Twenty years ago I was wondering how long before we found catfish in many of our major river catchments, given the popularity of the species in some quarters.
I'm surprised that we don't hear of more captures in Thames tributaries given that big catfish have been reported caught in the lower reaches of the river for yonks.
It's understandably difficult to access what long term impact they have on fragile river environments and is interesting to look at the continental rivers for a few pointers, taking into account that some have more favourable water temps. than our own rivers.
As I have been able to witness and observe the impact of an introduction of a few kittens into a three acre gravel pit that occurred on one of my club waters in 1992 / 3 , it has been interesting to note how things have panned out.
The English cats were stocked on the recommendation of the EA in order to rid the venue of Signal Crayfish that some idiot had released into the pit a few years before and had become intolerable .
The project is closely monitored by the club and authorities and seasonal nettings and electro fishing are undertaken to check on recruitment of all the residents.
The cats soon started to grow and breed with many 2 / 3 inch kittens showing, but at no time has the carp, bream or silver fish population shown any sign of depletion. The crays however disappeared within the first two years !
As many of the big cats in the pit are caught on pellet and boilies and not live baits, one would have to assume that they have a distinct preference .
So, besides the inherent risk of latching into a very large unwanted cat when carp fishing, there has been no discernible negative effect,... haven't noticed so many coots and mallards though !!
The criteria for the stocking was strict, with overflow , proximity to a watercourse etc all paramount considerations.
Cats are a species that we could do without in our rivers imo, but there have been times in past years when fishing cray infested stretches of the river Mole that I have wished that a few of them would swim upriver from mother Thames and fill their boots !!