Morphometric, swimming activity and raw oxygen air saturation data from experiments on CV Calanus finmarchicus in the Fram Strait, Arctic Ocean, in August 2019

Photographs were taken using a stereomicroscope onboard the ship. Fiji was used as the image analysis software (https://imagej.net/software/fiji). Swimming activity was measured using modified LAM10 activity monitors (Trikinetics), infrared light beam arrays which detect the movement of an individual copepod in the middle of a test chamber (clear acrylic tubes of 10 mm diameter and filled with 0.2 µm filtered seawater). Beam break events were registered on a laptop computer using proprietary Trikinetics software (filescan.exe). Oxygen consumption was measured in 10 individuals from each depth layer (20 individuals total from each station) for 2 days, using a Loligo microplate respirometry system (1700 µL well plates containing 0.2 µm filtered seawater), calibrated at 4 °C.