The following dataset contains fatty acids concentrations (in mg.g-1) and moisture data for 15 Atlantic mackerel individuals collected by hand line in the Baie de Douarnenez, France on July 26th 2020. Measurements were done at T0 (immediately after death) and repeated on the same individuals after storage at two temperatures (2-4°C or 18-20°C) for 6, 12 and 24 hours following death, and after cooking (grill or steam). Seventy-five measurements are therefore provided. Analytical details can be found in “Sardenne Fany, Puccinelli Eleonora, Vagner Marie, Pecquerie Laure, Bideau Antoine, Le Grand Fabienne, Soudant Philippe (2021). Post-mortem storage conditions and cooking methods affect long-chain omega-3 fatty acid content in Atlantic mackerel (Scomber scombrus). Food Chemistry, 359, 129828 (6p.). https://doi.org/10.1016/j.foodchem.2021.129828"