When does the bulk of the run of fish arrive? When is the best time to Salmon fish? Besides, when you can.
Really varies these days Rich, many rivers used to have a defined spring run, others were famous for grilse and summer salmon and others were autumn 'back end' rivers.
I don't think it's too sweeping a statement to say it's broadly recognised/become understood that most UK Salmon rivers have fish running almost all year round, the bigger the catchment and size of the river then the more that statement is generally true.
The Ness system had a fish on opening day which was Wednesday, it was caught on the River Oich which is at the western end of Loch Ness so the fish had travelled upwards of twenty five miles from sea to the river. It was probably heading (still is.... it was released) for the Garry so ultimately perhaps spawning late this year some 50 miles from the sea. In other words it will be 10/11 months before getting a shag. That's patience for you.
Thing is that fish may well spawn with another salmon that runs the river in November, this is because it's clear from research going into the system that fresh fish are running as late as December. This makes as early as January a calendar observation by us humans and of no relevance to the fish.
When is the best time to fish
Well, when you can and where you can afford are the answers (sorry). This all season/year round 'running' doesn't mean that these systems don't still have defined runs of spring or summer or autumn fish that they were famous for; it's just the fish have changed the rules.
H