I believe it's blended to give it the pink appearance. Runningwolf can better answer that one. Our Catawba was white as well. It tastes really good blended with a little concord.
Most Catawba is White. It takes an exceptionally good year to get some pink juice like last year. I blend something like Chambourcin or concord in with it to get the color I like.
I ferment it on the skins and it comes out a bit pinker than if you press before fermentation. A lot of the juice you buy (most actually) is pressed right away, so there is really no pigment in there to give it color.