Growth and seasonal changes in energy content of young Baltic Sea herring (Clupea harengusL.)

F Arrhenius
1996 ICES Journal of Marine Science  
Growth rates, hatch-date distributions and seasonal changes in energy densities of young-of-the-year (YOY) herring (Cllipea lzarenglls), the major Baltic Sea zooplanktivore, were studied in a coastal area. Otoliths (sagittae) showed daily patterns in microstructure, which we used to age the fish. The first increment (the hatch check) was formed at the end of the yolk sac stage. The averaged growth rate was estimated to 0.37 mm d-1 and 0.58 mm d-1 for larval and metamorphosed YOY herring,
more » ... ively. The overall growth for all young stages could be described with a fourth order polynomial relationship between length and age. Estimated hatching dates were distributed between March and June. This is earlier than normally assumed for the northern Baltic Sea and was probably caused by a warm spring and favourable survival conditions in 1993. Our data indicate the highest survival of YOY spawned from end of April to the middle of May. Young herring undergo seasonal and yearly fluctuations in body composition. There was an increase in energy density from 2200 to 2800 J g-l WWT and 2900 to 4800 J g-l \V\VT for larval and metamorphosed YOY respectively, with rather constant energy densities during the metamorphosis.
doi:10.1006/jmsc.1996.0100 fatcat:kqdcdoabxzhgnesimfdnfyijpi