UP whale unit to start world’s longest aerial survey of southern right whales

The aerial survey will be flown between Nature’s Valley on the Garden Route in the Western Cape and Muizenberg in Cape Town in association with SilverCross Aviation, and with the support of the De Hoop Collection and Denel Overberg Test Range.

An aerial view of southern right whales. Picture: University of Pretoria Mammal Research Institute Whale Unit

JOHANNESBURG – The University of Pretoria’s Mammal Research Institute’s Whale Unit on Friday announced that it would commence its 42nd annual southern right whale photo-identification aerial survey.

The aerial survey will be flown between Nature’s Valley on the Garden Route in the Western Cape and Muizenberg in Cape Town in association with SilverCross Aviation, and with the support of the De Hoop Collection and Denel Overberg Test Range, making it the longest uninterrupted datasets on any marine mammal worldwide.

An Airbus H120B helicopter will be used to survey the coast at an altitude of about 300 metres.

Dr Els Vermeulen, the unit’s research manager, said that the survey would primarily focus on southern right whales.

“All encountered whale species will be recorded, with a special focus on southern right whale. The data collected will be used to investigate the vital parameters of the population, including abundance estimation, population growth rate, survival, calving intervals and age of first parturition (when a female has her first calf). This allows researchers to accurately model the population demographic parameters over the long term.”

Vermeulen said that southern right whale females with calves as well as those with distinctive brindle colouration or markings would be photographed to allow for individual identification.

“Vertical images of the heads and backs of the animals will be taken, which will allow for recognition of the pattern formed by the wart-like callosities on their heads and, in some cases, of the white and grey pigmentation patterns on their backs,” she said.

According to the mammal research unit, sightings of females with calves decreased dramatically in 2015, 2016 and 2017, increased above normal levels in 2018, but dropped substantially again in 2019 and 2020. Sightings of unaccompanied adults (males and non-calving females) decreased drastically in 2010 and have not yet returned to normal levels.

Verleumen explained that this was due to pregnant females about to give birth completing their migration to South Africa to increase their calf’s survival chances.

“Additionally, data continues to show that females are giving birth to a calf every four to five years instead of every three years,” she added.

Southern right whales received their name from whalers who believed them to be the “right whale” to hunt, as they are predictable in distribution, generally slow swimming and float when killed. The species was heavily whaled in the past, which reduced the global population from about 70,000 individuals to a mere 60 reproductive females at the termination of southern right whaling in 1935.

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