One of the advantages of having been around a long time is that I have seen the slow cycles of life that impact on our rivers and streams.
Like most anglers, when it first became apparent, in the early 2000s, that the UK otter population was on the way to recovery, I was pretty concerned. It stood to reason that any additional predator arriving on the scene could pose a further threat to riverine fish populations, already under stress due to existing factors such as poor water quality and low flows. And surely few species are as vulnerable as barbel to an apex predator such as the otter? This, we reasoned, is because large barbel have no reason to be afraid of much and indeed are known to remain perfectly stationary when approached by scuba divers. Our worries were backed up by pictures of half eaten barbel dragged up onto the banks of the Wensum. Ouse, Kennet and other rivers and a marked decline in barbel populations in once prolific rivers like the Bristol Avon. Barbel fishing would be finished within ten years we were told.
Well here we are in 2017 and the pages of the angling press are still showing numerous captures of big barbel that should by rights have long been consigned to the digestive systems of the ‘otter plague’. Whilst it is undoubtedly true that the barbel fishing has declined markedly on a number of rivers, including my beloved Kennet, it has also improved in places like the Trent, remained excellent on the Wye and Severn and is showing healthy signs of recovery on the Hampshire Avon.
There is no shortage of otters in the middle Thames area where I live yet my friends and I have enjoyed some great barbel fishing during the final few weeks of this season from a river where multiple catches were never commonplace. And whilst I did witness the sad sight of a five pound plus chub lying dead and half munched on the bank I think it’s fair to say that overall the chub fishing has never been so good as it is right now on the Hampshire Avon. This winter I’ve had two hauls of of chub from the river exceeding 80 lbs and several of my friends have been catching a serious amount of six pound plus fish. So the otters can’t be eating them all as some of our well known ‘superstar anglers’ were predicting.
In my time in politics I learned that is sensible to try and base opinions on credible, objective evidence and sound science rather than prejudice and emotion. As an angler I know what I and my friends catch, I can draw conclusions from catch and match reports from the rivers I don’t regularly fish but I’m not a fisheries scientist and I don’t have a detailed knowledge of the stomach contents or eating habits of otters. Luckily there are those that do and I’m writing this piece to give prominence to an interesting piece of work by Professor Rob Britton and his colleagues from Bournemouth University who were also assisted by Pete Reading of the Barbel Society.
Rob, who is one of the UK’s leading fisheries scientists, collected otter spraint from the middle sections of the Hampshire Avon over an 18 month period. In the lab they analysed the various remains of the fish (and other animals) that were in the spraints, which revealed a true picture the species and size ranges of fish that the otters had been eating.
And guess what? There were precious few barbel bits to be found. Now stop reading right now if all this science and evidence makes you feel uncomfortable but if you want to know more you can find the full report here:
What do barbel eat?
Rob has kindly set out, in layman’s terms, the key findings of the study which were:
– the main fish species taken were those generally considered ‘minor’ species by anglers, such as minnow, bullhead and stone loach. Of those species of more interest to anglers, only pike were relatively prominent, although these tended to be relatively small pike (<45cm, usually smaller).
– we found that other than in winter, the remains of non-native signal crayfish were present in a number of spraints from all sections of the river, indicating they are now established in the river. This is bad news overall, as they have a lot of negative impacts. However, they might provide a food source for larger perch, chub and barbel.
– although we expected to find some remains of larger chub and barbel, we did not find any of their remains (scales or bones) in the spraints. It is important to note that this does not necessarily mean otters never take chub or barbel in the river. But we have no evidence from the spraint analysis to suggest they do.
finally, eels were taken by otters but never in high proportions. As eels are often taken by otters, their low proportion in otter diet might be a reflection of eel abundance being relatively low, given the plight of eel at present.
So, not a lot of evidence here to support the claims of the doom-mongers for whom this study might be regarded as a rather ‘inconvenient truth’. I also thought it would be helpful to hear from a guy who knows more the Hampshire Avon barbel than most
Hampshire Avon barbel and otters, a personal view by Pete Reading
When I first became aware that the otter population on the Hampshire Avon was on a road to recovery, I was, as many anglers were, a little concerned at the prospect of an additional predation pressure on fish. I am pretty sure that there had always been a small population about on the Avon and Stour, however; I saw my first ever otter on the Stour in 1976, and my first Avon otter 18 years ago.
I took the trouble to do as much research on the matter as possible, to seek advice from fishery scientists and ecologists, and to also give the matter some serious thought.
It seemed to me at that time that there was probably not a significant threat. Otters had been around on the Avon for millennia before their decline at the early part of the century, all previous research evidence showed that they mostly ate small fish, and a range of smaller prey species as the opportunity arose. Amphibians in spring, for example, eels when they were numerous, lots of invertebrates, including crayfish and mussels. Occasional small birds and mammals.
They are foraging opportunists, and it seemed very unlikely to me that they would bother with the effort of chasing and catching large fish in exchange for a small meal when other smaller prey was more abundant and easier to catch. It made no ecological sense for barbel to target and attack a large barbel, although it was possible that the occasional large fish that was moribund, old, sick, weak and an easy target would be recognized and tidied up.
I have now fished the Avon, and nearby Stour, for 46 years, and have not to this day seen a barbel that was apparently killed by an otter on either river, though I have seen two Avon carp. I have found a handful of dead barbel, as well as other species, but they were quite unmarked. Carcases of large fish that look like otter kills have apparently been found, but in very small numbers, but it must be remembered that fish are not immortal, and die on occasion anyway, especially when they get older.
The opportunity to contribute to some scientific research on otter diet on the river was eagerly accepted, and the skills of Prof. Rob Britton and his team at Bournemouth University in analyzing fish scales and spraint are nationally recognized. We had previously collaborated on analysis of Avon barbel scales, which gave some positive indications on the population structure, with a good age range and possible strong year classes.
The analysis of the spraint which I helped to collect with others did not come up with any surprises, with only one small barbel represented, and the few larger fish being quite small pike and chub.
The bones of large fish may not be commonly found in spraint, as noted in the article, since otters seem to only consume small amounts of soft tissue around the gills and belly area, or perhaps internal organs. It seems very likely, however, that lots of scales would unavoidably be ingested as the skin was broken and/or consumed in those areas. Fish are covered in small scales almost everywhere, but the underside of barbel in particular, right up to the gills and fins and all over the belly is covered in small colourless scales, and barbel scales are probably the easiest of all species to identify. I am sure that if a large fish were to be killed and eaten, scales would be ingested in large numbers and could identify and age fish, though ageing could be more difficult than with large scales of course.
I rather think that the main, most patently obvious reason why large barbel did not show up in the results of this study was that they are simply not being eaten very often!
This opinion is backed up by almost no evidence of carcases on the bank, and more importantly, the stable and probably improving nature of the barbel population on the river.
The spraint analysis did show that signal crayfish form a significant part of otter diet, more being eaten in the summer, and also that bullheads are a favourite prey item. This backs up previous work that indicate that otters are great foragers, almost grazing along the river bed and in the margins for small food items that do not involve expending a lot of energy. Hunting down double figure barbel makes no sense, and the evidence that it occurs to any significant extent just does not seem to be there.
I would say that based on my catches, and those of others, and my observations of fish in the river, that the number of barbel in the river has been stable for the last decade, and is in fact increasing.
Recognisable double figure fish are clearly surviving long term, average size is increasing slowly and steadily, and there are good numbers of smaller fish being seen and caught. Not just fish that could be accompanying males of the bigger girls, but fresh little two and three pounders, and huge numbers of tiny barbel in the 4-8 inch range throughout the river. It seems to me that the Avon has a very sustainable population structure in terms of barbel, and indeed most species other than roach, though there are signs of recovery there, as on the Stour.
A couple of years ago I had a catch four doubles in a day, and catches of two or three doubles in a day is not uncommon, but I have also had catches of six or seven smaller fish in a day in recent years, including several fish of less than three pounds this season.
I have spotted shoals of a dozen or more fish at times, and lots of tiny barbel all over the river. Avon barbel fishing is actually on the up, in my view, despite my being told six years ago that the river would be ‘finished in five years’ once the dreadful otters had eaten everything.
I was also told by anglers that the Avon barbel had been ‘decimated’, and that ‘every third barbel was ripped to shreds by otters’.
Total nonsense then, and now.
The chub fishing on the Avon is fantastic, with both large individuals and catches of a dozen 4lb plus fish in a day featuring regularly, and lots of evidence of small chub and strong year classes. Dace have made a huge comeback on the river, along with grayling, and the salmon fishing has made a dramatic recovery in the last three years.
Barbel seem to be spreading further upriver, to Salisbury and beyond into the tributaries.
I like to base my opinions on credible evidence, logic and reason; a scientific training helps with that.
All too often anglers jump to conclusions, seeing simple answers to complex questions, blaming something easy to hate for their perceived poor catches, and bankside rumour and gossip often seems to prevail over common sense and proper fact-finding and research.
It could even be that the otters are actually benefiting fish populations in the long term by keeping down numbers of truly ferocious predators like bullheads and crays, that must both consume untold numbers of fish eggs and newly hatched fry!
Angling Trust and Predation
Here at the Angling Trust we have to address the impacts of predation on more than just rivers and barbel stocks. There is absolutely no doubt that otters have been doing immense damage to a lot of stillwater venues which is why we have been active in levering in rod licence income to support the installation of otter fencing for affected fisheries.
Carp waters are especially vulnerable, particularly those near to rivers which the otters use as a highway. We have produced an action plan on otters and our full position on the problems of otter predation can be found here:
For what it’s worth my personal view is as follows:
Anyone who thinks there will ever be any public or political support for a widespread otter cull in response to anglers concerns needs a serious reality check. That said the legal protections introduced when otters really where an endangered species are now disproportionate for a species that is fully recovered.
Otters are apex predators and need no help from us in re-establishing themselves beyond no longer being poisoned by DDT or hunted for sport. They can have a very negative impact on fisheries, particularly stillwaters, if artificially introduced into the area in unsustainable numbers and any such introductions are irresponsible and must be opposed.
Natural England should put an end to any releases of rehabilitated otters which have been injured fighting with other otters, or through other causes. In these cases otters appear to have less fear of humans and can cause greater damage to fisheries. They are also highly likely to fight with other otters when they are released into their territories which makes the whole process somewhat self-defeating.
There are a host of reasons for the decline of barbel in some rivers and its revival in others. Destruction of habitat and spawning grounds is one. Poor recruitment exacerbated by the presence of signal crayfish is another as are low flows and poor water quality.
Of course otters have had an impact in some rivers, particularly on smaller streams but they are not, as the science shows us, by any means the whole story.