It takes time and effort to learn what marine mammals are present off the Mayo coast. One collaborative effort involving Dutch, Norwegian, English and Irish scientists occurred between 2008-2009 off the Galway and Mayo coast.
Bottlenose dolphins in Connemara and Mayo 2008-2009. Movement patterns between two coastal areas in the west of Ireland.
A total of 46 dedicated and 33 opportunistic boat-based surveys were conducted in the coastal waters off Connemara and Mayo in 2008 and 2009, resulting in 31 encounters with groups of bottlenose dolphins. Between the two coastal areas, a total of 201 photo-identification records of dolphins were obtained, resulting in a minimum number of 177 individual dolphins identified. More dolphins were observed in northwest Mayo (n=179, 89% of the total number of identifications) than in Connemara (n=92, 46%). (Report to NPWS
Oudejans_et_al_2010_Bottlenose_dolphins_in Connemara_and_Mayo.pdf )