Food consumption of larval, young and adult herring and sprat in the Baltic Sea

Abstract

The total food consumption of Clupea harengus and Sprattus sprattus, the dominant zooplanktivorous fish in the Baltic Sea, was estimated from published data on abundances, growth, mortality rates and diets using a bioenergetics model. Annual food consumption was 5.0 ×107 tonnes for herring and 2.4 × 107 tonnes for sprat. Larvae and young-of-the-year (YOY) of sprat and herring accounted for 50 and 45% of the total consumption respectively. Peak consumption rates occurred in August-September. The estimate for annual consumption of zooplankton by clupeids in the Baltic sea is four times higher than previous estimates, in large part by including the consumption by YOY and 1-yr-old fish. Also, a diet shift, from a mix of zooplankton, mysids and amphipods to only zooplankton, could have a significant effect on fish growth rate. At a fixed biomass consumption, the lower energy density of zooplankton would mean that this shift would decrease growth by c25% for older age groups. -from Authors