Data on mean longevity are not yet available. An indication that potential longevity can be very long was obtained by serendipity. A picture was taken of a female and her calf in 1935 in Florida. The animal was seen in 1959 off Cape Cod and irregularly until the summer of 1995. Assuming it was her first calf in the original picture and she was at the age of sexual maturity or eight years old, she would have been 67 years old when last seen.
Their close relatives, bowhead whales, have been recorded with lifespans approaching 200 years, so it's likely that right whales have very long lifespans.