Saturday, March 29, 2008

Science in Action!

Juerg is about to wrap up his first batch of experiments and I've asked him whether he could post a short summary of his endeavors.
Here we go:

"The Fiji Bull Shark Tagging Program is in its fifth season.

What started with a few pop-up satellite tags in 2004 is now a much broader research project aiming at understanding Bull Shark Behavior and Ecology. To summarize the first 2008 field season (January to March): it has been spectacular and highly satisfying!

We've collected lots and lots of data, done spectacular dives, the Sharks have been very well "behaved" and best of all: we learn more and more about these fascinating predators!

So far, we have deployed more than two dozens acoustic tags and a state-of-the-art miniaturized pop-up satellite tag.

Sharks equipped with Acoustic Tags will give us presence/absence data.
Whenever a tagged shark c
omes into detection range of a so called underwater listening station (receiver), it will be picked up and we will know what individual was there at what time of the day. Some of those tags also tell us the temperature inside the shark’s stomach - any guess what that could be?

The bulk of these tags has been hand-fed, mostly to Bull Sharks.
This is for sure the least invasive technique and Rusi has proven his usual mastery in ensuring that they were placed with the correct individual Sharks.
The downside of this technique is that the tags will only stay in for a few days to maybe a few weeks, but we are able to collect some very valuable data never the less.

In addition, we have attached a few acoustic tags externally and those will hopefully stay on the Sharks for much longer and keep us informed on how often and how long they visit Shark Reef and other reefs during the year.
For instance, we tagged Bumphead externally on February 23rd. That didn't seem to stress her at all and she hung around for a few days before going walkabout. Yesterday, she turned up with the tags still properly attached. Where did she go? Hopefully, the receivers placed on the other reefs will tell us.

But it certainly shows that most probably, the Bull Sharks do not spend all their time on Shark Reef but wander around, sometimes for weeks or even months at a time.

Here, Pop-up Satellite Tags could tell us more.
These tags collect temperature, depth and location data for a preset time interval. After that, the tags de
tach from the animal, float to the surface where they establish a link to a satellite to which they download the data - and we will eventually get an e-mail message ‘from the Shark’ telling us where it has been and what it has done!
Cool, isn’t it.

Well, of course it’s not quite that easy and and the data require a lot of analysis before we can safely say what has happened. But for sure, it’s exciting.
The satellite tag we have deployed this year is due to pop up sometimes next week.
So keep your fingers crossed that all goes well!

Besides these ‘technical’ approaches, we have also collected Observational Data, for example, who is feeding and how many times, who does not feed and just hangs out with its mates, plus how do the different shark species on Shark Reef interact with each other. Altogether, we are getting to know our beloved beasts better and better!

So next time you visit Shark Reef Marine Reserve, keep looking out for a tagged animal.
And enjoy the show!"

Thank you Juerg and Moce Mada!


Neutral Dive Gear said...

Hey! Terrific blog!

We'd like to add you to our blogroll... any chance at a reciprocal link?

Just let us know!

Keep diving!



Neutral Dive Gear said...

LOVE LOVE LOVE the pictures in this post, by the way.