The impact of anthropogenic pressures on sturgeon migration in the Lower Danube

Abstract

The Black Sea sturgeons are anadromous fish species [1], which migrate upstream on the Danube River for breeding. The distance traveled in the migration process varies depending on each species, from tens to hundreds of kilometers [2]. After breeding, the anadromous sturgeons return to the Black Sea and go back to the Danube after a time that varies depending on the species between 3 and 5 years [3]. All sturgeon species that migrate in the Danube basin are on the IUCN Red List of Threatened Species [4]. Considering that sturgeon migration is a condition of the existence of species [5], INCDPM developed in 2011-2017 extensive research studies of their behavior. Using ultrasonic telemetry, unique information volumes have been obtained on the behavior during sturgeon migration in different hydrodynamic conditions and under the pressures caused by anthropogenic activities. The intensity of poaching was also analyzed, resulting in that this pressure represents a real threat to the existence of sturgeon species. Over 70% of the total specimens monitored in research studies, developed by INCDPM during the over 7 years of research, were poached. The research was conducted in Ml compliance with the provisions of the EU Biodiversity Strategy for 2030 [6], which aims to conserve endangered habitats and species, including by reducing and eliminating by-catches.

Morphological changes analysis using 3D bathymetric surveys in Chilia Branch - Bystroe Channel bifurcation area

“…Special attention was paid to sturgeons [11] [12] [13] [14], considered a flagship species for the Danube River Basin and valuable indicators of water quality and ecosystem health, and was determined that they use Chilia and St. George branches for migration.…”

Captive growth analysis of Siberian sturgeon juveniles (Acipenser baerii J. F. Brandt, 1869) fed on a commercial fodder and its importance to a sustainable development of the aquaculture sector

“…Considerable efforts have been made to improve the farming conditions of the species to counter the over-exploitation of natural populations [2], and subsequently standardize the growing conditions. While, at least for Romania and the EU zone, sturgeon research in the wild developed at a fast pace, addressing various problematics, from age determination [3,4], telemetry [5][6][7][8], selection of reproduction habitats [9], body mass mathematical modeling [10] and migration [5,6,[11][12][13][14][15], in what concerns captive growth and breeding of the endangered sturgeon species, the scientific interest was significantly lower. 1216 (2023) 012021 IOP Publishing doi:10.1088/1755-1315/1216/1/012021 2 Environmental temperature and oxygen saturation are known to affect sturgeon development and physiology even at the larval state [16] as temperatures above 22 °C induce in A. baerii an increase in cortisol levels as a result of a probably higher metabolic rate.…”

Determination of the hybridization rate of Acipenser stellatus and Huso huso based on microsatellite analysis

“…Species within the order Acipenseriformes are distributed exclusively in the northern hemisphere of the Earth [1], [2], [3] and constitute an important group in the evolution and classification of fishes [4], [5]. They are a long-lived group of vertebrates that have successfully maintained their morphological characters for over 200 million years [6], [7], [8], but currently, according to the IUCN Red list (IUCN), sturgeon species worldwide are threatened with extinction [9]. Population declines of sturgeon species may be the result of hydropower construction, overexploitation of natural resources, but also pollution of the aquatic environment [2], [5], [8], [10].…”

“…They are a long-lived group of vertebrates that have successfully maintained their morphological characters for over 200 million years [6], [7], [8], but currently, according to the IUCN Red list (IUCN), sturgeon species worldwide are threatened with extinction [9]. Population declines of sturgeon species may be the result of hydropower construction, overexploitation of natural resources, but also pollution of the aquatic environment [2], [5], [8], [10]. The synergy of the aforementioned activities that have led to human socioeconomic development can have a strong negative impact on the health of aquatic ecosystems [8].…”

“…Population declines of sturgeon species may be the result of hydropower construction, overexploitation of natural resources, but also pollution of the aquatic environment [2], [5], [8], [10]. The synergy of the aforementioned activities that have led to human socioeconomic development can have a strong negative impact on the health of aquatic ecosystems [8]. Evidence of this has been observed in the Lower Danube watershed through the decrease in the number of species breeding in the lower part of the river, of six sturgeon species present in the past, only four are currently found [8], [10], [11], [12].…”