Monthly mesoozooplankton samplings started in 1959, performed by vertical tows of Hensen net (73 cm mouth diameter, 330 µm mesh size) from 100–0 m at towing speed of 0.3 m s-1. Samples were fixed in 2 % formaldehyde solution buffered with borax. No flowmeter was used. From 1959-2017 mesozooplankton was sampled on approximately monthly basis and data are available from March 1959 to December 2017 (with gaps) and include the abundances expressed as no.ind.m-3 at group level of the zooplankton groups such as Copepoda, Cladocera, Appendicularia, Chaetognatha, Tunicata, Ostracoda, Polychaeta, Decapoda larvae, various meroplankton larvae, Pisces ova, Pisces larvae and Hydromedusae/Siphonophora. From 2004 - 2012 the sampling program was interrupted. The samples from 2012 - 2016 are currently being processed and not yet part of this series.