Catalogue of Lakes in the Russian, Finnish and Norwegian Border Area = [Каталог озер в приграничном районе России, Финляндии и Норвегии] / Nikolay A. Kashulin, Vladimir A. Dauvalter, Sergey S. Sandimirov etc. - Apatity : Institute of the North Industrial Ecology Problems KSC RAS etc., 2008.

Fig. 60. Size and weight distribu tion of the sparsely rakered whitefish in Lake Aittojarvi. 50% 50 60% 45% 45 40% 40 50% 35% 11 35 4-* С 40% 30% И1 30 3о 25% ■ 25 £ 30% 20% /1:1 \ 20 < 15% 114 \ 15 20% 10% / H n j \ 10 10% 5% ■/ ppj 5 0% . 1... г _ . 0 0% -100 100 300 500 700 900 Weight, g 5 10 15 20 25 30 35 40 45 Length, cm 35 30 25 ■м С 20 э О Е 15 < 10 5 0 Fig. 61. Age distribution of the sparsely rakered whitefish in Lake Aittojarvi. Pike in the lake are mainly represented by large-sized individuals with an age of 8 to 11 years. The mean size and weight are 2005 g and 58.7 cm, respectively, although specimens with a weight of 4364 g and length of 82.2 cm do occur. The size of perch varies from 7-339 g and 8.6-29.5 cm, respectively. The average size and weight do not exceed 194 g and 22.0 cm. The age limit of perch is 7 years.The ratio between male and female perch and pike is almost 1. Fish p a th o lo g y The most frequently occurring pathologies of whitefish are pathologies of connective tissue expansions in the kidneys (78%). Liver destruction (fatty degenerations, mosaic structure and oblong shape of the liver) occurs in 27% of cases. Changes in the repro ductive system and gills are characteristic of 18% and 13% of the fish, respectively. H eavy m eta ls in fish The heavy metal (C, Ni, Pb, Cd and Hg) concentrations in the muscles of fish do not exceed the standard values (Table. 41). The Cu concentration (pg/g dry weight) in the liver of whitefish is 50 times higher than that in the muscular tissue, of Ni in the kidneys 10.5 times higher, of Cd in kidneys more than 100 times higher, and of Hg 4 times higher. The corresponding values for pike and perch are insignificant. Analysis of heavy metal accumulation in different fish species showed that Cu (liver) and Ni (kidneys) are more strongly accumulated in whitefish, while the Cd concentrations of all the fish species are at relatively similar, low levels. As a predator species, pike has a naturally higher degree of Hg accumulation in the muscular tissue compared to that in whitefish and perch (Fig. 62). 114 Catalogue o f Lakes in the Russian, Finnish and Norwegian BorderArea