The Azov-Black Sea Branch of the Russian State Research Center "All-Russian Research Institute of Fisheries and Oceanography" (VNIRO) is the only scientific institution that conducts systematic scientific observations of the status of jellyfish populations in the Sea of Azov, their spatial distribution, abundance and biomass, their size composition, and their impact on fisheries.
In 2025, studies of jellyfish distribution in the Sea of Azov and Taganrog Bay were conducted as part of three stages of a lamp survey—in June, August, and September—as well as a trawl survey of bottom fish in October and a survey of haarder and turbot in November and December. Continuous observations of jellyfish abundance in the coastal zone of the Sea of Azov were conducted across all major coastal fishing areas.
The study identified two species of scyphozoan jellyfish: the eared moon jellyfish and the pulmonate jellyfish. The distribution of these species was characterized by a patchy distribution both in the sea and in the bay. Furthermore, seasonal shifts in the dominance of these jellyfish species were observed. In June, moon jellyfish were predominantly present in the western and northern parts of the sea, with a small presence in Taganrog Bay. From August until the end of the year, the cold-water moon jellyfish were not observed in the recorded catches.
The pulmonate jellyfish demonstrated a stable presence in the study area. In June, this species was recorded in the sea, with its maximum abundance in the eastern part and minimum abundance in the northern part, as well as in the western and eastern parts of Taganrog Bay. The catches included large specimens with a dome diameter of up to 29 cm.
In August, jellyfish in Taganrog Bay were concentrated in the western region, while the highest abundance and biomass were observed in the northern and central parts of the sea.
September observations did not reveal the expected decline in the abundance and biomass of the rhizome jellyfish, as observed in previous years (2020-2024). On the contrary, their abundance throughout the Sea of Azov increased compared to September 2024. A decrease in the size and individual weight of jellyfish was also observed this year compared to 2022-2023.
In September, the highest abundance and biomass of jellyfish were observed in the northern part of the Sea of Azov, and in Taganrog Bay, in its eastern part. At the same time, extensive aggregations of jellyfish were observed along the entire coastal strip of the eastern part of the sea, from Primorsko-Akhtarsk to the Kerch Strait.
High jellyfish concentrations had a significant impact on fishery efficiency. From late August to early December, fishers were forced to suspend fishing operations in most coastal waters due to low target catches of aquatic bioresources and high bycatch of jellyfish in fishing gear. With the onset of November, a slight decrease in jellyfish abundance and biomass was observed, both in storm washups, coastal aggregations, and in fishing gear.
Thus, based on the results of the conducted research, it can be noted that in 2025, compared to 2023-2024, an increase in the abundance and biomass of the jellyfish in the Sea of Azov was observed, along with a decrease in its size and weight parameters and an increase in the duration of its autumn vegetation period.
VNIRO Press Service