GWS vs GWS - two!

Male GWS from the Neptunes with battle scars. In females, the scars could stem from either brawling or mating. Source.

Here we go again.

This is really highly disappointing.

DNS is usually strictly science-driven, with authors that know exactly what they are talking about. But alas, 5,000 dives or no 5,000 dives, Rocha is a Coral Fish guy, not a Shark behaviorist - and it sure shows, along with the fact that like many of his peers, he appears to be against Shark provisioning without having bothered to engage in even the most basic due diligence.

So there.

The Neptune Islands feature a natural GWS aggregation, meaning that the operators did not in any way cause it. Actually, they relocated to there from their initial site at Dangerous Reef once it became clear that GWS sightings at the Neptunes were more regular, numerous and predictable.

Read this - bravo Andrew and once again, no thanks to Barry Bruce whose unfortunate papers are now continuously being abused by the anti-feeding faction!

Anyway.

When the GWS reach those islands, they  sometimes brawl.

They are from two genetically distinct populations and likely do this in order to establish and re-affirm rank. Those confrontations are usually ritualized but can become combative. This behavior is species specific: the same happens in Guadalupe, another natural GWS aggregation, and e.g. the same is being reported from brawling Sicklefin Lemons at Moorea where provisioning has however created an aggregation that is not natural but instead man-made.

Conversely, although we observe the exact same hierarchical confrontations among our Bulls when they come back in January, in this species, dominance is being asserted by posturing and not brawling and therefore, we observe no intra-specific bites other than extremely rare genuine mistakes.

Back to the GWS.

Those confrontations are likely to happen where- and whenever GWS aggregate, and this specifically whenever new arrivals upset the established order - but it stands to reason that we are much more likely to observe them at those commercial sites and not out there in the wilderness, and hence those images, so far, stem from there. 

Do I need to elaborate?

Case in point, this recent video that is equally from the Neptunes.

See? No competition over food but same bite and same tail slapping etc - and remember Howard's video, equally from the Neptunes, equally featuring tail slapping and equally happening away from any bait?

Yes that would be evidence - and Rocha's conviction?

That this “brutal battle” wouldn’t have happened without human intervention and that the correct description of that video would be “Shark feeding by humans causes sharks to attack each other”; “Endangered species of shark forced into battle by human feeding"?

Nothing but the usual unsubstantiated anti-feeding claptrap!

Like I said, highly disappointing!

Sutor ne supra crepidam!

Guadalupe Great Whites - Paper!

Location data for the four satellite-linked radio-telemetry-tagged female white sharks during the pupping phase.

Epic!

Read the paper!

No I'm not going to write a synopsis as it is open access, short, incredibly interesting and informative, and crystal clear insofar as it does not contain any obscure scientific lingo - and anybody ever wanting to talk about Great Whites needs to have read it!
Yes, female GWS follow a two-year breeding and migration cycle, something no PAT tag has ever been able to document!

And, there is this.

Jorgensen et al. have proposed an alternative life-history hypothesis that is contradictory to the hypothesis proposed by Domeier. The major difference between these hypotheses pertains to the timing and location of mating. Jorgensen et al. speculated that white sharks are mating during their offshore phase, whereas Domeier proposed that mating occurs during seasonal, near-shore, adult aggregations...

The offshore-mating hypothesis is based upon the conjecture that a described vertical-diving pattern (rapid oscillatory diving (ROD)) is a result of a lek-like mating behavior in the core of the SOFA. This interpretation is problematic from several perspectives. Lek-like mating systems involve the gathering of males at a traditional site for the purpose of ritualized courtship display. The males compete for the attention of females, and in turn, the females select a specific male for mating. Although the peak in ROD behavior, and thus presumed offshore mating, occurs during June/July in a period when the distribution of males temporarily constricts, even the constricted offshore space is vast (estimated to be about 64,000 km²). Lek-like mating would require the males to be in a very small space to allow females to observe the courtship of several males at once. No electronic-tag data have ever indicated that sharks are densely populating a small, traditional offshore site. Lek-like mating systems have been described for some species of fish, but leks have never been seen among elasmobranchs. Females that mate in lek systems select a single male deemed superior to other males, thus the fact that white-shark pups from a single litter tested positive for multiple paternity argues against lek-like mating for this species. 

It is challenging to ascribe any behavior to vertical movement data in the absence of visual observations. The seasonal constriction of the SOFA and the ROD-type diving pattern could be due to the pursuit of a seasonally available prey. An expedition to this region during the constriction identified the presence of three species of spawning squid and sperm whales, but again, the absence of behavioral observations deems it impractical to assign any cause to the ROD diving pattern. Diving patterns and mating systems aside, there are other strong arguments against the hypothesis that white sharks are mating during the offshore phase of their migratory pattern. First, electronic-tag data indicate that males and females are largely segregated during the offshore period, and second, the proposed mating during June/July would equate to December/January pupping (accepting the 18-month gestation estimate). Females arrive at adult aggregation sites approximately in September, and depart in December to end of February. No YOY have been seen at the adult aggregation sites, no obviously pregnant females have been sighted at GI, and pupping is known to occur approximately April through July.

Bingo!

I really had to laugh out loud - remember?

Basically exactly what i said - which begs the question, does the man read my posts? What I did not know was the fact about multiple paternity - the exact opposite of what would be expected in lek mating!

Eat that, Sal!

Anyway.

Bravo Michael Domeier and Nicole Nasby-Lucas - this is truly seminal stuff. And, thank you for the chapter about conservation concerns! 

And I repeat: read it!

And now, watch this.

Right.

Looks like the bunch of dipshits with an opinion and a keyboard has spawned a dipshit with an opinion and a camera who is now publicly spouting the usual moronic rubbish all the way to having the audacity to post that picture of Junior! 

All so pathetically SvS.

But fear not, I'm not gonna dwell on the latter. 

As per Patric's update and after now many weeks of him having produced zero, zilch, nana da nada evidence for his assertions, I'm done with the man and his verbose excretions!

Anyway.

Does that mean that I now endorse SPOT tags?

It depends!

Research does not consist in slapping on some tags in order to then look at what happens - the scientific method demands that one formulate a (plausible - see the lekking fiasco!) hypothesis and then test it, for which one needs to employ the adequate tools.

So IF the hypothesis requires gathering multi-year data about a species that conducts large migrations and IF the animal comes to the surface frequently which is necessary for up-linking to the satellite, and IF the questions being asked are important, then I absolutely support deploying SPOT tags!

As I said here, research about philopatry is vitally important for conservation purposes!

Example?

The GWS that aggregate and regale the cage divers at the Neptunes are likely to be among the very same animals that munch on unsuspecting aquatic recreationists in Western Australia, quite possibly in tandem with GWS that travel there from SA.

Both hypotheses have already been validated by PAT tagging tracks, and possibly even via acoustic tagging - but we still don't have the full picture insofar as we don't know where they mate, where they pup (or do we?) and why, exactly, they and some of the SA GWS travel to WA.

That is simply vital information if we ever want to understand and then address and manage the mess in WA and protect those Sharks - and of course the people!

And how would one go about in gathering that info?

Assuming (which is not a given!) that the females of that Australian population follow the same 2-year cycle as those from Guadalupe, then SPOT tags would be the ideal tool, vastly superior to PAT tags that do not have that longevity! The ideal tagging location would be the Neptunes where the Sharks aggregate, and the operators there should really consider inviting a knowledgeable GWS researcher - out of intellectual curiosity but also very much in order to safeguard their assets!

But not Fischer's wandering circus!

I dislike the man but that's obviously not the issue.

The issue is that by today's standards, his methods are unnecessarily invasive. Domeier has proven that very large GWS can be caught and then tagged whist submerged; and he has also developed a cradle for the tags whereby there is only one single attachment bolt, thus greatly reducing the risk of fin damage. 

Is that perfect?

Certainly not - but it's a great improvement and in view of the importance of finally gathering the necessary information about that population, I for one could personally live with some possibly warped or shredded fins. But I would not publish any tracks - at least not at this time of public pressure and according political brinkmanship in WA. Imagine the fiasco of showcasing the Sharks' real-time location, only to have one executed by some overly zealous government bureaucrat - highly unlikely but why take that risk!

But I'm digressing as always.

All I really wanted to say is, epic and congrats!

Read the paper!

Spatial Behavior in Elasmobranchs - Papers!

OCEARCH tracks in SA - so far, highly ambiguous!

Interesting!

I've been remiss in not posting about several new papers.

This one by, among others, (the proudly left-brained, and obstinate) Michelle Wcisel, describes the movements of GWS in the Dyer Island and Geyser Rock system near Gansbaai and observes that they differ substantially from the GWS movements in Mossel Bay. As a possible explanation, it observes that the former Sharks are largely sub-adult to adult (= seasonal hunters of Mammals ) whereas the Mossel Bay Sharks are predominantly juveniles that feed predominantly on bony Fishes and Cephalopods.

Offical synopsis and great infographic here.

This one examines the abundance and sexual composition of GWS in Gansbaai in relation to the season and ENSO, and comes to the conclusion that females appear to favor warmer water whereas males do the opposite, possibly owing to competitive exclusion by the larger female conspecifics.

And this one by, among others, Tiger Shark supremo Yannis Papastamatiou describes the movement patterns of Reef Mantas at Palmyra Atoll with its two immediately adjacent lagoons. Whereas most Mantas in one lagoon alternate between lagoonal and offshore habitats, those in the other lagoon appear to be much more resident, possibly owing to the different hydrology and/or capacity of the lagoons to provide for adequate nourishment.

And the take-away message of it all?

What once again strikes me in all those papers, is how behavior is being mediated by the environment (= climate, geography, habitat but also occurrence and/or migration of prey etc) but also by factors like gender, age and of course, individuality - and this all within one and the same species!

And if Michelle and Yannis can show significant variance across the smallest of geographical areas, and this within one single population - isn't it only logical to expect even bigger differences between distinct populations that are completely separated both genetically and geographically?

Definitely a big yes for Tiger Sharks - and the GWS?

Even discounting the Fischer factor, it seems to me that all those many comments about those tagged GWS are tacitly assuming that all GWS must necessarily follow a life cycle that is analogous, if not identical to what has been documented by Domeier for the Guadalupe population.

But with the above in mind, is that even plausible?

Take the Atlantic.

Its hydrology (think: Gulf Stream), climate and fauna are very different from that of the Eastern Pacific. Other large Sharks like Great Hammers and Tigers have been shown to migrate smack into the middle of the Atlantic, quite possibly following prey - so why not some of those GWS. Other, possibly younger GWS could be following the Bluefin into the Gulf. Consequently, the overall picture is much more ambiguous - incidentally, much like in South Africa with its ENSO-mediated interplay between the Benguela and the Agulhas!

Australia?

There are two genetically distinct GWS populations that both migrate to the Neptunes where they intermingle as they prey on Pinnipeds - meaning that barring the discovery of some highly sophisticated reproductive isolation mechanism, one would have to assume that they mate completely elsewhere. And if so, this would be very different from what is being postulated for Lupe where the Pinniped colony appears to act as a focal point for mating!

Or the Mediterannean GWS.
Much more restricted habitat and quasi absence of Pinnipeds owing to the extirpation of the Monk Seal - surely this must have big effects on both their diet and migration!

Long story short?

We should really refrain from resorting to those very broad generalizations when describing the behavior of those different Sharks. Instead, let's stick to the evidence that keeps reminding us that things are complicated!

Agree?

Big GWS in Asia - Paper!

Geographical extent and size distribution of white shark observations. Color legend for country of observation occurrence applies to entire figure. A) Approximate location of observation or landing for individual white sharks. Circles on land indicate observations that only reported country of landing. Annual average sea surface temperature is indicated by color gradient. B) Percentage of white shark observations by country landed. C) Size of white shark observed by country landed (top two panels) and as a percent of all observations (bottom panel). Note–the Philippines observations did not have an associated animal size. 
Click for detail!

Great stuff!

Finally, somebody is describing those sightings from Asia.

It looks like the NW Pacific harbors its own distinct population of GWS, and it appears that Japan may be an aggregation site for large adults much like Lupe or the Neptunes, whereas geographically widespread sightings of subadults suggest that there may be multiple nurseries.

And, a female from the East China Sea measuring a whopping 6.02m is the largest ever reliably measured GWS anywhere, with an enormous individual from Taiwan reputedly even larger!

But check it out for yourselves.

Thankfully, the paper is open source, and it is brimming with interesting information.

Enjoy!

More about the Cage diving Paper!

Source.

I knew it!

Shark Alley could not have come soon enough!

Case in point, this latest post - LOVE the title! :)

It takes a look at Barry Bruce's latest paper on cage diving at the Neptunes, and where my post on the matter was always gonna be limited by the fact that I'm at best a more or less educated naturalist ignoramus, it is quite obvious that Megalobomb brings to the table scientific rigor and a wealth of hands-on experience in Shark research in general and in working with GWS in particular.

So, again, bravo!

GREAT that within the mix of Shark blogs, there's now one more that says it as it is whilst being backed by fact rather than agendas!

Keep them coming Megalobomb!

Fischer - Australia next?

Best pals, all smiles in Cape Cod - for now! Source.

Bingo.

And I cite.

You also have a history of secretly obtaining research permits without proper public consultation and awareness, and of then barging in on commercial GWS diving sites whilst disregarding the concerns of the local shark diving operators - and from what I hear, you are attempting to do the same right now in Australia. 

As a fellow Shark diving operator I cannot but disapprove of that MO. 
If you're so convinced of the validity of what you do, you should at least be willing to engage with all stakeholders, defend your POV and adapt your procedures in order to address any valid concerns.

And now - watch this.

Crafty crafty Mr. Fischer.

Playing to the fears of Shark attacks by claiming that he's there to make the beaches safer, and trying to use that to put pressure on the Ozzie federal and state governments by using the Australian media to harness public support. And playing the teary Shark savior card (oh how he suffers for the Sharks!) by suggesting that those GWS are about to go extinct, a fact that is not at all supported by the data - not in California, very likely not in Australia and especially not in Cape Cod!

Will the ploy work?

For now, neither the governments nor any reputable local researchers let alone the local Shark diving operators that ply their trade in the Neptunes want anything to do with him - and rightly so. By today's standards, the protocols are too invasive meaning that if so wanted, the same data can now be collected equally successfully but with far less stress on the animals and less damage to their fins - and without having to suffer through all that media circus and the bombastic self promotion, let alone the inevitable shit storm by the frothy anti-OCEARCH brigades!

But this is certainly not he last we will hear of it.

Fischer is an accomplished manipulator and not likely to give up anytime soon, the more as he disposes of some impressive assets and always manages to find some researcher to lend him credibility and support, at least temporarily - and then, they start believing the whole marketing spiel, get enamored with the media exposure and one's perceived importance and get badly burned in the process. Once the ego gets stoked, brain cells appear to wither, and now that Skomal is the new darling of Discovery, the path towards self destruction by implosion is all but guaranteed.

Seen it before many a time.

We now know the truth about Domeier, but it would be really interesting to hear what Fischer's other various past scientific collaborators from the back-stabbing Klimley to Johnson and Kock have to say now that the media circus has moved on!

Still happy and proud about the association? 

Is Fischer continuing to fund years of Shark research in SA as promised?

And where are those dozens upon dozens of announced seminal papers?

Questions questions!

To be continued no doubt!

White Shark Cage Operations - bad for the Sharks?

Ozzie Sam at the Neptune Islands - pic, obviously, by somebody else! Or not? Sam?

Here we go again.

Barry Bruce et al have recently published three papers on the GWS operations at the Neptune Islands.

• This one describes that the GWS aggregate around the berleying (= chumming) sites on small spatial and temporal scales but that they still roam locally and then depart for long trips to other locations in Southern and Western Australia in line with "normal" behavior for this population of GWS.

• This one describes an increase of numbers, and behavioral effects meaning that the GWS show increased residency, duration of visits and shallower swimming patterns, but that they may also become habituated to the berley and teaser bait, much like already mentioned here. All those findings however show high variability among individuals, with different residency pattern between "transients" and "temporary residents", and different individual behavior patterns when on site.

• This latest one basically summarizes the findings of the previous ones and also mentions that Shark activity varies seasonally but also in between years, the latter likely linked (that is me speculating) to the massive climatic variations of ENSO.

Barry is an excellent researcher and his findings are undoubtedly correct.

They are also not at all surprising because they just show that what the operators do in order to attract and showcase the Sharks does work.
In essence, they confirm the central statement of Juerg's paper that chumming and food provisioning are unlikely to fundamentally change movement patterns at large spatial and temporal scales, and seem to only have a minor impact on the behaviour of large predatory sharks; hence, the creation of behavioural effects at the ecosystem level seems unlikely.

Which brings me straight over to the conclusions.

With all due respect for Bruce who's certainly a good man, I once again find them highly irritating!
There is an all-pervading undertone of, for lack of a better description, don't upset the natural course of things which is rather ridiculous considering the REAL threats facing Sharks and the fact that actually,  the natural course of things and wilderness are alas very much concepts from the past.
The consequence of that mindset appears to be a frustrating unwillingness to look at positives but instead engage in unsubstantiated negative speculation that ultimately discredits the great work by the Shark diving operators, has led to unwelcome intervention by the authorities and has even been used by our detractors to further their anti-industry agendas.

Not good.

But let's look at some of the details.

The increase in numbers.

In essence, the results confirm Juerg's findings about our Bull Sharks, this however possibly with one crucial difference: whereas it is undoubtedly so that the increase in our Bull Shark sightings is a direct result of our provisioning, the Neptune Islands operation follows the global pattern whereby GWS cage dive operations are being set up where GWS already aggregate naturally - and as a consequence, the increase in numbers is more likely to be the result of a general increase of Australian GWS numbers (and those of their prey!) after their protection in the late 90ies.

The researchers state that

An increase in shark sightings at the North Neptune Islands would be consistent with an increase in population size in response to the species protection in Australian waters in the late 1990s (Malcolm et al. 2001); however, there are currently no effective population metrics in Australian waters from which to assess population trends or status. The lack of available measures of population size combined with these interannual variations makes it difficult to conclude population-level changes in abundance from these data.

Well, yes, maybe.

How about if the new Sharks were principally sub-adults and young adults? Would that not be a strong indication that 20-odd years of protection are showing an effect?

This is incredibly important - not only with regards to assessing the impacts of Shark chumming at the Neptune Islands, but also in order to better assess the current mess in Western Australia and mutatis mutandis, the necessity (or more likely not) of increased GWS protection in California!
Yes it is of course fraught with political conundrums as a population increase could eventually mandate a relaxing of conservation measures - but does that mean that researchers should dodge the issue and  risk reaching the wrong conclusions, as quite possibly in the present case?

Other than that, there are concerns that increased numbers (and residency) may lead to over-exploitation of local natural resources and possibly, to more brawling.   
But is that really the case?

Well yes, maybe.
But so far, this is unsubstantiated speculation - tho eminently testable!

But then again, assuming that the Neptunes are a mating site, would higher numbers not also lead to increased chances of mating due to the presence of more potential partners?
Retracted - they are NOT a mating site!

Local behavioral changes

Yes, like here in Fiji, they definitely happen - and so what?

The concern of the researchers is that the change in residency, diel patterns, and their local aggregation at the chumming sites may either harm the Sharks by preventing them from engaging in sufficient predation (but see above - so which is the risk, too much or too little?), or harm the environment at large by subtracting the Sharks and thus preventing them from fulfilling their natural functions there.  
But is that really the case?

Well yes, maybe.
But so far, this is unsubstantiated speculation - tho eminently testable!

And even if so, there is large individual variance meaning that these effects are certainly not relevant at the population level; and the remarks about habituation also signify that the effects are not long term as the Sharks catch on to the fact that they are being duped and eventually stop bothering.

Provisioning.

The papers appear to consider this the ultimate sin.

The reasoning is that allowing the Sharks to feed on the bait would provide them with food that is possibly calorically inferior to the pinnipeds they are supposed to target.

So lemme get this right.

Attracting the Sharks with chum and inducing them to waste time and energy on fruitless "hunts" where they get zero reward is apparently unproblematic - but compensating them for the caloric losses with at least some food is a big no-no?

With all due respect, this is just simply ludicrous!

Long story short?

This is valuable and important research - but I just don't like the gist of it.

Like many (but by no means all - and here!) of his colleagues, Barry appears to be of the general opinion that Shark diving operations are somehow bad because they somehow mess with nature.

In fact a more favorable interpretation of the results of his research may have come to the conclusion that the cage diving operations at the Neptune Islands trigger no fundamental changes at large spatial and temporal scales, that there are no fundamental effects at the population level and that effects at small temporal and spatial scales are likely small and so far unsubstantiated.

In essence, it's about whether the glass is half full or half empty.

Yes it's a matter of interpretation - but with every new paper getting published on the subject, the evidence is increasing that the immediate local effects of chumming and even provisioning are, if at all, very small indeed whereas the effects on the Sharks' life history are quite definitely negligible.

But of course that's only the strictly scientific aspect of the equation.

A more holistic view of Shark diving reveals important economic benefits whereby the industry generates multiples in renewable, sustainable local income when compared to the alternative of fishing. Although I remain somewhat skeptical of the positive effects of caged diving that showcase excited toothy macro predators at their very worst behavior and may consequently appeal more to the adrenaline junkies, it is also a fact that (cageless) Shark diving does create Shark advocates.

The above are important drivers of Shark conservation and in fact, the protection of the GWS in Australia is in large part the result of the incessant advocacy of GWS pioneers Rodney and Andrew Fox, and of Ron and Valerie after whom the Neptune Islands MPA has been named.

Barry Bruce of course knows that.

He is a frequent guest on Andrew's boat who provides help both logistically but also in terms of actual research via his and his father's foundation, and I would have hoped for some more empathy for the situation of the operators and solidarity in exchange?

It's not about changing research results - that would of course be totally uncalled for.

It's about a more positive interpretation - and why not engage in some research in order to at least substantiate one's reservations before concentrating on possible negative aspects and publishing recommendations that substantially impinge on the Shark diving operations!

And in general terms, why not look at that glass again.

It is not half empty - it is three quarters full, and the contents are pure unadulterated goodness!

No disrespect - just my opinion!

Baited Shark Dives and Shark Attacks?

Outright Shark feeding - even worse than chumming?

Oh well.
So much for being too busy to blog.

There has been a Shark strike in Western Australia.
From what I can discern, it very much appears to have been a predatory attack (Christopher???) and it comes right on the heels of Mr. Moore's decision to preemptively ban cage diving there. The apparent reason for that politically motivated stupidity was that South Australia had restricted cage diving there because Barry Bruce et al had discerned that berleying (= chumming) had caused a minimal change in GW distribution.
Nothing whatsoever to do with Shark attacks - but who gives a shit provided that one can engage in populist grandstanding, right? And this? Indeed: Neanderthal reactions!

Which brings me straight to the following.
I rather despise those couch farting Shark lists - but people do keep me in the loop about the rare noteworthy discussions; and so I got sent this remarkable, and provided that you got a sense of humor, incredibly witty post by the Grand Mufti of Shark behavior, non other than the forever unequaled Doc.
I hope he doesn't mind me re-posting it verbatim in all of its glory.

A key criticism of the ruling in Western Australia is that researchers were not able to show a causal link between shark attack and chumming at shark dives. Lets see how they might prove such a link using the scientific method. How about setting up two dive sites within say 5 km of each other. At one you use chum and feed the sharks from a feeding tube or box. At the other you attract sharks by low frequency sound attraction and again feed shark from some device that precludes odorant from getting to the test-beach 5 km distant.

Now if there are sharks around I wager they will very quickly be attracted to the baiting station due to currents which rapidly brings the olfactants to their nostrils---so you might get them trained up in just a few days. For the acoustic attractions the sharks have to be within about 500 m of the hydrophone and be fairly motivated at the time. This might take several months but eventually the sharks at both sites will be feeding regularly, and reliably but probably seasonally.

To be further certain about your experimental study population you would have to tag the sharks and possibly take genetic samples to be sure you are working with different animals at the two sites...ok it could be done. Thus you have established two relatively equal feeding sites with a control and a treatment trial....good!

So after about two years of preparations you can now set up an hypothesis: H0, the null hypothesis is that there is no statistical difference between the control and treatment groups with respect to shark attacks; H1 is the proof of the pudding---There is a statistical difference between the two.

Ahhh, but here's the rub: You would of course have to continue your trials until you collect and adequate sample size for your appropriate statistical tests that you would used to either accept or reject H1 or H0. Based only on the annual rate of shark attacks world wide, this will take on the order of 1,000 years depending on the seasonality of the sharks. Considering the paucity of attacks and the time required for a human generation, you should put in your will that for the next 50 generations your offspring must continue the experiment on a daily basis until each season ends, then start again next year when the season begins. Get my drift? So it goes for all such shark-attack research.

OK...I put it up there now you shoot it down. I personally would love to understand the motivation of why sharks bite naked apes. (see Gruber, S.H. 1988. Why do sharks attack humans? Naval Research Review 40(1):2-19.)

Bingo! :)
As I've said all along, those musings about Shark attacks amount to nothing more than conjecture, i.e. sometimes plausible but ultimately untestable hypotheses.

But is the whole story?
Is there really no evidence whatsoever to point us one way or the other?

I believe that in fact, there is.
Yes George the great doyen of Sesselfurzing should indeed finally creep out from behind his desk and have a reality check by doing a couple of Shark dives; but in this specific specific case, he may even be useful by staying right where he is, smack in the middle of his Sammelsurium of Shark attack data - and ditto for Collier!

What I'm suggesting is this.
Get a Masters student to mine those data and to analyze whether globally, there is any statistically relevant correlation between the location of Shark strikes and that of baited Shark dives!
Of course correlation, even if it were found, is not causation. And, this would not be testing the hypothesis that baiting leads to more Shark attacks. For that, one would have to proceed like Doc suggests and wait for several centuries. But it would at least give us an indication about whether the hypothesis is at least plausible and thus, worth testing!

Betcha the result it is a big fat zero!
And if so, wouldn't that be all the more surprising as common wisdom would suggest the exact contrary! Here's the long version of why this should be the case - but if you can't be bothered, here's the synopsis.

For there to be a Shark strike, a person and a Shark need to be in the same place at the same time (dooh...) and consequently, anything increasing the rate of such encounters increases the probability for such a strike.
When it comes to baited Shark dives, it thus follows that, equally trivially

• the more Sharks are present, the higher the risk of a Shark bite
• the more divers are present, the higher the risk of a Shark bite
• the more dives are being conducted, the higher the risk of a Shark bite
• the closer the divers and the Sharks interact, and the more frequently those interactions occur, the higher the risk of a Shark bite - meaning that protocols are incredibly important!

And then there's also the element of location, i.e. where those baited Shark dives are being conducted.
They are obviously being conducted where there are Sharks (dooh...) - but often, they are even located where Sharks aggregate naturally to mate and feed, e.g. around Dyer and Seal Islands in South Africa, the Neptunes in Southern Australia, Guadalupe, etc., meaning that those places are more dangerous to start with, something one may want to consider when analyzing the data.

But then again, maybe the above is a fallacy.
Maybe Shark dives habituate the Sharks to the presence of people, meaning that they become more relaxed or "tame" and thus refrain from biting. Let's not forget that agonistic (= essentially, defensive) behavior may well be one of the principal causes of Shark bites on divers! And if we put too many divers in the water, the Sharks may well decide to simply go away.
Yes as always it's complicated!

So how about it.
Will those guys finally let somebody analyze those data, and will those stupid assertions be finally outed for what they really are, nothing but rubbish and completely unsupported and probably even falsified by the very data collected by the people proffering them!

PS Patric here (thanks!) and Jillian here!
PS great comment on the attacks here!