how old chub grow to

does anyone know how old chub are suposed to grow to .listening to keith arthur this weekend i,m sure i heard him talk about a chub caught on the thames was about 30 years old ,the caller said it was about 7.5lb.i was led to think chub grow to around 13-14 years old

Interesting question Bridge, I know a couple of stillwaters that have contained Chub for years ...at least 15 in one case.

A quick look at some old EA survey results indicates that chub certainly live for at least 18 years and probably over 20 years, possibly 25 years.

25 years is a top end figure I've been quoted in the past...

The only way you would know for sure would be to tag a lot of chub both in stillwater and in the river, not only that but be lucky enough to have the tag returned on their death. I know that a lot of fish remain on the bottom after death so the chances of a follow up are very slim I would have thought, how else would you know for sure the average lifespan of a chub other than a calculated guess?

The AVERAGE lifespan of a chub is much much less. But for the lucky ones that reach a ripe old age, 18+ years is reached by about 2% of chub on the Dorset Stour (EA survey figures).

I agree with Greg and Mark, but I don't think anyone knows exactly how old they can grow... It is known that reading the age of a chub from a scale removed from its flank can only work for fish up to around 14 years or so. After this, the annular rings become difficult to read and all that can be said is that it is 14 years+. Some chub are easily identifiable (occasionally, one may be missing pectoral fins for example) and these specimens have certainly been caught by anglers many years apart.
As far as how long they grow for is concerned, I believe they increase in weight for around their first 12 years or so, but then tend to freewheel around a certain weight - fluctuating up and down during the year (sometimes by quite a lot). I caught a 6lb chub one winter, only to catch it again the following summer at almost a pound less. I didn't actually realise it was the same fish until I compared the photographs and recognised the same patch of damaged scales. Occasionally something will happen to a fish (maybe it will turn particularly predatory for example) and it may put a huge amount of weight on in a short period of time... so just because you have landed the same fish a number of times at around a certain weight, it IS always possible it may turn up at a much higher figure.

Trev (Chub Study Group)

Mark, I don't doubt for one minute what you say is true but how do the EA arrive at such a figure, how do they arrive at 2%? Is a scale reading accurate for an age reading albeit up to 14 years?

To arrive at any figure you would need a count of dead ones surely, hmmm! I am intrigued.

The EA do full river surveys on the Stour and Avon at about 30 sites every 5 years. They take scale samples and try to analyse the ages of the fish caught. Most chub caught are 2-5 years old. The fish go back alive albeit missing a couple of scales.

Fish only grow for a certain number of years. Grow, meaning there's frame, skeleton increases in size. It then grows no more, so a scale may say this fish grew for X number of years. It doesn't tell you it's real age, only the numbers of years it grew for.
The same applies for the operculum bone (gill cover), much more accurate way of reading how long a fish grew for. However, they can only be used if the fish is dead.

When a fish reaches it's optimum growing size, it may live quite a few years after that and increase it's body weight by laying down fat. Bit like us humans, we grow on average for 21 years. But at 41 very few are the same weight they were when they stopped growing. They have become Fat bar stewards

So you can only safely say from scales/operculum bone, the fish is at least X years old.
And hear's a fact that I discovered from scale readings of over 100 double figure bream from 7 different waters in the NW, they grow for no more than 12 years.

Scales from a Swale fish read in the late 80's showed the fish to be at least 23 years of age.
I beleive it was Tony A who did the reading, Trevor.

At 23.5" long and thought I had a record fish in front of me, untill the scales refused to go past 5lb-08oz A very loose skinned battered looking speciman

I don't know if Chub ever breed in small still waters , if the answer is no then providing the water is not stream fed as is the case in one water I know on private secure grounds
a rough idea could be had as to their longevity albeit out of their natural surroundings.

As "The Bad One" says above, the skeleton of a fish generally stops growing at "a certain age". The size of scales will not grow very much after this (or the fish would soon look very odd indeed!), but a very thin layer of growth may be seen for each year if you are lucky and the fish hasn't got too damaged. Tony did very well to identify that many annular rings, especially if the fish was a bit battered. Your fish of over 23 inches from the Swale from the 1980's may be one which had carried on growing for a year or two more than "normal" (like a human who continues to grow taller after most of his mates have stopped). Fish in spate rivers tend to be of thinner frame than those from slightly slower rivers (with a few exceptions) - if your fish had come from a river with a slower average flow, it may have been fatter and therefore much heavier. A fish of the same length from the Dorset Stour nowadays would certainly be a real monster. Saying that, back in the 1980's even Dorset Stour chub were generally thin, as many were infested with parasites in those days.

Trev

What an interesting thread….particularly in that point about the 12 year period for Bream frame/skeleton growth and after that its basically fat/spawn/tissue that fluctuates. Makes sense..very interesting !

Trevor Sawyer said:

Occasionally something will happen to a fish (maybe it will turn particularly predatory for example) and it may put a huge amount of weight on in a short period of time...

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I think this is a key point and maybe one exception…I believe Carp can change frame/skeleton size many years after being at a stable weight if there is a significant change in their diet, for example a fish that may start to take more protein, a fish that starts to take Crayfish for example. I wonder if Chub could go the same way if there is a significant increase in a protein rich food source…the influx of Signal Crays for example…

I've certainly noticed that chub populations can vary greatly in weight from year to year. A few years ago Mick Beecroft and I had some really good sessions on the Swale, catching up to a dozen fish at a time with around half the fish being over 5lb and topping out at 5lb 12oz. Obviously a significant number of fish in this stretch had piled on weight. They were obviously relatively young, fit fish so we expected that the following year we might get our 6lbers. No such luck! The following winter we returned and we were now catching similar numbers of fish, but most were below 5lb with the top weights around 5lb 4oz.

There had obviously been a food bonanza of some sort in the previous year which had caused a general increase in weight.

Philip said:

What an interesting thread….particularly in that point about the 12 year period for Bream frame/skeleton growth and after that its basically fat/spawn/tissue that fluctuates. Makes sense..very interesting !



I think this is a key point and maybe one exception…I believe Carp can change frame/skeleton size many years after being at a stable weight if there is a significant change in their diet, for example a fish that may start to take more protein, a fish that starts to take Crayfish for example. I wonder if Chub could go the same way if there is a significant increase in a protein rich food source…the influx of Signal Crays for example…

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Philip what I think is happening with carp is, because they are long lived 60+ years, they don't stop growing until they are about 40 years old.
However, they grow to the confines of the environment they in, and slow down the growth to a very slow pace.
Then they get an influx of food; crayfish get in, anglers start to pile in large quantities of bait, etc. I read the other day of one guy going through 625 kgs of boilies and 125 kgs of pellet in a season.
This influx of food lifts the constriction of their environment and they start to grow again in a spurt for some years.

This view is testable though scale readings and water temperatures, providing someone has kept them over a long period. Failing that, proxy records would have to be used. The best being ground temperatures for the area with a +/- 5 % variable.
Water warms up at about the same rate as the ground does. Less so on deep waters that stratify. But on waters that have a mean depth of less than 15 ft, it holds true. Rivers are different as they are subject to surface flow and the truism is more so btw.
I do know somebody who is doing some research into chub, water temperatures, spawning, etc but that's for him to report on, as it's his research.

By reading the scales from carp you could discern where the growth slowed down because of the environmental constrictions and the point where it started to spurt again. To avoid false readings you'd need to match it up with temperature records to make sure it wasn't down to natural conditions. A run of cold summers, which it's known the grow rate of any fish is slowed down. This is represented in the scale readings by the rings being closer together.
If the water/proxy records show it should have been good growing years and the rings show very slow growth for this time period. Then it would be safe to say that's when the fish reached the confines of their environment. If the growth rate then after showing the slow growth, then went back to wider spaced rings, some environmental factor(s) lifted the environmental constraints placed on the growth of the fish.

I wouldn't discount that it's possible with other fish, this could happen, but they may not live long enough for it to really show up as it would with carp.

I caught a one eyed chub from the wensum 16yrs ago at about 2.5lb......i had the same fish last year from the same stretch at 6lb.9oz....i know it was the same fish because of a big scar across it gillplate....i asume the eye was lost in an encounter with a pike as the scarring seems to suggest this....so this fish must be at least 20yrs old.

Very interesting …lots of parallels with rings on a tree, colder years matched against rings being closer together etc..

Makes sense what you say about the lifespan of Carp being so long that probably makes it easier to see and measure these things…I would love to see a study showing if there was a correlation between scale rings, weather records and bolies hitting the scene.

As you say with Chub it would be more tricky to measure, but maybe possible if some fish are hitting 20+ years.

Great stuff !

Graham Whatmore said:

The only way you would know for sure would be to tag a lot of chub both in stillwater and in the river, not only that but be lucky enough to have the tag returned on their death. I know that a lot of fish remain on the bottom after death so the chances of a follow up are very slim I would have thought, how else would you know for sure the average lifespan of a chub other than a calculated guess?

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Here in Sweden a guy who once hold the Chub record (for some days only) did a Chubresearch last year which included put radiotransmitters in the chub and then "follow" them and found of where they were standing once a week or something like that.

The reason for this was to research how the Chubs were affected of waterpower-stations and which places they did spawn at.


If radiotagget then you would probably notice if the fish would die? It ofcourse including to cath the fish and replace the transmitter before the batteries run out. And what says its lifetime isnt affected by the transmitter?

The conclusion is the same as yours, it cant be sad 100%.