Why no live minnows?

[tmrfish]

I suspect it is because of spreading diseases via minnows or the introduction of undesirable fish that escaped or were released as bait. I haven't been able to find any info on this. If anyone could post links to articles or information about the reasons why live minnows are illegal, I would love to read them.
Also, do the bait stores in Regina sell frozen minnows?
Thanks
TMR