When talking to anglers on the riverbank it is not unusual to hear "No, don't fish there, Otters have emptied the river"
The funny thing is, I heard the same thing about Cormorants a few years ago and Mink a few years before that and even about Pike when I was a kid.
Now I can't say that I still caught plenty of fish in these locations because, hey this is me! I don't catch plenty of fish anywhere! However, one thing that stood out to me even then was; Predators are always found with their prey. If there is no prey then there will be no Predators. These animals hanging around empty rivers is the same as a bunch of hungry humans wondering about an empty supermarket. It doesn't happen.
When I first started fishing it was disturbingly common to be told by anglers to take out and kill any Pike you caught as they "ruined fisheries". Now that was obviously a nonsense and is mostly accepted as such nowadays. Pike are a valued part of any mixed fishery and their presence does not significantly affect the quantity of fish in the area and indeed it can be argued the quality of the prey fish improve as the sickly and malformed are the first to be eaten.
Cormorants have moved inland for the last ten to fifteen years or so as a result lack of prey at sea (due to over fishing by humans). They are quite large birds that can eat a lot of fish but they are designed for catching fish in open water. Though adept swimmers, they do not have the tools for pursuing prey through reed beds, underwater snags and undercut banks. The result is that they will predate on river fish but will not be as effective as they are at sea or in open water.
The Otter is a however a river specialist and has the full skill set for chasing fish down amongst the boulders and tree roots.
The common demoniator with all the above is they are all bound by the equation of any predator/prey relationship - The numbers and success of the predator is directly linked to the number and success of it's prey. After all, one does not hear of the Serengeti being devoid of antelope because Lions live there! [OK, this analogy is a little facetious but you get my point.]
A lot of our rivers are in fact regularly stocked by the EA in any event so the management of these waterways is semi-artificial. Introducing an extra predator in to the equations at most requires a slight shift in stocking strategy.
It is my view that fishermen generally (and I include myself here) look for reasons and/or excuses why they have not caught fish. If you visit the same location on a number of occasions without success then it is easy to think that there are no fish there and urgo something must have happened to them. The reality is that there are any number of variables as to why you have not caught fish and it is wrong to pin the blame on just one possibility. A lack of fish in a stretch of water is much more likely to be down to water quality than the result of predation.
Commercial Fisheries offer a very different perspective on the problem. I have every sympathy with Fishery owners which are now having to look at tackling the issue of predation.
Some of these ponds were created before the re-introduction of the Otter took place so it is unfair to have expected the designers to take this in to account. However, animals predating other animals is not a modern phenomenon.
Commercial lakes are generally artificial, the high stocking density and relatively shallow water make them very vulnerable to ecological changes and managers are more than aware and prepared (hopefully) when it comes to disease, pollution and poaching. Predation is simply another factor that should be taken in to account at the design stage.
The re-appearance of the Otter and the ongoing threat of Cormorants and other predators should be seen in the same way as the threat from poachers, pollution or disease. Business decisions need to be made to address the threat. But the issue is one of business management not an "ecological disaster" as it is sold in some quarters. Fishery owners may have to alter the business model to allow for this which may involve investment such as making alterations to their venue. If so then such costs can and in my view should be past on to customers who want to continue to enjoy their angling. I see no problem with that.
I have been blessed with seeing Ospreys taking Trout at Eyebrook Reservoir (with much more success than I) and research shows that this fantastic bird may be making a long awaited come back. If this is the case then anglers will have yet more competition on the river bank. From this writers perspective it is the kind of competition I look forward to.
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