Monthly mesoozooplankton samplings started in 1950s, performed by vertical tows of Hensen net (73 cm mouth diameter, 330 μm mesh size) from 35–0 m. Samples were fixed in 2 % formaldehyde solution buffered with borax. No flowmeter was used. From 1950s-1995 mesozooplankton was sampled on approximately monthly basis and data are available from January 1972 to November 1995 (with gaps in 1975) 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 1995 the sampling program with Hensen net was interrupted and investigations continued with Nansen net, 125 μm mesh size.

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.