Biomass, growth, and diet of fish in forest lakes affected by alkaline mining water in NW Russia

Abstract

Waste water from the mining industry has altered the water chemistry of naturally oligotrophic lakes in the Kostomuksha area of NW Russia, resulting in high alkalinity and high concentrations of certain anions. Two such lakes, Poppalijarvi and Kento, and one reference lake, Upper Kuito, were sampled for fish using multimesh gillnets in three successive years, 2000-2002. The total CPUE (g gillnet -1 night -1 ) was 2.5 times higher in the affected lakes than in the reference lake. Perch and roach, the predominant species, grew well in all the lakes presumably due to an abundant supply of high quality macroinvertebrate food in their benthic habitats. The proportion of large piscivorous perch was notably high, especially in Lake Kento, probably as a result of low fishing pressure and the abundance of fish prey. Although detailed studies have revealed differences in the structure and function of fish gills and liver between the affected lakes and the reference lake, the environment in Lake Poppalijarvi and Lake Kento enables fast growth of the fish and promotes the existence of a high fish biomass.