AGE STRUCTURE AND LONGEVITY IN NORTH-ATLANTIC RIGHT WHALES EUBALAENA-GLACIALIS AND THEIR RELATION TO REPRODUCTION

Although there are a number of techniques for determining age in dead baleen whales, few exist for live. free-swimming animals. Photo-identi fication records of 374 cataloged individuals through 1996 were used t o assess the age of first parturition, the age structure and the longe vity of the North Atlantic right whale Eubalaena glacialis. Nearly the entire population is identified and the majority of the whales have e xtensive sighting histories dating from 1980, with some earlier sighti ngs dating as far back as 1935. The observed mean age at first parturi tion for females with complete sighting histories (n = 13) is 8.7 yr a nd the age at which whales are considered adults, based on the mean ag e of first observed parturition for all know-age females (n = 20), is 9 yr. Juveniles and calves constitute 26 to 31% of the population, con siderably less than in other baleen whale species. One whale is at lea st 65 yr old, and reproductive histories of others span up to 29 yr. A lthough the 65 plus yr old whale is possibly reproductively senescent, her apparent lack of calving may be due to anthropogenic factors or t o undocumented calvings.