Uptake of phosphorus, dioxins and DL-PCBS in lake Vättern : A Study of the Leisure and Professional Fishing of Signal Crayfish, Char and Whitefish

During the industrialization period in Sweden, the lake Vättern has been exposed to many different types of trials, in some cases it has caused damage to the lake. Emissions of various substances have affected the aquatic life directly and in the long term also man. The anthropogenic disturbances to which Vättern has been exposed have left an impression on many different levels that still matter today. Understanding what quantity and sources contribute to the amount of supplementation and the amount of loss becomes important in order to better care for Vättern. The aim of the project is to try to describe the loss of the element phosphorus and the environmental toxins: dioxins and dl-PCBs through specific fishing for signal crayfish, char and whitefish in Vättern. A historical basis for fish catches in Vättern has been used together with a compilation of sample data on phosphorus content, dioxin concentration and dl-PCB concentration in the organisms. By combining catch data with the data on substance levels in the organisms, an image is obtained of the annual extraction of these substances via fishing. The results of the project can be used against future catch data from Vättern in order to obtain a continued overview of loss of phosphorus, dioxins and dl-PCBs from the lake through fishing. However, the results only show that the loss of phosphorus through fishing has an extremely small impact on the total amount in the lake. It is not possible to say whether the result over the total loss of dioxins fished and dl-PCBs is of great or little importance to the total amount in the lake due to lack of data. Finally, a discussion regarding a proposal for a future choice of method that can be implemented to enable a broader basis for future projects