A Whale of a Weekend at De Hoop Nature Reserve

by CapeNature

When southern right whales visit the waters off the southern Cape coast during June and December every year they’re being watched – very carefully. So carefully in fact, that the research conducted represents one of the longest continuous studies of any marine mammal in the world. Aerial photo-identification surveys of the whales have been conducted by helicopter since 1979.

Why is this important?

The survey is able to identify patterns – changes in numbers and behaviour that provide insights into the overall health of the whales. The study also allows scientists to better understand the effects of climate change on the larger Southern Ocean ecosystem.

Why do the whales keep coming back?

Southern right whales 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.

What do we know about the current state of southern right whales?

The South African southern right whale population was estimated at around 6 000 individuals in 2018. Since 2009, the study has shown a marked decrease in the rate at which the population is increasing. This is obvious cause for concern and this year, the Mammal Research Institute Whale Unit expected that trend to be confirmed.

Then, late on Saturday 18 August, William Stephens of the De Hoop Collection in CapeNature’s De Hoop Nature Reserve heard some news that had him energized with excitement. He had just been notified by Jean Tresfon, a well-known Marine Conservation Photographer, that even with “all the bad news and negativity in the media, especially when it comes to the state of our marine resources”; he was thrilled “to share something rather more uplifting”.

Tresfon, together with whale scientist Chris Wilkinson had, early on Saturday morning lifted off from the Morning Star airfield into the crisp clear air – a perfect day weather-wise – to conduct an aerial whale survey for the Mammal Research Institute Whale Unit. Trefson reported that they encountered the southern right whales almost immediately, but it was when they reached the De Hoop Nature Reserve area that they were just blown away.

“The absolute pinnacle was at the De Hoop Nature Reserve -from Skipskop Point to Lekkerwater- where we spotted an incredible record-breaking 1 116 whales, or 558 cow/calf pairs, highlighting the fact that Koppie Alleen is without question the most important nursery area for southern right whales on the South African coast.”

CapeNature is proud to be co-funding the whale research this year and CEO Dr Razeena Omar remarked that “As the winter season draws to a close it is an exciting time to see this kind of positive growth in conservation numbers. The uninterrupted aerial survey database is critical to long-term efforts to assess the extent of reproductive patterns and species population dynamics.”

After nearly seven hours in the air they headed home. Tresfon later received a message from Els Vermeulen, head of the Whale Unit, advising him of the final numbers – 661 cow/calf pairs, plus 25 unaccompanied adults – a total of 1 347 southern right whales counted between Hawston and Witsands! Almost triple the amount of whales counted at nearly the same time – the first week of September – in the same area, in 2017.

While this news is heartening, only long term research can confirm whether whale numbers are definitely on the increase and there remains an urgent need for funding to cover the costs of flight operations.  For more information, contact Dr Els Vermeulen at the Mammal Research Institute Whale Unit at the Department of Zoology and Entomology, University of Pretoria.

  • Photos by Jean Tresfon

Write a Reply