Tracking abandoned, lost or discarded fishing gears of anglers by analyzing magnet fishers’ catch

Abandoned, lost, or discarded fishing gears (ALDFG) are major pollutants in water ecosystems, however, there is a serious lack of estimates on the loss of recreational fishing gears worldwide. To fill this gap, some recreationists like magnet fishers, who use neodymium magnets to retrieve metal items from water, can provide additional information. As they often remove ALDFG, we aimed to carry out the first social media analysis of their online content by searching ALDFG in their posts. During our work, we analyzed Hungarian magnet fishers’ posts, covering a total of 6 years from their initial activities on social media. In total, 2,889 posts were scanned of which 1,039 photos and 84 videos were analyzed. Magnet fishers caught 2,018 fishing gears while a total of 31 types of fishing gear were identified. Significant differences were found between flowing ( n = 1,959, mean ± SD = 12.89 ± 16.51) and standing waters ( n = 889, mean ± SD = 24.69 ± 31.39) in the numbers of fishing gears. Based on the results, we can conclude that ALDFG is a common freshwater pollutant in the country, and social media activities of magnet fishers can be used in detecting freshwater ALDFG containing metal.