18 July, 2013

Is a shark forecast in our future?

Check out the latest False Bay white shark manuscript just published in PLOS ONEWeltz et al. 2013. "The Influence of Environmental Variables on the Presence of White Sharks, Carcharodon carcharias at Two Popular Cape Town Bathing Beaches: A Generalized Additive Mixed Model." doi:10.1371/journal.pone.0068554

Sound elegant science, done like a boss, with female authors leading the publication.  Let this please be the beginning of a much needed shift in South African white shark science!

Take away message?  Make sure you double check the SST and moon phase before you go out.  Is this novel info?  For white shark science - yes, but for shore based anglers - no.  Nonetheless, it is great to see this kind of information translated into a language academics/government officials are capable of digesting.

So... any bets on how long it takes for a crazy to develop a sea-cooling 'shark barrier'? 

12 July, 2013

Sharknado - two fins up! [with spoilers]

I love these movies, because I was one of the many raised on Mystery Science Theater 3000 and, as a researcher, I can relax knowing that the audience is aware of the film's fallacy.  This is opposed to most (not all) shark documentaries, which have literally given me the night sweats as they are chock-a-block full of pseudo science or (spoiler alert) are completely faked.  Films like Sharknado purposefully take the piss and, considering what passes as a shark documentary now a days, Sharknado could be doing more good for sharks than bad - follow me out on this limb...

The film starts out with a scene on an offshore trawler where they are finning sharks.  Spoiler Alert: The fishermen get owned by the pissed off sharks.  Then, once the sharks are pissed off, they go into shore and start causing havoc while the unnatural hurricane (caused by global warming) hitting Los Angeles makes tornadoes which suck up the water full of sharks.  Sharks are then thrown around town killing people (since no one seems to be able to stand up and just walk away from the sharks after they have landed) or start swimming into the flooded streets (based on fact).

After a massive failure of logic (you really expect me to believe that one can dive into a shark's stomach chainsaw first and not cut up the girl that's trapped inside???), the take-away message is: Don't fin sharks and piss them off while simultaneously fucking with the climate, this makes Sharknadoes and no one's got time for that.  Is this worse or better than the take away message that killer sharks are your friends and you need sharks to breathe oxygen so save them?  They are both based on b.s. and which do you think is more effective?

07 July, 2013

New white shark aggregation area in South Africa!

Dicken et al. 2013.  White sharks Carcharodon carcharias at Bird Island, Algoa Bay, South Africa.  African Journal of Marine Science.

Perhaps this area isn't 'new', but this is the first time white shark presence at Black Rocks/Bird Island has been quantified and published.  Unfortunately the paper is not open source, so you will have to ask your academic friends to download a PDF for you.  This area highlights yet another aggregation determined by the presence of seals even though it occurs in the warm Agulhas waters, and also shows small shark sizes when compared to our stomping grounds.  Yet, I am dubious of the accuracy of surface white shark sizing.  Anyone who has been on a cage diving vessel has experienced a good debate of 'hoe lank is dat haai', and the ranges can be startling!  Also, as boats/cages get larger, so do shark sizes.

A good example of this is Gansbaai local, Nemo.  When all the cage diving operators were working with ~3.0m long cages, Nemo was sized at around 3.0m.  Then, when cages suddenly upgraded to 4.0m in length, Nemo suddenly grew to 4.0m in length and the sizing debate began...  Here's hoping that someone who has/is/will be using those laser measurement systems on white sharks publishes a nice comparison between observer bias, surface sizing and laser sizing!

But I am digressing as usual.  Check out the paper!