I also believe that this hybrid was brought in from another state. NJ's biggest bass lake is Lake Hopatcong and that lake is stocked with hybrids. In Pa. the most popular lake for bass fishing in the Pocono area is Lake Wallenpaupak which is also stocked with hybrids and standard stripers. I have caught both hybrids and regular stripers in Wallenpaupack back when I had a hunting camp in Masthope Pa.
I would think that if stripers were inclined to spawn with white perch there would be plenty of opportunity to do so in dozens of fresh water streams such as the Mullica River in Jersey, the Hudson in NY, the Ct. and Housatonic in Ct. plus dozens of other streams where both species exist in both the fresh water and brackish water sections, yet I have never heard of a wild bred hybrid striper of either white perch or white bass.
One requirement of striper eggs is that they stay buoyant after fertilization and that the spawn occurs in fresh water. So that spawning spot requires river flow and/or tidal action to keep the eggs afloat until they hatch. You will not get natural reproduction in a lake unless the stripers can get up into a major river far enough for the eggs to float in current until they hatch. Colorado river up stream from its impoundments, the St. Johns river system in Florida, etc. would be those kind of locations but Candlewood Lake has no moving water of consequence.
So my opinion is that it was brought in alive and released to be caught again or it was brought in and claimed to have been caught in Candlewood.
The hybrid striper programs in Pa. and NJ are popular and successful. When I have mentioned this to our Inland Fisheries people they have had no interest in starting a hybrid program.