<em>Calanus helgolandicus</em> weekly egg production at site L4 (50 15'N, 4 13'W) in the Western English Channel from 1992 to 2012.

The long series of high-frequency observations of <em>Calanus helgolandicus</em> reproduction is unique; no other such data-set exists. This fact, combined with the extensive information on the food environment (particulates, phytoplankton species) and experimental studies on the diet and reproduction of <em>Calanus</em> provides an important opportunity to advance zooplankton seasonal succession modelling, and investigations of inter-annual variability at higher trophic levels.