science/2018-12-14/even-fish-get-the-bends,-and-they-get-it-worse-than-humans

good article here in the west ,

worth a read as a reminder on dhuie survival and potential mortality rates when people keep on demersal fishing and releasing them thinking its all ok ...

https://www.abc.net.au/news/science/2018-12-14/even-fish-get-the-bends,-and-they-get-it-worse-than-humans/10612410?section=science

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OFW 11

evil flourishes when good men do nothing

 


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Interesting

Sun, 2018-12-16 13:48

So after reading that it would make sense to drop size limits and keep what you catch first? 

carnarvonite's picture

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Release weights

Sun, 2018-12-16 17:39

 All release weights do is take the fish back to the bottom, out of sight, where it dies and becomes food for other fish.

Bring you fish up very slowly and hope that this does the trick

Faulkner Family's picture

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 What john said is same as

Sun, 2018-12-16 17:47

 What john said is same as what i think. I have been told if you stop at about 15 mtrs for a minuit it can help . But who knows. I feel once you got your limit of demersal go chase other species that arent . 

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RUSS and SANDY. A family that fishes together stays together

tot's picture

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Tagging

Sun, 2018-12-16 18:19

So what about the years and years of work people have done with tagging?

Fish being recaptured more than once long periods of time after and still going strong?

Vented fish recaptures also.

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Faulkner Family's picture

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 you got a point. maybe its

Sun, 2018-12-16 18:42

 you got a point. maybe its got something to do with depths the fish came from. most of the tagging ive heard about the fish were from shallowish waters, also how fast was the fish reeled up.

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RUSS and SANDY. A family that fishes together stays together

Taffy's picture

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Dead Right tot

Sun, 2018-12-16 19:29

 Dead Right Tot, i remember Paul G posts on several Recaptures of Tagged Dhu fish,

And As John Said above , just bring them up slowley,and at least give them a chance on the Release weight

Meeuwissen's picture

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I like the attitude they have in the N.T

Sun, 2018-12-16 19:03

 

Signs of barotrauma

In waters deeper than 10m, most fish with any of the following symptoms are unlikely to be fit for release:

  • the fish’s stomach is pushed out through its mouth
  • the fish has a bloated stomach and bulging eyes
  • the fish can't swim down from the surface.
Ways to reduce barotrauma

You should follow all of these guidelines to prevent barotrauma when reef fishing in water deeper than 10m:

  • stop fishing if you have caught enough for your needs
  • target species such as barramundi or trevally that are less prone to barotrauma
  • keep reef fish you catch, within the possession limit, as they are unlikely to survive if released
  • change locations if you keep catching juvenile or unwanted reef fish
  • use large non-offset circle hooks, a minimum of 5/0, to prevent catching smaller fish.

If you are on a charter boat and you don't want to keep the fish, ask the skipper to target fish species that are suited to catch and release and are less likely to suffer from barotrauma.

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Stay salty

Pete F's picture

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 Very good

Mon, 2018-12-17 09:12

 Very good recommendations. 

 It is just wrong to continue to catch and release demersals, unless your fishing very shallow. You can see so much difference in the fish when you catch in less than 15 meters the fish are so much more athletic at the boat. You can get them to the boat and when they see it go all the way back down. 

Please do read the article and take it on board if you are fishing deep a slow retrieve or pause dose not do that much, I used to collect aquarium fishes and we found 45 minute deco stops were required from depths of 15 meters for some species to reduce the mortality's. There is a lot going on than just a fish swimming of it can have displaced organs etc. Baldchin stomach and intestines are a classic they might swim off or not float back up but a lot are cactus. 

Catch your bag and then go chase something else.

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 Cheers Treky

Jackalchub's picture

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I tagged a dhu before the ban

Sun, 2018-12-16 19:35

I tagged a dhu before the ban on an isolated lump.. sand for miles either way.. in 18m.. had a dive there the other day and found a school of 4 dhus.. one of them tagged, same size -  what are the chances. I’m not sure of percentage survival rates - but I know Steve Wiseman from westag has had a lot of recaptures.. I’d be pretty hesitant to say release weights don’t work.. caring for a fish before release can go a long way. 

sunshine's picture

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As any diver on here will tell you

Mon, 2018-12-17 06:46

The greatest pressure change is between the surface and 10 metres where the pressure doubles hence it is critical that you retrieve fish as slow as possible as they near the surface, generally you can almost see what you have with the clarity of our waters at that depth in any event.  Release weights work, absolutely no question in my mind but care of your fish is equally critical to their survival, don't drop them on a hot deck while you remove the hooks ....just basic care will greatly improve survival ! 

Pete F's picture

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 The gasses within the fish

Mon, 2018-12-17 09:16

 The gasses within the fish double every 10 meters, not just the last ten and the pressure increases by the same amount every ten meters of depth. 

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 Cheers Treky

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50%

Mon, 2018-12-17 07:26

 They are not saying dhu's do not survive release...some do survive...but 50% die. That is what you want to take note of. Pretty heavy. And yes in a perfect world you can bring them up slow, give them a deco if you think that is going to help..but generally it aint a perfect world out there with wind and currents, different levels of experience, jigging....watch and video...I do not see too many anglers taking it easy...etc etc. Even when you take it slow they sometimes come up knackered.

 

 

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As a scientific based person

Mon, 2018-12-17 07:55

don't like anecdotes as there is no proof, but always listen to people in the know. A couple of Pro Snapper fisherman that also charters paying customers of Denham had some interesting points and in their experience most released fish from deeper water don't survive.
They and others believe that less fish will die if a no size limit but keep your quota rule would improve their fishery and that is in their interest.
I argued that there would always be the element of upsizing and dumping the smaller already dead small fish.
It would be very hard to police a rule such as this.
But anything that sustains such a precious fishery as we have down here and in Northern WA surely is in the interest of us all.
Don't personally chase "true" demersals down here as I like whiting way to much!!! To me its like ICE to a former Eagle!!!

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little johnny's picture

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Stop if you don't want it

Mon, 2018-12-17 08:49

( once you have visual). Put in rod holder crack a beer or soft drink . 5 mins later bang rod starts bouncing full of life. Never fails they swim from top. I still carry release led in case.

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 Great post HezzyWow -  this

Mon, 2018-12-17 10:46

 Great post Hezzy

Wow -  this all sounds very familiar. Glad to see you haven't been shouted down on this one mate. Those who think dhufish stocks are at a healthy sustainable level - think again. Lots of juvenile Dhuies doesn't mean a healthy biomass - loss of main breeders 10kg + combined with lots of small fish are first signs of species decline.

Johnny 

Like your method of release / decompression. Not a big fan of release weights, but better than nothing.

Gunner

hezzy's picture

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gunner this has concerned me

Mon, 2018-12-17 13:03

gunner this has concerned me for a long time ,

the creeping perception among some fishers that dhuies in particular are surviving at higher rates than can be proved and that anecdotal evidence from a small % of dhuies that do get recaptured later is skewed proof all is well

i understand not all fishers do this or may have this perception , but time and time again we keep seeing videos posted up of fishers pumping dhuies to the top and follwoed by a write up of how many they caught and let go

education here is important ,and id like to see more done around that

there is a % of fishers who do take great care in thei handling & release techniques with dhuies and they shouild be applauded for doing so

but many others are not so well handled or released and if people where brutally honest they would know mnay get released out of sight to die within the week

this will impact recs as its increasing the mortality rate of dhuies above what it could be if people generally changed their practices when demersal fishing &
it is contributing to recs tac of demersals even though most wont be aware of that fact that mortality of released dhuis is being estimated and added each year

the current rules on size limits may well need to be re visited and see what recs prefer ,as up against the mortality info we have that is science fact backed

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OFW 11

evil flourishes when good men do nothing