I float fish in the estuary... but I also don't have any friends, so this hasn't been an issue for me.
The estuary is an area where salmon (we're talking about salmon right?) transition from salt to fresh. Depending on which part of the estuary you are referring to, the fish can either be feeding aggressively, or simply migrating fast up the channel into freshwater.
If they are feeding, chances are they are feeding on baitfish, or crab. These are hard to present under a float. Stripping flies, casting lures are easier methods to get them.
Once they start moving with the tide, they move fast. Take the tidal portion of the Fraser River for example, fish generally do not stop once they start going up the river. Two methods are commonly used to catch them, casting and retrieving lures can intercept them at spots where they slow down. Having bait anchored on the bottom and allowing the outgoing tide to carry the scent down the river draws them in. If the bait is freely drifting with the tide under the float, there's a lesser chance for the fish to find it.