If they are trying to reduce the amount of traffic and use of sonar in the Straight to quiet things down for the resident orcas.
I can only appreciate the need to reduce the stress on the smaller streams in a similar light. I can't believe how many of these guys are ripping around up there. It has be disruptive to the entire ecosystem/food chain. From the returning salmon, to the fry, bank erosion, damage to native plants, causing silt which can stifle insect hatches that feed fish and birds, chasing away mammals etc.
I agree, stick to the bigger water bodies. Put in a speed restriction, or something...