29 replies to this topic

[bmyates]

When sharks are angry they "arch" their backs and turn the pectoral fins down. This is known as the threatening behavior. They do it just before an attack. I've seen it before, when I had a bag of fish hanging behind me, and believe me, you don't want to see it.

I've attended numerous shark feeds, and the only time I've seen the arched back and downturned pectoral fins was in Kavieng, PNG, when a few of the silvertips assumed that posture as they came in for chunks of fish. In all other instances, they just swim in and grab some fish/chum, but didn't act like they were having to be "aggressive" to do so. In most cases, sharks are aware they are the apex predators in that situation, and don't seem to feel a need to prove it... Of course, that's just my experience.

[Rocha]

I've attended numerous shark feeds, and the only time I've seen the arched back and downturned pectoral fins was in Kavieng, PNG, when a few of the silvertips assumed that posture as they came in for chunks of fish. In all other instances, they just swim in and grab some fish/chum, but didn't act like they were having to be "aggressive" to do so. In most cases, sharks are aware they are the apex predators in that situation, and don't seem to feel a need to prove it... Of course, that's just my experience.

Yes, I agree, the behavior is so rare that I couldn't find a photo floating around the net to link to it here. I also only saw it once, in Cocos Keeling, when I had a bag of dead fish behind me and didn't want to let go of it

Maybe that's why the rules say they disqualify this kind of photo, it takes some provocation to get them in that stage.

[MikeVeitch]

actually, i have probably been in the water with as many sharks as anyone else here over the years and i have seen threat behaviour exactly twice.

And let me tell you, it is nothing like the behaviour you see in a shark feed. Both times it was with grey reef sharks. Sure you see the fins down etc on shark feeds when they are moving fast and trying to get the food, but.... it is soooo different from the real thing.

First time was at an island in the Tuamotus that we had only been to twice, as we were leaving the edge of the pass one of the greys went into "threat posturing" I thought i had seen that fins down posture during feeds.. but this?!? WAY Different.

Shark swam almost at standstill speed, fins way down, nose and back waaaaay up... and swimming in a perfect figure 8. I have never seen a shark move so slowly.. of course i didn't have a video camera and didn't want to get too close with the still. Some crazy people tried to get close but we got them away.

Second time, during mating season in Rangiroa, once again that amazing slow swimming and arched back. But then... we were at around 90 feet, it shot straight to the surface and straight back down, surface, down etc etc. I got the hell out of there faster than i ever have. That was the one and only time i have been afraid of being attacked, quite scary and gave a new found respect for sharks from someone who was invoved in daily feedings.. I thought i had seen sharks move fast before during feeds... NOTHING like this one...

I don't really want to see it again either cuz there was no way i would have had time to get my camera up to protect myself in that situation if it had shot at me instead of the surface.

[Jeremy Stafford-Deitsch]

Hi All,
John Bantin asked me to clarify the Shark Trust photo comp rules. I didn't write them - they were forwarded to me for comments last week. My comments, basically were:-

I presume it's fine for sharks to have been attracted in with bait and/or fed. The ST produced, years ago, a code of conduct for responsible shark feeding (common sense stuff, really). What we don't want (I presume...) is the sort of jaw-gape devilfish-from-hell image that hardly contributes to conservation initiatives.

I am hoping the requirement for large file sizes is dropped (unlikely) because then the point-and-shoot photographers can enter also, but we will see.

MV describes very well the full agonistic display of the Pacific-island-based grey reef shark. It appears to be most pronounced in sharks around these remote oceanic islands. However, there is discussion about how this behaviour relates to other swimming patterns of both the grey reef and other species of shark: various agonistic displays have been seen (or interpreted) in half a dozen (or more) species with the grey reef shark having, apparently, the most extreme form.

An excited shark will tense up and lower its pectoral fins not least as an aid to greater manoeuvrability. This, presumably, has an evolutionary connection with the fight/flight response. The question then is when other sharks lower their pecs or swim in cranky ways, is this also threat-display behaviour?


Jeremy Stafford-Deitsch.

[Scuba_SI]

This is the closest i can find to posturing, about 3 milliseconds later it was 150 feet away snarling at us from afar

Same as MV, a place where they don't see divers too often and i might have had a tuna head or two in my bc

not a good image, but as Rocha said there's not a lot of images of this behaviour, and i dont really want to see it again! That said, if you do see it, push a frenchman in front of you, sharks seem to like biting them!

Totally my fault and not their common behaviour

[Jeremy Stafford-Deitsch]

The entry info for the Shark Trust shark photo competition has been tweaked. Click on 'Photo Competition' on the left of the home page www.sharktrust.org for clarified info. Let's see if the digital brigade can match the soft focus, blurred and improperly exposed photos of the film generation...

There's a good essay on agonism in sharks on (tragically, recently deceased) Aidan Martin's web page here:

http://www.elasmo-re...s/b_agonism.htm

JSD.

[Gudge]

Yes, I agree, the behavior is so rare that I couldn't find a photo floating around the net to link to it here. I also only saw it once, in Cocos Keeling, when I had a bag of dead fish behind me and didn't want to let go of it

I've only seen the behaviour once as well and that was in Cocos (Keeling) too but I didn't have a bag of fish anywhere near me. I managed to get one shot, the shark in the background is happy the one in the foreground is definitely not happy:

[Jeremy Stafford-Deitsch]

...Just heard the file size has been downgraded to A4 @ 300 dpi which should open things up to more photographers.

[DeanB]

1st, I wish I could take piccies, but alas I'm a wee filmmaker

2nd, Just like to say well done to Jeremy for all his hard work. Nether yet had the chance to meet you sir, but I would gladly by you a beer and really everyone else (if i could afford it) who fights the battle for the beautiful creature that is, shark...

Dive safe (and keep your fingers)

DeanB

[SimonSpear]

...Just heard the file size has been downgraded to A4 @ 300 dpi which should open things up to more photographers.

That's a good move in my opinion, especially as the competition is aimed at as wide an audience as possible. There's no point using it as a tool to get people engaged in Shark issues and then excluding 90% of them by requiring a image that most would find it impossible to submit.

It should be a really good comp - I can't wait to see the finalists!

Cheers, Simon