I think the difficulty has always been, and still is, to track back to who it was who introduced a particular species into the water. I think the answer is no, but there have been many individual cases where ships were found to have brought some sort of species with them that they shouldn't have, and where they've certainly been forced to account in terms of returning and cleaning up any contamination that might have occurred as a result.
On April 30th, 2009. See this statement in context.