More on the Southern Right Whale.

Orrca members have been working through their records to answer some of the questions about ‘Alex’ the southern right whale, who made an extended visit to Sydney in August 1999.

Then Orrca President, Sam Barripp, said 'It’s exciting for us to be able to review our ten year collection of photos, sketches and reports to help answer some of the questions which have been put to us.'

How old is Alex? For any live whale, the answer can only be a ‘best guess’. First, someone has to estimate the length of the whale as it swims close by an object of known length, such as a boat. Estimates for Alex have ranged from 12 to 14 metres. How many years would it take Alex to reach those lengths? If Alex was an average sized calf at birth, her length would have been about 5 metres. By the time of her first birthday, Alex would have been about 8 metres. For the next few years the growth rate would be much slower, adding about 2 metres in the second year, and less than 1 metre in the third and fourth years. From then on, the growth rate slows even further. Alex is now 12-13 metres long, so this whale is possibly 5 or 6 years old.

The age estimate led to the next question: Is Alex really Dennis, the calf of Glenys? This mother-calf pair visited our shores in June and July 1993. No. A review of Orrca’s records show quite clearly Alex is definitely not Dennis (or Denise – to this day we don’t know the gender of Glenys’ calf.)

Orrca researcher, Samantha Fulton said, ‘There are fundamental differences in the pattern of callosities (the light coloured patches on the top of the head and jaws) between Alex and Dennis. We have examined all our photographs and sketches to check the number, shape, size and placement of each callosity on the head of both Alex and Dennis, and our conclusion is that they do not match. Nor do Alex’s callosities match those of calf named Josh, born to Zoe in late July 1993.’

(Although most people were unaware of it at the time, the southern right whales referred to in 1993 as Glenys and Dennis were in fact a number of different mother and calf pairs seen by Sydneysiders between 25th June and the end of August 1993. We have good records for two of these pairs, and reasonable records for a further five adults from that hectic few months in 1993.’) But, asked some people asked, wouldn’t the patches on Dennis have changed during the last six years?

The callosity pattern for each whale is as unique as our fingerprints, and stays for life. Each callosity corresponds to where we have facial hairs – on the chin, along the jaw, above the eyes and below the nostrils. The pattern is genetically determined, and each callosity is present several months before birth.

Very soon after birth, the callosities become covered with thousands of tiny crustaceans called whale lice which may make the callosity appear a whitish colour but they do not modify the shape of the callosity to the extent that the identification features are changed.

Other clues to the identity of each whale are scar tissue and the piebald patterns on the belly. Alex has a particularly distinctive light patch which doesn’t match with any other records for New South Wales.