Barbel in Nets

[stuart clough]

Found it!

Changes in blood cortisol, glucose and lactate in carp retained in anglers'keepnets

T. G. Pottinger
Journal of Fish Biology
Volume 53 Issue 4 Page 728 - October 1998

"Capture of carp Cyprinus carpio from holding tanks by dipnet, or from semi-natural conditions by rod and line, elicits a physiological stress response characterized by elevation of plasma cortisol levels. The transfer of carp to keepnets subsequent to capture does not increase or reduce the magnitude or duration of this response and in both cases plasma cortisol levels have returned to pre-stress levels within 24 h of the initial disturbance. The postcapture plasma cortisol elevation is accompanied by disturbances in plasma glucose and lactate levels but these are less consistent in severity and duration than the cortisol response. These data suggest that the retention of fish in keepnets following capture, does not represent a source of stress additional to that imposed by capture and has no effect on the rate of recovery of the fish from the initial capture stress."

Although this study was not carried out with barbel the general implication is that the capture (by any method, not just angling) is more stressful than retention in a keepnet.

If we accept that anyone who creates a set of guidelines for the handling of any given species has the best interests of that species at heart, then all that is required is some additional explanation of the reasoning behind each guideline. With such transparent reasoning thinking anglers can then agree, or agree to differ.

 

[Steve Spiller]

BOB,

What is your REAL problem????

I am not a member of the B.S, so I can see it from an impartial point of view.
It's obvious to me you have a MAJOR hang-up with the B.S, what is it?

Why do you keep asking questions of them and keep criticising them?

Are you better than them?

Could you do the job better than them?

What is it Bob?

Please tell me/them/us...!!!

 

[Phil Hackett HC/PCPL with Pride]

Stewart I?ll run the risk of being called a sycophant and thank you for your comments.
It did cross my mind to point to the research you?ve mentioned, which if memory serves me, was part funded by the NFA, but as the fire was combusting nicely, I reasoned that gasoline poured on it might just turn it into a raging inferno.

We?ll have to see, whether it does or doesn?t? ;0)

P.S was T. G. Pottinger one of your supervisors?

 

[stuart clough]

Hi Phil,
No, not a supervisor, and I wasn't involved in the study, although I have met him on a couple of occasions.

I think the fire will rage irrespective of scientific evidence, but having read the original article, and ploughed through the rest of the thread, I felt an opinion on stress and keepnets might help to move things forward. In principle I am in favour of codes of conduct and guidelines where they are genuinely aimed at improving fish welfare.

 

[Lee Fletcher 1]

Dear Stuart,Phil,

My bone of contention concerning barbel in keep nets was always the injuries said fish could receive from being placed in them and I refer to the type of mesh nearly all keep nets "used" to be made of. Now a days things have moved on a pace with keep nets being manufactured from better materials. For me personally, and I stress this is "only" my personal opinion, the real answer or solution to the keep net debate on either side revolves around the future development's that the tackle trade make in keep net material. I view this to be an on-going proccess.

Like Phil and Staurt, and along with many others, I was aware of the Pottinger paper which does present evidence of a scientific nature concerning stress factors placed upon fish whilst in keep nets. But what ever side of the fence we sit on, or indeed no side what so ever, final solutions will eventually come via the efforts of those who are striving to make fish retention better. Thank God that these people spend their development time working for better solutions instead of bitching about out it amongst themselves.

Regards,

Lee.

 

[Simon Kelshaw]

Ive always had a problem with the word "stress" when it comes to angling, and some opinion on the actual meaning from people who releases studies would be good.

Some Dictionary Definitions (dictionary.com)

Physics.

1) An applied force or system of forces that tends to strain or deform a body.

2) The internal resistance of a body to such an applied force or system of forces.

3) A mentally or emotionally disruptive or upsetting condition occurring in response to adverse external influences and capable of affecting physical health, usually characterized by increased heart rate, a rise in blood pressure, muscular tension, irritability, and depression.

4) A stimulus or circumstance causing such a condition.

Any clues to what type of stress??

 

[stuart clough]

Precisely Lee, so if a guideline was worded "it is not recommended that barbel are placed in keepnets due the risk of the fin rays becoming damaged and entangled in the mesh" the onus would then be on the trade to produce a mesh which aleviates this problem.

 

[EC]

'These data suggest that the retention of fish in keepnets following capture, does not represent a source of stress additional to that imposed by capture and has no effect on the rate of recovery of the fish from the initial capture stress'

Very interesting that Stuart!

I think the trade has tried to improve nets especially with the 'carp fishery approved' type, but there is obviously massive room for a breakthrough!

I think the EA minimum size for a keepnet is 2m (waits to be corrected) perhaps something shorter could be considered when maybe only 1 fish is being kept. Maybe the rubberised nets supposedly in the pipeline could be the answer!

 

[stuart clough]

Simon, in biological terms "stress" hormones result in modified responses to the norm. This might be a hightened sense of alertness once a predator is detected, which would reduce the amount of time spent looking for food and increase the time spent looking out for trouble.
If you went into a bank and were followed in by a man in dark glasses who you suspected was carrying a firearm, you would probably keep an eye on him! If you lost sight of him and someone shouted BANG, you would probably jump out of your skin. The same shout while you were relaxing at home would be unlikely to elicit the same immediate response.
The same type of hormones are also released when a fish is carrying a high parasite load, has suffered a physical injury or is exposed to pollution or low dissolved oxygen, and inevitably during capture. The problem comes when people directly equate stress to suffering. In fact the whole point of stress hormones is to allow appropriate responses to be made to potentially damaging or harmful situations, to minimise the risk of suffering.

 

[Lee Fletcher 1]

Dear Stuart,

""it is not recommended that barbel are placed in keep nets due the risk of the fin rays becoming damaged and entangled in the mesh" the onus would then be on the trade to produce a mesh which alleviates this problem."

The comment you make in the above reflects more or less what I said on the BS site a couple of days ago when Steve Pope asked the BS membership (internet ones anyway) for their opinions on the BS handling code.

For me, and certainly many others I would think, the way forward revolves around on-going technology? I don't happen to know hardly anything about rubber nets but am intrigued by the concept.

Regards,

Lee.

 

[Simon Kelshaw]

Hi Stuart, and thanks for the response, ive done a bit of readin about the old wibbly wobbly world, and while what ive read backs up what you say, the fact is the fish does not care, its a physical response with no emotional/concious mental response to stress.

you see I would have thought to suffer either Stress or Suffering, both of which in my opinion are an emotional response, the fish would need to have emotions and it doesnt, unlike me on a dark path, a fish cant feel panic or fear.

It would appear to me that keeping barbel in keepnets, or harming a fish, has more to do with Human emotions than the fishs, while we are talking about what is good for the fish, the truth is the fish does not care, its a programmed species isnt it? that has one thing on its non existant mind, procreation and survival of the species.

 

[Baz]

What makes a fish dash for cover if it suddenly sees your silhouette or shaddow?
Surely that is fear. If not fear then what is it?
If it is instinct, then is that some kind of feeling?

 

[Simon Kelshaw]

Found this to be a good read Baz, best I found in plain old english

http://www.cotrout.org/do_fish_feel_pain.htm

Think this paragraph down the bottom sums up your question. it refers to being hooked, but would imagine its a simular reponse to being spooked
-------------------------------------------
When a fish is hooked by an angler, it typically responds with rapid swimming behavior that appears to be a flight response. Human observers sometimes interpret this flight response to be a reaction to pain, as if the fish was capable of the same kind of pain experience as a human. From the previous explanation, it should be clear that fish behavior is a result of brainstem and spinal patterns of activity that are automatically elicited by the stimulation of being hooked, but that fish don?t have the brain systems necessary to experience pain. It is very important to note that the flight responses of a hooked fish are essentially no different from responses of a fish being pursued by a visible predator or a fish that has been startled by a vibration in the water. These visual and vibratory stimuli do not activate nociceptive types of sensory neurons so the flight responses can?t be due to activation of pain-triggering neural systems. Instead, these flight responses of fish are a general reaction to many types of potentially threatening stimuli and can?t be taken to represent a response to pain. Also, these flight responses are unlikely to reflect fear because the brain regions known to be responsible for the experience of fear, which include some of the same regions necessary for the emotional aspect of pain, are not present in a fish brain. Instead, these responses are simply protective reactions to a wide range of stimuli associated with predators or other threats, to which a fish automatically and rapidly responds.
-----------------------------------------

Si

 

[stuart clough]

Thanks Simon - in essence I think we are in agreement, it is just a matter of semantics. Stress in a biological sense is not an emotion, and I certainly did not suggest the fish "cares", it simply responds instinctively. The trouble, as I said, is that people tend to equate biological stress to suffering, which is not appropriate.

 

[Baz]

Thanks Simon.
Yourself and the recent posters are bringing some kind of sence to this thread.

 

[Wolfman Woody]

It is an instinct Baz, a survival instinct, but one that has no emotion. It's down to millions of years of avoiding danger without having the ability to rationalise it, which it can't do because it can't reason.

Dog chases a cat, cat runs. Cat and dog fight, cat usually wins. Ergo, why does cat run in first place? - Survival instinct. I can reason, but hasn't the time to initially and so runs to be on safe side.

The only change to its state is that it will breath heavier due to its short outburst of energy. It doesn't think afterwards "Oh, thank KAT, I nearly bought it that time." Once in safe territory it doesn't give it second thought.

 

[Wolfman Woody]

"I can reason" should read "It can reason".

Perhaps we reason too much!!!

 

[Andy S]

The biggest question that needs answering in my opinion has to be:

Are keepnets more harmful to barbel than other species of fish and if so WHY???

The two main answers to this question that i've found are:

1) barbel get the spine of their dorsal fins caught up in the mesh of the net resulting in damage to the fish.

2) oxygen problems due to insufficient flow of water over the fish and also more extreme problems should a larger fish find itself reversed in the net.

Does anybody disagree with either of the above 2 answers? Should you believe them to be true then its a question of to what extent is it damaging the fish?

e.g. a hypothetical... if 100 barbel were placed individually into a keepnet having been captured on rod and line, as part of a controlled scientific test. And 1 in 100 got their fin caught and 3 in 100 went belly up either during retention or shortly after release, what conclusions would you make?

If a further study again in controlled conditions released the fish after capture, (resting them upright in the flow until they were strong enougth to swim off), determined that 4 in 100 went belly up would your previous conclusion change?

I guess the point i'm making is that many of our conclusions, (including my own), are drawn from our limited experience of captures and other opinions that we've read NOT scientific fact. Do you think anybody would perform any scientific test to acertain just how damaging keepnets are to barbel? In the very unlikely event that somebody did put up the money for such a test it would be extremely difficult \ impossible even to carry out in a controlled way. We will I think have to rely on our flawed opinions.

My opinion is they shouldn't be kept in keepnets for the reasons given in the above 2 answers. BUT have I ever witnessed a barbel catch its fin in a keepnet... no. The more scientifically I look at the issue the more difficult and blurred my answer becomes.

 

[Big Swordsy :O)]

Dog chases a cat, cat runs. Cat and dog fight, cat usually wins.

I wish you had told that to my old dogs auntie Bonny (Ron's dad will remember her) who used to travel in the water board vans with My father and her owner Jack.

Bonney often used to amuse herself by killing the cats/rabbits in the neighbourhood they were working on, turning up at packing in time covered in cat fur and sporting a fat belly full of cat.

My dog Louie (Loinky doinkey) only ever caught two cats but neither of them were ever chased again. Hissing never really was much of a detterent to a three stone rampaging staffy....Happy days.

Shiregreen and sheffield in general never had so many small animals and songbirds!

I hate cats

 

[Andy S]

ps thats 100 fish retained individually ie 1 at a time NOT 100 in the same net. Im off to Collingham now with my dropnet ;-)

Woody, I think your right we do reason too much.