Concerned passers-by rang for help on Monday night after spotting the common dolphin in water off George Street.
Marine mammal rescue charity BDMLR (British Divers Marine Life Rescue) brought the mammal ashore and the Scottish Marine Animals Stranding Scheme was notified.
A spokesperson for BDMLR said: 'Unfortunately the dolphin had just been floating in the harbour area. It was a common dolphin and it had been dead for quite some time, it wasn't recent. We don't know if it was male or female. People can think when they see a dolphin floating that they are in trouble but sadly in this case it was too late to be able to help.
'The dolphin was brought ashore for the Scottish Marine Animals Stranding Scheme to collect if they want to.' The scheme collects data on strandings on all UK shores.
Last year BDMLR had 1,788 call outs - anyone spotting mammals in difficulty should call the charity's 24-hour rescue hotline on 01825 765546.
Yes! I would like to be sent emails from West Coast Today
I understand that my personal information will not be shared with any third parties, and will only be used to provide me with useful targeted articles as indicated.
I'm also aware that I can un-subscribe at any point either from each email notification or on My Account screen.