From the age of about five Enrico Gennari wanted to do research on the great white shark, and he is still pursuing this dream with his work at Oceans Research in Mossel Bay.
After completing his master’s degree in Natural Science at the University of Rome La Sapienza, he took a gap year to work as scuba dive master in Italy, before joining Ryan Johnson doing research on the great white shark. Together he and Johnson tracked a single white shark for 103 hours – quite an achievement as it had had never been done before.
In 2006 he enrolled for his PhD under supervision of dr Paul Cowley of the South African Institute for Aquatic Biodiversity (SAIAB) and Johnson at the University of Rhodes, studying the thermo physio-ecology of the great white shark.
At the same time he and Johnson and two other marine researchers Stephen Swanson and Toby Keswick, created Oceans Research, a private marine research institute focusing on marine top predators in the Mossel Bay area.
In order to share his passion with students from all over the world, he started an internship programme in 2008 where students can hone their practical research skills.
“Besides the great white a large variety of other sharks also occur in the temperate water off the Mossel Bay coast, such as the hammerhead, that has a nursery colony here, the bronze shark, the cow shark – a living dinosaur also known as the seven-gills shark, the smooth hound shark, thresher shark and ragged-toothed shark. Two of the latter were recently released here after years of captivity at the Two Oceans Aquarium in Cape Town.
“Fishermen know which sharks occur here, but bathers who don’t go beyond the breakers have no clue to the rich variety,” says Gennari.
Oceans Research among other things also does research on the physiology, habits, population, distribution and movement of the great white.
The whites that occur here are between two and three metres in length, an indication that they are immature, says Gennari.
Those in the Cape Town area are about five metres, which is an indication that the population is under pressure, because elsewhere they become up to seven metres in length.
The great white distribution between Cape Town and Port Elizabeth may be related to the Cape fur seal colonies in this area, as research has shown that their diet include these seals.
“The bulk of research has been done on great whites and we know more about them than any other shark species – and yet we still know very little.”
Only the great white poses a threat to humans. “As they can be dangerous it is better to stay away from areas where they are known to occur.”
During winter, great whites spend a lot of time near the river mouths (estuaries) of the Hartenbos, Great Brak and Little Brak Rivers, but they may also occur throughout the area off the coast. “They have to move around in order to breathe,” says Gennari.
“It is safer to stay away from the areas where they are known to occur, because there is always a risk. If you get out of your car in the Kruger National Park dressed like a zebra, it is not the fault of the lion if he regards you as prey. . .”
Humans not on the menu
Humans are not on the great white’s menu: they eat other sharks and sometimes even their own young, fish, dolphins, seals and crustaceans. “If a shark takes a bite out of you it is not because it is hungry – it is simply curious. It is a natural instinct – they sample everything. If you are not part of its diet, it simply spits you out and leave.”
Unfortunately a shark tests your edibility by taking a bite with its sharp end . . .
Fortunately only ten, fifteen cases of shark attacks occur annually worldwide, and only one or two every ten years in the Mossel Bay area.
“The purpose of our research and information talks is to remove the stigma attached to the great white and which is mainly due to movies such as Steven Spielberg’s Jaws, which depicts the white shark as a man-eater.”
“The more you find out about the great white, the more you realise your fear is biased. When you get to know the beauty and grace of the great white you can’t help but want to protect it.”
Conservation is essential considering that there are only between 2000 and 5000 great whites in South African waters. “Research indicates that great whites move along the eastern coast as far as Kenya, Tanzania and Mauritius. Up to 70% of the sharks that occur along the South African coast migrate to Mozambique. That is why it is important that legislation ensuring the conservation of the great white is also applied off the coast of other Southern African countries.”
In the cold Atlantic Ocean great whites sometimes migrate to the southern Arctic islands. “One individual moved up the Namibian coast but immediately turned back,” says Gennari.
The great white, which has the ability to maintain parts of its body temperature above the surrounding water – quite similar to land mammals – migrate to and from warmer and colder water. It was found that populations interbreed with Australian populations, but they are not separate species.
According to Gennari it is part of the great white’s lifestyle to migrate, but why they do it, we don’t know. “We know nothing about their breeding cycle and nobody has ever seen it mating or giving birth.”
And that is why he is so fascinated by them: “They go to places we know nothing about . . .”
Most of what people think they know about great whites is based on myth and misconception, based on sensational movies such as Jaws and misleading documentaries.
What he is absolutely sure about it that the great white – and other shark species – are endangered by the thoughtless actions of man, including illegal long-line fishing.
Long-line fishing involves baiting hundreds of hooks along kilometres-long fishing lines which are placed at different depths in the sea. The type of bait depends on the type of fish targeted, and whether fishing is done just below the surface or at the bottom of the ocean for which weighted lines are used.
When the long-lines are released during daytime, albatrosses and other seabirds immediately take the bait and are pulled below the surface of the water along with the baited and weighted lines, thereby threatening especially the albatross with extinction.
In the depths of the ocean the long-lines also catch fish indiscriminately. “Hundreds of sharks and other threatened fish species take the bait. By the time the long-lines are checked hours later the unintended catch is long dead and is simply tossed back into the sea.”
Long-line fishing in South African waters are strictly regulated, but the regulations are not enforced. Some owners of fishing trawlers blatantly ignore the rules, and recently several long-line fishing vessels have been spotted in the shallow waters off the Mossel Bay coast.
“Trawlers from a Port Elizabeth company have been observed,” says Gennari. There are no supervisors on board to ensure that the regulations are observed. Species included in the by-catch include great whites, Cape fur seals, black mussel-cracker, red steenbras and hammerhead sharks.
“To allow long-line fishing here is a bad idea, because even though there is an abundance of fish which allows trawlers to catch close to the shore, the practice can quickly turn into an ecological disaster.”
Tourists who think shark nets are the only way to keep sharks away from bathers, need to think again. “People believe shark nets are continuous and keep sharks away, but they do not realise that the sharks swim underneath the nets. Most sharks that are caught in nets were entangled – and died – while they were trying to leave to so-called protected area. In this regard shark nets are almost as bad as long-line fishing.”
At present an underwater electric cable that emits pulses that sharks can detect 50 cm away is being tested in Australia. These cables may be a good alternative to shark nets.
Gennari believes the great white is one of Mossel Bay’s undeveloped tourist attractions. “Tourists don’t want to talk about sharks. Yet great whites turned Gansbaai into a shark Mecca that is earning the town millions of rands a year.
Mossel Bay’s tourism industry is profiting from the abundance of great whites to some extent by offering cage diving experiences. “It is a wonderful experience to see the beauty and grace of the great white in its natural surroundings. Unless you see the fin above the surface of the water, sharks are basically invisible and the only way to appreciate its size and beauty is from the safety of a cage,” says Gennari.
He believes if cage diving is done correctly it can positively influence the public’s opinion about great whites. “Worldwide the cuddly panda is associated with nature conservation, and when people can see the beauty of the great white it will change their opinion.”
He believes chumming – attracting the sharks with fish offal – is not dangerous to people, as the sharks will not associate people with the food. “As long as you are inside the cage, the shark regards you as part of the cage, just as it sees you as part of the boat you are in.”
“The only way you will protect something is when your fear of it is addressed.” For this reason he does talks at the Nelson Mandela Metropolitan University in George, or addresses GCBR meetings, among others.
“One will protect something that you regard as beautiful and precious. We try to show people that the great white is beautiful and worthy of protection. Instead of allowing the great white population to become extinct as a result of long-line fishing, we want people to understand how unique and remarkable the marine life along our coastline is.”
Article by Tisha Steyn
Great White Shark
(Photo: E. Jacobs-Overbeeke)