Alex: Shrimp farming results in damage to the environment, because investors make quick profits from such farming and then abandon the farms.
Alex's 1st Claim
Shrimp farming results in damage to the environment.
Does Jolene imply that shrimp farming doesn't result in damage to the environment? No. If anything "unsustainable" may be a reference to damaging the environment, so if anything Jolene possibly agrees with Alex here.
Alex's 2nd Claim
Investors make quick profits on shrimp farms and then abandon the farms.
Does Jolene imply that investors don't make quick profits and then abandon the farms? Yes, pretty much. She says that these farms take , both of which don't like "not-quick profits".
She also says that most owners try to make sure the farms are productive for many years, which sounds like "not-quickly abandoned"
Goal
Look for an answer that talks about - whether or not shrimp farmers make quick profits and then quickly abandon the farms