Abundance and spatial Distribution of Reef-associated Sharks - Paper!

Shark Reef Marine Reserve: protecting the Sharks, their prey and their habitat! Great pic by Ozzie Sam!

And I cite.

Our study found shark abundance to be primarily driven by fish biomass amongst lower trophic levels and functional groups.

The importance of fish biomass in predicting shark abundance suggests the necessity of ecosystem level protection, involving all species and functional groups, rather than species-specific policies, such as shark sanctuaries, which might still permit on-going depletion of prey species.
Similarly, studies across a range of marine ecosystems have found that assemblages of top level predators such as sharks require both healthy environments in terms of prey availability, and a wide range of habitat zones to accommodate different species’ habitat preferences and to permit resource partitioning and ontogenetic changes in habitat use. Individual species or life stages preferentially use particular habitat zones or depth ranges, and, though often highly site-resident, reef shark species have been shown capable of making long movements between neighbouring reefs.

This implies that marine reserves that encompass a wide variety of habitats within the boundaries of the protected area may be more effective in preserving species diversity in the shark assemblage and providing the habitat niches required at different life stages. Very large MPAs such as the BMR, in contrast to more narrowly scoped or zoned protection regimes, have the additional advantage of protecting not only known and surveyed habitats but also the unknowns.

Bingo.

Like I've been stating for a while, e.g. here, we really need to shift away from the current narrow focus on species protection towards a much more holistic approach - and those mega-MPAs are an excellent way of achieving that aim.

Enjoy David and Jessica's paper!

Australia: Reef Shark mediated Trophic Cascade?

Competitors: Grey Reefies and Snappers. Source.

Well well.

Read this.

If I understand it correctly, it shows that several species of mesopredatory Snappers were doing great on reefs where (higher-ranking but equally mesopredatory) Reef Sharks were rare; but on reefs were Reef Sharks were abundant, the Sharks appear to have out-competed, or otherwise influenced the Snappers who had to shift their diet to less nutritious benthic invertebrates and were doing very poorly indeed as a consequence - synopsis here.

The conclusion being that

our findings suggest that overfishing of sharks has the potential to trigger trophic cascades on coral reefs and that further declines in shark populations globally should be prevented to protect ecosystem health.

Really?

Yes to the possibility of top-down effects - but if the Snappers' fitness was being adversely affected by the presence of Sharks, who, exactly, did benefit from it? Obviously not the Snappers - but also not the prey Fishes and Cephalopods that were still being killed; and also not the benthic invertebrates that were being killed on top of that.
So where is the evidence that Sharks help preserve ecosystem health = instead, is this not rather the negation of Healthy Reefs need Sharks?

Or am I missing something here?

PS: great comment by Michael in the comments section - thanks!
 

Whale Shark tourism in Ningaloo - Paper!

The strobe ban is baloney (and should be exchanged for a ban on self-promoting peroxide piranhas) - but other than that, this is excellent. Source - click for detail.
 

Wonderful!

Love love love the paper!

Great to see longterm monitoring much like we do here and has been done by Avi in Cocos! Also great to see that grouper challenge  winner Rob is being mentored by Shark tourism supremos Jessica and Mark. And finally, great to see yet another piece of evidence that when done correctly, Shark tourism does not harm either the animals or their environment!

This is obviously different, meaning that it is high time for the regulator to step in and step up - re-read this!

But I'm digressing.

Very well done!

Enjoy the paper!

Citizen Science is good Science!

Bingo.

Read this - and here is the paper!

Now we finally dispose of some powerful evidence that despite of many critical voices, citizen science really does work.

Of course we knew that already.

We've been employing trained observers to record data on Shark Reef since 2003, and those observations have been the backbone of many of Juerg's papers where they have complemented the data obtained via acoustic and satellite telemetry. In 2012, the concept has been expanded throughout the whole of Fiji where every six months, the majority of preeminent dive operators are participating in the Great Fiji Shark Count where they are counting Sharks, Rays and Turtles with their customers and passing on the data to the project team and ultimately, Christine. On top of that, Projects Abroad are now conducting such counts on every dive and uploading the data to eShark, meaning that Beqa Lagoon is now being monitored year-round.

And the results?

This is long term monitoring, and trends will only become visible over time - but when it comes to the Sharks, anecdotal evidence is already pointing to local declines. My hope is that we may well see an improvement once the authorities will have to increase their monitoring and management effort in line with the looming implementation of CITES.

We shall see.

But that's another story.

Congratulations to the indefatigable Gabe and the dream team from Western Australia for yet again an excellent job.

Bravo! 

Reef Sharks - new Papers!

Grey Reef aggregation - likely in Apataki's Trou aux Requins - stellar pic by Chip!

Great stuff!

This first paper is about Grey Reefies.

It's by the authors of the Fiji Shark tourism paper and really a nice piece of research - and kudos to Gabe on the first authorship!

Rather surprisingly, it caused quite a kerfuffle on Patric's blog - but as I said there, Patric's comments are a tad harsh, the more as that particular species is not a frequent target of the long liners. 

But the general gist, i.e. that publishing data about philopatry carries some inherent risks is of course correct. I did blog about it here and came to the conclusion that such data should be used for conservation and management purposes and only be shared widely if there is robust and above all, fully enforced local protection - something that certainly pertains to Palau, especially for the popular and highly visited stretch between Siae's and New Dropoff!

Nice re-cap here

And yes Patric - Palau lays east of the Philippines (not north, south or west)! 

And... ? :)

This paper is about Blacktip Reef Sharks.

Inter alia, this one is by the authors of that Lemon Shark paper who continue their observations and in-depth analysis of the Shark Population of French Polynesia as part of the ORP and CRIOBE.

It investigates the genetic makeup of the Blacktip population in several of those islands and describes that it is highly fragmented, meaning that gene flow (= Sharks traveling between populations) is low. The conclusion it draws is that in order to protect Sharks, it is better to establish Shark Sanctuaries rather than to try and protect them via MPAs.

Well, yes, that is certainly true in general - the bigger the better!

On the other hand, as a staunch lumper, I cringe at the recent trend of splitting everything. There are several ignominious examples from Avian, Amphibian and freshwater Fish taxonomy where the designation of many sub-species hast resulted in a plethora of tiny local populations, and subsequently, in the squandering of scarce public resources in the quest of preserving every single one of them - and this fatally reminds me of those occurrences. 

With Shark conservation being as difficult as it is, I'd be quite happy to see progress at the species-complex level - the more as otherwise, most of those tiny populations would succumb to the requirement of prioritizing one's resources by applying conservation triage!

But yes those Sanctuaries are great - at least for as long as Shark fishing remains so poorly managed!

And what about the implications for us here in Fiji?

The first one is that with such high residency levels, the Shark Corridor offers a substantial degree of protection much like in the case of our Bulls.

Other than that, we don't know - yet!

In Juerg's research, we've so far concentrated almost exclusively on the Bulls. But we have also recorded many observations about the other species, and our data base undoubtedly contains the answers to several of the same questions - that is, if somebody had the time to analyze them! But fear not, Juerg's next paper is already in the works, and it will contain much more info about the other species!

Of interest and contrary to all other Grey Reef aggregation sites I have visited, the SRMR harbors more males than females who however also appear more transient much like the Bulls and also leave for what we believe is the mating season in mid year. 

The Blacktips on the other hand appear to be very much resident, and it will be interesting to explore whether the females go walkabout to some nursery area like those in Moorea - which is highly likely as contrary to the Whitetips that appear to give birth in situ, we see zero small juveniles!

Anyway, I'm digressing as always.

Read the papers - it's great stuff, and kudos to the authors on a job well done!