Low concentrations of azaspiracids have been found in bivalve molluscs all over the Northern and Northwestern coast of the Iberian Peninsula. The detections started in June 2016 and lasted until March 2017. The observed toxin profile was dominated by AZA2, followed by AZA1 and some other AZAs that were detected only in some samples. Some compounds producing fragments characteristics of AZAs but that do not fit with any of the known ones were also found. The causative agent has not been identified but, in sight of the toxin profile in the bivalves, it seems that it should be a new species or strain. The detections of AZAs in bivalves in the Northern Coast was linked to downwelling or upwelling relaxation and, in the Galician Rías, took place (with only a few exceptions) in the outer (more oceanic) part, suggesting that the responsible species develops at the open sea and that the populations are advected to the shore.