The zooplankter Calanus finmarchicus is a member of the so-called “Calanus Complex”, a group of
copepods that constitutes a key element of the Arctic polar marine ecosystem, providing a crucial
link between primary production and higher trophic levels. Climate change induces the shift of C.
finmarchicus to higher latitudes with currently unknown impacts on its endogenous timing. Here we
generated a daily transcriptome of C. finmarchicus at two high Arctic stations, during the more extreme
time of Midnight Sun, the summer solstice. While the southern station (74.5 °N) was sea ice-free, the
northern one (82.5 °N) was sea ice-covered. The mRNAs of the 42 samples have been sequenced with an
average of 126 ± 5 million reads (mean ± SE) per sample, and aligned to the reference transcriptome.
We detail the quality assessment of the datasets and the complete annotation procedure, providing
the possibility to investigate daily gene expression of this ecologically important species at high Arctic
latitudes, and to compare gene expression according to latitude and sea ice-coverage