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

44% r 37% 30% 22 % 15% 7% 0% 0 100 200 300 400 50 150 250 350 Weight, g 12 10 8 6 4 2 0 450 > 3 о 67% 59% 52% 44% 37% 30% 22 % 15% 7% \ \ ■ p i n r ! \ V fill ш ш ш " 4 . У \ V '„ 1 - r > : : ] . 1+ 2 + 3+ 4+ Age, yrs 5+ 18 16 14 12 10 8 6 4 2 0 Fig. 30. Age distribution of trout in Lake Shuonijaur. The perch in Lake Shuonijaur have a length of 14.5 cm and weight of 51 g.The popu­ lation is mainly represented be 2-year-old individuals. The length of the largest speci­ mens does not exceed 20.3 cm and a weight of 140 g. In the sex distribution the number of male fish is three times higher than that of females. Fish p a th o lo g y Pathological changes in the organs of arctic char and trout occur most frequently in the kidneys (95 and 96%) and liver (59 and 57%). The pathologies manifest themselves as intensive colour changes of the organs and fatty degenerations (pale liver), and con­ nective tissue expansions (kidneys). H eavy m eta ls in fish The concentrations of heavy metals (Cu, Ni, Cd and Hg) in fish muscle do not exceed the standard values (Table 21). Nevertheless, the concentrations of Cu, Ni and Cd (pg/g dry weight) in other organs are much higher than those in the muscles: liver (41.7 for arctic char and 180.0 pg/g for trout), kidneys (20.5 for arctic char and 7.6 (ig/g for trout) and gills (over 3 pg/g). A similar distribution is typical for Ni: in liver (2.1 fir arctic char and 1.3 pg/g for trout), kidneys (16.2 for arctic char and 4.6 pg/g for trout) and gills (over 4 pg/g). Cadmium concentrations can reach 28.4 pg/g dry weight. Analysis of heavy metal accumulation in different fish species showed that Cu ac­ cumulates more strongly in the liver of arctic char. However, the trend for Ni is the opposite. There was a high degree of Cd accumulation in the muscles of arctic char, while for Hg it accumulated more strongly in the tissues of trout (Fig. 31). Fig. 29. Size and weight distribu­ tion of trout in Lake Shuonijaur. Catalogue o f Lakes in the Russian, Finnish and Norwegian BorderArea 65