Barbel Diet Analysis

[Ash Gould]

yeah, we are thinking on similar lines Paul. Skeletal growth is the significant issue here, not weight. I don't think fish are getting bigger skeletons just putting more weight onto their frames. I aggree with Fred Crouchs assertion that the proportions of fish have changed. I dont agree with alot of what he asserts but that rung true..

I bet if that Itchen fish had a few seasons on the pellets it would be a fat 17lber! And that a your average 17 lber in another riverwould have a similar sized skeleton to the Itchen 14??

 

[David Gauntlett]

Lots of speculation based on very little going on here

Lets throw this into the mix then. Fish, like reptiles and certain other species, continue to grow until they die. So...how does that tie in with the 'maximum frame size' theory being bandied about?

Just wondered

Cheers, Dave.

 

[Alex Gowney]

Lots of speculation based on very little going on here

Lets throw this into the mix then. Fish, like reptiles and certain other species, continue to grow until they die. So...how does that tie in with the 'maximum frame size' theory being bandied about?

Just wondered

Cheers, Dave.

I agree Dave. Does skeletal size increase with increased food resources as well? Also, Ash has commented on barbel but chub and tench have seen similar increases and I don't think that is merely down to weight gain on a skeleton that is the same size as a much lighter fish from 25 years ago. The whole bulk of the fish appears bigger and what governs a potential maximum skeleton size? Genetics?

 

[Ash Gould]

No theories being banded about, just hypothesising. Speculating in pure conjecture is what anglers do isnt it?

Untill we have evidence that fish are getting bigger skeletons then talking of fish getting bigger and growing is a misinterpretation, anglers only have evidence for fish weights increasing. The chub study group ask their member to weigh and measure their fish (as did the barbel catchers) I wonder if they have evidence of fish getting longer (which would be actual evidence for sekeltal growth).

Skeletal potential will be genetically pre-determined and whether that potential is realised will be dependent on environmental factors, hormones, diet etc

A quick google on to fish growth research suggests their organs might limit them from growing to super proportions, adding weight to the maximum frame hypothesis

 

[Alex Gowney]

Good points Ash. Many years ago there was speculation that every outsize fish (I think the article was focusing on chub) would be likely to be a fish that couldn't spawn. In other words the hormones or whatever internal workings affect spawning, were out of sync leading to exceptional growth.

 

[David Gauntlett]

I agree Dave. Does skeletal size increase with increased food resources as well? Also, Ash has commented on barbel but chub and tench have seen similar increases and I don't think that is merely down to weight gain on a skeleton that is the same size as a much lighter fish from 25 years ago. The whole bulk of the fish appears bigger and what governs a potential maximum skeleton size? Genetics?

I don't know the answers to those questions is the plain truth Alex, but I can speculate along with the best of them Given that fish do continue to grow until they die, it makes little sense to me that this growth would purely be body bulk, not skeletal growth to support that bulk. Put simply, in such creatures, death is obviously the major size limiting factor, but genetics, location and food supply must also play a significant role. The rigours of every day life, and disease will mean that in any given location, there will be a fairly well determined expected life span, just like the rest of us, and predation apart, there would probably be only minor variations on that expected span. They do not have the dubious benefits of the NHS to artificially lengthen their lives The only real exception to that would surely be down to genetics.

If you look at reptiles, which are another species that continue to grow until they die, you can see the effects of longevity quite easily. For instance, Australian salt water crocks living in protected areas, be that zoos or sanctuaries or whatever, often live longer than their 'real world' brethren. They have less competition, meaning less predation and more readily available food, and as a result often grow to prodigious sizes, and it is NOT just bulk...they grow longer too, which obviously means the skeleton is growing. The same can be said of captive or protected snakes...and so on. Why then would fish be any different? It seems to me that they are not. If you look at fish kept in ideal conditions, in well tended lakes lakes or tanks or whatever, they also frequently live longer, and increase in length, not just get fatter.

The effect of genetics is an entirely different matter. Donald Levey introduced his strain of carp to this country many years back, and he and customers of his introduced these stunning fish to many lakes, where they became legends, the stuff of dreams that most serious carper gravitated towards. They are in general slow growing, beautiful fish, which in ideal conditions grow to enormous sizes during their often 50/60 year life span. Sadly, the very fact that it takes many years for them to grow to 'cult status' size did not sit well with some folk.

Instant anglers require lakes crammed full of doubles, twenties and possibly the odd thirty, and they are in heaven. They care not a jot for a fishes history or pedigree, nor whether it has a distinctive garlic odour to it...just so long as they can catch a few every trip. Now, I am not criticising them for that, whatever turns a person on in angling is every bit as valid as my reasons for going fishing (providing its legal and within the rules), but it did provide a new market....fast growing carp. And so the 'Simmo' was born.

Mark Simmons, amongst others, set out to fix a fast breeding strain of carp to fill that market niche. By selective breeding, using the fastest growing fry from numerous batches for a number of years, he succeeded in him main aim. He short circuited natural selection and created a strain of carp which were genetically programmed to grow faster than normal. All fine and dandy then? Sadly, not quite. There are some very pretty Simmos about, there is no denying that...but there are also some horrible 'footballs with fins' and many other less than desirable offspring. There was another sad result of playing with genetics too. The fish do indeed grow fast...but as far as can be seen so far, they have a much shorter average life span, and they do not reach the mahoosive sizes that the average Leney does.

So, yes, of course genetics can alter the size and shape of carp, and any other fish species too. While these fish I mention were genetically altered via the interference of man, I am quite certain that the same sort of thing can occur in nature, albeit at a much slower rate. There will always be fish in any batch of fry that grow slightly faster, or slower or bigger than the others. When pure chance occasionally brings a male and female of any similar genetic bent together, then you WILL get fry that are far more likely to follow that bent in the future. You will end up with some fish that grow bigger, and/or live longer than those around them. If the water quality of a stretch where these these particular fish live is improved, and an unusually high grade of food coincidentally becomes readily available at the same time...then I cannot see how significantly larger fish would NOT be the end result. But, that is all pure speculation, yet again

Great fun debating this subject, especially so because no one is getting silly about it

Cheers, Dave.

 

[Ash Gould]

I don't know the answers to those questions is the plain truth Alex, but I can speculate along with the best of them

So, yes, of course genetics can alter the size and shape of carp, and any other fish species too. While these fish I mention were genetically altered via the interference of man, I am quite certain that the same sort of thing can occur in nature, albeit at a much slower rate. There will always be fish in any batch of fry that grow slightly faster, or slower or bigger than the others. When pure chance occasionally brings a male and female of any similar genetic bent together, then you WILL get fry that are far more likely to follow that bent in the future. You will end up with some fish that grow bigger, and/or live longer than those around them. If the water quality of a stretch where these these particular fish live is improved, and an unusually high grade of food coincidentally becomes readily available at the same time...then I cannot see how significantly larger fish would NOT be the end result. But, that is all pure speculation, yet again

Great fun debating this subject, especially so because no one is getting silly about it

Cheers, Dave.

Very good bit of speculation that. Good summary.

 

[Keith Speer]

Hi chaps, I am now back again having replaced my ageing PC with a new Mac.

Proving I suppose that you CAN teach an old dog new tricks!

Although a dog will always remain a dog!

I have spent an hour or so reading over the comments on this thread ( a most enjoyable hour I may say) and although my opinion has not changed I can see the merit of some of the comments made.

I still do not think that Barbel are reliant on anglers baits directly, I do think Barbel are getting larger BECAUSE of anglers baits, but even then I am not sure this is the only factor.

Let's consider some of the changes that have taken place over the last 30 years.


We now introduce more bait into our fisheries than ever before.

That bait is made up of higher value nutrition than ever before.

Our rivers are influenced by global warming.

Our rivers are also subject to climate change.

The inhabitants of our rivers are having to deal with new predation, Signals are a known influence on deposited eggs, Cormorants have influenced and in certain areas decimated the biomass of silver fish species and Otters have influenced the local migration of the larger fish species.

Some aspects of natural selection have been circumvented by our stocking policies.

In the main our waterways now carry less industrial pollution and more domestic effluent and, possibly more concerning, more man made Oestrogen known to promote the hermaphrodisation of freshwater fishes.


I suspect ALL of these factors have a effect on the size of all fish, and as we live in an ever changing world, things are bound to be changing now that will have an effect in future years, but even if you consider only the short list I have come up with, there are too many variables to come to a definite conclusion.

Because we now have more material wealth we can spend more money on more and better bait, I believe this has an effect on both the fish directly, but more importantly, all river life will gain, even if the fish do not eat the 15 kilos of boilies you just threw in, something will, bait does not just go away, even if the bacteria consume the bait the higher level consumers will benefit.

We know that fish grow bigger in the more southerly European countries, even Holland, basically on the same latitude as the English midlands has approx one month longer growing season, and the size of the indigenous species in Holland prove this, the fact that the temperature of our planet has risen and the seasons are becoming warmer , must have an effect.
Even the addition of just two weeks of milder weather will influence the feeding habits throughout our river systems.

Someone mentioned the biomass of fish species within a river system being fairly constant, I don't actually believe this, I think the biomass will be slowly increasing, if only due to the warming effect I mention in the last paragraph.
Those of us that are old enough to remember, thirty years ago the larger rivers like the Thames were full of silver fish, despite the pollution issues, and had been for years, these days the vast shoals of Roach and Dace have largely disappeared, this might be due to the new predation I mentioned, it might be because of breeding difficulties due to endocrine disruptors from the pill, whatever the cause they are gone.
If there IS more and better nutrition throughout the river, something will benefit, nature ALWAYS finds a away, in all probability, species like the Barbel, which in there larger sizes have no natural predator, will become beneficiaries.

It is for these reasons I do not take much from the recent survey and it is worth remembering:-

Often, to understand the answer, you actually need to know what the question means.

As for Skeletal frame, I know of one fish that has been captured at 20lbs 7oz and since then has been caught at various weights down to as low as a big 17 and then back up to a big 18, in a period of less than one calendar year.
I expect it will continue to grow to up to and possibly over the current record, which is when I intend to catch her!

We have a BRFC meeting on Thursday next, I shall ask Nigel about his thoughts on fish size when we get a quiet moment over lunch?
Should be interesting!

Tight lines chaps.

 

[John Walker]

Dave, you mention simmos, a good typical subject on genetics, genetic modification is basically taking the good selected aspects and cutting out the unwanted atributions, then intensely breeding and culling until the strain is reached the desired levels ect, basically this is genetic modification, farmers and breeders have been doing this for 100s of years with animals, skeletal growth ??? the heaviest chub i caught so far was far from the longest, no doubt whatsover that oil laced pellets have encouraged weight gain and fat gain
now any fit animal including man if gaining fat levels will usually turn a lot of it into muscle and lets face it barbel are one of the fittest fish out there,
they already are or have tried selective breeding with barbel, personally i prefer to catch real wild natural river bred fish but release of the stocks specially bred will undoubtably breed with our natural stocks and if conditions and food is available in right amounts then fish will get bigger, my thoughts are more on climate/ weather temperatures ect, will warmer climate produce heavier fish due to better digestion of food ect?

 

[Graham Elliott]

Just keep feeding her Keith. Without the food she won't get heavier.

Graham

 

[Tim Lennon]

Whilst there seems to be some confusion between selective breeding and genetic modification, selective breeding could indeed be a contributory factor.

Are the Calverton fish farm barbel selectively bred? Intentionally or otherwise? i.e. are the "runts of the litter" discarded?

How long have fish farm barbel been used for stocking our rivers?

In the good old days, fish were simply moved from one river to another. I think I'm right in saying that the original Severn stocking was with fish from the Kennet.

Interesting...

 

[Pete Reading]

Calverton fish are taken from wild broodstock, usually from the Trent, but they have used Loddon fish at times, unless any changes have taken place since last time I was there.
They have stocked with the larger fish selected from a year class at times, I believe, but the last lot we had for the Stour were a mix of the natural stock, of varying sizes.
There was a theory that selecting the bigger ones could have been selecting a higher proportion of females, but not been investigated.

As with salmon, there is a risk of interfering with natural selection, in that fry fed on from artificially hatched eggs are not weeded out by natural losses, and less `streetwise` fish are introduced, carrying weaknesses that would otherwise be removed by their early demise!

Artificial stocking will always involve such risks, but hard to prove if there is any significant effect!

Sustainable, natural recruitment must always be best, but the habitat needs to be there to support it, of course!

Selective breeding of barbel has not been used in its strictest sense at Calverton, in that the parents were always wild stock, and it would have to be done over many generations to produce a different strain of barbel.

Not sure how long Calverton barbel have been produced, the EA website will possibly have that info.

 

[Dave Taylor]

Whilst there seems to be some confusion between selective breeding and genetic modification, selective breeding could indeed be a contributory factor.

Are the Calverton fish farm barbel selectively bred? Intentionally or otherwise? i.e. are the "runts of the litter" discarded?

How long have fish farm barbel been used for stocking our rivers?



Interesting...

Don't quote me on this Tim, but I believe Calverton started it's coarse fish breeding program in 1986, I wittnessed Calverton barbel being introduced to the Wey in 1993. I think the farm goes back to the 1930s and bred trout.
dt

 

[Tim Lennon]

They have stocked with the larger fish selected from a year class at times, I believe...

Surely this could easily have had an effect, Pete?
If the runts were weeded out of a batch, and this super batch then went into a river with no/low barbel population, then they and their progeny could easily be bigger than "normal"?

Dave, the 80s sounds about right to me for the start of fish farm stockings.

 

[Fred Wilton]

Fat cannot be turned into muscle.Fat in food can only be used for energy,carbohydrate can be used for immediate energy use or stored as fat for later energy use.Only protein can become muscle and can also be use as energy.

 

[Pete Reading]

Yes Tim, in that they were possibly mostly female and were of higher average size, but it would take many generations for a natural population to change in average size, I would say. Environmental growing conditions would affect them more than their basic genetics too!
For example, the Wensum fish at Lyng were Calverton fish, that grew to large size until they were 20 plus, but did not seem to reproduce effectively, and died out eventually, helped by some predation.
A generation for barbel, based on average lifespan, would be 20-25 years, so it would be 50 years plus before you could even start to say that the occupying barbel are a strain that grow bigger, as I understand it. The next lot of 20 year olds would need to be of comparable size, and if they breed at about 4, you are talking 25-30 years before they appear in the population. It would take hundreds of years to become apparent, really.

We know very little about barbel populations, something that the BS supported PhD project currently underway will inform us about. Most of our rivers have non-native populations of stocked fish in quite early stages of development, and very hard to reach any real conclusions or compare river with river.
The BS is also supporting DNA analysis of UK barbel scale samples, which should help to establish if native barbel are different to each other in any way, but all the stocking will complicate matters.
It is common for newly introduced species to experience an initial boom in populations, followed by an apparent decline that eventually settles into a stable level, but lots of other factors come into play, such as habitat destruction/improvement/climate change/human influences.

Fascinating, is it not, but as I suggested earlier, not wise to leap to hasty conclusions or a simple answer to it all!

 

[Derek Funcks]

Yes Tim, in that they were possibly mostly female and were of higher average size, but it would take many generations for a natural population to change in average size, I would say. Environmental growing conditions would affect them more than their basic genetics too!
For example, the Wensum fish at Lyng were Calverton fish, that grew to large size until they were 20 plus, but did not seem to reproduce effectively, and died out eventually, helped by some predation.
A generation for barbel, based on average lifespan, would be 20-25 years, so it would be 50 years plus before you could even start to say that the occupying barbel are a strain that grow bigger, as I understand it. The next lot of 20 year olds would need to be of comparable size, and if they breed at about 4, you are talking 25-30 years before they appear in the population. It would take hundreds of years to become apparent, really.

We know very little about barbel populations, something that the BS supported PhD project currently underway will inform us about. Most of our rivers have non-native populations of stocked fish in quite early stages of development, and very hard to reach any real conclusions or compare river with river.
The BS is also supporting DNA analysis of UK barbel scale samples, which should help to establish if native barbel are different to each other in any way, but all the stocking will complicate matters.
It is common for newly introduced species to experience an initial boom in populations, followed by an apparent decline that eventually settles into a stable level, but lots of other factors come into play, such as habitat destruction/improvement/climate change/human influences.

Fascinating, is it not, but as I suggested earlier, not wise to leap to hasty conclusions or a simple answer to it all!

Crikey Pete, do ya fancy a pint

 

[Graham Elliott]

Fred.
Are you saying that barbel fed on a protein rich diet with carbohydrates will have more muscle and fat than those that arn't and will generally weigh more?

If so.....I wonder why barbel have become so much bigger over the past 30 years.......

 

[Keith Speer]

Hi chaps,

Perhaps Derek's idea is not a bad one, if we all got together in a hostelry we could expand this discussion?

Must be some merit in that, after all 12 pages and not a sign of any mud slinging!!

I'm not a regular pup go'er but I would make an exception for a chat about this.

Tight lines all.

 

[Tim Lennon]

A generation for barbel, based on average lifespan, would be 20-25 years, so it would be 50 years plus before you could even start to say that the occupying barbel are a strain that grow bigger, as I understand it. The next lot of 20 year olds would need to be of comparable size, and if they breed at about 4, you are talking 25-30 years before they appear in the population. It would take hundreds of years to become apparent, really.

I'm afraid that I'll have to disagree with you here, Pete.
By your reckoning (above), this would mean that there are only two generations of fish in the Wye!

Having said that, in my previous posts I wasn't thinking about the creation of a barbel master race as a result of repeated selective breeding, I was suggesting that an isolated population of stocked fish could easily be of a higher than "normal" average size. Perhaps the Wensum stocking that you mentioned supports this suggestion?

all the best, Tim