Subject: Tuna and Marlin

From: [email-masked] (CKIII)
Date: 28 Aug 1995 08:47:44 -0400

I was recently told that Tuna and Marlin species will die within a few
days once the fish has been caught by hook and line even though it is
released quickly and appears in "good shape".  The reason given was a
build up of an enzyme during the landing fight that will soon prove fatal
to the fish.  Any comments on the scientific accuracy of this comment, or
was this a farsical answer to the catch-and-release practices of many of
the blue water sport fishers?

Charles Kennemore
[email-masked]

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From: Steven Poet <[email-masked]>
Date: 28 Aug 1995 16:38:14 GMT

My understanding is that if you fight anything to complete exhaustion
and then throw it back, its chances of survival are pretty slim.  That's
why they say do not fight trout for very long if you are going to 
release them.  FWIW, The enzyme is probably CK (creatine kinase)
and in mammals is an indicator of muscle tissue break down.
The muscle break down products wreak havoc with the kidneys and
can lead to death (this is basically what happens with
"downer cow syndrome").

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From: [email-masked] (Steve Kaimmer)
Date: Mon, 28 Aug 95 13:18:43

We have done work with Pacific Halibut caught in trawl nets in the 
North Pacific.  Background, from camera work we know that Halibut may 
swim ahead of the trawl for 30 minutes or more before 'falling back' into 
the net - probably from 'exhaustion'.  Once released onto the trawl 
deck, these fish appear 'dead', little muscle tone, no opercular 
pressure.  Some (not all) of these fish, when then put into a holding 
tank on deck, will appear quite robust in anywhere from many hours to a 
day.  

In article <[email-masked]>, [email-masked] says...

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From: [email-masked] (Flip214)
Date: 28 Aug 1995 21:54:11 -0400

My wife is a fishery biologist specializing in the tagging and recapturing
of billfish.  She is currently working on a report about billfish that
were tagged and released in very poor condition or where the fish was
thought to be dead.  You must understand that the recapture rate for any
billfish is very low to begin with (less than 2%) but I was suprised to
find that there were many cases of fish that were recaptured after they
were thought to be dead.  Some of which had been hooked in the eye or had
even had their stomach outside their body.  As a fisherman I have seen
many billfish come to the boat apearing to be dead only to be revived
after being swum next to the boat for a period of time.  I think that the
billfish tournament rules say it best in that a fish has a better chance
of survival in the water than on the deck of a boat.
Good Luck.
Greg

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From: Steven Poet <[email-masked]>
Date: 29 Aug 1995 16:06:37 GMT

Point well taken about the survivability of fish in water vs. land.
It sounds like your wife is doing what needs to be done... figuring
out what is going on with the fish.  Any knowledge which will help
the survival of these fabulous animals is priceless.  Using what "we"
know about other living critters with respect to muscle trauma can be
helpful as well.  My large animal medicine professor used to say 
"mammals are mammals, use what you know".  I know fish are not mammals,
but cells are cells and general physiology principles may apply.

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From: [email-masked] (Mike Prager)
Date: 29 Aug 1995 21:19:49 GMT

> released quickly and appears in "good shape".  The reason given ...

To put a fishery management perspective on this: I have looked at a
few population dynamic models of fish stocks, and when they
include nonzero hook-and-release mortality, they present very different 
relative pictures of management strategies than when they don't. 
In general, the existence of hook-and-release mortalities makes size 
limits and bag limits less appealing, and closed seasons and areas 
more appealing (as far as limiting total mortality), as one might expect. 
Something for fishermen (both recreational and commercial) to think about....

Mike Prager                   [email-masked]
.................Speaking for myself, not for Uncle Sam.

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From: [email-masked]
Date: Thu, 07 Sep 95 12:07:01 NZS

<snip>
>>  I think that the
It's a question of values: To a catch-and-release advocate, the chance 
that the marlin will probably survive and can be possibly be caught again 
is a good thing. From the point of view of the non-fishing public, the 
change that the marlin might die as a result of stress or hooking 
injuries is a bad thing. 

With millions of people starving to death world-wide, does wasting large 
amounts of increasingly scarce seafood justify the knowledge gained? Or 
is tag-and-release being used by vested interests (the recreational 
fishing industry) in much the same way that the Japanese continue to kill 
whales for "science"?

One thing for sure - the best way to ensure a fish's survival is simply 
to leave it alone. I get real uncomfortable when I here people use the 
"any chance of survival is better than none" justification. That kind of 
platitude by catch-and-release advocates encourages a lot of destruction, 
and wastage. But then again when people amuse themselves by "fighting" a 
fish that can't fight back, and whose only defence is to try to flee, 
those kinds of platitudes are to be expected.

Season closures and area closures would appear a more effective 
conservation measure.

- Craig Arfman, New Plymouth, New Zealand

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From: [email-masked] (Flip214)
Date: 7 Sep 1995 10:08:15 -0400

What happened? did you have some kind of religious experience out on the
water one day?  Is this the same person that was sharing your striped
marlin tactics and favorite lures with me?
There is no argument against your way of ensuring the fishes survival, Of
course not fishing would solve the problem of any depleted pelagic fish
stock.  (Except there would be no way to document this if everyone stopped
fishing, so how would we really know?)
If this is truly your position than I feel it is admirable, I do not agree
with it at all, but you are certainly entitled to try to convince others
to see things your way.

:One thing for sure - the best way to ensure a fish's survival is simply 
:to leave it alone. I get real uncomfortable when I here people use the 
:"any chance of survival is better than none" justification. That kind of 
:platitude by catch-and-release advocates encourages a lot of destruction,

:and wastage. But then again when people amuse themselves by "fighting" a 
:fish that can't fight back, and whose only defence is to try to flee, 
:those kinds of platitudes are to be expected.

:I  had been thinking about that too. Nice to know that it works. The 
:lure hookup % on striped marlin can get really frustrating, and I've
tried 
:every trick in the book. Was he using the 
:softhead to keep the mackeral from coming apart at that speed and 
:then fishing it like bait after the strike (freespool, stop the boat, 
:wait for the pause, etc.)??  Did he mention if he was  using both halves 
:of the moldcraft over the bait or just the outside one??

This is the same author?  Don't you think it is a little hypocritical to
preach leaving the fish alone and then worry about your hookup %?

The long and short is that fishing does involve killing, (so does eating a
hamburger)
the ocean is a resource that in my opinion can and should be responsibly
harvested.  As far as sportfishing is concerned it is simply that sport. 
All of the data I can find shows that billfish stocks are not over
exploited and the survival rate for properly released fish is higher than
you might expect.  The major pressure to billfish population comes from
comercial longliners who simply throw dead marlin and sailfish (and a huge
number of sharks) back in the ocean.  These fish have a near zero survival
rate when hooked for 24 hours.  I have seen the data about recreational vs
comercial fisherman and the numbers gathered by each, but in respect to
Tuna and Marlin there was no data.  Marlin are not always recorded as a
comercial catch and are almost never harvested by recreational anglers. 
If you are truly concerned about the frightened fish that is only trying
to get away, The first step in preventing this might be for YOU to stop
catching them and then worry about others.
Greg Cousins
Ft. Lauderdale FL

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From: <test@test>
Date: 8 Sep 1995 23:41:17 GMT

This is not altogether the right story about what goes on inside a fish 
after it is caught, and fights the line for a while. All fishes, and 
people, burn glucose in their muscles, from either glycogen stores, or 
>from  other metabolic pathways, including those leading to and from fat 
stores. As long as their is plenty of oxygen flowing from the gills, 
through the arteries and capillaries to arive at the working muscles, 
this is a relatively simple process of converting nutrients to work, and 
heat. If oxygen becomes limiting, or is used up, then another 
biochemical pathway kicks in, and the metabolites are different, as the 
various alternative pathways are used to move energy around to the 
muscles. The major end product of anoxic metabolism is Lactic acid, 
which is a normal component of biochemical processes, but the build up 
can cause some pain, and general acidification of the working tissues 
and those adjacent. That is why your muscles smart after too much 
activity, or prolonged stress.  The oxygen carrying capacity of blood is 
very sensitive to local acidity (pH), and tends to unload under acid 
conditions, often leaving the down stream sites a bit under oxygenated.

All this tends to lead to delyed total recovery, but tunas, in 
particular, have the highest levels of the enzymes that reconvert lactic 
acid back to readily metabolized biochemical components, that it would 
take a real tough, low level of oxygen situation to stifle their 
recoveries. Yet, we know that the acidification of the muscle, and the 
blood itself can cause prolonged stress for the fish, or you.

It is probably easier for a fish to die from acidosis than for a human, 
simply because you would pass out, or stop painful activities long 
before you would die. Fish, tunas and billfishes, have no miraculous 
means for resting as they really must swim continuously to stay in the 
uper, oxygenated water column. Now we have a dilemma. The fish must slow 
dowm and recover its metabolic balance, which they do remarkably well in 
contrast to many species. The tissues have quite stable enzyme levels, 
and very volatile nutrient substrate levels, and by-products, which is 
what varies. 

Fish can and will die from fighting the lines, more rapidly in warm 
environments thatn in cold ones, as a function of available oxygen. The 
second, and more critical issue for big fishes like tunas and marlins is 
the temperatures attained by their muscles during long struggles on the 
end of fishing lines. Their body temperatures can and do attain levels 
that are sufficiently high that it denatures the muscle proteins, and 
the flesh can eventually become hydrolyzed by enzymes that leak from 
cell organelles, essentially digesting from the inside. This is the 
source of what has been called "honey-combing" of fish flesh, that was 
first identified in tunas and billfishes caught on longlines, in warm 
ocean areas. So the mysterious short-term mortalities following tagging, 
or catch and realease, is likely to be more related to the over heating 
than to acidosis, although both probably work toward the same, painful 
end.

I hope that this helps you understand why I quit "fishing for fun" over 
twenty years ago, although I commend anyone that can,and will eat what 
they catch. Tunas and billfishes are wonderful species, amongst many, 
and should be appreciated, and only played on a line for the shortest 
period possible, then killed and eaten. Experts in fish tagging have 
worked for decades on quick, efficient means for tagging animals in 
special research environments, and that is still a very primitive way to 
learn what fishes do. Modern techniques include attaching sonic tags, 
and special elctronic logging technologies that record for months to 
years what and where fishes do things. These are inportant information, 
in learning how to maintain healthy populations, and how to minimize the 
costs of catching food fishes. That is the purpose of fisheries 
management. Tagging is an archane science, at best. 

I hope this helps you understand what is really going on. I wrote the 
bokk on The Physiological Ecology of tunas, with my colleagues, about 
twenty years past. We love the subject, the way these critters have 
evolved to share the ocean's very disparately distributed food webs, and 
can only hope that human's will learn more quickly how to better deal 
with our general ignorance of the oceans, and the important ecosystems
that provide our needs. Have fun! Be kind, and be healthy.

Gary D. Sharp

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From: <test@test>
Date: 8 Sep 1995 23:44:08 GMT

Gary D. Sharp

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From: [email-masked] (Christopher Jones)
Date: 9 Sep 1995 03:49:51 GMT

In article <[email-masked]>, [email-masked] (Flip214) says:

>rate when hooked for 24 hours.  
>
>
Greg

I'm not sure which data you're looking at, but I conducted assessments
for sailfish and white marlin using ALL yield data reported and indices
of abundance for 30 years from countries around the Atlantic.  Every model 
run showed fully exploited to overexploited stock status in the western
Atlantic for sailfish and overexploited for white marlin in the western 
Atlantic (published in ICCAT proceedings). There has been a fairly 
substantial decline in biomass through the 80's and into the 90's for 
billfish.  It's true that longliners, particularly the Japanese, remove 
the lions share of billfish biomass, and survivorship is extremely low 
after an extended time on the hook.  A tough problem to tackle.

Chris