THE ABUNDANCE AND DISTRIBUTION OF EGGS AND LARVAE OF SPECIES BELONG TO CLUPEIDAE IN THE SIĞACIK BAY
Project no. 1143 · Status: Kapanmış · 2016
Summary
This study was carried out on a monthly basis at 16 stations between November 2016 and May 2018 in the Sığacık Bay, İzmir. For ichthyoplankton samplings, vertical plankton tows were carried out using WP-2 type plankton net with a ring diameter of 0.57 m and a mesh size of 350 µm. Depth, temperature, salinity, oxygen and pH values were measured at the research stations. The minimum-maximum and mean surface temperature values measured throughout the year in the Sığacık Bay were 13.5-24.2 and 18.4 ± 0.15 °C, respectively, while the minimum-maximum and mean dissolved oxygen values were 6.75 - 8.56 and 7.52 ± 0.01 mg/l, respectively, the minimum-maximum and mean salinity values were 39.2 - 39.9 and 39.55 ± 0.006 psu, respectively, and the minimum-maximum and mean pH values were 7.93-8.43 and 8.17 ± 0.002 ppt. Among the ichthyoplankton samples, two species belonging to the Clupeidae family were identified; European pilchard (Sardina pilchardus) and round sardinella (Sardinella aurita). The eggs and larvae of the European pilchard samples were obtained between October and March (13.5- 20.1°C), the maximum being in February (mean temperature 15.29 ± 0.57 °C) while round sardinella samples were obtained between May and August (17.7 - 24.2°C), the maximum being in May (mean temperature 19.8 ± 1.31°C). The mean abundance values of all European pilchard eggs and larvae in all stations were 81 individuals.10 m-2 while the mean abundance values of all round sardinella eggs and larvae were 88 individuals.10 m-2. In European pilchard, egg diameter value was 1.32-1.78 mm (1.54 ± 0.09 mm mean value) and the oil globule diameter was 0.12-0.21 mm. In round sardinella egg diameter value was 1.21-1.48 mm (1.36 ± 0.06 mm mean value) and the oil globule diameter was 0.10-0.15 mm. The majority of the eggs and larvae of both species were found at stations between 25-75-m-depth. It was thought that clupeids do not prefer Sığacık Bay as a spawning area. However, for better clarification, further ichthyoplanktonic studies should be carried out in a longer period, considering the fluctuations of clupeid stocks in the Sığacık Bay.