Thursday, September 04, 2014

Pelagic Bull Sharks?


Wow.

If you can, please watch this.
Yes it's long but well worth the effort.



I'm stumped by the revelations at the end.
Apparently, Reunion's Bull Shark are not resident but only seasonal and apparently, they could be spending a large amount of time in the open ocean.
If so, this would mean a big shift in what we know about this species.

Or maybe not. 
Maybe this is simply more evidence for the environmentally mediated behavioral plasticity I've posted about here. Maybe those Bulls rely on migratory prey and only return to Reunion to mate - think of Playa where contrary to Fiji, there is merely a short Bull Shark season that is being linked to reproduction and where so far, nobody knows what they do during during the remainder of the year.
Maybe.

And the hypothesis of heightened aggression during the mating season?
Not convinced. Aggression is not predation and to me, those described strikes point to predatory events rather than agonism. Plus, our Bulls don't feed during mating season - but then again, this applies to Fiji and maybe, those Bulls behave completely differently!

Long story short?
It is complicated!

1 comment:

dr said...

Indeed very interesting
Some thoughts:
Maybe from time to time they migrate longer distance (not all) and that
on a regular basis (at some places)?
For the Bull Sharks in Réunion it could be the same as for Chumphon
Pinnacle/Sail Rock and for Vava'u. Maybe they spend there juvenile
time at some of this places as they are potentially good feeding grounds too,
also mating there and then coming back "home".
Rivers of Madagascar for Réunion, Fiji for Vava'u and Chumphon for
Chumphon Pinnacle/Sail Rock (possibly some other places around?)
Compared with Chumphon (80km), Madagascar - Réunion and
Fiji - Vava'u is quite a distance (650km)
Or Vava'u and Réunion are the exeptions, who knows, but very interesting.
But if they going south about 400km, its not so farfatched i think.

Probably you have some more updated news on Chumphon and Vava'u?

By the way, found this nice footage, by checking if the Dive Site was
called Sail Rock
https://www.youtube.com/watch?feature=player_detailpage&v=GiuTbdoEyz4#t=62

Cheers
Daniel