Abstract
Generalized linear models were used to assess the influence of diel vertical migration (DVM) on Continuous Plankton Recorder data for adult (stages V and VI) Calanus finmarchicus . To simplify interpretation, the data were first divided into individual months and modelled using a Generalized Linear Model incorporating factors for long‐term trend and daylight. The fitted models reveal that, at certain times of the year and particularly during the spring and autumn, the chances of catching a stage V or VI C. finmarchicus at 7 m depth are greater in darkness than during daylight. The magnitude of DVM was shown to be generally statistically independent of long‐term trend, which is a conclusion that fails to support other published results produced from the same data.