Those differing concise* posts about catfish from Windy and Philip above, I feel like I want to add a 'like' to both yet one has to be wrong
Or does it?
No, I dont think it does.
My post was about the effects of introduction of Catfish to a water that as far as I know did not have any native population until they were first introduced by German anglers to the Rio Segre in the 1970s, or the reservoir of Mequinenza in 1974, depending on which source you believe. Other Googles and suggested origins are available...
The report that I posted was taken from a seasoned professional reporting his personal experience of observations over decades, week in week out on the river with his clients. A knowledgeable and authoritative source of information.
His account details the progress of the initial effects of Catfish introduction to a very temperate river with an enormous head of potential food and no previous Catfish population, nothing more.
Philip's post in contrast (as I read it, please feel free to correct me if I have it wrong) sets out the conclusions of an assessment of the integration of an
established native population of Catfish in the slightly cooler South West of France. An assessment and account I have no reason to doubt.
Given time I would anticipate that the Ebro will also and eventually reach a similar level of integration and accommodation with the other native fish species. Especially in the light of my informant's observations the last time we met in 2016 that many large Catfish were dying for apparent lack of food and that the Carp and other silver fish population were showing signs of a mild resurgence.
How long it will take for there to be a balance achieved I have no idea, but I suspect it may be a matter of decades rather than years. On the other hand the growth rates in such a huge and warm river are an order of magnitude greater than anything we experience here in cold, grey and damp old blighty.
In passing I understand from other reading over the years that the main predator for Catfish is Catfish... which explains why, in an established and balanced population, the big boys keep the population down by eating the Kittens. In the Ebro, when first introduced, there would have been no equivalent population of young Catfish and no need to eat them, given the huge feast on offer.
* "Concise..." Sarky bugger. There is a reason for my nickname you know, and it's not because I am a weather Jonah !