The Fisheries Act is very useful in some circumstances, and those circumstances might even include some farms where you have, say, a pipe coming from a dairy, with milk waste going into the stream. You can say “that pipe and that farmer, that's a problem”, but many of the pollution issues that freshwater fish face are non-point source pollution. It's too much fertilizer applied over large areas of farmland, it's large numbers of farms, or it's erosion from multiple places. So yes, the Fisheries Act is nearly useless for those kinds of problems.
On May 4th, 2010. See this statement in context.