Environmentally induced short-term variability in the growth rates of larval herring

The growth of herring Clupea harengus larvae within a patch tracked for approximately 20 d in the Orkney-Shetland area (north of Scotland) was investigated using otolith microstructure and, in a supporting role, condition factor analyses. Daily otolith growth responded conservatively to external factors, there being significant autocorrelation within individual otolith increment sequences. Past growth history explained most of the variation of the data. Both otolith microstructure and condition factor analyses yielded consistent results, indicating that short term variations in growth rate were related to environmental factors such as wind-induced turbulence level, and changes in illumination and prey concentration. A dome-shaped effect of wind-generated turbulence on larval growth was detected, which indicated a maximum response at a wind speed of approximately 14.5 m s(-1), a value very close to the speeds predicted by theoretical studies to generate maximum ingestion rates of larval fish