Egg production rates of Calanus glacialis (Jaschnov) were measured in the laboratory (in 1985) and in the field (in 1983-1984). In the laboratory, daily egg production was studied over one month at alternating feeding and fasting conditions. Spawning ceased after 3 d of starvation and started as soon as females were reintroduced to food. Egg production increased stepwise at 3-d intervals. Females survived more than nine months in captivity. In the field, egg production was measured during PREMIZEX 1983 and MIZEX 1984 at 5 and 16 stations, respectively. High egg production was found in polynyas on the East Greenland Shelf, where melt water induced stratification which supported a spring bloom. Highest egg production was converted into 6.1% body carbon female-1 d-1. Under thick pack-ice no eggs were spawned. Spawning was induced in females from a station with low food abundance by feeding them on board ship. These results from both experiments and field studies show that egg production in C. glacialis is closely related to food availability. Thus, C. glacialis exhibits a reproductive behavior similar to that of C. finmarchicus, but not C. hyperboreus, the other two dominant species in this region. © 1987 Springer-Verlag.