My question: Can you tell me about/help me find information about sturgeon species (wild and/or farmed) in Hawaiian waters. I have looked in all the obvious places on the Web, but there seems to be nothing much written/published on the subject, aside from some brief references to Hawaiian sturgeons on sport fishing and culinary websites. 

I recently found the mummified (i.e., VERY dried) remains of what appears to have been a small sturgeon on a local Maui (Hawaii) beach. The "remains" consist of a large patch of skin with scores of empedded dermal scutes or denticles identicle to those I've seen in photos of a Stellate Sturgeon (Acipenser stellatus). This species is anadromous (lives in fresh and brackish/saline waters) and typically reaches about 1.5 meters length at maturity, which is about the size of the fish this specimen belonged to.

I've lived on Maui for about 10 years and know a lot about the zoology of marine vertebrates and invertebrates, but I had no idea that there were sturgeon species in my local waters. I had heard that the Big Island had a small but growing fish farming industry that included a few companies that farmed sturgeon species. It might be that my mummified specimen once belonged to a farmed fish.

Any info you might be able to impart would be most welcome.

I don't think that there are sturgeon native to the waters around Hawaii. As you say, sturgeon are anadromous (or most are) and so migrate from fresh to saltwater. however, I'm fairly certain none spawn in Hawaii freshwaters and they are not oceanic travellers. So a wild sturgeon that found itself near Maui would  - I think - be one that had got badly lost (which is possible of course!)

Perhaps more likely is that either it was a different type of fish - the drying out may have made it appear more sturgeon-like than in life. According to the Star Bulletin there was some sturgeon aquaculture in Hawaii … index.html

i don't know whether this is still ongoing. i also don't know if they use a saltwater rearing step as in much salmonid farming - if so then escapes are always possible.