Southern right whales
The southern right whale, Eubalaena australis, is a baleen whale species only found in the Southern Hemisphere, between 20 and 64 degrees South. As with most baleen whales, they undertake an annual migration from their summer feeding grounds in sub-Antarctic waters, to their winter mating and calving grounds in coastal areas in higher latitudes, such as the coast of southern Africa.
Southern right whale females give birth to a calf every three years on average. After a gestation period (pregnancy) of about 12 months, the female will give birth to a single calf that will stay with her suckling for approximately one year. Subsequently, she has a year of rest in order to recover and prepare for her next pregnancy. The calving interval is thus typically 3 years. They usually give birth to their first calf when they are eight years old.
Southern right whales are characterised by the white patches (callosities) on their head, mostly in areas where hair follicles are present. These callosities are inhabited with tiny crustaceans called cyamids or whale lice, which gives the callosity a typical whitish colouration. The pattern these callosities form on the whale’s head is unique for each animal and is used by researchers to identify each whale individually.
Southern right whales received their name from the old whalers, who believed it to be the “right whale” to hunt, as they are generally slow and float when killed. These whales were hunted in the 20th century to near extinction, leaving only a mere 60 reproductive females (or less than 1% of their original numbers). However, they were among the first whales to be protected internationally (in 1935) and have been recovering ever since. The current global population estimate is believed to be around 14,000 individuals, only about 20% of pre-exploitation levels.
Identifying a southern right whale
Southern right whales are individually identifiable through the callosity pattern on their heads. These patterns are unique and stable for life. Additionally, distinct dorsal colouration patterns can aid in the identification of individuals.
Using an identification software, the callosity pattern of an individual whale can be extracted on the computer, and automatically matched against previously identified southern right whales, collated in the national South African catalogue.
As the callosity pattern of calves are not yet fully formed, calves can only be identified from birth if they have a distinct dorsal colouration pattern.