Blog about "The World's best Shark Dive" by Beqa Adventure Divers.
Featuring up to eight regular species of Sharks and over 400 different species of fish, Shark diving doesn't get any better!
It obviously begs the question, did the Tiger kill the Manta.
I'm also amazed at those many Reef Sharks as I've never seen them scavenge like they are doing here.
And I must add that all those unprotected punters are a scary, scary sight, the more as Tiger Sharks are known to vigorously defend their meals, and perceived interlopers have already been grievously injured.
Much of it depicts the situation at Raine - including the Turtle lovers, Turtle tagging, Tigers scavenging and finally, Tigers attacking Turtles, and the Turtles' defensive maneuvering.
That's quite a handful of prominent authors - but in essence, this is a re-interpretation of some of the data collected by Richard, Adam and Ian whilst on the venerable Undersea Explorer that have already led to this paper from 2012 I posted about here.
Which is why the authors stress that much of the above is speculation.
The experimental design was aimed at deciphering long-term movements, and the present fine-scale analysis is very much based on inference rather than actual scientific evidence; but having said that, Richard and Adam have logged hundreds of man hours at Raine, and tell me that actual predation events on healthy Turtles are very rare and tend to be confined to the start of the breeding season when there are less Turtles and the Tigers are just arriving hungry. On a busy year, Raine will yield up to 2,000 dead Turtles, meaning that after a while, the Tigers are more than sated and really could not care less about chasing after healthy Turtles.
Like I said, very nice - but now things are changing.
BHP the mining giant is giving a lot of money to the Raine Island Green Turtle Recovery Project, and the island is being made more Turtle-friendly by eliminating features that could kill them and by protecting the nests against inundation. This means that less turtles will have accidents, and that any distressed Turtle will be aided by the turtle lovers and consequently, adult Turtle mortality has already been reduced by 50%.
And the Tigers?
What happens at Raine is part of a system - and if you tinker at one end, it stands to reason that there will be consequences at the other.
Will the Sharks predate more on healthy individuals whilst expending more energy in the process - and if predation increases, will that have an effect on the behavior of the Turtles? Or will the Tiger Sharks gradually stop coming? And what are the effects of this diminishing resource on their population?
Here's what I think - and yes I'm totally speculating.
Research in Hawaii has shown that those Tiger Sharks are able to regularly exploit determined ephemeral resources, and our own observations at Shark Reef indicate the same for our Bulls at Shark Reef. In essence, one of those Sharks will stumbles upon an opportunity, is able to memorize the experience and will henceforth come back to exploit it. This is learned individual behavior, not something that is genetically encoded or communicated by conspecifics or the like.
At the same time, our observations and those of the GWS people indicate that individual Sharks will favor determined strategies, e.g. individual GWS will attack the teaser bait consistently in one determined way; and on Shark Reef where we have a hand feeding and a bin feeding tribe of Bulls with very little overlap, those specialized hand feeding Bulls will gradually stop visiting when we temporarily suspend hand feeding,
Could it be the same for Raine Island?
Could there be always the same Tigers, and could those individuals be specialized scavengers that would not switch to outright predation but instead, would eventually stop coming once there are not anymore enough carcasses to feed on?
Dunno - but that's certainly testable, or not?
And another thought.
If one believes Domeier -and I certainly do- what happens at Guadalupe is essentially a GWS feeding and mating aggregation. Could the food pulse during the pupping season of the Northern Elephant Seals maybe even trigger mating, and could it be important for the success of the ensuing pregnancies?
And could what happens at Raine Island be the same, meaning that if the Shark aggregation slowly disperses, finding mates would become more difficult and reproduction success would be lower?
When the video came out in August and the usual dipshits started using it as "proof" that Sharks are harmless, I decided to look the other way; but now it turns out that one of those dudes is none other than my pal Allen who managed to overcome his angst and reluctantly hop into the fray. In case you wondered, I would never ever ever ever!
Ils sont fous, ces Sudafricains - as in batshit crazy! :)
Plus, there is that Bull Shark, see Allen's pic at top.
You can check her out at 0:04 and she sure does not look good!
Over here, such an emaciated, wrinkly animal is usually either sick and/or very old - or more rarely, simply famished after having gone walkabout during the pupping and mating season whereby it usually manages to bulk back up in no time at all.
Anyway, this is pretty epic.
Allen tells me of multiple GWS, a dozen plus Tigers, plus Bulls, Duskies and Blacktips all feeding simultaneously which is in itself totally spectacular. Maybe I haven't been paying attention - but I was under the impression that the only two species reported to scavenge on Cetaceans are GWS and Tigers, and stand accordingly corrected. This sure raises all sorts of interesting questions about inter-specific competition and dominance, etc., and would certainly be great science fodder - any takers?
Of special interest to me is the apparent lack of aggression between the Tiger and the Bulls - and despite the Tiger's jaw deformity: may those passes at the end of the video be agonism all the way to early jaw gaping?
These
photos were taken this afternoon in Coral Bay inside the reef.
Yesterday a sick or injured humpback whale was spotted not too far off
the back of the reef, and it must of died overnight, and our wonderful
garbage trucks of the sea, Tiger sharks have
come in to clean up the mess. Other sharks also hanging around the
carcass include, lemon sharks, black tip reef sharks, bull sharks, and
grey reef sharks and possibly tawny nurse shark as well!! What an after
noon! We will see what is left of it tomorrow....
A (likely already weakened) Blue Whale was killed by Bull Sharks in New Caledonia and then later devoured by Tiger Sharks. The observations by Eric Clua and Jonathan Werry reveal a whole array of behavioral patters both when feeding but above all, when interacting among each other that range from the usual displays of dominance and agonism, to totally unexpected and amazing stuff - or did you know that they tail slap each other?
Very useful, especially for those lovers of TB and Aliwal!
