Publication Date:
2022-05-31
Description:
The Bornholm Basin has a distinct hydrographical pattern in terms of temperature, salinity and oxygen. Due to the strong differences in density, there is a strong vertical stratification of water masses and ichthyoplankton as well. The vertical distribution of fish eggs and larvae was investigated in a period of 27 hours at an anchor station. Samples were taken at three hours intervals with a closing net. The species composition of fish eggs and fish larvae in (), both in percent, was found to be 79.7 (84.0) sprat, 17.5 (15.0) cod, 1.3 (0.6) rockling, 1.5 (0.4) flounder and 7.3 dead eggs. To control for water masses around the station, double oblique hauls with a ring net were performed, as well as measurements of temperature and salinity. The vertical distribution of sprat and cod eggs showed considerable differences. Sprat eggs were most abundant in the upper 40 metres, whereas cod eggs were found only from 40 metres downwards. The few eggs of rockling and flounder showed a weak accumulation between 40 to 65 metres. Sprat and cod larvae were present throughout the whole water column, decreasing in numbers with depth. The maximum abundance overlapped for sprat and cod between 40 to 65 metres. However, sprats were also common in the upper layer, in which cod were present in small numbers only. The larvae of rockling and flounder were generally scarce and not found in every sample. No aggregation was obvious at certain depth levels.
Type:
Article
,
NonPeerReviewed
Format:
text
