Koroleva I.M. The status of whitefish population from Chuna Lake in the Lapland Biosphere Reserve Russia. International Journal of Environmental Research. 2008, V.2, №2, p. 111-124.

Kashulin, N. A., et al. Among the whitefish selected at the spawning area in autumn, there was a significant amount of non­ spawning individuals that year. The number ofnon­ spawning individuals in the matured part of the population of 5+ and older age accounted for 34­ 55% (Table 6). Among those who have missed spawning dominated female fish. It has been noted earlier that the whitefish from Lake Chuna would spawn every year (Vladimirskaya, 1951). Later, 14 % of the matured population was represented by non-spawning individuals (Reshetnikov, 1966, 1980). At present, the share of non-spawning whitefish is as great as 38%. The change recorded in whitefish population inhabiting Chuna Lake, under normal reproduction (no commercial fishing), could have been resulted from long-term air-borne industrial pollution. At present, the sex composition of the population has also changed, if compared to the 1950-60s data, according to which, in the early 1950s, male fish dominated over female fish by Table 4. Percentage ratio of fish of elder age-groups in the whitefish population in Lake Chuna, according to literature and own data (in % of the catch) age, yrs period of researches 1961-1962 2000-2001 5+ 26.9 34.9 6+ 38.2 26.9 7+ 16.1 10.0 8+ 6.3 1.1 9+ 2.0 0.4 10+ 0.8 0.4 11 + 0.7 - 12+ 0.4 - 15+ 0.1 - factor of 3.4. Later, in the 1960s, the number of male fish was twice as many (1.97:1). At present, this proportion is 1:1. On the whole, in the catches of spawning and feeding areas, female fish domi­ nate by factor of 1.5. It should be noted also that in the younger age groups the number of female and male fish is the same. Among the fish at the age of 4+ and 5+ male fish generally dominate. But at the age of 6+ and older female fish domi­ nate in the population, but among the fish older than 7 years, male individuals are single or absent. This is probably connected with higher death rate of male fish of older age groups. The pollution processes have far-reaching effects on the repre­ sentatives of aqueous ecosystems. For instance, in case with whitefish sampled from Lake Chuna, these effects are clearly observed during decades. Beside the change in the whitefish population, recorded also was true decline of the average size-and-weight values of other fish species over the recent decades (Fig. 6). Pathological changes o f fish Ranked the first among the pathological changes o f whitefish of Lake Chuna are the changes in liver related to granular and fat degeneration of parenchyma, focal haemorrhages manifesting themselves in change of color and form of the organ. Kidney pathologies included changes of the organ’s structure, water retention, focal necrosis which were visually identified as granulation and connective-tissue expansions in the tail part. Change of gills most often included necrosis ofgill epithelium and the so called “anemic ring” 11.8%) (Fig. 7).Pathologies of other organs were visually identified in single cases. Scoliosis was found in 1.8% of the fish. Whitefish gonads developed practically without any visible anomalies. On the whole, among the fish in the catches of 2000-2001 only 1% was healthy. In the course of studies there was one case of stones in kidney or nephrocalcitosis recorded. It should be noted that pathologies of liver and kidney of whitefish were more typical for younger (under 3+) and older (over 7+) age groups. It is likely connected with the fact that fish of younger age groups is to a greater extent sensitive to the toxicants effect. As for the fish of older age groups, its mechanism of detoxication is more energy-consuming, which intensifies pathological changes of organs.The analysis of Cu and Ni concentrations, the main pollutants in the catchment area of Lake Chuna, was based on the results of seasonal observations during the year. The highest Cu concentrations were found in liver ofwhitefish of Lake Chuna. The maximum mean Cu concentrations throughout the study period accounted for 102.8 mkg/g dry weight, in some individuals, the Cu concentrations accounted for 434 mkg/g dry weight. Kidney comes next in the mean copper accumulation - 7.1 mkg/g dry weight. The Cu concentrations in gills was 27 times less than that in liver (Fig. 8). On the whole, the Cu concentrations in tissue of whitefish showed high variability. 116