The information I have is that several "ich" ending surnames appear in my hometown of Cabo Rojo, Puerto Rico in the late 1700s-early 1800s. There were Ursulich (my direct ancestors), Wiscovich, Petrovich (both related to me by marriage later on), and maybe others. Our research indicates that they came from Dalmatia/Croatia, part of the Austro-Hungarian Kingdom. They were merchants and sailors. At least some came from Ragusea, and apparently via Venice (also part of the same kingdom at the time). They were Catholics (either born or converted, as the Spanish Empire, of which Puerto Rico was at the time, was Catholic). Part of this history is documented in a will left by my Ursulich ancestor. It is possible that your Wiscovich relative came from Puerto Rico, although I believe the mass migration from P.R. to USA began much later, in the early 1900s.
There are still Wiscovichs in Cabo Rojo.