Dolphins are reported to live for between 40 and 50 years, and sometimes longer. That does not mean that all dolphins live that long though and many have shorter lives.
The dolphins of Sarasota Bay in Florida have their lifespans measured using an ‘Annual Survival Rate’ (the percentage of animals alive a year later) of about 0.961, which suggests a life expectancy of about 25 years.
In the Indian / Banana River area, the Annual Survival Rate is estimated at between 0.908 and 0.931 which suggests a life expectancy of only between 10 and 14 years. (Source dolphinear)
Scientists at the Sarasota Dolphin Research Programme, have studied the dolphins there for decades and know the ages of most of the dolphins. The Programme reports that the oldest dolphin they know in the Sarasota Bay is a female named ‘Nicko’, who was estimated to be 64 years old in January, 2013. They estimate that another dolphin called ‘Ms Mayhem’ is 54 years old.
They say that male dolphins do not live as long though. A male called ‘Jimmy Durante’ was 50 when last seen in 2009
The reason for shorter lifespans may be connected to pollution, disease, attacks by predators such as sharks or humans, or injury. Being well cared-for in captivity does not guarantee a long life either.