The Possible Thoughts of Walker – Chub

By Richard Walker

A recent experience, if that is the right word, has got me thinking about the direction that angling might be taking in say 25 years, that is, in 2005. Of course, one would expect to see great improvements in tackle design, based on significant improvements in the materials available, and the increasing use of computers to solve the many problems facing designers trying to get the best out of those materials. One would also expect angling as a sport to develop in directions that are not perhaps apparent yet. What is difficult to predict in 1980 is that the British climate might be substantially warmer than it has been over the last two decades, and it is this and its future effect on how big our specimen fish might grow in the future that I would like to discuss in this first of a short series of articles.

In the past, I have lamented the decline of our rivers; the gross abstraction, the canalisation and pollution. Other factors have caused a decline; disease like the perch disease and columnaris, excessive boating and parasites like those that gravely affected chub in the Hampshire Avon. Indeed, back in the early fifties it was hard to see much of a future at all for angling on our rivers.

Though the improvement in tench and carp weights might be unexpected, there were several predictable factors. Improved waters in the principal form of flooded gravel pits, selective breeding, in the case of carp, and the introduction of plenty of food all contributed to the great changes that will have taken place by 2005. The prolonged growing season increases this potential further. The many mild winters and absence of winterkill mean that carp are able to grow for most of the year instead of barely half of it.

What really intrigues me is the comeback of chub, barbel and perch. I’d like to write about chub in this first article.

There is little doubt that big chub were in serious decline on many rivers from the late fifties onwards. We first noticed this on the Hampshire Avon in the early sixties. Fish that should have weighed over five pounds barely made three. It was when we opened them up that we found them heavily infested with hookworm. In other rivers, the decline was less marked and at the time we concluded that excessive weed cutting was partly to blame, and the effect of the trout farming has yet to be accepted. On the nearby Dorset Stour and the upper Great Ouse, the chub certainly declined to the point that six-pounders became extremely rare, and even five-pounders exceptional. Here the reason was principally the extensive and repeated dredging that destroyed the natural features of the rivers. In 1975, some of the local Avon anglers started to question the weed cutting on the Avon, for it often seemed to be done to keep the water authority staff employed, and it was encouraging to see that by 2005 there was much less cutting taking place.

On the Ouse and Stour, the rivers have had over thirty years to recover from the worst of the dredging and once again, these rivers are producing chub worthy of the name. The Thames and Lee, suffering badly from boat traffic, abstraction and other problems in 1980, with their big chub in decline, surprise me more than the other rivers. My old friend Peter Stone largely abandoned the Thames in recent years, preferring to fish the local gravel pits. Not only has the incessant boat traffic made fishing impossible, the fishing has been increasingly poor, with, as far as chub are concerned, a four-pounder being exceptional. And yet 25 years later the Thames and Lee are producing chub well over seven pounds, even eight pounds: truly exceptional fish.

I believe that a combination of factors has allowed chub to grow big again. Firstly, there is much less dredging, and therefore the type of cover needed by big chub remains in place. Secondly, the lengthened growing season, possibly a third longer than in the seventies substantially increases growth rates. Thirdly, there is much less competition from other fish. Dace appear to be almost rare, and there are less small chub about. I am not sure it is possible to quantify the effect that the almost extinction of eels has had yet you can be certain that it is important. The much reduced weed cutting is a factor on the Avon though not elsewhere. The fact that chub are much bigger again on unfished stretches of the Dorset Stour and Thames as well as heavily fished parts like Throop seems to indicate that heavy baiting is only one factor in increasing chub weights. There is some evidence that the very biggest chub are being caught from the places where the most bait is being introduced. Is it a case of the anglers fishing where the biggest chub live or the chub congregating where the most anglers fish? From what John Adams has told me there is an element of both.

And what of the invasion of signal crayfish? There is little doubt that big chub will thrive on a diet of their young, but they have no impact on the chub of Stour and Avon in 2005 where they are all but absent.

As I see it, there are more questions than answers in 2005.

What rivers are producing substantially bigger chub in 2005 than 1980? Are there any that have remained static? Or even declined (a substantial increase in barbel numbers could cause this)?

Has the massive decline in eels had an effect in food supply?

What is the potential for stillwater chub?

Is the growing season for chub substantially longer in 2005 than 1980? And by how much?

What effect does a large population of signal crayfish have on the chub population and their growth rates?

Do big chub migrate to heavily fished, and baited, stretches of river where bait like trout pellets and boilies are introduced?

What size will rod-caught chub reach? Ten pounds looks a realistic possibility; though, as ever, it will be an exceptional fish indeed.

Does cormorant predation reduce competition for food? And what is the impact on growth rates of chub of having far fewer dace, roach and small chub in our rivers?

Why did the chub in so many waters end up in such poor condition in the sixties and seventies (thin bodies)? Did any specific pollution cause this, like DDT? Are modern pollutants like oestrogen-mimicking chemicals having an effect on fertility and growth rates?