Do Bull Sharks have Friends? New Paper!

Spoiler: maybe yes maybe not!

Remember Mike's speculative hypothesis?

In brief, I opined that as their prey is comparatively scarce, evolution would select for large predatory Sharks to be solitary in order not to have to share their kills. 

But whereas that appears to be largely correct for Tigers and Whites, anecdotal evidence and some papers (and here) indicate that Bull Sharks appear to mostly travel in pairs or small groups, and I was eager to see whether our enormous data base could help shed further light on the issue. Yes our Shark feed is obviously an artificial aggregation - but I speculated that if certain individuals would preferentially turn up together, this might be a strong indicator that they might also be traveling together when not attending our dive.

The initial findings were promising.

The data showed some unequivocal, albeit rather weak long-term associations as illustrated e.g. in the following sociogram.

 

Sociogram depicting the social ties between individual bull sharks observed on the study site on ≥34 dives for the time period from 2011 (C). Only GAI values in the highest 30% were included to highlight the strongest associations between dyads, with thicker edges indicating higher GAIs for both individuals observed throughout the entire sampling period (red nodes), and individuals which were not observed throughout the entire sampling period (blue nodes) - click for detail.

 

Impressed? 

Me too, initially - but then came the crux with the bloody interpretation!

Did those Sharks really turn up together because they like each other? Or was it because their core ranges overlap with the Shark Reef Marine Reserve = they just happen to live in the vicinity? Or because they share some behavioral trait that makes them bolder/more curious/more opportunistic/weaker hunters = more prone to visit our feed? Or are they maybe the remnants of a cohort of siblings who stayed together in the river nursery and have traveled together ever since? Questions questions!

Short answer: who knows - which is kinda disappointing!

But, we now have a starting point.

Those numbers in the sociogram all correspond to known individual Sharks, and somebody could now invest some time into observing how they actually interact during the dive - and assuming that the visual observations confirm the initial evidence, one could then try and equip selected individuals with adequate sensors like cameras and/or say, business card tags to see what happens once the Sharks leave Shark Reef and/or take tissue samples to determine their relatedness, etc.

Yes that's a lot of work - but that's what we do, so keep watching this space!

Long story short, so far so good!

Enjoy the new paper! 

 

PS - Juerg here, courtesy of Tom.

IMO the semantics are a lot of splitting of hairs (= do we KNOW that they're not friends?), the more as I believe that some are, and that some (like Blunt and Maite) are very much the contrary - but then again who am I to say!

So thanks for the publicity, much appreciated!

PPS - another really nice piece here - well done!

Fiji Bull Sharks - Paper!

Yes those would be our samples - click for detail!

Remember?

 

That was then and alas, nothing much has come of it.

For some reason that eludes me, Christine never got around to actually publishing the relevant paper, and a later attempt at resuscitating the effort failed due to a general lack of interest and/or funding and/or time, or whatever. Plus I've been told that nowadays, the newest and shiniest tool for population studies is SNP markers and not anymore microsatellite DNA - and I'll most certainly leave it that, the more as that's about as much as I understand.

Or not - so correct me if I'm wrong.

Enter our indefatigable friend Kerstin!

She is now a newly minted, and highly deserving PhD - and the latest paper from her thesis once again confirms that the insular Bull Shark population from Fiji is genetically different, and likely closed = isolated from its continental counterparts. 

In essence, this means that our Bulls are truly unique and that they spend their whole life right here in the archipelago without ever engaging in large transoceanic migrations across deep water trenches and vast distances. And no, they also most definitely do not travel to Vanuatu and Australia for mating as was recently publicly proclaimed from the peak of Mount Stupid!

Obviously, this makes them specially precious but also, especially vulnerable - and Tashi's My Fiji Shark initiative, especially pertinent!

 

And the taxonomic consequences?

Years ago my ichthyological guru told me that a species is what a geneticist tells you it is - and very sadly and despite of my best efforts all the way to outright begging, the relevant Shark taxonomists remain firmly of the opinion that the present genetic distinction doesn't warrant declaring a new species. 

And when it comes to our Bulls at least being a possible (and I would add: obvious!) subspecies or race, I'm being told that apparently, in Shark taxonomy one just doesnt do that . 

Oh well - but we will keep on trying!

Anyway, great job!

Enjoy Kerstin's paper!

 

Oh and - please, Adopt Your Shark Now! 

Thank you.

 

GTs vs Sharksuckers - Paper!

 

Remember this post?

 

That was not the only observation by far.

This never before described novel hunting technique probably started as an attempt by a single innovative Giant Trevally, only to be quickly adopted by the the whole gang of miscreants. At its apex in late 2011, the 15m Take-out had become a veritable gauntlet, with dozens of GTs targeting the Sharksuckers whenever a Bull would come in for a feed. The Trevallies would wait in front of the feeder and then follow the Shark throughout the feeding area, only to then return to the starting point in order to intercept the next approaching Bull.

Of interest, not all caught Sharksuckers would perish as some would manage to latch on to the attacker,  only to then jump back onto a passing Bull Shark - click on the the pic at the top.

 

It however all ended at year end.

When the Bulls get ready for pupping and mating and are less interested in our bait, we relocate the feed to 25m where the topography is completely different and the trajectory of the feeding Bulls is much less predictable. And then most of the Bulls leave for 4-5 weeks, and the few who remain feed way less, thus further greatly reducing the predation opportunities of the GTs.

Whether it was the above and the Trevallies lost interest, or whether the individual Sharksucker-hunting GTs moved away or were fished: the fact is that we've never witnessed that behavior again.

But we had plenty of footage.

Here's a quick-&-dirty little iMovie edit of some memorable moments. Yeah I know the slo-mo kinda sucks - but you get the gist and I promise that I'll post something better later on.

And now Juerg has also written the paper - finally!

On top of the above story, it also describes other really interesting observations of Sharksuckers at Shark Reef and other Shark provisioning sites in Fiji.

Press release here, additional clips here.

Enjoy Juerg's paper!  

Fiji's Sharks in Peril - Paper!

Remember? It is still happening!

Well well - watch.

And this is the paper.

Shame that it's hidden behind a paywall, the more as it is being hailed as a major achievement which it quite possibly is - but I will leave that determination to others.

What however irritates me is the characterization of Fiji.

The press release has quite obviously been re-worded as the initial version stated that Fiji's Sharks are functionally extinct which is a load of horse manure -  but even after the redaction, we are still being flagged as being particularly problematic which is just not true.

Here's the corresponding graph - click for detail.

Seriously, WTF?

Fiji down at the bottom - and then e.g. Tonga of all places near the top? Lemme tell 'ya that having extensively dived, and lived in both countries, this is just wrong wrong wrong in so many ways - which obviously begs the question, may other data sets be equally faulty?

So what exactly happened?

Having consulted the relevant map for Fiji, I learn that having dropped 382 BRUVs on 14 sites, they only recorded 5 Shark and 7 Ray species, and this only on 28.7% of the videos which is perplexing to say the least. But having asked, it turns out that instead of tapping the available local capacity and know how, they decided to parachute in some dude from New Zealand who I hear may have only sampled the sites of a particular NGO and not a representative cross-section of Fiji's reef ecosystems - and if so I can certainly leave it at that. *

Now compare that fiasco to the data of the GFSC.

Or to the fact that in our little region alone, we harbor at least 10 frequently encountered Sharks = GHH and Zebra, plus our usual Bull, Tiger, Sicklefin Lemon, Tawny, Silvertip, plus Grey, Whitetip and Blacktip Reefies, with several other diving operators and also research papers reporting the same and even more, equally ubiquitous reef-associated species like Scalloped Hammers or Blacktips from many other locations.

And then there's the simply massive data set from the hundreds of  BRUV drops by Projects Abroad that had incidentally been initiated in collaboration with the very same Demian Chapman who is one of the paper's leading authors - surely one should have added those sightings, too?

And the data from Tonga?

They are from a grand total of 24 drops on two sites... see what I mean?

Anyway - it is what it is.

Whereas the situation here is most certainly not remotely as bad as depicted, there is equally clearly room for improvement, see e.g.this old assessment, Kerstin's papers here and especially here, and also the description of Fiji's Elasmobranch fishery here at page 188 ff.

In brief and despite of the reduction in the Asian demand for their fins, our Reef Sharks and the juvenile Sharks in the riverine nurseries are now increasingly being targeted as an alternative source of protein as many of the traditional food Fish stocks are being depleted.

And to top it off, we're now witnessing a massive Covid-19- induced increase of indiscriminate fishing and poaching that is  threatening years of conservation efforts and also indirectly threatening our Shark populations by obliterating their prey.

Talking of which, I really did like reading that

Without an absolute estimate of the abundance of sharks, it is difficult to know how effective the estimated levels of conservation potential might be in restoring shark populations in reef ecosystems that have been degraded by overfishing.

Although research has shown that fully recovered reef fish communities have biomasses between 1,000 kg ha−1 (ref. 27) and 1,500 kg ha−1 (ref. 12), we have no current estimate of the size of the forage base that is required by a recovered shark population, or how the bottom-up effects of prey biomass might influence the recovery potential of reef sharks.

A key question remains as to whether management strategies that only pursue shark conservation can make substantial or limited gains, relative to those that include the restoration of the wider reef ecosystem.

If the restoration of the whole ecosystem is necessary to fully restore shark populations, our results underscore the need for managers to engage with the wider social, economic and cultural drivers of marine exploitation.

Could not agree more!

Long story short, the paper is certainly welcome.

Far from being defeatist, the authors suggest several pathways for improvement that I can only second, albeit with the usual general caveats (= e.g. follow the links here).

The good news is that here in Fiji, there is already some progress, namely the fin ban, the CMM for Sharks by the WCPFC  (incidentally once again courtesy of the simply unequaled Shelley) and an upcoming, WWF-sponsored, long overdue NPOA (Sharks) that will provide a framework for subsequent regulations and pacify the FAO.

And then, hopefully, we will get The Big One.

No, likely not a Shark Sanctuary but instead this comprehensive regulation - and having checked, all appears to be on track for the December deadline at the end of this year!

In any case, we stand ready.

Thanks to Tashi Blue's boundless and also, infinitely endearing passion and commitment, her My Fiji Shark project has been able to accumulate a nice little war chest that will greatly help us assist with the implementation of the regulation.

So fingers crossed and yes, very much to be continued!

But I'm digressing as always.

Enjoy the Shark paper!

Oh and, Adopt your Shark now!

* PS - Demian informs me that there was no parachute science as the vast majority of drops was effected over several years by that local NGO - which obviously begs the question, what went wrong?

Wrong habitat/site selection? Lousy bait?

Anyway, it is what it is.

Selective Removal of Problem Sharks - Paper!

Click for detail!

Hah!

Remember this paper?

Now Eric et al have doubled down with this further publication that specifies possible techniques for first, a) establishing a data base of potential perpetrators and then, b) identifying and removing individual problem Sharks after they have attacked a person.

Well what can I say.

Like I've already stated here, I am absolutely convinced that problem individuals do indeed exist, much like what has been shown with large terrestrial predators. And I'm equally of the opinion that removing them selectively (whatever that means) would ultimately be vastly preferable over indiscriminate broadcast culling - though having said that, there are obviously other solutions (like eg hazing, etc) that would need to be exhausted beforehand!

But that's the theory.

In general terms I remain unconvinced that individual profiling and selective removal is a practicable solution for large geographical areas featuring thousands of potentially dangerous Sharks, like, say, the USA or Australia. There methinks that one will need to continue trying to reduce the risk and mitigate the consequences - but by the same token, one will have to accept that the odd Shark bite is ultimately just simply inevitable and part and parcel of coastal living.

And in comparatively small areas?

Interesting to see Cocos and Reunion mentioned in the paper!

I've said what I wanted to say about both situations back then and really got nothing to add - maybe with the exception that Reunion looks like an ideal testing ground, the more as there is already an adequate scientific infrastructure allowing for the proposed broadcast DNA sampling and visual identification. So by all means, go for it - tho bon courage trying to establish a feeding station like suggested! :)

Anyway, all very interesting indeed!

Knowing Eric, something is likely brewing - and if so, godspeed, Fair Winds and Following Seas and all!

To be continued no doubt!

 

GWS Clans at the Neptune Islands - Paper!

Very interesting!

Check this out.

Press release here, stories e.g. here and here.

In brief and assuming I understand this correctly, those GWS don't turn up randomly but appear to favor (and hence possibly travel with) determined buddies and even form distinct groups that appear to persist for years. Nice to see Johann, Charlie and Andrew among the authors, and kudos to GSD member Rodney Fox Shark Expeditions for having enabled yet another stellar paper - and incidentally, congrats for the great new boat! 

And here in Fiji?

Remember Mike's totally speculative hypothesis?

That was obviously several years ago, and today we know quite a bit more. Specifically, we have learned that although our dive has minor local impacts, effects at the ecosystem level remain negligible as our Bulls continue to roam and do neither get conditioned to coming ever more frequently, let alone residing here or changing their migrations or mating cycles, etc; nor do they in any way become dependent on our handouts - tho I was certainly wrong when speculating about the nutritional value of the Tuna heads! But be it as it may, the restaurant analogy remains fully confirmed.

And the part about the Bulls likely being solitary?
I still believe that in the case of those large reef-dwelling Sharks, and barring any cooperative hunting for which we have zero evidence, evolution would have selected against traveling with, and thus having to compete and/or possibly even share meals with conspecifics.

But then again, who am I to say.

I can't divulge too much - but I can say that 10 years after that post, we are finally about to reveal some conclusive evidence!

Fiji Time anybody? You betcha! :)

So keep watching this space.

To be continued!

Stegostoma tigrinum?

The sandy morph of S. tigrinum: transitional (A–D) and adult (E–H). Close up of the skin pattern on the right lateral flank of a transitional specimen (B–C) and of remnants of the transitional pattern on flank and caudal-fin tip of adults (F–G). Click for detail.

Oh well

After the demotion of the Manta Rays, now this.

Looks like they've changed the species name of the mimic Zebra Shark. I first thought it was just a bad joke - but having asked my Zebra Shark guru, she replies,

Yes. I reviewed it as did Will White. 
They did a pretty thorough job with the taxonomy, though whether it’s worth changing the species name is open to debate me thinks.

Methinks, too.

But then again, they really did do a thorough job so this may indeed be it.

But see for yourselves.

Le fasciatum est mort - vive le tigrinum!

 

High Seas: Sharks vs Fishing - Epic Paper!

Posted with kind permission - thank you! Click for detail!

Behold!

Story here, here and here!

This is really beyond phenomenal - especially the tracks!
Just look at the GIF at the top - I mean, seriously, how bloody awesome is that!

Philopatry anybody? 

And the overlap with the fishing fleets?

Having spent countless hours looking for birds when trolling offshore, I know all too well that the prey is not distributed evenly but instead comes in patches, and that consequently, predators converge - and it only stands to reason that as we are supplanting the Sharks as the top predators on the high seas, their footprints will increasingly overlap with that of our commercial fleets, leading to high mortality rates both due to targeted Shark fishing but very much also due to (more or less) unvoluntary bycatch - see this rather recent report about the status of pelagic Elasmobranchs in the SoPac.

Earlier papers e.g. here and here - and here is also an important paper describing the grotesque irony of those fisheries being increasingly unprofitable, story here.

Anyway, huge kudos to Nuno and David - this has truly been a titatic endeavor!

Solutions?

Possibly the postulated well-placed (and well-enforced!) pelagic MPAs but that sure ain't gonna be easy (and here!) - and read this about the need to better identify, and then include those few remaining marine predator refuges! And what about the continued Climate Change-induced poleward shifts (and here!): shift accordingly?

Detail detail! :)

Yeah I know I know.

That's a lot of links - but they are simply a must as things are complicated!

Enjoy the paper and the links!
 

Two Years of Strap - Field Note!

2016-2018 - click for detail!

Remember that poor Shark back then in 2016?

We named her Strap and have kept tabs ever since.

And here comes the according Field Note documenting the initial worsening and then, thankfully, improvement in her situation all the way to the point where the strap did eventually burst and has since mostly fallen off .

My personal take-away?
First and foremost, this once again proves the value of our continuous long term monitoring where our humongous data base is documenting over 15 years of Shark diving and the life history of a whopping 250 individual Sharks!

And boy talk about being tough!

During the course of the whole ordeal, she never appeared to be particularly inconvenienced and  instead maintained her agility and continued to compete successfully during the aerial feeds. In fact I fully expect her to completely heal to the point where she will shortly look similar to Gillette who only upon very close inspection appears to have survived a very similar incident.

Intrigued?

Strap is up for adoption, so there - and don't forget to upgrade in order to receive your quarterly updates!

And because I can.
Here is the entire Field Note for your perusal - as always, great job by Juerg and for the first but certainly not last time, by Tashi Blue!

Please click for detail and, Enjoy!

White Sharks vs Sevengills - Paper!

First image of Sevengills on this blog = as always, great pic by Peter! Source.

Just in case you've missed it.
Watch.

I must say that I really like it.

Obviously, correlation is not causation so we'll never know 100% - but as somebody who has been equally documenting long-term changes in abundance that are likely partially due to competitive exclusion, I can only applaud the authors for advancing an astute and I believe highly plausible hypothesis.

But go see for yourselves.

Paper here, synopses here and e.g. here.

Enjoy!

Individual Shark Profiling? Yes and No!

Click for detail!

We're stuck inside waiting for Mona to unleash.

So there - have you seen this paper?

In essence and if I understand it correctly, it hypothesizes that Shark strikes are not a function of Shark density but that they are instead caused by specific individuals that are so disposed, e.g. possibly particularly bold  - and that as a consequence, the adequate management response would not consist in broadcast culling but that instead, one should surgically remove such problematic animals, much like what is being done with terrestrial problem predators.

And yes that person mentioned at the end would be yours truly.

So let me clarify where I really stand on this.

I agree with the hypothesis, albeit with caveats.

Ages ago, I penned this post about Shark strikes which I believe is still valid. In brief, the causes for Shark strikes are manifold =  whereas some of the interactions are due to predation or happen out of aggression and/or competition and/or self defense,  others are purely retaliatory or not at all driven by intention but simple mistakes (= NOT mistaken identity which is completely something else and  controversial) - and for these latter two categories, Eric's considerations probably would not apply. 

And anyway, for the large majority of cases, determining the specific intention of specific bites is obviously impossible and possibly also ultimately irrelevant.

But of course we can always speculate, see here.

And as somebody who has named, personally knows and spends an inordinate amount of time diving and interacting with individual Sharks and can thus observe their behavior, I can unequivocally confirm that they display great individual behavioral variability - and this very much including the propensity to bite!

In fact, among our Bull Sharks there is e.g. one particularly haughty lady who does not like to be touched and will always retaliate by trying to bite us when we do so; or there is another one, a small male, who despite of many years of hand feeding, appears just simply too stupid to understand the proper etiquette and always comes in too low and too fast, and is thus a constant safety risk to the feeders. Same-same for a specific Gray Reefie who has repeatedly bitten the hands of our feeders - and thank you for bodyguards and especially, for steel gloves!

And then there is XYZ (name withheld).

This is a very large female Bull Shark who can only be described as being sinister and dangerous, this insofar as she is extremely assertive, will frequently approach us closely and not in what we perceive as a friendly way, and needs to be fended away and dominated.
And one day, and I believe because she was cranky for having lost a dominance confrontation with another big female, she has already bitten one of our staff who was incidentally not in the slightest inconveniencing her; this in what I personally interpret as Übersprungverhalten or displacement behavior, or maybe simply the venting of accumulated aggression. Again, we will obviously never really know - but she is certainly an animal of concern.

And when it comes to those predatory strikes.
They are fundamentally different from the examples above as IMO predation = feeding got nothing to do with aggression and/or boldness, and why would it.
But I absolutely believe that some Sharks will sometimes target and consume a human; and I also absolutely believe that given what we know about their learning capabilities, ontogenetic dietary shifts and their individual behavioral variability, we can also absolutely not exclude that this or that individual may develop an individual propensity (or reduced aversion) for targeting humans, which is what Eric appears to postulate.
Yes this is obviously speculative and so far unproven (and likely untestable) - but it is I believe at least plausible - and as long as it is, and as long as it not actually disproven, it is also not false! 

And remember this shit? 

It mentions, and even depicts that ominous OWT who has been alleged to have bitten no less than three people - and this by so-called Shark experts in a so-called peer-reviewed scientific paper !

Anyway, back to Eric's paper.

Yes in theory, there could absolutely be individual Sharks with as propensity to bite humans; and yes in theory, selectively eliminating those would absolutely be preferable to indiscriminate culling!

So I absolutely support it as a theoretical approach to mitigating Shark strikes! 

And in practice?

Unfortunately, there prospects for success look totally unrealistic.
In terrestrial habitats, identifying, monitoring and managing individual animals is comparatively easy - but doing so in the ocean is obviously a completely different matter as the territory is immense, there are thousands of Sharks leading a life that is essentially cryptic as for human observers, everything happens "out of sight" - and thus, identifying, monitoring and then eliminating the individual perpetrators as suggested would generally speaking be extremely expensive and logistically extremely onerous if not outright impossible.
With that in mind, the suggested list of measures aimed at identifying problem individuals, albeit certainly erudite, is more pie in the sky than a viable recipe for success. Or should we e.g. really try and catch, tag and tissue sample every single large predatory Shark in Australia - and then try and catch a single individual perpetrator after a strike?

And, when, exactly, would one effect the removal.
After a first bite? After two or even more? Lethal bites or not? Or would one remove the Shark preemptively already upon identifying a problem in behavior, or e.g. undesired levels of testosterone or cortisol?
And before the removal, whatever the latter means, one should obviously first try other approaches akin to e.g.the hazing and/or other deterrents and/or protections and barriers one would be using in terrestrial situations - correct?

Detail detail!

But of course there could be exceptions.

Specific circumstances obviously vary, and there could be individual, albeit probably rare conditions favoring Eric's approach.

Examples?

The situation with our above-mentioned XYZ could e.g. escalate to the point whereby despite of our best efforts in trying to deter and/or train her, we would have to come to the conclusion that she is becoming too much of a safety hazard. 

Then, we could be forced to choose between either closing down our Shark viewing operation or selectively removing her.

Or take e.g. Cocos.

Remember that Tiger and then, this subsequent event?

Yes this is completely speculative - but considering how well the good people of GSD member Undersea Hunter Group know their Sharks: what if they were able to determine that it was the same, individually known individual? 

If so and considering the risk of further attacks vs the tourism income: could this maybe escalate to the point where the park authority would have to make a decision?

And finally, Reunion Island.

There, the comparatively small territory and likely comparatively small number of potentially dangerous Sharks that could thus be potentially identified individually may well warrant trialing Eric's approach - this particularly in view of the ever-persistent calls for more Shark culls!

Or not?

But again, these are rare exceptions.
In the overwhelming majority of cases, Eric's suggestions, albeit intellectually interesting, are just not sufficiently practicable for them to constitute a viable alternative strategy.
Alas!

And finally, what about this beauty?

I can only note that Neff the token Shark attack apologist remains as predictably irritating as always, the more as his arguments are little more than straw men.

• Yes the hypothesis by Victor Coppleson of there being "Rogue Sharks" has not been proven - but a) as per above, the fact that something has not been proven does not necessarily mean it is false, either and b) Eric expressly differentiates his hypothesis from it. 


• Yes as per above Eric's hypothesis does not apply to all Shark bites - but that does not invalidate it a priori!


• Yes often when asked, the public does not support Shark culls - but a) they continue to happen and b) more importantly, Eric does not at all advocate them but on the contrary, he very clearly and unequivocally sees his approach as an alternative to them!

Anyway, all very interesting indeed.

And in the meantime, Mona has come and gone. And we are doing just fine thank you.

Let's go Shark diving!

PS - Bingo...
PPS - Michael here - thanks!
 

Elusive White Sharks - Paper!

Still one of the very best: iconic image by Terry Goss - click for detail. Source.

Great stuff!

If you're into GWS, this is a must read.

Great job by Charlie in getting feedback from the quasi-totality of GWS researchers, which sure makes for an interesting assortment of names; great questions that  obviously also pertain, mutatis mutandis, to other Shark species;  and last but not least, great bibliography for further reading!

So well done folks, and thank you!

 

Enjoy!

Fishing for Sharks in Fiji - Paper!

Click for detail! 

How times change!

Remember Kerstin's master thesis and subsequent paper about coastal fishing in Fiji? 

Back then when she did her survey a mere five years ago, the data revealed that most caught Sharks were primarily being kept in order to sell the fins to the local bêche-de-mer traders who in turn would export them to Asia.

Not so nowadays.

Kerstin has once again interviewed dozens of fishermen all across Fiji and the news is not good. On top of discovering that indiscriminate overfishing and poaching have very unfortunately become ubiquitous, Shark fishing has fundamentally changed.

As the Asian demand, and thus the prices for the fins have crept ever lower, and as most middlemen have vanished due to the closure of the local bêche-de-mer trade, most caught Sharks are now being caught incidentally and consumed directly by the fishermen themselves. This is very much in line with international developments (and here! and here!) where as the prized Fish are being fished away, the once-eschewed Shark meat is increasingly being consumed as an alternate source of protein.

And where Sharks are still being targeted by small-scale commercial fishermen, it is for the local trade in the Fish markets where Shark meat is being sold as a cheap alternative to chicken and where you can buy a bundle of neonate Sharks for a fistful of dollars, but also in order to sell the fins directly to the local Asian restaurants.

This is obviously of concern.

Whereas trying to manage the fishery by monitoring the trade is comparatively easy, trying to monitor thousands of subsistence fishermen is not; and it is also of particular concern to us to discover that the fishermen are targeting the juveniles of Scalloped Hammerheads and especially Bull Sharks in the river nurseries, see the graph at the top.

Solutions?

Look no further than this commitment by Fiji at the 2017 UN Ocean Conference where I'm highly confident that good things will happen sooner rather than later. And when that eventuates, we will be standing ready to assist with the monitoring and enforcement like announced.

And yes: please Adopt Your Shark Now!

But I'm digressing as always.

Enjoy Kerstin's paper!

 

Rats and Coral Reefs - Paper!

Click for detail!

Very nice!

Remember the Mantas vs Coconut trees paper?

There, introduced Coconut trees were shown to reduce seabird abundance by being unsuitable as roosting and  nesting trees; here, this new paper examines the effects of invasive rats killing off seabird colonies in Chagos and shows that as a consequence, the biomass of Coral Reef communities adjacent to rat-infested islands is substantially smaller than next to rat-free islands.

Stories here and here.

Required reading - enjoy!

PS - Good job, poop!

 

Sharks in the Ba Estuary - Paper!

Love love love this pic - source!

Behold!

Nice job by Tom et al.

From what I gather, whereas the field research has been challenging, the paper has been a rather traumatic experience - and no, no need to elaborate, the more as the good news is that this finally completes Tom's master thesis and that consequently, he can now fully concentrate on his already impressive career as a conservation photographer and filmmaker. 

So big congrats Tom - in every sense!

And the Ba estuary?

Our own ongoing research suggests that it may well be more than a mere aggregation and parturition site, and confirms that it is certainly a place of great interest warranting protection - but  these things are complicated and take a lot of time, and bycatch mitigation and enforcement will always be a huge challenge, meaning that at present, I'm alas not terribly hopeful for the short term.  

But hope springs eternal, and we're certainly going to stay on it.

In the meantime, enjoy Tom's paper.

To be continued no doubt!

A Global Perspective on the Trophic Geography of Sharks - Paper!

Click for detail!

Awesome!

Read this. 

Yes that's a whole lot of authors, among which some people I like a lot = for once cooperation has been absolutely stellar and one has to congratulate Chris for having been able to pull this off, and for having laid the foundations for a global collective of researchers investigating Sharks by means of stable isotope analysis.

Press release here, report here.

And no, all is so clear and exhaustive that I really got nothing to add!

Kudos - very impressive indeed!
 

Breaching OWTs - Paper!

GSD member Epic Diving - best operator to dive with OWTs. Source.

Very nice!

Read this!

It is obviously not only about breaching OWTs, but the breach it describes is totally spectacular - story here. 

Yannis and Yuuki are quickly establishing themselves as the gurus of small multi-use electronic packages that can be temporarily affixed to the Sharks in varying configurations, and are thus able to help find answers to the most diverse scientific questions.

Way to go Team Predator!

Like always, very impressed.

Kudos!
 

Inverted Trophic Pyramids - Paper!

Watch.
 

And now, read this = very interesting!

And with all that evidence, it appears pretty conclusive that those infamous counter-intuitive inverted trophic pyramids do indeed exist.

And the examples at top?

Still not at all convinced, see this post - and I cite from the paper,

However, instances in which energy is exogenously sourced to create top-heaviness (e.g. from another time or another ecological space) present more opportunity for healthy debate.
If, for instance, we allow ourselves to view the operation of communities at non-traditionally ambitious spatial and temporal scales, many of these systems become less top-heavy – or not top-heavy at all. Top-heavy coral reef communities in which mobile consumers draw energy from neighbouring pelagic communities, for example, begin to look more Eltonian when the dynamics of multiple communities are viewed collectively. 
The underlying challenge is that by habit or necessity, the modus operandi of many ecologists is to survey the biomass contained within a community in a snapshot fashion – and such practices poorly acknowledge the spatially and temporally remote processes that shape community structure.

Bingo - exactly like I said!

Yes fished remote islands and atolls have less Sharks and big predators (because they have been fished away) and feature conventional trophic pyramids - but unless convinced of the contrary, I must insist that those pristine, unfished ones still don't feature those inverted trophic pyramids (read it!) - at least not permanently!

Anyway.

Enjoy the paper!

 

Reef Shark Competition - Paper!

Reeftop hunters: Blacktip Reefies. Fantastic image by Tom!

And talking of those Reefies.

Here's another great paper.

Assuming I understand it correctly, it illustrates how Grey and Blacktip Reefies segregate spatially and are thus able to partition their habitat and consequently, its resources = prey. 

Whereas I've always believed that the Greys would always outcompete the Blacktips based on size and aggression, the paper conclusively illustrates how the segregation is based on the the fact that each species derives a competitive advantage by being better adapted to specific spatial niches, i.e. the forereef for the Greys and the backreef and lagoon for the Blacktips - incidentally, much like is being illustrated at Shark Reef!

Once again, I'm impressed by the scope and the rigor.

Well done Yannis and Co - and impressive lineup, too! :)

Required reading - enjoy!

 

Shark-mediated Trophic Cascade in Fiji - Paper!

Reeftop predators: Blacktip Reefie and Bluefin Trevallies - great pic by Allen!

Nice!

Read this.

It illustrates how Reef Sharks influence the behavior of seaweed grazers and consequently, consistently influence the size and distribution of seaweed on the back reef of Votua, i.e. right in front of the iconic Eco Café, home of Fiji's very best wood-fired pizza, friendliest service and most beautiful smiles. 

 

  Click for detail!

Well done Doug and Mark.

I must really say that this is science at its best, with observations leading to questions and then a proper hypothesis that is being rigorously tested, exactly as it should be. What I also like, is that the authors refrain from unduly exaggerating and generalizing the role (and trophic ranking!) of Reef Sharks but instead attribute the cascading effects to the specific situation alone - again exactly as it should be.

Required reading - story here, nice synopsis here.

Enjoy!