Expert takes on plight of local dolphin

Published Apr 25, 2014

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Cape Town - Southern Africa’s only endemic dolphin, the Heaviside’s dolphin, may be at risk because of over-harvesting by the hake fishing industry on the West Coast.

This is one of the findings of the first in-depth genetic study of this dolphin species that occurs only between Cape Point in the south and the southern Angolan coastline in the north.

The study, by Cape Town-based conservation geneticist Keshni Gopal, also found that all Heaviside’s dolphins (Cephalorhynchus heavisidii) are related, and that losing even a small number of these animals could have a severely negative impact on the species.

While one earlier study estimated that there were about 6 300 of these animals visiting the southernmost distribution range from Cape Town to Lamberts Bay, there is no current information on the size of the overall population.

“We have no idea, because nobody has calculated the abundance of the entire population,” she said. Gopal’s research earned her a PhD in zoology by Pretoria University.

Heaviside’s dolphins are currently classified as “Data Deficient” by the IUCN Red List of Threatened Species, because so little is known about their population size and life history traits, including direct and indirect threats that may lead to their extinction.

Gopal, 33, collected biopsy tissue samples from 395 of these animals in Table Bay, St Helena Bay, Lambert’s Bay, Hondeklipbaai and Port Nolloth, and from near Luderitz and Walvis Bay in Namibia, over four summers.

She used a “Hawaiian Sling” – a type of pole-spear specially designed for use on small cetaceans (dolphins and whales).

She then did her genetic analysis at the Leslie Hill Molecular Laboratory of the Kirstenbosch-based SA National Biodiversity Institute, where she works as a scientist.

 

Using a bi-parental inheritance gene marker that gives a more contemporary view of a population, she found the Heaviside’s dolphin can be broadly grouped into northern and southern meta-populations.

But when using a maternally inherited gene marker, which gives a long-term overview of the population, Gopal identified six smaller population units.

Knowledge of such units is vital to ensure effective conservation management strategies, and her data will also help substantially to update the species’ conservation status. “What is currently known about its biology and behaviour comes from opportunistic research rather than long-term studies,” Gopal said.

“Hopefully the results of my study can be incorporated into risk assessments and much-needed conservation management and monitoring strategies for this species, and help towards its long-term survival.”

Gopal attended Cravenby Secondary School and did her undergraduate and honours studies at UWC. While doing her MSc at Stellenbosch University, she helped discover a new species of rock lobster, Palinurus barbarae, off southern Madagascar.

While she was often taken to the beach as child, it was probably her father’s fish tanks at home that sparked her career interest, she said.

“It’s always been my childhood dream to study marine science. I had thought this would be more on the behavioural side, but I got involved in genetics during my Honours year and I’ve just stayed with it ever since.”

The sight of an albino Heaviside’s dolphin off Hondeklipbaai during one of her sampling trips is a particularly precious memory, and an “unexpected but positive” spinoff to her research work was the opportunity to share this information with locals in some West Coast fishing villages, she said.

“The fishing communities in these areas have adopted the dolphins as their own, and I often receive messages from them informing me about ‘their dolphins’ and of new additions to their area.”

 

Local wonder

The Heaviside’s dolphin is incorrectly named.

According to Wikipedia, it was originally called the Haviside’s dolphin, after a Captain Haviside, who brought a specimen from Namibia to Britain early in the 19th century.

But at some point, the species was misspelt as Heaviside, with this spelling derived from the name of a prominent surgeon, a Captain Heaviside, who collected whales and dolphins and other animal species.

This name stuck and is now the most common in scientific literature, although some authorities still use the original name of Haviside’s dolphin. - Cape Argus

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