Investigations on the reproductive biology of the anchovy conducted during the 1987-1992 period in the northwestern Black Sea, the main spawning area of this species in this sea, are summarized. The spawning takes place in summer in the warm upper layer, within a wide temperature range (16-28°C). Reproduction occurs mostly in coastal waters, especially in estuarine areas with low salinity (7-18‰). The embryonic period lasts for about 24 hours (at 22.0-23.4°C) and the pelagic eggs are elliptical (long axis: 1.5-1.9 mm; short axis: 0.8-1.2 mm). By late summer, some of the young fish born at the very beginning of the spawning period may become mature at a body length of 55-65 mm and a weight of 1.2-2.4 g and take part in spawning. The spawning process is characterized by a clear daily rhythm: ripening and ovulation at about 9 p.m.; spawning from 9 p.m. to midnight; resting from midnight to 6 a.m.; forming of a new spawning batch from 6 a.m. to 9 p.m. Frequency of spawning depends on water temperature and varies during the spawning season, reaching its maximum -daily spawning- by the second half of June. On average, each female spawns more than 50 times a year. Individual batch fecundity depends on food availability, water temperature and body size. (Prepared by the Editors). |