My initial google-fu did not indicate as much and your comment made me research as to why. These animals take decades to reach sexual maturity and the last time a wild sturgeon was known to have reproduced in Germany was in 1964. So while they have been reintroduced, no one can say for sure yet if that reintroduction has been successful.
There are some baby sturgeons that Germany hopes will result in a stable population. However it will be decades before anyone can tell if that was successful. That isn’t at all comparable to the Americas where somewhat stable populations have persisted. We’re talking about creatures that live longer than humans and reach sexual maturity later. There is a very real chance that predators and invasive species will prevent or otherwise complicate any reintroduction efforts.
To say there are wild sturgeon in Germany when there hasn’t been a known wild birth since 1964 and the few they have in their waterways were all captive bred releases from caviar farms is disingenuous.