A considerable amount of fresh fish is wasted, due to imprecise shelf life estimations that lead to relatively short use-by dates. This study aimed at evaluating a newly developed sensor measuring cadaverine headspace concentrations, as a rapid and precise measure to estimate within a realistic DK retail scenario freshness and shelf life of imported tuna loins. To achieve this the cadaverine concentration as measured by liquid chromatography-tandem mass spectrometry (LC- MS/MS) in tuna steaks from different biological replicas undergoing storage at 2 °C, were associated to the freshness states and shelf life as determined by the Quality Index Method (QIM) and microbial measurements. The cadaverine sensor responses of tuna stored under the same conditions were compared to the validated LC-MS/MS concentrations and benchmarked towards the QIM and microbial counts estimation of shelf life. The results indicated that the novel cadaverine biosensor allowed an estimation of freshness and transition of acceptable to unacceptable quality of the tuna steaks comparable to other methods such as LC-MS/MS determination of cadaverin, QIM and determination of microbiological counts. The composition of the microbiological flora during storage, consisted mainly of Pseudomonas fragi but also other Pseudomonas spp, Vibrio spp., Brochothrix thermosphacta, H₂S producing bacteria and Enterobacteriaceae, the latter only in relatively low numbers. The novel biosensor technology appear to be a promising rapid and cost efficient method for evaluating freshness of several types of fish products in addition to fresh tuna, which will support the sustainability of the fish industry.