Conservation Biology

Friday, March 09, 2007

CONSERVATION OF GREAT WHITE SHARKS

The white sharks are classified in the kingdom Animalia from the phylum Chordata, they are of the class Chrondrichthyes from the family Camnidae and genus Carchardon. The white sharks are scientifically called Carchadon Carchardrians [1]. The great white sharks are known as the white sharks, white pointer or white death [2]. They are extremely large, body shaped like torpedo with silver to blue – grey colour and white underside with pointed snout. They have a Standard Dorsal fin (is on top of the shark), pectoral fins (bottom - front and rear) and Caudal fin (crescent shaped tail) and additional of two small pelvic fins. The fins are important because they drive and guide the sharks through the water in a streamline motion like that of an airplane. White sharks have 3 000 teeth arranged in several rows, their teeth are in the shape of a triangular and are 7.62 cm long [1].

The white sharks are more likely to be found in ocean water, deep or coastal waterways but especially Islands with high populations of Pinnipeds. Pinnipeds are defined as the marine mammals that are characterised by hair, flippers, e.g. sea lions, elephant seals etc. They can weigh up to 3175 Kg but the average weighed between 1361 to 2268 Kg and they are 3 to 4.5 m long. The white sharks feed on seals, elephant seals, sea lions, other fish, dolphins, sea turtles, otter, small toothed whales, carrion etc [1].

These types of sharks are less abundant globally than other sharks. Should there be a high fishing rate; the population of the great white sharks will be lowered because their reproduction and growth rate is slow [3]. The female white sharks can reproduce from 12 to 15 years and the male from 8-9 years. The gestation period for the great white shark is more than a year [4]. Their annual reproduction rate is 2-6 pups and this is considered as the slowest reproductive rate [5].

Minister of Environment and Heritage, Dr David Kemp of Australia indicated that the great white sharks declined by 20% over the last three generations and in some areas [6]. Australia is recognised being the world leader in the protection of the sharks. South Africa, USA, Namibia, Malta and the Maldives are also protecting the great white sharks [6].

Human have impact in the declining of the white sharks, during the mid of 1960’s the gills nest were placed in the large coast of KwaZulu Natal, South Africa. The main aim of placing the gills nest was to protect the bathers from the sharks. As a result, the white sharks and other sharks travelling along the coast are still entangled in the nest and they die of asphyxiation. Asphyxiation is a death that results from lack of supply of oxygen to the brain. However, the sport fisheries threaten the great white sharks worldwide. The sport fisheries seek the white sharks as trophies and if accidentally caught by commercial fisheries that price their fins [3]. Some other people hunt the large jaws of white shark because they can have USS 10,000 for collecting the jaws [4]. The fins of the sharks are valuable in the Asian fish market because they are used as the shark fins soup [3].

Dr. Ramón Bonfil, shark expert, WCS Conservation Fisheries Scientist, in partnership with the South African Marine and Coastal Management Branch, with collaboration of University of Pretoria, University of Cape Town and Natal Sharks Board launched a study of great white sharks. They were using a satellite tracking devices and other techniques to collect information on the movement and seasonality of the great white shark. The research started in 2002 and since 2002, they attached 43 satellite tags of which 25 tags were the pop-up archival tags (PAT Tags). The PAT tags records the environmental data surrounding the shark once every minute. The data gathered is send via satellite at a later programmed time at the end of the experiment. The remaining 18 satellite tags were attached to white sharks during their research. At the end of their study, the following will be known: specific preferred habitats of the sharks, how to design the protection measures that will guarantee the survival of the great white sharks globally [3].

The sport fisheries together with the commercial fisheries must stop fishing the great white sharks. The sharks also showed that they hunt people, in 1995, Australia launched its bit to conserve the great white shark and on the very same day one of the fisherman, David Weir was attacked and killed by a great white shark [6]. The net that is placed in the ocean to protect the bather should be of the size that will not injure the sharks because the great white sharks are also declining because of the asphyxiation. The system that is used by the Dr Ramon Bonfil and his team should be followed, as they are aiming to design the protection measures that will guarantee the survival of the great white sharks.

References

1. Anonymous. Unknown Date. Great White Shark Taxonomy & Description. [Cited 08/03/2007: 11h00]. Available from:
http://www.tigerhomes.org/animal/great-white-shark-taxonomy.cfm.

2. Wikipedia contributors. Great white shark [Internet]. Wikipedia, The Free Encyclopedia; 2007 Mar 8, 06:23 UTC [cited 2007 Mar 9]. Available from: http://en.wikipedia.org/w/index.php?title=Great_white_shark&oldid=113517316

3. Bonfil R. 2002. South Africa. Great White Shark Conservation. Marine Conversation Program. [08/03/2007; 14h00]. Available from: http://www.wcs.org/international/marine/marineafrica/gws.

4. The White Shark Trust. 2002. South Africa. [Cited 08/03/2007, 13h00]. Available from: http://www.whitesharktrust.org/pages/index.html

5. Kemp D. 2004. Australia Moves to Protect the Great White Shark. Australian government. [cited 07/03/2007, 12h00]. Available from:
http://www.prbo.org/cms/index.php?mid=215

6. Cribb J. and O’Brien N. 1995. Call to protect great white shark. The Australian [Cited 08/03/2007, 10h00]. Available from:
http://ink.news.com.au/mercury/mathguys/articles/1995/950914a1.htm.


Image credits

1.http://www.apexpredators.com/store/showCategoriesProducts.asp?categoryID=6

2. http://www.wcs.org/international/marine/marineafrica/gws

Ms Evelyn Maleka
CSIR, Research and Development Core
P.O. Box 395
Pretoria
0001
Tel: (012) 841 2133/2807
Fax: (012) 841 4405
Email: emaleka@csir.co.za
http://malekaevelyn.blogspot.com/

7 Comments:

  • Where are you getting these incredibly precise figures (especially paragraph 2 - what do the averages mean there?)?

    By Blogger NcK, at March 19, 2007 9:11 AM  

  • This comment has been removed by the author.

    By Blogger Masingita Lizzy, at March 19, 2007 1:45 PM  

  • This comment has been removed by the author.

    By Blogger linette, at March 19, 2007 3:25 PM  

  • Hi Evelyn

    You talked about the protection of white sharks in Australia without mentioning how these sharks are protected. What is the current state of white sharks now under the new minister of environment and heritage in Australia, Ian Cambell?

    By Blogger peter, at March 19, 2007 3:32 PM  

  • Hi Nick

    Should you follow the linked referenced there, you will see where those figures come from. You will find the figures written in lbs/pounds so you can convert them to Kg. The average there refers to the average weight by the great white sharks, for example, if you are a lecturer and you analysis the results of your students, just like the average marks, however, some of the students performed well but most of them got certain amount, then that is the average.

    Cheers

    By Blogger Maleka Evelyn, at March 20, 2007 1:07 PM  

  • I know what an average is, but you haven't explained what average is being employed - mean, median or mode? (Your example doesn't help much either.) This isn't explained in the relevant references either.

    Also, note the difference between the amount of significant figures used in the references and in your text - reference 1 has no decimal figures, while yours has two figures after the decimal point. You can't pretend to more precision than is found in the reference (and in fact, because centimetres are smaller than the inches they used, the level of precision you've invented is even higher than that)!

    Just be careful...

    By Blogger NcK, at March 23, 2007 12:41 PM  

  • Hi Peter

    In Australia, they are using the net as well to protect the sharks. I tried to check the status of the shark under Ian Cambell but I did not find anything about that. I will keep on searching should I found something I will come back to you about that.

    By Blogger Maleka Evelyn, at March 27, 2007 11:28 AM  

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