A bucket of bait, the future of a lake – Fishing in Lake Balaton

Abstract

This study examines the potential environmental impact of recreational fishing on Lake Balaton, the largest freshwater lake in Central Europe, which is predominantly used for leisure activities, including angling. In recent years, fishing activities have steadily increased, with an estimated 20 000 to 35 000 individuals engaging in fishing during the summer months. The Hungarian National Angling Association (MOHOSZ) currently reports its membership exceeding 1 million. Despite statistical evidence indicating a rise in fishing activity, limited data are available concerning its effects on the lake’s water quality, thereby prompting this project. The initial hypothesis posited that fish feeders may substantially contribute to the nutrient load that threatens the ecological integrity of lake ecosystems. This is primarily due to the widespread, often unregulated use of groundbait, both locally and globally. Fish feeders introduce nutrients such as phosphate, nitrate, nitrite, and ammonium into the aquatic environment–compounds that are recognized drivers of algal blooms and ecological deterioration in freshwater systems. However, the specific influence of these feeders remains uncertain due to a lack of targeted studies. The objective of this research is to quantify the release of plant nutrients from fish feeders, which are commonly based on corn or fishmeal, along with various additives. Laboratory experiments were conducted using suspensions made from Lake Balaton water and selected fish feeders, mixed in predefined ratios that reflect typical angling practices. Concentrations, including phosphate, nitrite, nitrate, and ammonium ions, were determined by using a spectrophotometer. The data obtained were subsequently compared with findings from analogous studies.

The results demonstrate that fish feeders contribute approximately 0.11 to 0.35 metric tons of phosphorus per week, corresponding to a cumulative input of 1.37 to 4.25 metric tons over a three-month period. For inorganic nitrogen compounds, weekly contributions ranged from 0.10 to 1.69 metric tons, resulting in a total input of 1.21 to 20.32 metric tons during the same duration. These findings suggest that recreational fishing may play a more significant role in the eutrophication of Lake Balaton than previously thought.