Nope. Margin note at the bottom of YS185 indicates that if they could, their Catch would be reduced to +0 in value. Which it isn't.
And for what it's worth, I don't think it's best to model fetches as having unrestricted shapeshifting Powers. Going by what I remember from the books, if they show up in a given form they're staying in that form until at least the end of the scene. Been a while, so I could be misremembering, but if I were writing them up I'd put a heavy Limitation on their Shapeshifting powers.