Wednesday, 24 October 2012

A Debate 'Otter than Ever

I only had a photo of a scottish otter and knew you would tell the difference
After a bit of a discussion over concern about recolonising otters (not to mention signal crayfish and spurious zander catches!) this weekend
(see Daniel Everitt's blogpost
it has been a subject at the forefront of my mind. However, having been out of the angling loop for so many years until early 2011, I am always in danger of stating the obvious without realising that someone has said it before, probably yesterday (or, worse still, several years ago!), but there has been something nagging at me which needs airing, at the very least to satisfy my curiosity

A number of british record rod-caught freshwater species sizes are now far in excess of weights one might have anticipated 20 years ago. I note that record barbel, bronze bream, carp, chub, tench, zander, etc., are now unrecognisable from those I remember and close-on 20 of the current records have been set since the dawn of the current millennium, but why, it's not as though angling has only just been invented is it?

This must have been discussed in the angling press in the past but of course I am oblivious to this and strangely a good amount of research has not uncovered any clues; having said that, if I had read anything from those quarters I wouldn't know whether to believe it, so sensationalist is that sector of the sport. This could imply that it was discussed so long ago that the information has not found it's way onto the web because it's widely known or that it really hasn't been touched on in any detail (unlikely)

Two immediately obvious potential causes spring to mind and would probably spring to anyone's whether they had been away from the sport for so long or not...but then you'll tell me this is common knowledge/claptrap so at least I'll be clear on that!

The first is to question whether breeding for introduction to commercial fisheries is sufficiently far 'advanced' that some species of fish can be bred to grow bigger? I am sure this must be possible but why this would be of interest to anyone other than someone on some kind of simple misplaced glory-hunt is beyond me

Fast food for fish. The new logo

The second thought I had is that certain, probably artificial, baits might serve to increase fish weight like a sort of Chubway fishy fast-food overdose, or but this might be more readily applied to stillwater fish which would more likely rely on such a food source if angler's bait is all-but the only option available to them and a tendency toward unnaturally increased size would soon then become a self-fulfilling prophesy once they reach proportions which would be unsustainable without anglers' bait, that or they die anyway...or fail to put on further weight. Carp would be a typical example of this, were it true, as many of the larger fish I see photographed seem to have disproportionately large distended bellies perhaps blatantly belying a trait of this nature. So, on over-stocked new 'commercial' fisheries which have been fished heavily since their first opening and before natural food levels reached anything like their full potential, and never could, this seems perfectly logical. That other matter of the pointlessness of fishing such venues is surely therefore self-evident and there are other moral issues here which there isn't time to cover nor would I want you to nod off, yet. I digress, a touch, but some of the photographs I have seen of outsize carp clearly display these traits with the increased weight fairly obviously largely attributable to their increased bellies. Conversely some of the fish I have recently seen photographs, displayed in blogs I follow, of smaller carp with a more 'wild' profile appear a much more desirable and laudable target with some attributable natural beauty

Am I wrong or am I simply missing something here?

The above could also apply to stillwater bream and tench but as for river fish, such as chub, what explains their sudden increased size? Are they really so consistently fished for on rivers that such a reason could apply here too? It seems unlikely

Is it possible that the otter is to blame for this too?!

If we could cast our imaginations back to when otters were widespread, many of us will struggle as their steep decline occurred in the 1950's (when habitats were being trashed by tidying-up of water courses, pollution, etc.), they would undoubtedly have been a significant predator of fish over a pound and possibly the main one. I am not sure how significant their impact extends to the subsequent proliferation of stillwaters but if we were to extend this thought a little it would not be beyond possibility that the presence of otters might have controlled the maximum size of river fish before they became legally protected in England in 1979 and found themselves 'near threatened' of global extinction according to the IUCN red list

If river fish sizes have been able to grow with less predator control, other than the constraints of species preying on smaller fish and the latters maximum lifespan, as they have in the recent past, is it inconceivable that the past two decades may prove to be some kind of historical peak, when we look back in future, now that otters are back (in Warwickshire)?

An otter needs to eat around 5lbs of food per day, they are big mammals, with a male holding an extensive territory of up to around 25 miles of water, and not necessarily a single watercourse, with maybe a couple of females and, from time to time, perhaps half a dozen young within that same territory. It is therefore possible that if otters are eating fish of all sizes they would probably find it easier to catch bigger sluggish ones than lively young ones, it is also a more profitable prey. So if they do this they can, by default, control the maximum fish size in a river by thinning out the bigger ones and leaving less of them to grow to record breaking proportions. The chances of a record fish are reduced and, by implication of the above, the average size of those regarded as specimens will be lower too

Tony Miles' 1989 publication with the author holding a predator large enough to take a pound chub

Thinking chub here in the main, I have referred to Tony Miles book 'The Complete Specimen Hunter' before and what is interesting in this context is that the implication of his writing in 1989 is that a 4lb-plus chub is a good size and anything over 5lb a genuine specimen, perhaps comparable with a roach of well over 2lbs, but in 2012 a four pounder hardly warrants a mention and it is clear that many bloggers are looking for at least six pound plus fish to light their respective candles. Not only this but the number of these bigger fish being caught is quite staggering, indeed 12 of the top 20 of the Chub Study Group list have been captured since 2000

Maybe specimen angling on more natural/naturalised waters has experienced an halcyon period without the participants realising it and the otter will now bring that back to a level of normality. We may even need a new record list like sort of 'drug enhanced' and 'clean' athletics world record lists!

Anyway all that is just a theory without much substance other than a bit of common logic but it seems plausible don't you think? My only 'concern' about this, coming at it now as a selfish angler, and whether the above is true or not, we may see otters become slightly more common than their territories can realistically support longer-term for a short period at which point it is likely that fish and other prey species will be over-plundered until the predator experiences 'die-off' to a level of natural equilibrium, a phenomenon known by ecologists as 'overshoot' of the 'carrying capacity' of the habitat. This could be brief but in an animal with such a large individual range one might perhaps assume it could take sometime now that I am lead to believe local rivers are at carrying capacity of male otters

The Complete Specimen Hunter, Tony Miles (Crowood), 1989
The Angling Trust website
Chub Study Group List of Top 50 Chub
IUCN red list

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