Behavioural Rhythm Of Cod During Migration In The Barents Sea

No abstracts are to be cited without prior reference to the author.The results show that rhythmic behaviour occurred temporarily in 12 of the tags. Spectral density distributions of depth and temperature time series show that rhythms within 24 hour are most common. In 11 out of 12 tags where vertical migration (DVM) was detected, this occurred during summer and autumn. In 7 out of 8 tags where semi-diurnal tidal cycles were detected in the temperature series, this occurred during April-May. In some tags diurnal or semi-diurnal cycles appeared in both depth and temperature series. Diurnal rhythms are periodically important for adult cod, but the results are not consistent for all tags and therefore no firm and general principle for such behaviour can presently be concluded.