With a little more time on my hands, I thought I would attempt a more complete reply to questions raised by Kush, Riveraddict, and Norseman regarding weight in flies for Atlantic salmon.
As noted, Quebec is the only province in Canada where weight in the fly is legal for Atlantic salmon. The ten-dollar question is whether weight added to the fly does one any good at all (at least where Salar is concerned)?
In most circumstances that I encounter in Eastern Canada, I believe weight added to the fly in the form of lead wire, lead eyes, brass tubes, etc., is counterproductive even where its use is allowed. Quebec (where weight in the fly is legal) is primarily a summer fishery: the peak of the run is generally late June and early July. For most rivers (the Matane may be an exception), the bulk of the run is in by mid-August with, of course, a few stragglers yet to trickle in.
Atlantic salmon under most conditions are a very surface-oriented fish: in common parlance, they are "looking up" most of the time. There are various reasons for this behavior. Salmon are hunters; they approach and kill their prey, in the manner of many sea-going predators, from below.
As active, fresh-run salmon will travel quite a distance both horizontally AND vertically in the water column to grab a fly, adding weight to the fly may remove that fly from the window in which salmon are tuned to look for prey species. That is not to say that a quick-sinking fly will not work. I prefer, however, a light and lively fly that darts and dances through a salmon's window of opportunity, and stays there for as long as possible.
I make a strong distinction between the taking behavior of summer-run and fall-run Atlantic salmon. Summer-runs seem more likely to 'chase' a fly and will often do so over very great distances. I saw a large cockfish on the York last June that travelled over 20 feet in under a second to grab my buddy Greg Pearson's fly; he took it like midnight lightning.
Fall-run salmon are far more territorial than their summer-run cousins. They are more likely to crunch a fly that invades or 'intrudes' upon their territory. They will follow a fly quite a distance laterally (i.e. horizontally), but seem reluctant to power up through 4-6 feet of water to grab. When they do follow a fly, they do not seem to be chasing it, more like 'escorting' it out of their immediate environment.
There is, of course, crossover behavior between summer-runs and fall-run salmon. As fall-runs (due in part to declining water temperatures and in part to the proximity of spawning) are less likely to grab a surface fly under most conditions, a little weight in the fly may be useful. Keep in mind, however, that in New Brunswick and Nova Scotia, where the best fall-run salmon rivers are to be found, and it is illegal to add weight of any kind to the fly.
Fall-run Atlantic salmon are much closer in behavior to winter-run steelhead than they are to summer-run salmon. In fact, I call my Fall fishing "steelhead fishing for Atlantic salmon." I do not weight my flies as I want them to 'hover' and remain at the optimal depth for as long as possible; I carry 12-14 interchangeable tips to optimize my search for that depth.
The Maritime rivers of Eastern Canada do not have the push of water throughout the season of the big West Coast rivers. There are no glaciers or snowmelt from 10,000' peaks to help maintain even flows. Under most conditions, weighted flies for Atlantic salmon in Eastern Canada, where legal, are not necessary and may be counterproductive due to the surface orientation of Atlantic salmon.