I was finally able to track down the ratings. Monster Ark scored a 1.7. It was the second highest program on Sci-Fi for the week and the highest film for that week.
However, we must look at the bigger picture. One, the film was the only original film for that week. Two, there was only a handful of new original programming on the network. And three, it didn't come close for the weekly (in most cases, repeats of repeats) on cable as a whole.
Successful for Sci-Fi Channel.