Keen to teach people about misconceptions about sharks, Ocean Steward Natalie dos Santos, reflects on a recent free-diving experience with the apex predators – and lessons learned elsewhere.
As freedivers, we are lucky enough to often spend time underwater with many blacktip (Carcharhinus limbatus) and ragged-tooth sharks (Carcharias taurus) at Aliwal Shoal, one of South Africa’s recently expanded Marine Protected Areas (MPAs) and top diving spots in KwaZulu-Natal.
Observing these graceful and curious animals in their natural environments, one can learn a lot about their behaviour. Photographing sharks allows us to share their unique beauty with others and to teach people about the misconceptions of sharks and the importance of protecting them – especially during shark week!
A blacktip shark passing by. Photo Natalie dos Santos.
Besides being important as sentient beings, sharks play a major role in keeping ecosystems healthy. An interesting Ted Talk by marine ecologist Dr. Enric Sala explained that the healthiest coral reefs have huge numbers of sharks that keep everything in balance. They keep numbers of other carnivores in check, which maintain numbers of herbivores, which keep coral reefs from being overgrown by algae. By doing this, sharks ensure that there is a high diversity of all species in an ecosystem. They also remove weak and sick animals from ecosystems.
Sharks are apex predators – few animals eat them. Because of this, they are long-lived and have low reproductive rates.
Over fishing
Take the dusky shark (Carcharhinus obscurus) for example. Female duskies only reach sexual maturity around 20 years of age, giving birth after a gestation period of about 22 months once every three years.
When overfishing meets slow-growing species, the outcomes are not good.
Female dusky sharks also return to the same area in which they were born to give birth, putting them in danger of localized over fishing pressures.
A ragged-tooth shark at Aliwal Shoal. Raggies became the world’s first protected shark species in 1984 and are protected in our waters. Photo Natalie dos Santos.
Over the past few years, shark population numbers have dwindled due to overfishing.
Blacktip sharks were last assessed as near-threatened in 2005 by the International Union for Conservation of Nature (IUCN) due to their low reproductive rates combined with fishing for fins, meat and vitamin-rich liver oil by both recreational and commercial fisheries.
Blacktip sharks are near-threatened due to low productive rates and fishing for fins. Photo Natalie dos Santos.
Sharks are hunted directly for their fins to make shark fin soup in some countries, but are also affected by over fishing of other species too. When fish population numbers get too low, sharks will move away since there are no fish left to eat.
When this happens, entire ecosystems become unbalanced. Fishermen who depend on sharks for their livelihoods will end up paying the price of their absence.
Where fins should be. Blacktip sharks can grow to 2.4m long, weighing up to 100kg. Photo Natalie dos Santos.
Shark fishing is all that many of these fishermen know. People are trying to teach them to protect sharks rather than to kill them; using ecotourism through diving as an alternative source of income.
A great example is Cabo Pulmo National Park in Baja California, Mexico. This area was only made a no-take marine reserve after fishermen decimated fish populations. Sharks had moved away and corals were overgrown by algae; leaving little besides an underwater barren.
Barren waters
After ten years of protection, ecosystems are thriving again, says National Geographic Explorer-in-Residence Enric Sala, who started the study in 1999,
Sharks had moved back in such high numbers that Sala said he had seen more sharks in one dive at Cabo Pulmo than he had seen in the last ten years in the whole Gulf of California. It is one of the best places to dive today; creating a sustainable source of income for locals.
“When we can align economic needs with conservation, miracles can happen”, said Sala.’
Learn more about the Cabo Pulmo National Park in this Ted Talk by Sala
This brings much hope that protection of an overfished area can lead to thriving ecosystems that had not only bounced back, but increased in recovery by over 400%!
The South African government has recently gazetted 20 new MPAs where sharks can thrive and maintain healthy ecosystems.
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Natalie dos Santos is a final year University of KZN marine biology student enrolled on Roving Reporters environmental journalism programme. She hopes to use photos of her free diving experiences to teach others about the ocean, its inhabitants and why we should protect them.
EXPERTS MIFFED ABOUT SHARK WEEK
This article on sharks was prompted by Shark Week – an annual, week-long TV programming block at the Discovery Channel. Shark Week originally premiered on July 17, 1988, devoted to conservation efforts and correcting misconceptions about sharks. But as it grew in popularity, becoming a bit hit – the longest-running cable television programming event in history – many biologists and scientists worry that it focuses too much on the sensational and not enough on science. >> Read more
FEATURED IMAGE
Photo of the Discovery Channel Headquarters in Silver Spring decorated with a fake shark as part of Shark Week. Photo by Hurricanedc taken in 2012 for Wikimedia Commons.
Shark Week too sensational?
View Discovery’s latest Shark Week episodes here and let us now your thoughts on scientists’ concerns that Discovery Channel has focused too much on the sensational.
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