Saturday, March 30, 2013

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?

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!

3 comments:

jsd said...

I wish researchers who are determined to criticise responsible shark diving/feeding operations would spend half as much time considering the impact of the millions of tonnes of dead and dying marine animal discard thrown back into the oceans by commercial fishing boats -- and then attempt to calculate the effect that has not only on the oceans but on the sharks that learn to follow those boats and gorge! You might as well criticise a mouse for the damage it does burrowing around in a house while ignoring the impact of a hurricane flattening the whole city.

DaShark said...

Amen brother...

And what about those squillions of commercial and recreational fishermen chumming and baiting, and then cleaning their catches and throwing the waste into the ocean. And what about the conditioning by the spearos.

Oh well - ever since the Florida debacle, this appears to be a lost debate, at least in the public domain.
It's just a shame witnessing that some researchers simply don't seem to get it - and they are the ones who are supposed to be have the brains! But in all fairness, the newer generation appears to be much more enlightened and also, much more conservation-oriented!

jsd said...

Putting on my hat as a Professor of Pseudo-Psychology (Monty Python University) I think there are 2 psychological aspects kicking.

(1) It's just obvious (innit?) that you shouldn't feed-and-dive with big, nasty sharks. I mean it's just so obvious it's dangerous. ...It doesn't matter how many times you do it and 'get away with it' you will always get clobbered somewhere down the line. I'm right, and one day I'll be proved right so you might as well admit I'm right before it's proved. The 'Promissory Note Argument' that can never be falsified.

(2)Jealousy. Yup. All those people who want to believe sharks are mindless, people-eating toothy monsters (and are too scared to go on a shark feed dive because they 'know' how dangerous it is) -- the 'sport'-fishermen, spearfishermen and various types of Ocean Trasher. They can't (at an unconscious level) stand the fact that others are feeding-and-diving with sharks and making these pseudo-heroic idiots look like what they are. Jerks. Meanwhile, in Florida, shark feeding was banned because of the wails of spearfishermen (anyone consider banning spearfishing if spearfishermen are getting bothered by sharks?) and ignorant politicians agreeing with (1) above because that's where the popular votes are.