This article is from the Dolphin
FAQ, by Jaap van der Toorn
The maximum age for bottlenose dolphins is between 40 and 50 years. The average age a dolphin can get (the life expectancy) can be calculated from the Annual Survival Rate (the percentage of animals alive at a certain point, that is still alive one year later). For the dolphin population in Sarasota Bay, the ASR has been measured to be about 0.961. This yields a life expectancy of about 25 years. For the population in the Indian/Banana River area, the ASR is between 0.908 and 0.931. This yields a life expectance between 10.3 and 14 years. So the actual life expectancy differs per region.
R.S. Wells & M.D. Scott (1990) Estimating bottlenose dolphin population parameters from individual identification and capture-release techniques. Report International Whaling Commission (Special Issue 12): 407-415
S.L.Hersch, D.K.Odell & E.D.Asper (1990) Bottlenose dolphin mortality patterns in the Indian/Banana River System of Florida, in S. Leatherwood and R.R. Reeves: The Bottlenose Dolphin, pp. 155-164, Academic Press