Monday, May 30, 2016

Paper: does Shark feeding harm the Sharks?

Provisioned Whitetips at Shark Reef - at risk? Great pic by David Fleetham.

Bingo - very interesting!

But first.
Quick quick - download the PdF as it will eventually disappear behind a paywall!
And now, and I cite, 2008
"Best practice" among cage diving operations apparently consists in just teasing, but never actually handing any bait to the Sharks.
Were I a Shark hugger, I would immediately object that letting the Sharks waste precious energy on fruitless "hunts" is to be rejected as it is likely harmful to the animals.
And this example from the Coral Sea?
It's actually very similar: the paper reveals that the metabolism of those provisioned Whitetips increases by about 6.5% on feeding days compared to non-feeding ones, and that the according incremental energy expenditure is not likely to be offset by the feeding as the dominant Grey Reefies consume the bulk of the (calorically inferior) bait.

Click for detail!

Like I said, very interesting!
The authors postulate that even if the Whitetip Reefies were to compensate by hunting more, this would come at a cost to other activities like resting or reproduction, and that consequently, the Shark feed at Osprey is likely to negatively impact their health and fitness, albeit only minimally.
In fact, what is actually being bemoaned is that the Whitetips are NOT being fed but only inconvenienced and teased - think about those caged GWS dives where feeding is illegal, and draw the inevitable conclusions! :)

Not good, and certainly warranting further investigation!

And our own feed?
I'm not so concerned about the other Sharks as they don't usually rest during the day - but our Whitetip Reefies are certainly equally at risk. What however makes me slightly more optimistic, is that our visual observations indicate that they wake up and remain active for a far shorter time frame; and that contrary to Osprey where the operators dump the food, we do hand feed and have always made sure that all the Sharks get a fair share of the handouts.

But we will certainly investigate!
And on top of that, we will also consider handing them calorically superior food like maybe Sardines or the like!

To be continued - and do read the paper!

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