Some become the victims of trophy hunters for their sought-after jaws and teeth, others get tangled in commercial fishing nets. Looking at ways to conserve the serve these impressive creatures has of deep has become the long life work of a number of scientists, including some working in the Western Cape.
Among them is Ram�n Bonfil, a researcher at the Wildlife Conservation Society in New York, who has spent the last couple of weeks tagging the great whites in Gansbaai and Struisbaai.
The project, a joint collaboration between the Wildlife Conservation Society, Marine and Costal Management, Cape Town and Pretoria universities and the South African Museum, started a year ago with tagging of four great whites using satellite-linked transmitters.
Ten more have just been tagged and another 12 are planned for next month. Bonfil has studied great whites for many years buts say there are large gaps in their knowledge about sharks.
�We need to gather information about the sharks� movements and migration to determine whether it is necessary to protect them in more countries.�
South Africa was the first country to introduce protective legislation in 1991 as a precautionary measure against dwindling populations.
The great white shark is also protected in Namibia, Australia, Malta and parts of the United States.
�We need to know the routes these sharks take. For example, do they swim beyond protected waters in South Africa or Namibia and land up in Mozambique where they have no protection?�
The team has been using pop-up archival transmitters tags, which are secured by a tether to the base of shark�s dorsal fin, and trail behind it in water.
The sharks are lured to the boat using seal decoys and chum, a liquid mixture of fish products.
The tags store information like the temperature of the water and the depth to which the shark swims. It can also indicate more or less where the shark is.
Before fitting a tag, Bonfil programs it for a specific time, such as six months or a year.
After this period the tag automatically detaches from the shark and pops up to the surface. All the data that has been collected is then transmitted by satellite to Bonfil�s computer in New York.
Bonfil said occasionally the tags released accidentally before the time. �On a shark we tagged last year in Mossel Bay, I started receiving data, just after 11 days�
It showed the shark had moved 820km from Mossel Bay to Port Johns and had spent at least 24 hours continually at depths between 100m and 750m.
For the Wildlife Conservation Society the project is just purely about conservation but for the team t Marine and Costal Management, it is the also about studding the impact of cage diving industry.
Herman Oosthuizen, principle oceanographer at Marine and Costal Management, said they were also interested in studding whether sharks became conditioned to the cages (where they are lured with chum), which would help regulating this industry.
Marine and Costal Management spokesperson Mike Meyer said acoustic tags have been fitted on some 80 to 90 great whites.
Recorders had been moored to in Mossel Bay, False Bay and Gaansbaai and would pick up the individual with a kilometer radius.
�We can tell what time the shark passes and how long it stays in this area. It gives us a residence pattern- what they do and where they go during the day and the evening.�
Bonfil said there was lot of work to be done in finding conservation solutions to protect great whites worldwide.
�People still look at great whites as brutal monsters. It will take a lot of hard work to change that perception and for people to learn to respect them as they would any other animal.�
� Fiona Fitzpatrick
2003