The Numbers - revisited

Ever heard of the Monty Hall problem?

Me neither, until the silly con-troversy about the correct Shark numbers exploded in the blogosphere.
I stumbled across this prime example of counter-intuitive numbers crunching (try it, you'll be surprised!) after researching the Bayesian Inference, a method of data analysis that is based on Baye's Theorem and promises to deliver better results than its more conventional counterpart. Having once studied the latter, I can now attest to the fact that they will both trigger equally severe migraines.

The reason for my digression into the arcane realm of advanced statistics is that I've finally managed to read the relevant paper dealing with those controversial numbers, and that the researchers pride themselves in having applied Bayesian statistical methods when analyzing their data.
Its title is Global estimates of shark catches using trade records from commercial markets and you can download it right here.

In a nutshell, it comes to the conclusion that based on the Shark fin market, as of 2000, the global annual number of Sharks killed was between 26 and 73 million, with a median value of 38 million (you can find this at the bottom of page 1119).

That's certainly useful information as it attributes an order of magnitude, tens of millions, to that specific problem.

What I found more interesting are the numbers on page 1121 that attribute orders of magnitude, and consequently, relative values, to the trade in fins of the 11 identifiable species, i.e. Blue, Silky, Oceanic Whitetip, Sandbar, Shortfin Mako, Great Hammerhead, Bull, Dusky and Tiger , plus unspecified Hammerheads and the Threshers - which if you run the numbers, incidentally means that approx. half of the inspected fins were of unknown origin.

Still, and I'm repeating myself, the whole thing is nothing more than an erudite crapshoot.
You may want to scroll to page 1117 and the chapter Extrapolation to global trade volumes where an attempt is made to estimate the global trade figures based on the hard data available, i.e. the number of fins traded in Hong Kong. You will undoubtedly notice that there's a formula which is undoubtedly theoretically impeccable and, one would think, should thus yield impeccable results.

But only in theory.
The practical problem is of course that every single one of its variables is based on assumptions.
Plausible as those may be, that sure is a lot of cumulative speculation and the end result is accordingly rather fuzzy, a fact that the researchers themselves are more than willing to concede.

Also, please keep in mind that the paper only investigates the number of Sharks killed and then traded for fins.Granted, those may indeed be the majority (or maybe not if one considers the waste of discarded bycatch) and thus a strong indication for the scope of all global catches and granted, the latter numbers would be obviously higher - but claiming anything beyond that would just be utter speculation and of little help to the cause of Shark conservation where we need to advance credible, fact-based and verifiable arguments.

I've said it before, the numbers per se are rather irrelevant.
To be of any use, they must be put into context, by comparing them to what is known about the status of individual species in individual habitats - as in page 1122 where the researchers have applied their findings to the situation of the Blue Sharks, the species which is yielding the largest amount of fins.
These are their conclusions.

Acknowledging the margins of error, and the likely downward bias of trade-based estimates, our evaluation,using a Pacific numbers-based reference, suggests that blue sharks globally are being harvested at levels close to or possibly exceeding MSY (Maximum Sustainable Yield).
In contrast, our comparison with an Atlantic, biomass-based MSY reference point suggests catch levels may be less problematic.

But then, this.

Given that we have no population estimate, we are not able to evaluate the actual sustainability of our estimated catch levels. The MSY reference point is the highest possible catch that could theoretically be sustainable, and thus any catch that approaches or exceeds this level is of concern.

And this.

As a result of the global nature of our assessment we cannot evaluate the exploitation status of individual populations.
Furthermore, the blue shark is one of the most prolific and resilient of shark species (Smith et al. 1998; Corte´s 2002) and thus our blue shark results cannot be used to make inferences about other shark species. Conclusions regarding the sustainable or unsustainable use of other species, and thus the shark fin trade as a whole, will require more detailed species-based stock assessment reference points.
However, given the lower productivity of the other species common in the fin trade (Smith et al. 1998; Corte´s 2002), the large difference between trade-derived estimates of exploitation and the catch estimates reported to the FAO adds to growing concerns about the overexploitation of sharks.

Alas, we don't seem to have those data.
Plus, and that's one of the recurring threads of this blog, time is running out and we must stop procrastinating.
Collecting and analyzing the required data is difficult and tedious, sometimes impossible, and whilst this happens, the stocks may well decline below their Minimum Viable Population size and be irrevocably doomed for extinction.

Until we know more about the parameters that determine the MSY, and thus, the extent at which each species can be harvested sustainably given its current numbers, its life history and the attributes of its individual habitat, it is imperative that we apply the precautionary principle and pre-emptively halt, or at least severely curtail any further harvesting whenever, and as soon (!) as we perceive that the animals are being overexploited.
On a happy note, that's what I understand just happened in Florida, which is great!

With that in mind, the current debate may be intellectually stimulating - but other than generating a lot of incestuous and superfluous sound bites about the pathetically trivial imperative that we need to get the facts right before opening our mouth, it is of little practical use.

May I thus humbly suggest that we, yours truly included, stop vociferating and revert back to the mission at hand, to try and protect the animals we all profess to love.

The Numbers: The Chickens have come home to roost - again!

Dead Sharks in Kesennuma. No, this NOT about Shark Finning, and no, they have NOT been killed for their fins alone or the like!

Oops indeed!
From my Weekend Rant.
The numbers?
The numbers are just that, numbers.
If one does not put them into context by comparing them to what we know about individual species in specific locations, they say nothing about sustainability which is the only thing that counts.
Yes we all know without having to resort to peer reviewed science that many local, and possibly even some global populations of some Sharks have been severely depleted, and that their disappearance is of concern – but for the time being, that’s basically all we can assert.

So far, there has been one single paper trying to shed a light on the actual numbers being caught, and this only based on data from the Shark fin trade. Read it!
The paper is based on a series of (probably plausible) assumptions that are heaped upon more assumptions, and consequently, the results are merely expressed in orders of magnitude. Specifically, the authors come to the conclusion that the fins traded annually came from between 26 and 73 million Sharks, with a median number of 38 million.
Does that really allow us to honestly state that up to 73 million Sharks are being killed each year, as everybody and his dog has started to assert?
Kudos to Seafood Watch for doing it right: It's estimated that tens of millions of sharks are killed around the world each year for their fins is much better - but then again, have they been killed for their fins?

As I said, the above numbers are only about the global Shark fin trade alone.
They do not cover many other Shark fatalities due to bycatch or targeted food fisheries where the fins are not being introduced into the fin trade. Also, that was then and the trade has very likely increased since. It is thus entirely plausible to assume that the “real” number is higher, and it is perfectly OK to say so.
It is however totally unacceptable to make up numbers on the fly, be it as many as 100 million, let alone over 200,000 million (!!!) which is just plain ludicrous and quite frankly, a total disgrace! Yes, I'm being frank! :)
The good news is that I know that somebody is working on a peer reviewed paper about the global number of Shark being killed – but once again, unless put into context, those numbers will mean absolutely nothing!

And what about the Rate of Depletion?
Is it really true that 90% (or 99, or 70 – whatever!) of global Shark stocks have already been wiped out? Compared to which original baseline count, done when, where and by whom?
Where are the data?

And is it really true that Some marine biologist have suggested as soon as 2020 these magnificent creatures may be extinct – and if so, who is claiming such utter baloney?
Those endangered species of Sharks will become commercially extinct long, long before they will become biologically extinct! But there's a caveat: it is however probable that some local populations may have shrunk to the extent that they may have accumulated extinction debt and that they may be too small to be able to withstand the pressure of a large environmental shock, like the current anthropogenic Climate Change – re-read this post!
...
Also, not every fin that is being sold has been finned!
Statements like over one hundred million sharks are caught and finned alive are thus doubly misleading!
...
If we want to be credible Shark advocates, we got to do our homework and first of all, be informed about the animals we love!
Science is always in flux and today’s insights may quickly become tomorrow’s fallacies, meaning that we must keep abreast of the latest research results and not base our knowledge on old publications and approximate hearsay.
Most importantly, we the amateur naturalists should never make up things on the fly, nor should we idly re-interpret what is considered to be the accepted consensus.

This does not mean that we should not challenge the current status quo, as that is precisely the process by which knowledge is being advanced!
BUT: the only accepted technique for doing so is the Scientific Method and as always, let me warn against the siren calls and intellectual shortcuts of the self promoters, quacks and charlatans - see on top!

All researchers I’ve ever met have always been eager to engage in informed discussions and to entertain different hypotheses, if adequately supported by according observations.
Those researchers are neither omniscient nor omnipresent and often, observations by common mortals like us have greatly contributed to the advancement of scientific insights - so even if you have no academic background, don’t be shy and speak up!
But do your home work first!

Or, as I said before .

Can we maybe just be a little more humble and less righteous, the more since Conservation is so complicated?
Maybe progress towards more facts and less truthiness (read this!)?
Can we maybe just open our eyes and wonder at the magnificence of what IS instead of trying to make things up?

We are the amateurs.
Can we please listen to what the professionals are telling us – the principal message being that extreme positions (on both sides!) are inhibiting Conservation and appropriate Management measures?
Recent example? Right here – like it or not, the man has a point!

If we want to educate others – let’s educate ourselves first!

That was in March.
Now, the lead author of the numbers paper (yes it is open source and available online - read it!) Shelly Clarke, has reached out with a wail of despair about the way Shark advocates are abusing the numbers she has estimated. It's the Shark Con all over again - and talk about a pathetically flat learning curve!

And I cite.

Exaggeration and hyperbole run the risk of undermining conservation campaigns.
Presenting a high but scientifically unsubstantiated number like 100 million can discredit otherwise valuable advocacy for better resource management and monitoring.

Pretty bloody embarrassing huh.
Pretty bloody dangerous too, as now the other side can rightfully claim that the lead author of the only paper dealing with the issue is asserting that Shark conservationists operate with fake data. So as a reminder, here's the actual citation from the paper, hidden somewhere in the general scientific gibberish at the bottom of page 119.
Estimates of the total number of sharks traded annually worldwide, based on all fin positions combined, ranged from 26 to 73 million year^-1 (95% PI), with an overall median of 38 million year ^-1.

Not very helpful is it.
Couldn't she have said it like in her post, i.e. as of 2000, the fins of 38 million sharks per year were being traded through the fin markets, but the number could range as low as 26 million or as high as 73 million? Could she not have put that estimate into the Abstract at the top?
But, it is what it is - and anyway, those numbers mean nothing unless put into context!

Long story short?
We gotta stop exaggerating and making things up - is that so difficult to understand?

Which brings me straight over to the Oxygen.
Claiming (one of dozens, talk about a bloody memetic viral infestation!) that if the Sharks get wiped out we will all suffocate is just total unadulterated rubbish! Period!
And if that were not stupid enough, I already get a whiff of the attempt of linking Sharks and Global Warming! WTF?

How long til that, too, will bite us in the ass?
It is, as always, up to us!

Weekend Rant!

Time for a rant!

From a message by a friend

Agree that there is much breathy hyperbole and blatant nonsense written about sharks and conservation, but I suppose that this is inevitable when concern is high but facts are few, with the most solid data residing in relatively inaccessible scientific papers.

Generally I take a sanguine or even charitable view toward the popular Jeremiads you have castigated since the goals of the authors are generally in concordance with mine, and these often painfully well-intentioned folks are far more able to communicate values effectively and educate a large audience than someone who uses words like sanguine or Jeremiad, no?
And education does seem to work in the long run.

Totally agree – BUT!
I’m getting terminally irritated that people who purport to be Shark conservationists and are perceived to represent the whole movement continue to make public statements containing ludicrous assertions and statistics.
This is not only not helpful - it directly undermines our efforts by allowing the other side to assert that we’re nothing but a bunch of lunatics who operate with false claims.
Is that what we want?

Yes it’s an old grievance of mine – but enough is enough.
So there.

But first, check out this piece of equine manure!
Very timely indeed – thank you!



Wow!
Pure sharkitarian snake oil!

There are no Shark attacks?
Right!
Please re-read this!

Sharks?
When talking conservation, talking about “Sharks” is utterly useless!
The fact is that “Sharks” are neither threatened with extinction, nor are "they" apex predators – only a small minority of species are apex predators, let alone keystone species, and the species that are particularly at risk of extinction are several large predatory Sharks, many of which are pelagic; possibly some deep water Sharks; and maybe Whale Sharks – full stop!
Other species are doing no better and no worse that any other Fish that is not subjected to exceptional fishing pressure – meaning not particularly great but not particularly catastrophically, either.
List here (search for "Sharks"), criteria here.

The numbers?
The numbers are just that, numbers.
If one does not put them into context by comparing them to what we know about individual species in specific locations, they say nothing about sustainability which is the only thing that counts.
Yes we all know without having to resort to peer reviewed science that many local, and possibly even some global populations of some Sharks have been severely depleted, and that their disappearance is of concern – but for the time being, that’s basically all we can assert.

So far, there has been one single paper trying to shed a light on the actual numbers being caught, and this only based on data from the Shark fin trade. Read it!
The paper is based on a series of (probably plausible) assumptions that are heaped upon more assumptions, and consequently, the results are merely expressed in orders of magnitude. Specifically, the authors come to the conclusion that the fins traded annually came from between 26 and 73 million Sharks, with a median number of 38 million.
Does that really allow us to honestly state that up to 73 million Sharks are being killed each year, as everybody and his dog has started to assert?
Kudos to Seafood Watch for doing it right: It's estimated that tens of millions of sharks are killed around the world each year for their fins is much better - but then again, have they been killed for their fins?

As I said, the above numbers are only about the global Shark fin trade alone.
They do not cover many other Shark fatalities due to bycatch or targeted food fisheries where the fins are not being introduced into the fin trade. Also, that was then and the trade has very likely increased since. It is thus entirely plausible to assume that the “real” number is higher, and it is perfectly OK to say so.
It is however totally unacceptable to make up numbers on the fly, be it as many as 100 million, let alone over 200,000 million (!!!) which is just plain ludicrous and quite frankly, a total disgrace! Yes, I'm being frank! :)
The good news is that I know that somebody is working on a peer reviewed paper about the global number of Shark being killed – but once again, unless put into context, those numbers will mean absolutely nothing!

And what about the Rate of Depletion?
Is it really true that 90% (or 99, or 70 – whatever!) of global Shark stocks have already been wiped out? Compared to which original baseline count, done when, where and by whom?
Where are the data?

And is it really true that Some marine biologist have suggested as soon as 2020 these magnificent creatures may be extinct – and if so, who is claiming such utter baloney?
Those endangered species of Sharks will become commercially extinct long, long before they will become biologically extinct! But there's a caveat: it is however probable that some local populations may have shrunk to the extent that they may have accumulated extinction debt and that they may be too small to be able to withstand the pressure of a large environmental shock, like the current anthropogenic Climate Change – re-read this post!

Shark Finning?
Shark finning does not equal catching Sharks. It is a specific, particularly wasteful and particularly cruel harvesting technique and for these reasons alone, it certainly needs to be stopped.
But is everybody aware that stopping the finning does not necessarily stop the fishing? The most widespread remedy against Shark finning is to legislate that the Sharks must be landed with their fins attached. This reduces the number of Sharks that are being killed as the carcasses take up a lot of space in the hold of the vessels – but as many examples show, Sharks are still being landed with their fins attached in what clearly appear to be unsustainable numbers.
Also, in many third world countries, local fishermen (and poachers!) have already wiped out many of the traditional food fisheries and as a consequence, many people have added Sharks to their menu, meaning that there is a substantial and increasing Shark food- , as opposed to Shark fin fisheries.
Thus, if we want to save Sharks stocks from overfishing, Stop Shark Finning! petitions alone are simply not adequate – we must also campaign for their protection!

Also, not every fin that is being sold has been finned!
Statements like over one hundred million sharks are caught and finned alive are thus doubly misleading!

Cascading Effects?
Yes there is a seminal paper by Myers et al. that essentially shows how the removal of large predatory coastal Sharks in the Northwest Atlantic led to the explosion of the population of Cownose Rays who in turn wiped out the Scallops, and the industry depending on them, in Chesapeake Bay. More details here.
Great paper – but it has one weakness: nobody was harvesting those Cownose Rays!

But in the real world, coastal Sharks are not being selectively removed alone.
Instead, fishermen target both the apex- and the mesopredators (and the prey), meaning that asserting that removing the big Sharks will inevitably lead to a population explosion of mesopredators (many of which are incidentally Sharks!) who in turn will wipe out the grazers which in turn will lead to an explosion of algae who in turn will smother the reefs can be totally wrong.
In a way, it is now us who have unwittingly assumed the role of apex predators and are keeping the lower trophic levels in check – see many terrestrial habitats where most apex predators have all but disappeared but where there has not at all been a total collapse of the system!
I’m not saying it is not so: I’m just saying that the empirical evidence is scarce and that once again, those effects will vary according to habitat and species composition.
See Ferretti et al. for more details!

As to the role of Sharks in their habitat and the widespread explanation that they weed out the sick and dying and thus keep the gene pool of their prey healthy, etc?
Certainly intuitively plausible: but to my knowledge, whereas there is plenty of research about the role of terrestrial predators, such effects have not been conclusively documented for Sharks – yet!

Which brings me straight over to Climate Change and Oxygen Production!
Check this out.



Did you hear that?
Who has come up with the glorious idea of linking Shark conservation to the Oceans’ production of oxygen?
Yes the Oceans provide for about half of the planet’s oxygen production through the photosynthesis by phytoplanktonic Algae and Cyanobacteria (but then again, probably not!). This (incidentally, to a very small extent), and the sea water’s capacity to dissolve CO2 make it that the Oceans are also Earth’s largest active carbon sink.
It is also certainly true that the Oceans have a great influence on the weather, and that millions of people depend on them for food.

But this got nothing to do with Sharks!
The principal threats to oceanic ecosystems are probably Climate Change, Acidification, Overfishing, Pollution and Habitat Degradation – not the fisheries for Sharks!
It is just not plausible and there is certainly no scientific evidence indicating that if one selectively removed all Sharks
- the oxygen production would cease due to the disappearance of phytoplankton
- the oceans would cease to be a carbon sink
- the weather would change
- fisheries would collapse and humankind would starve
or any other similar stupidities that happen to be en vogue among some Shark activists!

Shark Intelligence?
This very much smells like the newest up-and-coming Shark conservation fad.
Does the fact that some Sharks migrate and that they are capable of memorizing locations automatically mean that they are particularly intelligent? Why are some quarters asserting that it is so, when this is in no way being claimed by the authors of those migration papers?
Sorry Richard – I still think you rock! ;)

Are Monarchs particularly intelligent? Wildebeest?
What about Bees who are not only capable of finding and memorizing the location of a food source, but then also fly back to the hive and convey that information to the other bees – so effectively. that those other bees can find the food without being guided there by the finder?
Hell, that’s even smarter than what we know about the so much hyped Dolphins!

Frankly, I dunno.
My gut tells me that migration and spatial orientation are not good indicators for intelligence. Yes it is amazing behavior – but animals doing amazing things are more often than not simply well adapted to their ecological niche, and behavior that comes across as being remarkably clever is often hard wired and the result of evolutionary selection as opposed to volition.
Example? The amazing Anglerfish!
Perfectly camouflaged and provided with an ingenious lure, they are highly successful at ambushing their unsuspecting prey. Totally clever – and yet one of my ichthyological gurus assures me that they dispose of the lowest brain-to-body mass ratio of all Fishes!

Sharks BTW have a relatively high brain-to-body mass ratio, somewhere between Teleost Fishes and Mammals..
But although we all intuitively know what intelligence means conceptually, it is nevertheless difficult to define, especially in animals - and even more difficult to compare, see the Bees and the Dolphins!

When it comes to Sharks, the one person who knows most about the topic is probably Doc who has demonstrated remarkable learning and problem solving capacity in Lemons, very much in line with what we experience daily with our Bulls.
My gut feeling is that as always, different species will display different abilities, and that those predatory species with the widest trophic niches requiring the widest range of predatory strategies and thus the highest adaptive capabilities will be perceived as the most intelligent - but then again, a friend may be on to something when he remarks
Incidentally, since humans filled a generalist predator niche at one time before we graduated to planetary predator class, would we not inevitably tend to think that other generalist predators like sharks are particularly intelligent?
Yes, it's complicated!

Still, I fully agree with Wolfgang that Tiger Sharks come across as being way smarter than, say, Whale Sharks that I incidentally perceive as being particularly dumb - and who incidentally migrate like crazy!

But those are clearly personal perceptions, not objective data.
Whereas I’m convinced that all of our Bull Sharks have distinct personalities and that they develop affinities to specific persons, I also know that we humans have a fatal propensity for anthropomorphism, i.e. for attributing human faculties to animals.
So, yes, let’s love them like crazy – but let us not assert that our feelings are being equally reciprocated, or the like!
Yes Emma very much appears to love Jim (and there’s absolutely no doubt whatsoever that Jim loves Emma!) – but she is very likely being bribed with massive amounts of juicy handouts and is just being the opportunistic feeder Tiger Sharks are!

Having said that, there appears to be clear evidence that the behavior of some Sharks goes well beyond that of mere automatons that are solely driven by genetic programming.
In fact and going back to, say, Tigers and Bulls, aren’t high flexibility and adaptive capability precisely what we would expect evolution to select for in a generalist predator – meaning that some of what we perceive as being intelligent behavior may be genetically encoded, but that there must also be scope for individual decision making, individual learning, individual preferences, individual personality, etc. which may indeed be good indicators for intelligence.
Again, I don’t know - but precisely because of that, I would never proffer any strong statements one way or the other!

Long story short?
If we want to be credible Shark advocates, we got to do our homework and first of all, be informed about the animals we love!
Science is always in flux and today’s insights may quickly become tomorrow’s fallacies, meaning that we must keep abreast of the latest research results and not base our knowledge on old publications and approximate hearsay.
Most importantly, we the amateur naturalists should never make up things on the fly, nor should we idly re-interpret what is considered to be the accepted consensus.

This does not mean that we should not challenge the current status quo, as that is precisely the process by which knowledge is being advanced!
BUT: the only accepted technique for doing so is the Scientific Method and as always, let me warn against the siren calls and intellectual shortcuts of the self promoters, quacks and charlatans - see on top!

All researchers I’ve ever met have always been eager to engage in informed discussions and to entertain different hypotheses, if adequately supported by according observations.
Those researchers are neither omniscient nor omnipresent and often, observations by common mortals like us have greatly contributed to the advancement of scientific insights - so even if you have no academic background, don’t be shy and speak up!
But do your home work first!

Or, as I said before .

Can we maybe just be a little more humble and less righteous, the more since Conservation is so complicated?
Maybe progress towards more facts and less truthiness (read this!)?
Can we maybe just open our eyes and wonder at the magnificence of what IS instead of trying to make things up?

We are the amateurs.
Can we please listen to what the professionals are telling us – the principal message being that extreme positions (on both sides!) are inhibiting Conservation and appropriate Management measures?
Recent example? Right here – like it or not, the man has a point!

If we want to educate others – let’s educate ourselves first!

And here endeth the weekend rant!

PS Patric's take: WOW!!!

Too Many!

I did like Patric's Sunday Sermon.

It's in the comments section of this post, after which he has posted this one.
Both deal with the numbers circulated by some Shark activists and warn that if we argue with faulty data, we lose credibility and ultimately harm the cause. All very truthful, important and timely indeed.

Thing is, maybe it's really not that much of an issue as nobody really knows what's going on anyway.

Take the assertion that 90% of all Sharks have been wiped out.

"Sharks"?
Cookie Cutter Sharks? Greenland Sharks? Whale Sharks? Pigeye Sharks?
I've said it before, like "Birds", "Sharks" is an amorphous concept that leaves very little scope for generalizations. What we seem to know is that the stocks of some of the large, oceanic species like Silky, Oceanic Whitetip, Blue, Scalloped Hammerhead and the Threshers that are being targeted in tandem with other apex predators like the Tuna and the Billfishes have collapsed. Other coastal species, like e.g. the Caribbean Reef, Bull and Tiger appear to fare better and are still locally abundant.
Clearly, the assertion is not true - but then, what is?

Think baseline count, the original 100%.
Do we have that information?
I'm inclined to believe that when somebody tells me that over 90% of the large Sharks in the Mediterranean have been wiped out, it is based on fact. The Mediterranean Sea is surrounded by many highly developed countries that could well have established the apparatus for collecting population data and for monitoring any fishing taking place there, and the changes that the relatively recent industrial exploitation of Fish stocks have brought about in the last 30-40 years.
But how about, say, Yemen, another place where there is a large Shark fishing industry? Do you really believe that there are reliable data about the Sharks being landed in comparison to before, or a reliable census of Shark stocks in the Southern Red Sea compared to 1960?

And with that in mind, are the numbers of Sharks killed every year really between 25 and 75 million? 100 million? Or even between 150 and 200 million as one Shark conservation website claims?
And again: is that relevant? What species are we talking about? And how do those numbers relate to the total size of the relevant stocks and the carrying capacity of their habitat? Is that 1%, 10% per annum, or is it more than that? And what is the rate at which those stocks replenish?

Thing is, nobody knows and all of the numbers that are being circulated are nothing more than elaborate and more or less plausible estimates, with huge discrepancies based on individual assumptions (how much goes under- or un-reported, etc) and mathematical models.
Thus, the theoretically impeccable rule postulated on an interesting and intelligent conservation biology blog, that one needs to manage populations in function of the minimum viable population size is certainly highly interesting - in theory. But in practice, it's utterly useless and once again, nothing but an erudite crapshoot when applied to the urgent need to preserve marine species that are often spread across immense areas. Is it really plausible to postulate that approx. 5,000 Blue Sharks spread across the vastness of the Oceans would ensure that the species would survive? And who, please, would be able to count, let alone manage them?

But as I said, the numbers are rather irrelevant anyway.
What is relevant, I believe, is that anybody who has knowledge of the Sea is aware that the marine environment in general and Sharks in particular are in real bad shape.
I remember sailing into Cocos’ Chatham Bay in the eighties and there would be Shark fins crisscrossing the surface everywhere, and heaps of huge Silvertips on every dive. Or sitting at Dirty Rock and witnessing a never ending procession of Hammerheads that would completely fill my field of vision - up, down, left and right, as far as I could see. They were thousands - and today, a couple of hundred are a major event. Or take the Silvertips on the Burma Banks and the guaranteed Whale Shark sightings at Richelieu Rock: gone, likely forever. Or diving with Blue Sharks off San Diego: not anymore commercially viable.
And the list goes on and on and on.

This, and not a set of numbers that are not very tangible and may, or may not be factually correct is why many of us have become Shark conservation advocates.

Want a number, as in how many?
How about: Too Many!

The principal threat to large oceanic Sharks is the fishing industry that targets their fins. This fishery appears to be unsustainable, as witnessed by the reported regional (and some say: global) collapse of stocks.
Here, the main thrust of any conservation efforts needs to be sustainability: first, the stocks that have been overly depleted need to be allowed to recover and after that, one has to agree on quotas. All of that should be based on proper data that so far are largely lacking and until they have been gathered, it is imperative to apply the precautionary principle, operate under worst-case scenarios and to err on the side of caution.
But once the data have been collected, we must be willing to compromise and to allow for the sustainable (and ethical, meaning no finning) harvesting of Sharks as long as there will be demand for their fins – and yes, for the umpteenth time, I’m repeating myself!

On the other hand, and very much depending on location, the principal threat to coastal Sharks appears to be habitat degradation coupled with fishing pressure.
Here, on top of promoting sustainable fishing, one needs to focus on preserving the habitat, be it coral reefs or the equally important nursery areas. This is precisely the kind of work conducted by us here in Fiji, by having established a marine reserve, by now focusing our work on the river nurseries and by sponsoring plenty of research aimed at helping us take the correct decisions. And yes, we’re also engaged in promoting pro-Shark legislation, conservation and awareness.

There’s much to do and it’s not going to be easy.
But maybe contrary to others, I really do believe that it’s neither impossible nor too late.
Shark conservation has come a long way and despite of the inevitable setbacks, we thankfully appear well on course to changing perceptions and to finally depict and treat Sharks as what they are: not unpredictable monsters nor misunderstood pets – but charismatic predators that like their terrestrial counterparts need to be respected and above all, to be protected as they are important and often essential elements of their habitats which they help to regulate.

Long story short: everybody who loves Sharks will find a suitable niche where he can make a useful contribution.
But like Patric, I just wish that everyone could abstain from gratuitous sensationalism and activism and really focus on the task at hand, to engage in effective and pragmatic Shark conservation. That includes less idle chat and more hard and often tedious and frustrating work, less dogmatism and more compromise, less propaganda and more hard facts, less infighting and more coordination, less squandering of precious and finite resources and goodwill.

And above all: lots of love and respect for the animals and passion for the cause!

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!

About our Sharks

Pic: Adi by Michael Aw

More Sharky stuff from our new website.

Welcome to our Shark Diving pages!

This is what has made us world-famous and this is likely the main reason why you have decided to consult our website.
Good choice!

First and foremost, forget everything you may have seen on other Shark dives!
The Shark Dive is like nothing you can experience anywhere else - guaranteed!

Contrary to regular SCUBA diving, there is no pre-determined set of guidelines governing Shark diving as all Shark diving protocols are always highly situation-specific.
Each operator must devise his own set of diving and safety procedures depending on the individual locations, the species mix and other variables, foremost of which very personal considerations - like one's experience and beliefs on the matter in terms of what one is aiming to achieve, how and why. For us, the latter is first and foremost Shark Conservation and Shark Research and the Shark Dive is merely a means to facilitate that goal.

All of that is explained in the following sections "About diving with Sharks" and "The Shark Dive" and also in the pages devoted to Shark Reef Marine Reserve and the Fiji Shark Project. We strongly recommend that you familiarize yourself with the contents in order to be best prepared for this unique and exhilarating experience!

When it comes to our Sharks, you have the chance of seeing the following 8 species:

Whitetip Reef Shark (Triaenodon obesus)
Blacktip Reef Shark (Carcharhinus melanopterus)
Grey Reef Shark (Carcharhinus amblyrhinchos)
Silvertip Shark (Carcharhinus albimarginatus)
Tawny Nurse Shark (Nebrius ferrugineus)
Sicklefin Lemon Shark (Negaprion acutidens)
Bull Shark (Carcharhinus leucas)
Tiger Shark (Galeocerdo cuvier)

We are maintaining an exhaustive database about our Shark dives and as of January, 2009, we dispose of over 2,000 complete data sets. This enables us to run statistical models in order to try and figure out whether there are any recurrent patterns governing the presence, and behavior of our Sharks.
However, weather patterns in the South Pacific are subject to wide year-to-year variations due to the influence of the El Niño Southern Oscillation. It is only fair to assume that this will also influence Sharks as part of the Marine Ecosystem. Many more yearly data sets will have to be collected in order to hopefully once largely take this specific variable out of the equation.

So far, preliminary insights can be summarized as follows.

Our Whitetips, Blacktips and Greys are resident and can be encountered at any time during the year.
Numbers vary between just a few and approx. two dozen depending on variables like weather and tides but also, the presence of other larger Sharks, foremost of which the Tigers.
Whereas the Blacktips are largely confined to the shallowest depths, the Greys and Whitetips are most prevalent at 10m but will occasionally venture down to the Arena at 30m.

The Silvertips, Nurses and Lemons are what could be called "regulars".
They probably live in close proximity to the feeding area (maybe deeper in the Beqa Channel) and turn up shortly after we enter the water. With the exception of the Nurse Sharks which are nearly always there, their appearance is more sporadic and not -yet- predictable.
As with the other Sharks, numbers vary: up to fifteen Nurse Sharks and up to six Silvertips or Lemons. Like the Bulls, these species are confined to the deeper reaches of between 15 and 30m.

Our Bull Sharks are the stars of The Shark Dive and we have devoted a lot of resources in trying to better understand their behavioral patterns (click on image for bigger resolution).
In general terms, they turn up in ever increasing numbers in January and are very consistent through August where numbers start to dwindle in view of their birthing and mating season in October-December where one is likely to see only a few individuals, most of which sub-adults.
Maximum numbers during January-April can be as high as 40 individual Sharks on a single dive and with 47 named Bull Sharks as of January, 2009, we may well be looking at a population size of in excess of 100 individuals.
As with the species above, the Bull Sharks are not residents of the diving area but ascend from deeper water once we start the dive and "call them in" by baiting the ever-hungry Giant Trevally and Red Bass.
We have learned to distinguish between "regulars" that turn up very frequently, and more transient individuals that are individually known but only turn up sporadically. In very general terms, we are however witnessing some sort of "rotation" by all Bull Sharks, whereby individual Sharks will turn up for one week to ten days and then disappear, only to turn up again weeks, or even months later. This may be an indication for the size of their range (probably not a territory, a term that implies that it is defended against conspecifics) or it may be an indication that they are not really bound to any range or territory at all but roam freely throughout the whole archipelago instead.
So far, the data we have collected via our satellite and acoustic tags are not sufficient to precisely interpret this rather surprising behavioral pattern, but they are nevertheless a good starting point for formulating advanced and testable hypotheses .

When it comes to our known five Tiger Sharks, the data collected so far are rather inconclusive.
Preliminary evidence suggests that they are less prevalent during the top Bull Shark period of January through April. The reasons for this are unknown and subject to speculation: it may be due to the overwhelming presence of the Bulls acting as a deterrent, or it may be due to some regular occurrence like their breeding cycle or other seasonal feeding opportunities elsewhere, like the flooding of rivers during the wet season, Turtle aggregations etc. Again, this is pure speculation and would have to be confirmed by e.g. obtaining further insights into their seasonal geographic movements via acoustic and satellite telemetry tools.
Once the Tigers turn up, they will make regular, although sporadic appearances, this probably due to the very large area they are known to patrol. Of interest, they mostly turn up during our second, shallower feed.

All-in-all, we believe that The Shark Dive is well worth a visit year-round.
What is certain is that every single dive is different - but always exciting, intriguing and highly rewarding!

The Numbers - a Conspiracy?

It's estimated that there are 100 million sharks killed every year.

This total has such caché it even has its own moniker; ‘The Magic Number'.

But in today's world, where big numbers wash over us with indifference, ‘One Hundred Million' is losing it's lustre. Most of us owe that on our credit cards. So shark conservationists are continually polishing ‘The Magic Number' to keep us hooked.
Scare mongering or just plain scary?

This according to Howard Sawyer.
The citation is from The People who count Sharks, a piece I've already linked to last November. But after Ms Clarke's public wail of despair, it is well worth re-reading. It eloquently develops the case for why the numbers are faulty and it also hints, so far only obliquely, at the fact that we may all be the victims of a despicable conspiracy perpetrated by an unholy alliance of self serving conservationists and researchers. Oh how very Shark Con and incidentally, how very Global Warming! :)
Totally not so, see below - but it's a good read so please do.

Incidentally, have you finally read the paper?
Yes I know it's the poster child of horrible scientific gibberish that appears to have been written specifically in the purpose of confusing any layman, yours truly included. I've honestly tried to decipher whether the numbers refer to the period of 1996-2000 or to 2000 alone and have failed miserably - even after re-reading Ms Clarke's wail that is equally unhelpful: what does as of 2000, the fins of 38 million sharks per year were being traded mean, exactly: in 2000, on average in the five years leading up to 2000 - or what?
Also and owing to the many assumptions made in reaching the above conclusion, there is a staggering error margin which is expressed in the fact that the authors point out that the number could have been as low as 26m (-32%) or as high as 73m (+92%). Not very conducive to instilling any degree of confidence in its scientific accuracy is it. And incidentally, have you ever asked yourself why 73 and not, say, 72.5m?
Divide it by 365 days. See? Purely coincidental? :)

Anyway, this is how I interpret it - correct me if I'm wrong.
Between 1996 and 2000, the global Shark fin market was processing the fins of tens of millions of Sharks every year.

And that's it!
When it comes to the global markets for Shark fins, this is actually the only assertion the paper makes, meaning that:

• nobody knows for what purpose those Sharks were killed (actually, we don't even know whether all have been killed or whether a few may have died of natural causes in an aquarium or the like - but I'm obviously splitting hairs), ie for their fins or principally for food or in self defense or for research - or for no purpose at all because they were mere bycatch, one of the major causes of Shark mortality!
  


• nobody knows how those Sharks were killed, ie caught on long lines or in gill nets, purse seines, drift nets or in bottom trawling gear, or shot by spear gun or harpooned or caught in fish traps, etc
  


• nobody knows how many of those Sharks were finned and the bodies dumped overboard, and whether the Sharks were alive or dead when that happened
  

but much more importantly,

• nobody knows how many more Sharks whose fins were NOT introduced into the fin trade died during 1996-2000!


• nobody knows what happened in 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009 and 2010
  Period!

Does that mean that we don't know anything about what's going on now?
Well, in a way, that's exactly what it means - but of course there are published data about trade volumes after 2000, although they are widely believed to be highly inaccurate as reported volumes are thought to be way too low as they do not comprise IUU, and as some Countries do not report at all.

But, nobody is preventing us from speculating.
We can make plausible assumptions and back-of-the envelope calculations that will however remain untested hypotheses as long as nobody engages in the tedious work of properly verifying or falsifying them using the Scientific Method, likely by meta-analysis of the data that have been published as opposed to going out and trying to obtain original data sets.

Provided that we are honest and declare that we are speculating, it is I believe safe to assume that today, the Shark fin market is larger than ten years ago, tho as the following oldish graph illustrates, this is not just simply a given as local Shark stocks get exhausted and new legislation may curtail the activity.
Click for detail.

Anyway, assuming the fin market has grown, do we know by how much and starting from which baseline?
No we do not.

It is also I believe totally logical to assume that the total number of Sharks that are being killed each year is larger than the number of Sharks whose fins are being traded thru the fin markets.
Once again, we however don't know by which factor - especially nowadays where each and every fisherman knows of their value and knows how to contact a friendly middleman who will be eager to buy & aggregate them and then ship them to Asia.

So, let's look at some of the statements.

Over 200,000 Million Sharks are taken each year, many illegally, caught to support a growing industry for shark products in the Asian market. Most fins being used as a starch to thicken Shark Fin soup which has no taste but is thought to have magical properties and a sign of wealth!...
... is just plain ludicrous - no it is NOT over 200 Billion (!) Sharks and the fins got nothing to do with starch nor are they believed to be magical!
I mean, seriously...

How about
Every year, about 100 million sharks are brutally murdered and of these 100 million, an estimated 73 million to 100 million of the deaths are results of shark finning, the process in which a shark’s fin is cut off and the shark is thrown back into the ocean to die. If this continues at the rate it is at right now, all 440 species of sharks may be extinct within the next decade or two. The population of sharks as a whole has already dropped 95% since the 1970s, simply due to finning.
OK(-ish) for the approx 100 million but nobody is estimating that 73 to 100m are being finned, let alone alive, nobody but a fool is asserting that all species will be extinct within the next 10-20 years and there is no statistic whatsoever showing that 95% of all stocks have been wiped out since the 70ies, let alone finned!

And the ubiquitous
Up to 73m Sharks are being killed each year, or statements that the growing demand for shark’s fin soup, a Chinese delicacy, kills between 26 and 73 million sharks a year, or People kill 73 million sharks per year (Really? Not even a modest "up to"?) and the like?
Better but still inaccurate! These are numbers from 10 years ago - can anybody show me a single trade statistic that has remained unchanged since? Plus, these numbers suggest some degree of accuracy - what if in reality, the 2010 number turned out to be, say, 87 million?

So, what is going on?
Is this a nefarious conspiracy by Shark conservationists and researchers who want to perpetuate their job at the expense of the poor fishermen?

My call?
Many Shark conservationists are hopelessly ill informed, and a few may well be inflating the numbers as they are under the completely misguided impression that doing so will make for a better case - but that's that. These are well meaning people who try to do good but with inadequate means.

The NGOs?
One would assume that they would know better but once again, many probably simply do not and parrot what others have asserted before them - tho it looks like a very few very small ones have long relinquished the path of credibility, scientific and otherwise, and are merely the marketing arm of personal inflated egos!

And the researchers?
To my knowledge, none of them is asserting any of that nonsense - and if they did, they would have to elaborate on how they have come to that conclusion or they would have to kiss their scientific gravitas and career goodbye!
With one exception that is, the token whacknut - but then, what did I say about the gravitas etc?

A conspiracy?
Hell no, it's merely a motley group of well meaning, mostly ill informed people and orgs wanting to do the right thing.
Me too, I've sinned in the past, as in here.



But now, I know better.

Now, I say stuff like
We know that ten years ago, about forty million of sharks were being killed each year - and now, that number is probably even higher!
or if I want to keep it short
Tens of millions of Sharks are being killed each year
But then, I add
What we DO know is that this is completely unsustainable and that it causes grave and permanent damage to our oceans - which I believe is the far more important statement!

But is that really so?
How many Sharks are there, and are we killing 1%, 2%, 10%, 30% of them each year? Is there such a thing as sustainable Shark fishing and if so, what is the Maximum Sustainable Yield? What happens if we kill too many? And if we stop killing them, will they multiply unchecked like Savyer's Serengeti lions (bollocks: ever heard of trophic pyramids and predator-prey cycles?) and start devouring us, as Capt'n Bill rants?
More of this in an upcoming post!

For now, this much.
This is never happening in a vacuum - this is being used to advocate legislation that will deprive fishermen of income and quite possibly, of their livelihoods. With that in mind, we owe it to them, but also, to ourselves not to cheat and to use misleading perceived "marketing", or whatever, but to be truthful and fact based instead.

Yes Bill is clearly mental - but he is also wily and will catch on to our shenanigans, so why do we continue to provide easy fodder for people like him?
The situation for many, if not most species of Shark is really, really dire and there's absolutely no need whatsoever to inflate numbers and to come up with ludicrous propositions like the moronic correlation to the ocean's production of oxygen which is my current pet grievance.

And then there's this.
Assume we succeed in having laws enacted based on misleading data - what would prevent the legislators from repealing them once we got caught out?
Think we would ever get a second chance after such a fiasco?

So, let's do it right from the outset.
Let's inform ourselves and then, let's just say it as it is.
That, and not cheating will have us win this fight in the long run.

Agree?