U. Niermann et al., DISTRIBUTION OF ANCHOVY EGGS AND LARVAE (ENGRAULIS-ENCRASICOLUS CUV) IN THE BLACK-SEA IN 1991-1992, ICES journal of marine science, 51(4), 1994, pp. 395-406
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 demo
nstrated that the bulk of anchovy eggs acid larvae were distributed in
the upper 3-m layer, but in downwelling areas eggs and larvae were fo
und down to 70 m depth. In contrast to earlier studies, vertical hauls
obtained during the present investigation contained higher egg number
s in the southern and particularly south-eastern Black Sea than in the
north-western region, which is known as the main spawning area of anc
hovy. Long-term sampling by the Institute of Biology of the Southern S
eas, 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, c
oinciding 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 fisher
ies, although the drastic changes in the Black Sea ecosystem (due to p
ollution, eutrophication, and heavy fishing) have also had an effect.