This information comes from a government report on the Trym in 2014.
Peter Coleman-Smith has uncovered the following
I looked into the Government data on fish in the Trym catchment and found that there was an electro-fishing survey undertaken in June 2014. I’ve tried various searches and this was the only data on the Trym catchment I could find. I’ve downloaded the data and played with it a bit. It’s very interesting. See the graph below:
So, as recently as summer 2014 there were brown trout in the Trym. This date is after the pollution event I’ve heard about (but have no details on) which occurred in 2013. I see this as pretty positive. Very interesting how bullheads (imagine a freshwater goby) are present in the Trym at Combe Dingle but not upstream of that in any numbers. Also three spined sticklebacks are the main species upstream of this on both tributaries. That said, this was a round of surveying, so who knows what the prior or subsequent trends have been and what the current fish population looks like.