Remy Moreau – a crusty crawfisherman who lost everything between Katrina and the Deepwater Horizon spill – is about to commit suicide in the marsh, when he discovers a mysterious trinket that he desperately hopes will lead him to a legendary treasure left behind by pirate Jean Lafitte.

Character names shouldn't be in loglines. Their names are irrelevant for a logline

You spend to much time on back story as a result the logline is way too long.

"When he discovers his crazy grandfather's treasure map in his attic, a suicidal fisherman blindly follows the map in the hope of saving his crawdad business, but must battle a brutal but famous treasure hunter for the spoils."

A little to much character background. Why does he think the treasure will save everything? Is there anything that he needs the money to solve, other than just being poor.

During a suicide attempt a man that lost everything in hurricane katrina finds the treasure map of Jean Lafitte which triggers a hunt to change his life.