Saturday, January 29, 2011

Shark Reef - the Bulls!

Fantastic pictures by Lill - click for detail!

Et voilà
- finally!
Here's the first research paper about our Bull Shark family!
Thankfully, Juerg has posted it on PLoS ONE, one of the open source journals and I can thus spare myself having to post any excerpts.
Just this.

Seasonal and Long-Term Changes in Relative Abundance of Bull Sharks from a Tourist Shark Feeding Site in Fiji

Juerg M. Brunnschweiler 1, Harald Baensch 2
1 ETH Zurich, Zurich, Switzerland, 2 Department of Biology, University of Nebraska at Kearney, Kearney, Nebraska, United States of America


Shark tourism has become increasingly popular, but remains controversial because of major concerns originating from the need of tour operators to use bait or chum to reliably attract sharks.
We used direct underwater sampling to document changes in bull shark relative abundance at the Shark Reef Marine Reserve, a shark feeding site in Fiji, and the reproductive cycle of the species in Fijian waters. Between 2003 and 2009, the total number of Carcharhinus leucas counted on each day ranged from 0 to 40. Whereas the number of C. leucas counted at the feeding site increased over the years, shark numbers decreased over the course of a calendar year with fewest animals counted in November.
Externally visible reproductive status information indicates that the species' seasonal departure from the feeding site may be related to reproductive activity.

Long-term trend in relative abundance of C. leucas at the Shark Reef Marine Reserve, Fiji between 2003 and 2009.

Great job - but of course, 40 Bulls is so yesterday!
Last year, we've already had way more and my prediction stands than one day in 2011, we'll finally reach three digits! So far, chances for that really look good: we're now averaging 35+ and have already identified a dozen or so newbies, among which several large mature females. To see them pop by for the first time in over ten years of feeding is really quite remarkable and a good indication that Fiji's Bull Shark population is healthy and thriving!

And a paltry sixty named Bulls?
Check out the list: we've now nearly got double that!

Dark grey bars denote the number of identified sharks at the beginning of the respective year; light grey bars denote the number of individuals added to the list during the respective year.

Long story short?
We're not even scratching the surface, and the future looks bright indeed!

Plus, there's this.
Our data base is very likely the most exhaustive documentation of any commercial Shark dive anywhere. We've started collecting data in 2003 and have accumulated approx. 2,000 sets that include a plethora of variables about weather conditions, numbers and species composition, inter- and intra-specific dominance, feeding behavior and much more. Consequently, this paper is but a first excerpt, with already several more in the works that will focus on the various species and very possibly, even on social and other interactions - including those between our feeders and the animals!

Once again, this illustrates the value of long term monitoring.
As my favorite biodiversity and conservation blogger CJA Bradshaw correctly remarks (please read the post!), good ecological data are ESSENTIAL to avoid some of the worst ravages of biodiversity loss over the coming decades and centuries. And I may add, this applies particularly to marine ecosystems and also, to Sharks! We are thankfully witnessing a global pro-Shark movement that has already led to the establishment of Shark Sanctuaries in Palau, the Maldives, Raja Ampat, Honduras, Hawaii and now the CNMI. Hopefully, they will achieve what they were designed to do, i.e.ensure the long term survival of those Shark stocks.
But although I am hopeful that they will, only time will tell - and we will only know if we establish baseline counts and set in place good monitoring systems!

Wouldn't this be is a great task for us in the industry?
We are the in many ways the gate keepers and should also be the stewards of those ecosystems that give us so much joy on top of providing for our sustenance. Plus, and contrary to both the researchers and the fisheries officials: we are always out there and thus best suited for collecting uninterrupted long term data sets.

Please think about it.
Yes it's tedious and yes we are busy - but as Bradshaw said, it really is essential!