Barotrauma

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Yesterday I had a large pork roast which left me feeling and probably looking quite bloated. Is this the same as barotrauma. If I was to be released outside and made to run shortly after this traumatic event, I probably wouldn't have survived.
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Unchilled quart bottles of Lion Red used to have the same affect on me. I've learned a little bitsince those days.  I've also learned a little bit about barotrauma and the smart money seems to say don't release fish caught from deep water.  
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I have one other example of barotrauma
About six months ago during a concrete pour, the young fulla (numpty) was told to ask the driver to back up a bit. Numpty left the wheelbarrow right behind the truck in his blind spot. The obvious result was some serious barrowtrauma.
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Originally posted by Coutta Coutta wrote:

I've also learned a little bit about barotrauma and the smart money seems to say don't release fish caught from deep water.  

That maybe so however I have pulled snapper up from 220-240m and they have shown no signs of barotrauma and have released well. On the other hand I have pulled similarly sized snapper (50-60cm) from 40-50m and they have suffered the effects of barotrauma.
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Originally posted by kitno kitno wrote:

I have one other example of barotrauma
About six months ago during a concrete pour, the young fulla (numpty) was told to ask the driver to back up a bit. Numpty left the wheelbarrow right behind the truck in his blind spot. The obvious result was some serious barrowtrauma.


hahaha, 9/10 for that LOL
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I'll pay that one too Kitno. But Fish Addict, most will swim away but how long did they last after that.  Bit hard to see 240 metres down. Bit like tow vehicle, lets just all have our own opinions and hope nothing breaks down.
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Originally posted by Coutta Coutta wrote:

But Fish Addict, most will swim away but how long did they last after that. 

Neither you nor I know the answer to that. The point I was trying to make was that some fish appear to be able to cope with barotrauma better than others irrespective of depth. Snapper are certainly a lot hardier than some other sought after species here in WA. How about your kingfish, we regularly see them being spiked back in, are they also casualties? Again, I don't believe you or I or the so-called scientific experts can conclusively say one way or the other.
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I was watching a fishing show here in the states and they where catching what looked like hapuka but smaller they were up in Seattle area, when they caught a type of fish that had to be released they had a release mechanism that they clipped onto the fishes mouth and sent it down on a weighted rod, the guy was saying it’s 90% effective to for survival, they were in 100+m of water I was quite impressed with the whole deep release.
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Originally posted by Fish Addict Fish Addict wrote:

 How about your kingfish, we regularly see them being spiked back in, are they also casualties? Again, I don't believe you or I or the so-called scientific experts can conclusively say one way or the other.

I don't worry about kingfish at all, based on the fact that I've never had to spend any time "reviving" one that I've released. When diving with them, I've seen them change depths very fast when chasing baitfish. It seems like something they are built to do. 

You are right, none of us know for sure what really happens. You can only base your opinion on scientific evidence, as weak/strong as it may be, personal experience and common sense. 
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Originally posted by viscount viscount wrote:

I was watching a fishing show here in the states and they where catching what looked like hapuka but smaller they were up in Seattle area, when they caught a type of fish that had to be released they had a release mechanism that they clipped onto the fishes mouth and sent it down on a weighted rod, the guy was saying it’s 90% effective to for survival, they were in 100+m of water I was quite impressed with the whole deep release.

I saw release weights being used in WA when fishing for dhu fish. Like you, I was also impressed. Not so sure now. If you are dead set on releasing a fish caught in deep water, then a release weight is probably a good idea. The point that I made earlier still stands though, recompression doesn't mean reversal of barotrauma. 
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Originally posted by Fish Addict Fish Addict wrote:

 ..some fish appear to be able to cope with barotrauma better than others...

With the pressure change from 200+m to the surface, the increase in volume of any gas filled cavities is so great they have probably burst, rather than just inflated. The critical word in your comment above is 'appear'

How about your kingfish, we regularly see them being spiked back in, are they also casualties? 

Although Kingfish have swim bladders, they have evolved a completely different feeding style that involves regular rapid changes in depth. Undoubtedly some are casualties, but probably not due to barotrauma. Possibly their swim bladders can be physically vented rather than the gas needing to be reabsorbed. Jack Macks used as livebaits are similarly unaffected by multiple trips involving hundreds of metres of depth change.

Again, I don't believe you or I or the so-called scientific experts can conclusively say one way or the other.

Correct, but if the scientific evidence mostly starts pointing in the same direction, you need a fairly compelling reason to ignore it.

Just out of curiosity, why are you releasing 50-60cm snapper pulled up from 200m+ ? WA fishing rules ?

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As those of you who dive will know the percentage change in pressure should be considered too.  every 10m depth of water is equivalent to 1 atmosphere pressure.  eg. Pull a fish up quickly from 10m to the surface and the pressure on the fish halves.  Pull it up from 40m to 30m and the percentage pressure change is only 20%.

Fish survival after release: I recall seeing a write up of a study where fish caught were placed in cages at depth so they could judge medium term survival rather than "it swam away" results.  I don't have links to it now but if I recall correctly the medium-term survival was not good (and I think they included fish that had their swim bladders spiked too).  The study wasn't on snapper - but I think it was a relative ...

Personally - I keep all the fish I catch and avoid the undersized ones.  (but that's because most of my fishing involves seeing the fish first and then putting 6mm or 7mm steel shafts through it so it's not so practical to release).


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I like the scientific study. In summary - No mortality if released from 21m or less. Great news. 2 in every 100 fish released from 30m die. Over 30m it increases dramatically to almost half. 
On that basis, anything coming up from 30m+ should be kept if legal. If it's 20-30m and the fish appears healthy, I think it can reasonably be expected to survive. 

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Originally posted by JW JW wrote:

I like the scientific study. In summary - No mortlaity if released from 21m or less. Great news. 2 in every 100 fish released from 30m die. Over 30m it increases dramatically to almost half. 
On that basis, anything coming up from 30m+ should be kept if legal. If it's 20-30m and the fish appears healthy, I think it can reasonably be expected to survive.

I think that is balanced and sensible based on what we know. Those numbers are pretty much what I use as well. 
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Originally posted by waynorth waynorth wrote:

Originally posted by Fish Addict Fish Addict wrote:

 ..some fish appear to be able to cope with barotrauma better than others...

With the pressure change from 200+m to the surface, the increase in volume of any gas filled cavities is so great they have probably burst, rather than just inflated. The critical word in your comment above is 'appear'

How about your kingfish, we regularly see them being spiked back in, are they also casualties? 

[COLOR=#0000ff]Although Kingfish have swim bladders, they have evolved a completely different feeding style that involves regular rapid changes in depth. <span style="color: rgb0, 0, 255;]Undoubtedly some are casualties, but probably not due to barotrauma. </span><span style="color: rgb0, 0, 255;]Possibly their swim bladders can be physically vented rather than the gas needing to be reabsorbed. Jack Macks used as livebaits are similarly unaffected by multiple trips involving hundreds of metres of depth change.</span>[/COLOR]
<span style="color: rgb0, 0, 255;">
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Again, I don't believe you or I or the so-called scientific experts can conclusively say one way or the other.

Correct, but if the scientific evidence mostly starts pointing in the same direction, you need a fairly compelling reason to ignore it.

Just out of curiosity, why are you releasing 50-60cm snapper pulled up from 200m+ ? WA fishing rules ?




Responding to your comments:
With the pressure change from 200+m to the surface, the increase in volume of any gas filled cavities is so great they have probably burst, rather than just inflated. The critical word in your comment above is 'appear'
The key word in your response is 'probably'.

Although Kingfish have swim bladders, they have evolved a completely different feeding style that involves regular rapid changes in depth. Undoubtedly some are casualties, but probably not due to barotrauma. Possibly their swim bladders can be physically vented rather than the gas needing to be reabsorbed. Jack Macks used as livebaits are similarly unaffected by multiple trips involving hundreds of metres of depth change.
The key words in your response are 'probably' and 'possibly'.
Here in WA we have a close relative of the NZ yellowtail kingfish, the samson fish (Seriola hippos). Similar to your kingies these have a swim bladder vent near the back of the fishes mouth which allows the expanding gases from the swim bladder to escape. The samson fish or sambos as we call them don't release as well as your kingies despite being closely related. Release weights in WA are mandatory but you need a heavy release weight of 2-2.5kg to get a big sambo down to depth again. Do they survive?

Correct, but if the scientific evidence mostly starts pointing in the same direction, you need a fairly compelling reason to ignore it.
I am rather sceptical of some scientific evidence as it appears to me that the evidence is so easily manufactured to produce the desired result. I'll give you an example. Some years ago a survey was done by a very GREEN minded university professor here in WA. The survey was to determine WA dhufish numbers. These fish are very much sought after as a table fish and are endemic to a relatively short length of the WA coastline. They frequent areas where structure exists and flat corals. The survey consisted of setting up a number of fish traps and cameras on the seabed and the conclusion reached was that WA dhufish numbers were in serious decline and that recreational and commercial take must be reduced significantly. It was only later that the location of the fish traps and cameras was made known. Many were placed on fish deserts well away from structure or corals. Clearly the placement of the traps and cameras were set to achieve the desired result.
The positive from this research however was that the pros were prohibited from fishing in an area approx. 100km north and 100km south of Perth. Within a year or so of this coming into effect the numbers of WA dhufish, snapper and other sought after species increased noticeably.


Just out of curiosity, why are you releasing 50-60cm snapper pulled up from 200m+ ? WA fishing rules ?
The snapper are by-catch. The target species in the 220-240m depths I mentioned is what we refer to as Greyband, or more correctly called Eight Bar Cod or Eight Bar Grouper. WA fishing regulations allow each angler only two greyband per day or two snapper per day. The average sized greyband is in the 10-25kg range so these are more sought after to give some value for the 40nm each way trip.
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Post Options Post Options   Likes (0) Likes(0)   Quote Muppet Quote  Post ReplyReply Direct Link To This Post Posted: 07 Aug 2018 at 5:21pm
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How is that I have seen snapper intercept baits from 20m+ at 7-5m? It has taken literally two seconds for them to do it in, my friends who kayak fish with me will attest to what I see and how I catch them. I am not the only one either other kayak fisherman up north who catch them in deep water see them rise much higher in a very short span of time. In fact these are the guys who infuenced my way of fishing.   
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That's the great thing about the scientific method Fish Addict - when you publish, you then have your research scrutinised by others with similar expertise. Peer review will quickly identify flaws in your methodology, findings, or conclusions - even in your motivation, as may have been the case in the example you gave above. The real problem arises when different experiments - equally rigorous, all peer reviewed - produce different results. 

Sometimes, a meta-analysis of multiple relevant experiments can show a clear trend, as my admittedly semi-scientific research did. I found only one that bucked the trend, & I didn't include it above as it was from a popular sport fishing magazine & clearly lacked the scientific gravitas of the other studies. 

I'm not a marine biologist so I can't state as a fact that a snapper's swim bladder inflated to 20 times it's original volume will burst, but I suspect it probably (there's that word again) will. Nor do I know how kingfish, jack macks, or even Muppet's snapper manage to change depth so rapidly without damage. Possibly (there's another one) they don't bother filling their swim bladder when they are actively hunting, relying instead on water flow over their pectorals to provide lift. 

Just my thoughts, opinions, observations, research - all tossed out there for others to accept or reject as they will.  

Good luck with those Greybands.
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Maybe the fish get blown up in the process of doing everything they can to shake the effects of being hooked. Just a bodily function(reaction) just like when they **** and piss and even spurt out eggs or milt just before they do or may be about to die. 

  
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As good an explanation as any Muppet. More questions than answers here.
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