Tuesday, July 02, 2013

Silkies vs Grey Reefs - Paper!

Very interesting!
Abstract here.

Juerg will be delighted.
He is currently formulating his newest paper that deals with the relative abundance of Sharks within Shark Reef, and this is really going to be helpful, albeit maybe more by juxtaposition that by analogy. 
We, too, have experienced notable changes over time but contrary to what has been observed in Jeddah where declines are being attributed to fishing, I believe that what we witness is the result of competitive exclusion, possibly coupled with the effects of the establishment of a (completely different) competing Shark dive in the near vicinity.
But that's for Juerg to analyze, so take it with a grain of salt.

And the other topics?

Boldness vs numbers.
Where our observations coincide is that like in the case of those Silkies we, too, observe an increase in boldness with increasing numbers, this certainly with respect to our Bull Sharks that have become positively pushy during the hand feed, forcing us to continuously adapt our procedures. 
At the same time, when away from the immediate feeding area, they however appear more habituated to humans insofar as they appear less reluctant to approach whilst at the same time behaving way more relaxed all the way to having practically stopped engaging in agonistic behavior like jerky swimming, gulping and bumping. Notable exception: our ever irascible Marlen who will immediately retaliate against any attempt at manhandling her!
This may possibly apply also to the Blacktip Reefies that from being frustratingly shy 10 years ago have become increasingly feisty - this with the caveat that although their numbers have certainly increased, this is most likely attributable to conditioning and learning.

I was intrigued by the observed lack of intraspecific and inter-specific aggression in the Red Sea - especially considering that the Grey Reefs are notorious!
Here, we clearly observe the latter whereby the Bulls will bite and hustle away other species, and when it comes to the former, we observe no overt aggression but never the less detect clear signalling of dominance, this usually by the larger and/or bolder individuals.

This once again confirms the findings of all Shark behaviorists and incidentally, all Shark divers that Shark behavior is context driven but also individually diverse - see also the other Silky Shark paper by the same Chris Clarke et al here that hypothesizes individually diverging foraging strategies.
And since yer at it, read this, too!

And there's a bonus point!
When googling the mysterious Danah Divers, Marine Research Facility, Jeddah, Saudi Arabia where Chris apparently acts as the Operations Manager, I stumbled across this remarkable story by Tom Campbell. So now you know how the SOSF has come about!
And incidentally, have a look at this - now THAT's what I call a dive boat!!! :)

But I'm digressing as always.
All in all, really very nice - kudos!

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