In case you weren't aware, sturgeons are regularly kept in public aquariums. Public aquariums do have the resources. That man didn't have to transport the fish himself; he simply could have let it go and alerted the local fish and wildlife department, and they could have found it. I didn't state that species was going extinct; however, I said that old specimens are becoming incredibly rare, and it's true.
This specimen could have very well helped ichthyologists; you don't know much about zoology, do you? Scientists would have been able to perform so many studies and draw statistical data, such as what factors can help increase the lifespan of a sturgeon, and help them live longer. That would also yield a greater amount of caviar, keep in mind.
Nice strawman.