I've fished there in the spring and summer in the past.
In the spring I did not find them to be a problem, this I believe was probably due to the water temperature being quite cold. With this in mind they may have slowed down by October, provided the temperature is starting to fall.
When there in the summer I found the poisson chats to be a nightmare for any baits not meshed up.
To be on the safe side I would always make sure on a trip to Les Quis that I had plenty of netting - plastic not womens stocking and was familiar with using it.
On my last trip when they were very active I caught well on Mistral Rosehip. These were straight out of the bag, not air dried and were meshed in plastic netting.
I did not have alot of confidence in the bait they were selling.