One night a friend took his son and son's gf out shrimping here in Oak Hill, when the critters began to chow and the Eau de Deet was not on board he d/l this app and it worked.
Couldn't hurt for free!
http://www.appstorehq.com/antimosquitofree-iphone-32864/app

Sorry JJ, no manatee repellent! I can tell ya don't throw the corn leaves and silks overboard if ya ever carry any out for supper waiting for the tide to turn! One late afternoon we anchored up sideways and had a some chicken and corn on the cob waiting for the tide to switch. We tossed the vegetation, and the silks floated south, then about dark came back north with a manatee who managed to nearly get in the boxnet which we had hanging over the side to deploy after setting out lights and drifting back. He did break one of the ropes before getting on!