niches thus liberated can be filled, for example, in our own southern 

 seas, by the introduction of sea fish: the Baltic herring and the Black 

 Sea anchovy and garfish to the Caspian Sea, the Japanese pike-perch to 

 the Black Sea (Rass, 1965, 1975). The unoccupied niches are easily 

 filled by autointroduction of undesirable, useless or even harmful 

 species, utilizing human technology. Therefore, it is important not to 

 delay introduction, efficient transplantation and acclimatization of 

 desirable commercial and food organisms needed by man. 



405 



