Hi!
Gota Alv river is stocked with severeal thousands of salmon smolts each year, the first salmon was just caught a few days ago, usually salmon starts coming in by may.
There are two places you can go for flyfishing Gota Alv:
Lilla Edet:
SFK Laxen- Sportfiskeklubben Laxen
Trollhattan:
Trollhättans Laxfiske
Both of these fisheries are situated just below hydropowerplants, the one in Lilla Edet has a really short fly fishing only zone however the turbine that regulates the waterflow on the flyfishing zone is supposed to be down for maintenence this summer so it might be unfishable, in trollhattan the first salmon is usually caught in june but the bulk of fish arrives in trollhattan be August and onwards. In trollhattan there's also a flyfishing only zone.
There are other alternatives close to Gothenburg that might be more interesting to flyfish:
River Atran in Falkenberg(2 hours by car):
Ätrans Sportfiskeförening | Falkenberg
River Viskan in Veddige(1,5 hours):
Fiske i Viskan (Kullagård, Åsbro) (iFiske.se)
River Orekil in Munkedal(1.5 hours):
rekilslvens Laxfiske, Munkedal
River Savean in Partille(15 minutes):
Sportfiskarna Göteborg - Säveåns laxfiske