Integrated sturgeon survey in the northern Caspian

 

The qualitative and quantitative composition of trawl catches, the distribution of sturgeon, mullet and other fish species in the summer at depths from 4.5 to 13.0 meters were studied. An assessment of the ecological conditions of the habitat of aquatic organisms and the state of the food base of aquatic biological resources (ABR) was also carried out, the contamination of roach and silver carp observed here was studied. Throughout the voyage, a route census of the Caspian seal was conducted.

 

The studies were carried out in the waters of the western part of the Northern Caspian, a 9-meter bottom trawl with a keel insert was used as the accounting gear. Trawl catches were sorted by species composition, the size and weight indicators of the caught fish were determined, some of the fish were subjected to a full biological analysis, the rest of the fish were returned to their natural habitat after measurements. Samples of the gastrointestinal tracts of the fish were delivered to the Volga-Caspian branch for further office processing.

 

At each station, the depth, transparency and temperature of the water at two horizons, air temperature, wind direction and speed, and sea waves were measured. To determine a number of hydrochemical and toxicological parameters, samples of water and bottom sediments were collected and subsequently processed in the laboratory. Hydrobiological work was carried out - sampling of zoobenthos.

 

The results of the trawl survey will allow us to determine the number of sturgeon fish, mullet and other types of aquatic biological resources, and assess the qualitative structure of fish populations. The collected materials will be used to assess stocks, calculate the number, total allowable catches and recommended catches of sturgeon, marine, semi-anadromous and some river fish, and assess the state of the aquatic biological resources habitat.

 

VNIRO Press Service