Results of research conducted by the sturgeon laboratory of the Volga-Caspian branch of VNIRO

Spawning run data was collected by recording sturgeon bycatch during the semi-anadromous and freshwater fisheries in fishing grounds. The sturgeon were immediately released alive into their natural habitat. The results of studies on the distribution and status of sturgeon stocks in the Caspian Sea were obtained during a trawl survey of sturgeon in the Caspian Sea.

 

Monitoring studies showed that the number of anadromous sturgeon in the spring seine catches was low due to the low abundance of the spring-run Russian sturgeon population. After a long hiatus, specialists from the Caspian branch of the Federal State Budgetary Institution "Glavrybvod" began harvesting the Deep River Fishing Facility (RLF) in the summer of 2025. These operations were also monitored by branch specialists, which confirmed the dominance of the winter population of Russian sturgeon.

 

The dynamics of the winter population of Russian sturgeon in the autumn period were characterized by a 1.4-fold increase in bycatch from September to October. In recent years, the bycatch of young fish (up to 96%), which have not reached the size corresponding to the term "commercial length," has been high among Russian sturgeon spawners migrating to the Volga River in the river seine.

 

The stellate sturgeon population has been in a depressed state in recent years, reflected in the slow dynamics of its spawners. The decline in fish numbers is due to the very low level of natural reproduction and the decline in artificial reproduction in recent decades.

 

An analysis of sterlet distribution in the river channel based on average catches for 2025 revealed a redistribution of the species from the Volga-Caspian Shipping Canal to the upper Volga Delta, where stable catches of individuals of various sizes were observed. Sterlet can undertake relatively long feeding and spawning migrations of up to 180 km, leading to changes in the location of concentration sites along the river's longitudinal profile. In some sections of the river, sterlet individuals can form relatively stable concentrations that alternate with areas where sterlet numbers are low.

 

During the summer and fall of 2025, staff from the Sturgeon Laboratory, together with colleagues from other laboratories within the branch, conducted two scientific cruises in the northern Caspian Sea aboard the research vessels "Gidrobiologist" and "Issledovatel Kaspiya" to study the distribution and status of sturgeon stocks and their juveniles at sea. During the cruises, the species composition of trawl and net catches was determined, and the size and weight of the caught fish were determined. Blood samples were collected to assess the physiological condition of the sturgeon. Fin fragments were collected for subsequent molecular genetic analysis. Sturgeon habitat parameters, including food supply, were studied. In the northern shallows, the species composition of fish in July was characterized by aggregations of Russian sturgeon east of Maly Zhemchuzhny Island and north of Rakushechnaya Gorbachek Bank. In August, sturgeon fed in their traditional feeding areas, on Srednyaya Zhemchuzhnaya Bank, where fingerlings were also observed. Stellate sturgeon were caught only sporadically.

 

Thus, the results of the river and sea studies will allow us to estimate the abundance and stocks of sturgeon species and develop a forecast of the total allowable catch for 2027. Data collected during the August juvenile sturgeon distribution cruise will be used to identify nursery areas for the next generation of juveniles in the northern part of the sea and to assess the contribution of artificial reproduction to maintaining and restoring sturgeon populations in the Caspian Sea.

 

Model studies of stock recovery scenarios for various sturgeon species, based on the collected data, will allow for a well-reasoned defense of the need to extend the ban on commercial sturgeon fishing at the annual meetings of the Commission for the Conservation, Rational Use of Aquatic Biological Resources, and Management of Their Shared Stocks.

 

 

VNIRO Press Service