Standard length, dry weight and swim bladder percentage gas of Cyclothone species from the IDEADOS and BATHYPELAGIC cruises in Northeast Atlantic Ocean and Mediterranean Sea

This dataset contains the values of standard length, dry weight and percentage of gas in Cyclothone spp. swim bladder collected during the Bathypelagic cruise (from 24th May to 23rd June 2018) and IDEADOS cruise (from 12th to 29th July 2010). Samples were obtained with MOCNESS-1 m² (with a 0.2 mm mesh size) zooplankton net during day and night hauls carried out from the surface to 700-800 m during IDEADOS cruise, and to 1800 m in the Bathypelagic cruise. Fish for size frequency distribution were preserved in 5% buffered formalin, and those for weight measurements were frozen at 20°C, and then dry weight (DW, ±0.01 g) and standard length (SL, ±0.01 mm) were measured at the land-based laboratory. The percentage of area with fat tissue (%FT) in Cyclothone spp. swim bladders was linearly regressed against standard length (mm). The maximum percentage area with gas (%GAS) was then estimated as 100-%FT.