I know pretty much everything about stingrays and sturgeon, so I don't have any questions. Some of the basic questions you should be prepared to answer/information you should be ready to disperse include:
Sturgeon are prehistoric fish. Know about their ancestry. Population decline due to lucrative caviar market. Caviar collection without hurting the fish. Sport fishing as a means of protecting the population, due to increased revenue surrounding the fish.
Stingrays - how they are dangerous, the different kinds, how big they get, how many (read few) people are killed by them, the danger (or lack thereof) that they pose to swimmers, snorkelers, and most importantly people who wade in the ocean.
Additionally, you might want to research the fairly popular sport of spearfishing for stingrays. Apparently the meat can be very good.
If anyone ever told you that I give a damn, they damned well told you wrong!
The other day I was eating Starbursts and watching TV, and then a Starburst commercial came on. I was like, damn, that's profound.