Pallas’s Gull Ichthyaetus ichthyaetus and Fish Farming of the Palearctic: Review

Abstract

The Pallas’s Gull Ichthyaetus ichthyaetus is a piscivorous predator and scavenger, some breeding populations of which are vulnerable and require protection. This study analyzes the status and distribution of Pallas’s Gull in Palearctic fish ponds—man–made bodies of water where fish concentrations are controlled by humans and can be many times higher than natural values. The aim of the study was to assess the state of the Pallas’s Gull in the fish farming of the Palearctic over the last ≈ 60 years. The review was based on > 1100 publications found in the search engines Yandex, Google, Google Scholar, eLybrary. Between the 1960s and 2020s, the Pallas’s Gull was discovered in 46 fish farms in the Palearctic. Breeding has been established in 3 fish farms, breeding has not been established in 38 fish farms, and birds were present in 5 fish farms, but the status was not specified. There were 35 places of contact with fish farms in Europe, and 11 places of contact in Asia. The average area of fish farms with which Pallas’s Gull came into contact was 10.7 km² (n = 21). Fish farms support non–breeding individuals –– vagrants, visitors, summer or winter residents of different age classes. Fish farms cannot be considered as important places for the reproduction of the species. The network of fish farms plays a certain auxiliary, but far from decisive role in maintaining the population and the current multidirectional expansion of the species’ range in the Palearctic. The hypothesis about the possible important role of reservoirs and fish farms in food supply and the distribution of Pallas’s Gull beyond the historical range was not confirmed in studies of fish farms.