Distribution of anchovy eggs and larvae (Engraulis encrasicolus Cuv.) in the Black Sea in 1991-1992

Two international surveys of anchovy eggs and larvae were carried out in the Black Sea at the beginning of the spawning season in June 1991 and during the main spawning period in July 1992. Horizontal tows demonstrated that the bulk of anchovy eggs and larvae were distributed in the upper 3-m layer, but in downwelling areas eggs and larvae were found down to 70 m depth. In contrast to earlier studies, vertical hauls obtained during the present investigation contained higher egg numbers in the southern and particularly south-eastern Black Sea than in the north-western region, which is known as the main spawning area of anchovy. Long-term sampling by the Institute of Biology of the Southern Seas, Sevastopol, shows that, in the northern Black Sea, the number of anchovy eggs and larvae found since the mid-1980s is lower than in the early 1960s. The sudden decline of anchovy ichthyoplankton in 1989, coinciding with the outburst of the recently introduced Mnemiopsis sp. (Ctenophora), supports the hypothesis that this gelatinous zooplankton species has played a role in diminishing the Black Sea anchovy fisheries, although the drastic changes in the Black Sea ecosystem (due to pollution, eutrophication, and heavy fishing) have also had an effect.