Growth response of pikeperch larvae in relation to body size and zooplankton abundance

Abstract

The most critical period at onset of feeding in pikeperch Stizostedion lucioperca is short (<5 days at 20° C). The larvae are sensitive to prey density during the first week of exogenous feeding. First‐feeding larvae of 6.5 mm total length (LT) needed prey densities of >585 prey l−1 to maintain mass (Cmaint), whereas 5 days older larvae of 7 mm LT Cmaint= 55 prey l−1 and for 11 mmLT larvae Cmaint<10 prey 1−1. Changes in specific growth rates for larvae of 7 and 11 mm were similar to a type‐II functional response curve reaching a specific growth rate of 26 and 30% day−1, respectively, at 1000 prey l−1, whereas the 6·5 mm larvae showed a linear growth response reaching a specific growth rate of only 9% day −1 at 1000 prey l−1. The results suggest that prey density is a limiting factor, which might contribute to the high variation between year‐class Strengths.