A breakthrough by Kiwi and Australian researchers has revealed amazing new insights into the patterns of southern right whales, which could aid efforts to preserve the endangered ocean giants.
Their work has found how migratory behaviour among the whales is learned by calves from their mother in the first year of life - something which has helped shape the genetics and population recovery of the species.
The study, published overnight in the journal Scientific Reports, is the first of its kind to link migratory habits to the genetics of such a large moving network of marine mammal.
Led by former Auckland University scientist Dr Emma Carroll, now at the University of St Andrews in the UK, the research team was able to demonstrate how young whales acquired their migration preferences from their parents in a practice known as migratory culture, causing them to follow the same routes to get to their desired destination when they grow older.
Further, this migratory culture had an effect on genetic patterns observed in both the summer feeding and winter calving grounds of the whales.
The team took up to 20 years to collect enough skin samples from southern right whales in certain regions around Australia and New Zealand, due to their endangered status.
They then analysed the unique DNA markers of each whale, which allowed them to build a map of the population structure and relatedness in the species. Micro-chemical markers were also tested for each whale, which revealed its feeding ground preferences.
"Whales that showed similar feeding ground preferences were more likely to be related, using both maternally-inherited and bi-parentally inherited DNA markers," Dr Carroll said.
"There were also significant differences in maternally-inherited DNA markers among winter calving grounds, consistent with the idea that there is maternally-directed learning of these migratory habitats."
The researchers hoped that their study would shed more light on the current issues facing this large, long-lived species of marine mammal, which were still recovering from the effects of whaling.
Dr Rochelle Constantine, from Auckland University's marine mammal ecology group, said the species was hunted so intensively, mainly throughout the 1800s, that it was almost lost.
A long-running genetic and photographic identification programme, operated from the university, was tracking southern right whales around the Auckland Islands, where they were mainly found, but increasingly now also around mainland New Zealand.
"Part of understanding the recovery of the species is movement patterns - where does it go feed? Where does it go to calf?" Dr Constantine said.
"This study shows that the patterns of mothers are really important because the calf is always accompanying its mother, and therefore that calf will learn where to travel."
Southern right whales
• During the breeding season in winter and spring, they are mostly found in the waters around the subantarctic Auckland and Campbell Islands but there are occasional sightings around mainland New Zealand.
• Typically black in colour but can have irregular white patches.
• Their flippers are large and paddle-shaped, and while they're slow swimmers, can be very acrobatic and are also inquisitive.
• Range in size from 4.5m-6m (newborn) and 11-18m (adults).