The times of spawning of plaice, dab, sprat and pilchard were studied by determining the times of day and night when their very recently-spawned eggs were to be found in the plankton. The plaice in the southern North Sea were found to spawn between 1900 and 0600 h in early January, but extending to 1100 h by mid-February. The dab in the same area spawned throughout the 24 hours but rather more intensely between midnight and noon. The spawning of the sprat in the Irish Sea in January and early March was limited to the period 2200 h to noon, with most spawning between midnight and 0400 h. The spawning of the pilchard in the English Channel in June was limited almost comppletely to the six hours from 2000 to 0200 h.