The dolphin was found stuck in the branches of the River Lee.
Cork Fire Brigade were called to Wandesford Quay, close to Cork city centre to help the animal.
A passerby saw the dolphin in difficulty and alerted the fire brigade, who helped him become free.
The dolphin appeared to swim away out to sea but was found dead this morning.
His remains were moved to the zoology department of University College Cork, awaiting an autopsy.
No such thing as an ordinary day in this job!
Last night crews from Anglesea St responded to an animal rescue incident in the Lee.
A distressed dolphin that was trapped by branches was sucessfully rescued by firefighters before heading safely on its way. 🐬🚒 🚨#notjustfires pic.twitter.com/k0goJgipOw— Cork City Fire Brigade (@CorkCityFire) September 10, 2018
DOLPHIN UPDATE: Unfortunately despite the fact that crews rescued this dolphin late last night and it swam off downstream, we can confirm that a dead dolphin has been found in the River this afternoon.@UCC zoology department assisting with the handling of the remains. ☹️ 🐬🚒
— Cork City Fire Brigade (@CorkCityFire) September 10, 2018