Tuna Cnr

Nick Clayton

WFF Supporter
In some of our discussions about fly fishing for tuna there has been some discussion about the practice of cnr with these fish and whether or not the fish could handle it.

Anyway, I came across this video today and thought it was pretty interesting. Not trying to make any definitive conclusions one way or another here, just thought this video was interesting and thought maybe some others would too.

 
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mbowers

Active Member
In some of our discussions about fly fishing for tuna there has been some discussion about the practice of cnr with these fish and whether or not the fish could handle it.

Anyway, I came across this video today and thought it was pretty interesting. Not trying to make any definitely conclusions one way or another here, just thought this video was interesting and thought maybe some others would too.

You beat me to posting that! :)

My take away was 7 out of 22 tags were a dead fish or no response (I'd guess tag sank with dead fish or was damaged by predators) so about 30% of fish did not survive..
 

Nick Clayton

WFF Supporter
Yeah I suppose one of the problems with this sort of study is there is little way to determine what the actual cause of death is for any fish that is released and eventually dies. The one fish he mentioned that he thought it was most likely eaten by a shark based on a spike in temperature in the tag that made him believe it was inside the stomach of a shark. Of course he then mentions wondering if the act of catching and releasing a fish could have consequences that result in it being easier prey for a predator. Who knows.

Interesting stuff, and cool to see someone studying this even if it's not a huge sample size and some of the results
 

mbowers

Active Member
Yeah I suppose one of the problems with this sort of study is there is little way to determine what the actual cause of death is for any fish that is released and eventually dies. The one fish he mentioned that he thought it was most likely eaten by a shark based on a spike in temperature in the tag that made him believe it was inside the stomach of a shark. Of course he then mentions wondering if the act of catching and releasing a fish could have consequences that result in it being easier prey for a predator. Who knows.

Interesting stuff, and cool to see someone studying this even if it's not a huge sample size and some of the results
Why could the fish not have been eaten by a bigger BFT? They're warm blooded too!

I'm fine with death in first 2 days attributed to catch and release and anything else considered normal. If the fish that was eaten after 3 weeks needs an interaction with humans cause of death I would blame that on the fact it had a tag to carry (extra drag, infection?) which is NOT the fault on CNR but just part of doing science..

I did not like to see lip gaffing suggested as good CNR practice: perhaps necessary for tagging tho. Dehooker or even better light wire barbless hooks that bend out is the way to go IMHO!
 

SilverFly

Active Member
Can't view the video on my work computer either (fun filters) but CnR with albacore would be a nice option if the mortality was low enough.

For me kill/no-kill depends on the type of trip. There is a definite meat aspect to this fishery but I'd prefer stocking my pantry on a live bait trip. On a fly trip, I'd rather focus on enjoying the fishing and not have to deal with processing a ton of fish on board and filleting back in port. IF we can CnR with some confidence of survival, it would be nice to set a mutually agreed boat limit based on how much everyone is looking to take home. Not that that was a problem last year.

And yes, I think a de-hooking tool would be best so the fish never left the water.
 

DimeBrite

5X Celebrity Jeopardy Champion
Those 7 tags failed to transmit data. That does not mean the tuna died after release.

You beat me to posting that! :)

My take away was 7 out of 22 tags were a dead fish or no response (I'd guess tag sank with dead fish or was damaged by predators) so about 30% of fish did not survive..
 

mbowers

Active Member
Those 7 tags failed to transmit data. That does not mean the tuna died after release.
No it doesn't. I think it was 6 that did not transmit. But the alternative to death on release is the program spent all that time and money on satellite tagging and the tags are only 70% reliable. That seems like a pretty stupid scientifuc method. :) (spelling error left for dramatic effect)
 

Chucker

Chucking a dead parrot on a piece of string!
No it doesn't. I think it was 6 that did not transmit. But the alternative to death on release is the program spent all that time and money on satellite tagging and the tags are only 70% reliable. That seems like a pretty stupid scientifuc method. :) (spelling error left for dramatic effect)

If you can come up with a better way, then I am sure people would like to know!

Having not read the study, I don't know exactly the capabilities of the tags they used, but they likely had a built in pressure release so that the tag would pop up if the fish died and sank straight away, as well as a timed release for tracking.

The main problems with non response from PSAT tags seem to be that they get stuff growing on them that stops them from floating and transmitting data to the satellite. Or they get eaten. In this case they probably had a short tracking duration to get by the first problem so maybe all those other tags were munched!

What I did notice in the video was a lack of sterile technique when they attached the tags. They made a big hole in those fish!
 

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