian, Finnish and Norwegian Border Area. Finland, Jyvaskyla: Kopijyva Oy, 2008.

The average weight of trout is 484 g and length 34.9 cm. The length of some trout specimens reaches 44.3 cm with a weight of 810 g. The sex distribution of trout is dominated by males - 1:2.5. The oldest registered trout age is 7 years. Arctic char was represented by a single sample, which was a 5-year-old mature female fish with a weight of 762 g and length of 40 cm. Perch in Lake Stuorajavre is represented by small-sized fish with an average weight of 89 g and length of 17.7 cm. The largest specimens do not exceed 373 g and length 29.0 cm. Fish with a weight of under 100 g and length of 14 - 16 and 18 - 20 cm dominate in the population (Fig. 55). The sex distribution of fish is characterized by a slight dominance of males (1.3:1). Fig. 55. Length and weight distribution ofperch in Lake Stuorajavre. 150 250 Weight, g 14 4 4 % 14 12 38% 1 12 10 31% 10 8 > 3 25 % 8 о 6 Э 19% 6 4 13% 4 2 6 % ' ' ' '\ 2 0 0 % И 1 ! 1 i..1 . 0 10 14 18 22 26 Length, cm 30 > 3 Overall, pike has an average weight of644 g (maximal - 1107 g) and length of 42.3 cm (maximum 49.8 cm). Males dominate over females. Fish p a th o lo g y The most frequently occurring pathologies of whitefish are expansions of the con­ nective tissue and grainy structure of the kidneys (more than 90%). The frequency of kidney pathologies is also high and amounts to 50%; they appear as a change in colour and degeneration of the tissue (pale liver). Disorders in the reproductive system are the rarest, and occur in the form of anisochronous and asymmetric maturation of the gonads (about 6%). In addition, whitefish have irregular rakers line and warp of the rakers in 23% of cases. As regards pike, two fish had an unsatisfactory state of the liver (28.6%). The liver was greenish in colour. H eavy m eta ls in fish Heavy metal concentrations (Cu, Ni, Pb, Cd and Hg) in fish muscle do not exceed the established standard values (Table 38).). However, Cu concentrations ([ig/g of dry weight) in fish liver are higher than in muscles (from 9.5 [ig/g in perch to 132.8 |ig/g in trout). ).The same holds true for Ni in fish kidney (from 1.1 |ig/g in pike to 2.7 |ig/g in perch). The concentrations for Ni in skeleton reach 4.4 |ig/g (in whitefish) and 5 |ig/g (in pike). The Pb concentration is the highest in the gills of sparsely rakered whitefish (0.8 |ig/g). Mercury accumulates more strongly in fish kidney, and the highest levels occur in whitefish (1.6-2.9 (ig/g) and in trout (1.6 (ig/g dry weight). Analysis of metal concnetrations in different fish species shows that Cu accumula­ tion in trout liver is 6 times higher than that in other fish species (Fig. 56). There are no significant differences in Ni accumulation between the above fish species. The highest 106 Catalogue of Lakes in the Russian, Finnish and Norwegian BorderArea