644 BIOLOGY OF THE SEAS OF THE U.S.S.R. 



Table 275. Yields offish in the Caspian Sea in 1956 



Catch Catch 



Breed 10 3 centners Breed 10 3 centners 



Starred sturgeon 64 Catfish 128 

 Sturgeon 54 Pike 123 

 Beluga 10 Vobla 623 

 Herring 410 



Total Acipenserida 128 ^ , ' 8 « 



Pike perch 217 other fish 355 



Golden shiner 270 



Carp 161 Total catch 4,306 



Avifauna 



Much serious damage to the fisheries of the Caspian Sea is caused by fish- 

 eating birds, chiefly cormorants, herons, sea-gulls and pelicans (A. Pak- 

 hulsky, 1951). The stock of fish-eating birds in the Caspian is more than 

 six hundred thousand head and the quantity of fish consumed by them 

 (1948) is about a million centners a year, 70 per cent of which is taken by 

 cormorants. Moreover, the birds propagate a series of intestinal fish-worms; 

 sea-gulls are the cause of violent epidemics of ligulosis affecting a great 

 number of vobla. 



Gulf of Karabugas 



The Gulf of Karabugas is most remarkable ; it can be considered as the final 

 stage of the process of the eastern Caspian inlets turning saline ; these, with 

 their narrow finks with the Sea, run deep into a desert country with a hot and 

 dry climate. The ratio of the content of ions in the Caspian waters when they 

 are concentrated, which does not alter in the Mertvyi Kultuk and Kaidak 

 inlets (as S. Makarov and D. Enikeev (1937) have shown) does, in the Gulf of 

 Karabugas, alter in the direction of an increase in the content of sodium 

 sulphate. 



The Gulf of Karabugas is the largest sodium sulphate body of water in the 

 world. The area of the Gulf of Karabugas (about 14,000 to 15,000 km 2 ) as 

 well as its depth and salt content have changed considerably owing to fluctua- 

 tions in the level of the Caspian Sea (this has dropped by 193 cm between 1929 

 and 1945) and in its depth and the form of its connection with the Caspian Sea. 



The greatest depth of the Gulf of Karabugas is now only 4-5 m, whereas 

 once it was 9 m. The level of the Caspian Sea is 3 m higher than that of the 

 Gulf of Karabugas. 



In 1939 the inflow from the Caspian Sea to the Gulf of Karabugas de- 

 creased from 25 km 3 to 6 km 3 ; it rose again, however, in 1946 to 12 to 14 km 3 

 owing to the deepening of the strait. The water of the Gulf of Karabugas has 

 become considerably more saline in the last 60 years : 



in 1897 salinity comprised 16-4 per cent by weight 

 in 1929-30 salinity comprised 20-5 to 21-0 per cent 

 in 1938 salinity comprised 28-1 per cent. 



