brilliant doco on the ocean's super predator

[Warren]

I think it was just Clive Palmer going out for fish and chips.

[Ken Gargett]

Ken, no offence taken at all, I appreciate it how you are going into the details of the media coverage (well, you are a practicing journalist yourself), and I’d like to discuss it. Have also seen this version now on the web.

Please excuse a long answer to a long question. We could have done per PM, but perhaps others may like to follow or chime in in that discussion if interested.

First of all let me say that I totally agree with you regarding some of the poor-form media coverage, which is partially in no way better and using similar “tricks” as the documentary does. Main point or technique here to criticise is the omission of facts for making a better argument / better fitting the picture.

But I’d rather not go into all this media hype, which will lead us nowhere, but instead rather go directly into the presented data from the tag. Because this is where the story started, and where everybody tries to fit in the subsequent findings, in order to get it in line with a somehow precast picture – The giant animal that must have swallowed this 3-m shark lady.

And here, indeed, I found a slight difference to the other docu I saw, in where it was reported that the tag, after going down to the seafloor lay motionless (no pressure/depth alteration) for quite some time prior to the steep temperature rise. Unfortunately, I can’t find that version on the web anymore, neither is any sound scientific report to be found, not to mention a peer reviewed scientific paper on the whole issue (if anyone would have or could direct me to that, I would very happily reassess my statements!)

So, what are the facts we are presented with?

1. We are being told that the shark had been equipped with this pop-up device, which (usually) takes position when surfacing (most probably using some sat-nav system like Argos, perhaps in combination with GNSS), ambient temperature and pressure (dive depth)

2. At one point, at “4 a.m. Xmas eve”, after a long journey up and down along the southern coast of Australia, the tag (I will be talking about the tag, not the fish), now near the original deployment site, suddenly quickly descended (“plunged”) rapidly to a depth of 580 m, presumably the seafloor at that position.

3. The film animation shows us a downward trajectory along the shelf slope

4. The temperature reading during that time was 46 Degrees F (7.8°C) = ambient water temperature (quite stable if you ask me - no stratification of the water body there? Anyway, minor issue here)

5. Then, after a – to us undisclosed – period of immobility, the temperature started to become erratic (this info I have taken from another website, where someone asked the bloke some questions) and then stabilized to somewhere about 78 degrees F (25.6 °C). We don’t know nothing about the inertia (time lag) of the temperature sensor, again perhaps a minor issue.

6. Thereafter it rose up to shallower depths and remained within a depth range of betw. the surface and 330 feet (100 m) for another eight days before being released and then popping up to the surface.

“It was obviously eaten. What’s gonna eat a shark that big, what could kill a 3-m Great White?” Dave Riggs asks in the film at that point. Implying that the whole animal must have been “eaten” and even claims gigantism of said predator due to genetic defects (guess not in the film, but cited in later interviews, however, I wasn’t able to verify the authenticity of the statements), instead of simply discussing the more obvious.

To interpret these patterns and findings, there is absolutely no need to assume a giant or even a larger predator!

As other scientists have mentioned, a rather normal-sized shark could have ripped out a piece during a fight, or Ken, as you quite logically and reasonably point out, it could have even been effected by an orca (group?) attack.

A ripped out piece could then simply have sunk to the seafloor, without any “chasing down”. After settling on the seafloor, it lay there for a while (unfortunately, no info available as to for how long), before being swallowed (I’d rather not say “eaten”, see below) by either the same or another animal. Or, if it was the same shark it might have dived down with the chunk (and not the whole fish) in its jaw before finally tearing it apart and swallowing it later, undisturbed by any conspecifics, at greater depth. Or, the shark was killed(even by a boat could theoretically be an option – depending on the depth from where the “sudden plunge” started, but – again – no precise info given….) and sank – still complete – injured or dead to the seafloor.

So far so good, needs no giant predator to explain that, don’t you agree?

I will go even further and say, in the case the pop-up device had been mounted to a kind of base mount (which is done sometimes, but we don’t know here), it were even conceivable that it had been ripped out of the shark without killing the animal, just the plain instrument (prerequisite: negatively buoyant in that state). After dropping to the seafloor it could have been ingested by another animal.

Some questions which you might wish to ask at this point:

Question: But the shark must have actively been chased down, no other predator is swimming that fast?

Answer: Depending on the form and mass of a ripped out chunk, it could sink quite rapidly. Alternatively, a shark keeping the chunk in its mouth could have had the same effect. However, we are not presented with any facts, any sinking/diving rates. Neither to be found elsewhere.

Q: But the animation film clearly presents us a chase down the shelf slope.

A: The animation implies a trajectory, which may or may not have been provided by the device, since a horizontal geographic position could only be taken when at the surface. Unless other means were on board (such as e.g. 3-axis accelerometry which could facilitate a kind of reconstruction of the under-water trajectory), but which we are told nothing about. This shown trajectory might be purely for illustration (I’d rather not say fictional) and be simply derived from plotting depth over time. Therefore, the device could have likewise been dropped passively in the same spot where it had become detached from the shark. Let's assume it were indeed equipped with a 3D-Accel., then the high-res data would easily provide further insight, as to whether there was a fight at some point. Thereofre, I'd rather thiink that this sensor-option had not been on board.

Q: But which of the three discussed animal groups then you’d think could have accounted for the ingestion, you don’t believe it is a giant shark?

Answers:

1. Giant squid: No - No reports of elevated body temperature in squid (that I would know of) and very unlikely to be able to ingest the device as a whole due its particular mouthparts (beak). Ok, that has also been ruled out in the film quite quickly (but see below).
2. Orca – an easy and immediate No. Are not reported yet to dive that deep. And more importantly – would have very easily been identified from its particular dive pattern (regular surfacing for breathing) during the following 8 days. As well as the expected higher temp-level. Therefore, the question for the “killer whale” brought up in the film was purely for dramaturgical reasons, as it must have been clear from the first look at the data record – well….granted.
3. Shark. Most likely a Yes – due to the “behaviour”, and body temperature – BUT didn’t necessarily need to be a giant or even a large shark at all. A chunk of meat including the tag, as described above, could have been swallowed by any larger or even a smaller than 3-m shark. And it even need not be the same animal that was responsible for ripping it out in the first place.

Q: But given it was only the tag perhaps incl. a mounting base (therefore negatively buoyant) bar any flesh that had been ripped out and dropped to the floor – why would a shark want to “eat” that?!

Answers:

1. The electronics of that tag produces a magnetic field. Sharks are known for their highly developed senses for that. Evolution has given them the means for chasing prey even in the dark etc. by detecting the muscular activity of their prey species. This magnetic field could have caught the attention of another shark (whether giant, large or small)
2. Sharks have long been reported to swallow all kinds of non-digestible litter. So would be absolutely in the realms of the possible, no surprise at all.

There still remain a lot of questions to me, too, but as long as we are not presented with the original data, or at least a serious, documented analysis of it, but instead just this film footage, we have no chance to evaluate these statements and findings.

And that is the main issue here, when I say this doesn’t live up to any scientific standards.

All the statements made in the film could theoretically be in fact a valid case, I am denying nothing – but we are not given any proof for that at all, neither by this film or by any other supplementary statements.

And as for claiming the first record of giant squid in the area, that you mention, Ken, made by the team. Sorry, but that is bs. Again, could be, no arguing here, but not any proof given - mind you, a proof is a verified observation and not a guess:

We are simply shown a poor aerial photo showing a large, pale-coloured piece of “something” and a shark that is obviously preying upon or pulling with it. Could also be a leftover of a larger whale carcass that has been scavenged upon (there were a lot of feeding frenzies shown in the film). Later, we are shown an albatross feeding on a squid tentacle… huh, really??!! Normal food of these birds! The film making allusion to the giant squid, and this tentacle is a – well I won’t got so far and say “tiny” - but at least deriving from a smaller to intermediate sized species, certainly not a giant. Yes, they do not state it directly in the docu, but the dramaturgical setting and the closeness to the previous considerations lets the viewer suspect that this might in fact be a part of a giant squid – sorry, but this just isn’t honest journalistic documentation.

The whole film produces a dramaturgy catching for attention, no-holds-barred (hilarious the inclusion of the yarn spun by the two old whaler’s, just great ….). Understandable of course since this guy needs to sell his films, nothing wrong about that. And again – I am not saying this could not be the case. I am saying there are much more obvious and more simple explanations for it. Everything else still is speculation. While this all could be POSSIBLE – we are not presented with ANY PROOF supporting it.

Seriously, this film needs to be taken with a large grain, or let me say with a ‘chunk’, of salt. Smithsonian Institution presenting this in the way they did has lost a lot of its credibility to me.

Cheers

Paul

Hi Paul.

Many thanks for all the time and effort in the response. I suspect we are not that far apart on general thoughts, though there are a few things you mention that makes me still think we are working from slightly different versions (or to be honest, when I rewatched it yesterday, as I have seen it a few times, I was on the exercise bike so perhaps my concentration was not as focused as it should have been).

One point, you like the word ‘swallow’. I think one of things that the filmmaker did was try and convey, without ever saying so, that the shark was swallowed whole. Leave aside whether there might be creatures out there that could do that, I don’t see that here. But this might be just semantics.

And I think we agree both the journos and the filmmakers have used tactics and techniques which do neither credit. Again, leaving that aside. And I should say I still really enjoyed it.

I’ve never seen any suggestion that the tag lay motionless on the sea floor. And my understanding is that these things are recovered because they are so buoyant – though if attached to a large chunk of dead shark, it might have. Not certain if this one had any sort of homing beacon, though that would make sense, or if they just rely on those who find them turning them in. My version has always had the tag descending at speed – certainly far faster than the rate of just sinking, a change in temp and then spending around 8 days at a constant 26-ishC, not that far below the surface but then popped out and was found. The inference being it was crapped out and floated to shore.

I don’t know if the tag has to ‘surface’ to record its position – would seem odd in a fish that does not need to surface. But my impression was that there was no information being transmitted back at any time. My version suggests that they only get the info when they recover the tag.

My version has the tag descending at a far greater speed than would occur if it had come loose and sank. They left little doubt about that. I wondered if perhaps our shark had chased something (possible and then the tag came loose or it was then attacked after chasing something itself and lost the tag – this was never considered in my version). Don’t recall any specifics, other than it headed down at speed. My version also suggested an angle. If the tag can record without being on the surface, which was certainly the impression I gained, then they could presumably assess that it did descend at an angle. I would presume it does not need to surface as, for the following 8 days, they made the point that whatever had swallowed it did not come to the surface (one of the reasons for ruling out orcas).

Note your comments re a period of immobility. There was no suggestion of this in my version. We were certainly left with the understanding that the temperature change was fairly much immediate (unless, of course, my concentration wavered – always possible). Then it sat around the 26C 100 m below the surface. The suggestion was that it was possible that this could have been the temp if swallowed by a killer whale but unlikely. It was much more likely to be the temp in a big shark.

As for the comment re killer whales and the depths, we were told that the depth was certainly in the range commonly used by killer whales. As for the gigantism, yes, nothing in my version on that. Quite a bit on Mulga, the huge great white, which would have been more than big enough to do this, without any genetic defects.

I would agree that it is possible a smaller shark could have gobbled up a chunk of the shark after it was killed by something else. I would think it unlikely as we see, in an unrelated bit, even large great whites took off very quickly when Mulga turned up. I struggle to see them trying to pinch a chunk of our shark from Mulga or whatever shark, as they are just as likely to be dessert. And you don’t see that many small great whites around these regions. Self-preservation has them elsewhere. But yes, it could have been a frenzy of some kind, or possibly a smaller shark cleaning up after our shark was attacked by a big shark or an orca. But as I mentioned above, we were certainly given the impression that the tag pretty much went from our shark to the next one, without any time on the sea bottom. And if there is evidence of the tag on the bottom, it throws out everything we were shown. Would absolutely change things. In that case, it makes it considerably less likely that a ‘super predator’ was involved.

Agree re the shark’s propensity to eat anything and if the tag was on the floor, completely understandable. But as I mentioned, we were certainly led to believe that was never the case. And if it was, this is all moot.

You mentioned the mounting base. My version shows the tag being placed in the shark and there would appear to be nothing like that.

But I do agree that there remain questions.

Re the squid, my apols if I indicated “first sighting”. I did not mean first sighting there. My version has the expert not saying the photo was definitely a squid. He says either the biggest squid he has seen or something he does not know. My version has the killer whales attacking the “squid”, not a shark. So not sure if you got different footage or simply meant to say killer whale.

Completely agree re a chunk of whale carcass. That was my first thought when I first saw it. The piece of tentacle could be octopus, but reasonably large whatever – I guess everything relative. But certainly not conclusive. If from a squid, my version makes the point – actually does say so, hence why I really think we are still working from different versions – that it is either from a small squid or it is the tip of a tentacle of a much larger one. Could be either. Not final conclusion given.

From what I saw, you can’t draw any conclusions that are absolutely definitive. I think the evidence, as far as was presented, does suggest our shark was chased and killed by a larger creature, most likely a shark but possibly a killer whale. It was then eaten, or at least the part of it with the tag was eaten, by that creature or less likely, something else.

If this was a trial, you’d not get a ‘beyond reasonable doubt’ verdict, but I think you would get ‘on the balance of possibilities’.

[Bill Hayes]

Saw this doco today. My take on it was that they concluded that the tag most probably ended up inside a Great White Shark because of the temperature.They dramatised it and took us through some of the possibilities because it is a TV show for entertainment purposes. I enjoyed it and learned quite a bit. I think the most interesting part of it was the canyon with the seeping of nutrients could be the reason for the gathering of large predators to feed on squid...and that squid's brains are like doughnuts surrounding their beak. I have seen another doco about a similar area closer to the USA where sperm whales hunt the squid and white sharks stalk them to be lead to the squid.

[Fugu]

Hi Ken,

I have watched the version pointed to by Greg (btw thanks Greg!).

Ken, the problem here – as we now clearly see – is that we are forced to guess, make assumptions and discuss findings. Was there any clearcut published and conclusive data, everything would come without question.

The earlier version I saw months back clearly pointed out a halt, some kind of stop after the plunge. Be it or not, even if there wouldn’t be, that still doesn’t rule out that e.g. the dead shark could have plummeted down and was then – immediately or after a while – scavenged upon by other sharks. The point I am making here is a simple one: The animal that ingested the device needs not necessarily having been the cause of lady Alpha’s death.

Just for additional explanation, will address a few points you brought up. However, guess both of us won’t be able to convince each other, and I have no intention of doing so, since the poor documentation of data just doesn’t allows us to:

- Rate of descending during “plunge” – How rapid was it then? We are nowhere presented with a precise figure, just a spoken sentence of a sudden “quick” or “rapid plunge”, implying a rapid “chase”. In a swimming shark, even in a rapidly swimming one, vertical movements appear rather slow since the animal usually dives in comp. shallow angles. A vertical sinking of a ‘piece’ or a whole body (i.e. dead shark) could happen considerably quicker. From the plain depth recording such would appear – in comparison to the previous recording of the shark’s normal behaviour – rapid of course.

- Technology: Again - had it been published somewhere, everything would be clear to us. Now, we need to guess, which really is a nuisance.

The tag needs to surface occasionally in order to get a positional fixing. There is no way of doing so when permanently submerged. This is possible due to the shark’s particular behaviour of irregular surfacing, where at least the tip of the dorsal fin, not always but occasionally projects out of the water. The same does the antenna then. Data are being archived, no need to transmit, but a satellite contact needs being made for location fixing (like your mobile-GPS needs to). The track is then being interpolated between subsequent surfacings, resp. successful satellite contacts.

Would it be submerged all the time, the track would need to be reconstructed by vectorial analysis of some kind of 3D sensor (dead reckoning). Every yachtsman/woman among us knows that this is prone to considerable error propagation and such navigation does need some independent “groundtruthing” from time to time for full or partial correction. The errors of this vector addition will accumulate over time, and on top, drift from currents causing parallel offset and general displacements of the surrounding water mass may have to be corrected. Therefore, there is no way to reconstruct the route (thousands of miles!) like they did using such technique or such technique alone. But the main issue here is, it would be tricky to do so with a tethered device, since it has no fixed orientation with regard to the animal’s body.

Therefore that lets me assume they rather weren’t able to determine trajectory angles (both vertical and horizontal) in the diving animal. Again, someone show me the original data or at least point me to an original temperature and depth trace and I will happily reassess all what I’ve said.

The cold seep finding – yes, I also think that this is the true message of this story (but which gets somehow lost among the other supposedly more spectacular stuff mixed in). Although, the phenomenon itself is nothing but new and even not a very uncommon phenomenon.

As Bill just pointed out, yes, I agree we should take it as entertainment, nothing more, nothing less, with a touch of science behind it. I am not dismissing that they put a hughe amount of labour and passion into that project.

I will leave it at that, Ken. But will be happy to discuss particular aspects even further per PM, if you wish, in order not to bore other members with lengthy excursions.

For those of you interested in nature documentaries – just yesterday the exceptional BBC docu ‘Earthflight’ by John Downer appeared again on TV (sorry no free-version to be found). There is a short, about 1.5-hour version, but the original series consists of six parts covering all continents. Breathtaking highspeed and wide-angle closeup pictures in flight (and for those interested in fish and fishing – even quite a few fish-eating species there - well, Ken I guess you will know this one). Really worthwhile watching for those who haven’t seen it yet.

Paul

[Bill Hayes]

I don't believe the cold seep finding gets lost. The whole show builds to it's discovery. Yes, there are many other cold seep findings that have been discovered but they found another one to study where predators seem to congregate on a regular basis perhaps. The presenter, if I remember correctly, makes quite a point about this being important. If the seeping was revealed in the first minute of the show, it wouldn't be all that entertaining to the general public. The data might have gaps, causing a range of conclusions but in my opinion it is an entertaining and worthwhile documentary that helps us pose a few questions and open a few eyes on the habits of ocean predators. Good discussion. Cheers.

[Fugu]

Alright Bill. If you got the impression nothing is lost the better. Perhaps it’s just me due to having concentrated a wee bit too much on the mysterious predator thing and seeing that a bit more critical than others would do. Regrettably, only that was what all the media-fuzz was about. One cannot completely acquit the authors of fuelling that. But obviously that’s part of the game today. Cheers mate.

[Ken Gargett]

Hi Ken,

I have watched the version pointed to by Greg (btw thanks Greg!).

Ken, the problem here – as we now clearly see – is that we are forced to guess, make assumptions and discuss findings. Was there any clearcut published and conclusive data, everything would come without question.

The earlier version I saw months back clearly pointed out a halt, some kind of stop after the plunge. Be it or not, even if there wouldn’t be, that still doesn’t rule out that e.g. the dead shark could have plummeted down and was then – immediately or after a while – scavenged upon by other sharks. The point I am making here is a simple one: The animal that ingested the device needs not necessarily having been the cause of lady Alpha’s death.

Just for additional explanation, will address a few points you brought up. However, guess both of us won’t be able to convince each other, and I have no intention of doing so, since the poor documentation of data just doesn’t allows us to:

- Rate of descending during “plunge” – How rapid was it then? We are nowhere presented with a precise figure, just a spoken sentence of a sudden “quick” or “rapid plunge”, implying a rapid “chase”. In a swimming shark, even in a rapidly swimming one, vertical movements appear rather slow since the animal usually dives in comp. shallow angles. A vertical sinking of a ‘piece’ or a whole body (i.e. dead shark) could happen considerably quicker. From the plain depth recording such would appear – in comparison to the previous recording of the shark’s normal behaviour – rapid of course.

- Technology: Again - had it been published somewhere, everything would be clear to us. Now, we need to guess, which really is a nuisance.

The tag needs to surface occasionally in order to get a positional fixing. There is no way of doing so when permanently submerged. This is possible due to the shark’s particular behaviour of irregular surfacing, where at least the tip of the dorsal fin, not always but occasionally projects out of the water. The same does the antenna then. Data are being archived, no need to transmit, but a satellite contact needs being made for location fixing (like your mobile-GPS needs to). The track is then being interpolated between subsequent surfacings, resp. successful satellite contacts.

Would it be submerged all the time, the track would need to be reconstructed by vectorial analysis of some kind of 3D sensor (dead reckoning). Every yachtsman/woman among us knows that this is prone to considerable error propagation and such navigation does need some independent “groundtruthing” from time to time for full or partial correction. The errors of this vector addition will accumulate over time, and on top, drift from currents causing parallel offset and general displacements of the surrounding water mass may have to be corrected. Therefore, there is no way to reconstruct the route (thousands of miles!) like they did using such technique or such technique alone. But the main issue here is, it would be tricky to do so with a tethered device, since it has no fixed orientation with regard to the animal’s body.

Therefore that lets me assume they rather weren’t able to determine trajectory angles (both vertical and horizontal) in the diving animal. Again, someone show me the original data or at least point me to an original temperature and depth trace and I will happily reassess all what I’ve said.

The cold seep finding – yes, I also think that this is the true message of this story (but which gets somehow lost among the other supposedly more spectacular stuff mixed in). Although, the phenomenon itself is nothing but new and even not a very uncommon phenomenon.

As Bill just pointed out, yes, I agree we should take it as entertainment, nothing more, nothing less, with a touch of science behind it. I am not dismissing that they put a hughe amount of labour and passion into that project.

I will leave it at that, Ken. But will be happy to discuss particular aspects even further per PM, if you wish, in order not to bore other members with lengthy excursions.

For those of you interested in nature documentaries – just yesterday the exceptional BBC docu ‘Earthflight’ by John Downer appeared again on TV (sorry no free-version to be found). There is a short, about 1.5-hour version, but the original series consists of six parts covering all continents. Breathtaking highspeed and wide-angle closeup pictures in flight (and for those interested in fish and fishing – even quite a few fish-eating species there - well, Ken I guess you will know this one). Really worthwhile watching for those who haven’t seen it yet.

Paul

hi paul

not so much a matter of convincing me - i think i know exactly what you are saying and i have no issue with it.

it may be that there was not so much pure scientific data included because they didn't have it, which would be disappointing, or because the filmmakers felt that going too much down that track robs the film of some of its drama and makes it less saleable.

if nothing else, i suspect one aim has been achieved - getting people interested in what did happen.