Photo-identification studies by UCC researchers of the group estimate that there are over 100 dolphins in the lower estuary. Gestation is about 12 months. The calves are paler than the adult and young calves may be surfacing very close to their mother. The mother may continue to suckle the calf for over a year but the calf starts taking scraps of food after a few months. Males mature at 10-13 years and can live up to 40 years.
Females live to a similar age.
The rich waters and shelter of the Estuary provide a haven and breeding ground for the Shannon s resident dolphins. They can be seen to toss a fish into the air during feeding. The geographical and tidal conditions of the Estuary make an ideal hunting ground for the dolphins. Salmon, mackerel, herring and sprat, the favourite fish of the bottlenose dolphin, are particularly plentiful.