The Annan can be split into three sections with the lower reaches extending from Annan to Dormont, the middle reaches extending from Dormont to the junction with the Kinnel and the upper reaches from here up to Moffat.
Essentially these boundaries are defined by the gradient and current speed in these sections with the upper and lower parts being fairly fast flowing and relatively shallow. The middle reaches is part of a large flood plain that has very little gradient and as a result the river meanders through the valley bottom. The flow is much slower than the other two sections with deep pools very common. As the river is not particularly large migratory fish can distribute themselves throughout very quickly given the right conditions.
As there are a large number of substantial tributaries throughout the rivers length not all the fish will make a helter skelter run straight to the top in a spate and instead will spread themselves out fairly evenly throughout.
If the water remains very low concentrate your efforts on the bottom section of the river until October after which the urge for the fish to move towards their spawning areas encourages them to move up irrespective of water conditions. August to October is also the time that anglers have greatest opportunity to catch the true giants of the river, salmon that run well past 25lb and occasionally over 30lb. The largest known of in recent years was a fish that was estimated at over 35lb.
Unlike the salmon the sea trout don't require the same quantity of water and they will run on all but the lowest flows. In general the earlier fish tend to move through quite quickly and the fishing on even the upper beats can be remarkably good in May. They quickly distribute themselves around the whole of the catchment and by June there will not be a fishery on the Annan that does not have a population of these fish present.
Bridge Pool near Lockerbie