Debunking myths on Mediterranean great white sharks

(first posted on 1 Nov. 2010; adapted from an article appeared in Italian on La Rivista della Natura)

Towards the end of summer 2009 the welcome news arrived that great white sharks still exist in the Mediterranean. A newborn female, slightly longer than 1.5 m, sadly met her fate in the bottom of a trawl net. Fishermen from the island of Lampedusa reported the event to Simonpietro Canese, a researcher from ISPRA who was inventorying marine biodiversity in the Strait of Sicily.

It has been a while since the occurrence of the species in the region was in the news. The Mediterranean population of great white sharks, Carcharodon carcharias as it is known to scientists, is listed as Endangered in the Red List,

Great white shark (Carcharodon carcharias) off...

due to inferred significant reduction in numbers during the last decades. Although the reason(s) for decline is uncertain, the dismal conservation status of bluefin tuna, the sharks’ main prey in the region, is a likely candidate.

I don’t expect all readers to share my sense of elation, experienced in learning about the continued presence in our seas of the great predator. After all, there are not many species left on the planet which are able to devour a human being, and the great white shark is one of them. The perspective of being thorn to pieces by a sea monster still evokes in all of us an instinctive sense of horror; however in this case our instinct is unjustified, because in the Mediterranean there is little substance to the problem. This consideration provides me with the opportunity for trying to debunk some of the most common myths concerning the presence and dangerousness of great white sharks in the Mediterranean Sea.

Myth n. 1. Great whites enter the Mediterranean from the Atlantic through the Gibraltar Strait following ships. False. The Mediterranean hosts a resident population of these sharks, which are found in the region regularly (although in low densities), and breed here as well, as indicated most recently by the unlucky newborn from Lampedusa. By contrast, great white sharks are quite rare in the north-east Atlantic Ocean, so that in fact the exact opposite is more likely.

Myth n. 2. Great whites live in the open seas, and rarely come close to the coast. False. It is not on the basis of the distance from the coast, but on the basis of the presence of their prey that great white sharks decide where they want to be. In other seas, such as for instance off California, southern Australia and South Africa, these sharks are frequently found in few metres of water in front of rookeries of seals and sea lions, which are their main course in those locations. Significantly, great white sharks get occasionally caught in tuna traps (almadrabas or tonnare), which are laid along Mediterranean shores to intercept migrating bluefin tunas.

Myth n. 3. Great whites are a significant threat to Mediterranean swimmers. False. Please don’t get me wrong, there have been episodes in which a great white shark killed a human in the Mediterranean: to be exact, 21 cases in the entire basin in more than a century (1907-2010), i.e., 0.2 attacks per year on average, the last of which occurred 23 years ago in the bay of Baratti (near Livorno, Italy). A modest death toll indeed, compared for example with the tens of persons who die every year in Europe as a consequence of a bee sting. Casualties from shark attacks in the Mediterranean become even less significant considering every summer bathers in the Mediterranean waters number in the tens of millions.

This is a typical example of media bias: when a great white shark appears near our coasts it goes on TV right away, whereas nobody takes notice of the much more dangerous hornet.

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23 comments to Debunking myths on Mediterranean great white sharks

  • Jonas

    Regarding Myth n. 1, Great Whites enter the Mediterranean from the Atlantic through the Gibraltar Strait” You may consider your statement, please see this link about White Shark probably heading for the Gibraltar Strait from the Atlantic: http://officetoocean.blogspot.se/2012/02/huge-great-white-caught-in-morocco.html

    • Giuseppe

      There certainly can be movements of GWS to and from the Med across Gibraltar, however the myth I want to expose is that the Med is a “safe bathing area” which is only occasionally visited by GWS entering the Med through Gibraltar, perhaps following ships, as is quite often said and written in the popular press. The report from Morocco in your site is interesting and I thank you for bringing it to my attention.

  • Daniel Cebrian

    The Mediterranean population of Great whites is a distinct one isolated from the Atlantic one possibly half a million years ago. It is genetically closer to the Australian one and breeds in the Strait of Sicily. Atlantic male wanders contribution to the genetic pool seems uncertain, since the Mediterranean population variability looks too low.

  • Shanker

    The great whites in the Mediterranean are genetically distinct from the ones found in the Atlantic. DNA testing has confirmed that they are in fact Australian ‘migrants’; sharks that lost their way several thousand years ago and ended up in the Med. Here’s the link:

    http://www.telegraph.co.uk/science/science-news/8137374/Mediterranean-great-white-sharks-are-Australian.html

    That said, I find some of Jonas’s points interesting. There may be some mixing occurring and if it benefits the survival of the species I’m sure a lot of conservationists will be glad! After all this is already happening among different blacktip species off Australia:

    http://news.discovery.com/animals/sharks/hybrid-shark-australia-climate-change-120103.htm

    • Giuseppe Notarbartolo di Sciara

      Good point! In fact, the research you mention (see full reference below) points to the likelihood that the GWS population in the Mediterranean is even more endangered than what it is normally considered to be.

      Gubili C., Bilgin R., Kalkan E., Karhan S.U., Jones C.S., Sims D.W., Kabasakal H., Martin A.P., Noble L.R. 2010. Antipodean white sharks on a Mediterranean walkabout? Historical dispersal leads to genetic discontinuity and an endangered anomalous population. Proceedings of the Royal Society of London Series B Biological Sciences 9 p. doi:10.1098/rspb.2010.1856

  • Chris

    0.2 attacks per year on average, the last of which occurred 23 years ago in the bay of Baratti (near Livorno, Italy).

    False. Unless you are thinking of deadly attacks. On the 6st Septemter 2008 the Slovenian diver Damjak Pesek was attacked and fatally injured by a Great White of the shore of the remote island of Vis (Croatia). He was was spearfishing with friends and obviously carried dead fish on his body he speared before.

    http://www.croatiantimes.com/index.php?id=1389

    • Giuseppe Notarbartolo di Sciara

      Thank you, I wasn’t aware of that episode, which should now be taken into account. However, one more attack during the last quarter of a century doesn’t really change greatly the soundness of my point.

    • Italo E. Foddis

      The Slovenian diver Damjak Pesek was attacked but not killed by a great white shark.

    • Giuseppe Notarbartolo di Sciara

      I did, and tried – so far unsuccessfully – to get the attention of the Barcelona, Bern and Bonn Conventions Secretariats hoping that they would contact the Government of Tunisia to ensure that such episode won’t happen again. Apparently, what is shown in the video is not an isolated episode. Considering how endangered GWS are in the Mediterranean, I also tried with IUCN’s Species Survival Commission and the Shark Specialist Group, but was unable to make much progress on that front either. Will continue.

  • Ian Fergusson

    Great summary, Giuseppe. Thanks for your efforts re that Tunisian episode. As you note, the wheel of better fortune turns painfully slowly when endeavouring to secure protection for this species in the Mediterranean, but hopefully collective pressure will eventually work. I was in Tunisia just a fortnight ago and the growing number of tuna ranch pens I could see before landing at Enfidha was very troubling…

    • Giuseppe Notarbartolo di Sciara

      Ian those tuna ranch pens aren’t going to go away soon so something has to be done. We will continue to try, thanks for the encouragement.

  • Michalis

    A newborn GWS was caught off the Greek coast about a month ago. I will provide a link but please don’t ask me to translate the whole thing. it’s obvious (το με ατ λεαστ) from the photos that it is a GWS

    http://www.enikos.gr/society/157439,FWTO-_Piasthke_leykos_karxarias_sthn_Kef.html

  • Marcus

    The photos of the shark caught in Greece look more like a Mako (from the teeth and the eyes) than a Great White. Scroll down on the following link to see pictures of a juvenile Mako. Also note the dark snub on the nasal tip – http://www.mexfish.com/fish/makshrk/makshrk.htm

  • Bosko

    In the April 1999. Near the coast of Montenegro, local fisherman caught juvenile of great white shark in the net.
    Shark was 1,8 m in length.There are photos of it in the local tavern “Tri ribara“ in the coastal village Rafailovici in Montenegro.

  • Jonas Fischer

    Dear Giuseppe, maybe Great White Lydia will go through the Gibraltar Strait soon, of the Portugal coast now (http://www.ocearch.org/tracker/), what do you think?

  • John O'Brien

    Dear Giuseppe

    I read your artical with great interest.
    I work on the end of a long breakwater off gibraltar. On Monday 5 of my divers and one other person reported seeing a large Shark take a seagull off the surface on two occasions. (Both reported by defferent people)
    The Shark they say came half way out or the water, had a pointy nose and as it turned over its under belly was white and about 3m long.
    I at first ridiculed the story but they are very experienced and old lads who swear by it.
    Is it possible it was a GWS ? Are there any other species that match this description?
    Kind regards
    John

    • Giuseppe Notarbartolo di Sciara

      John, what your divers saw could have been a GWS, however it could also have been other species, e.g. a mako or some Carcharhinid (although 3 m is a bit large for many of these). The characters in the description fit GWS and mako but they are not 100% diagnostic. In any case both species are known for that area, so unlike the seagull, I am not too surprised. All the best,

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