James Allman was sentenced to one year of probation and fined $10,000 on Friday in federal court.
Allman of Port Salerno had pleaded guilty last year to helping set a large "ghost net" adrift off the shores of Martin County in January 2004. A protected sea turtle died after becoming entangled in the net.
The net, which trapped the juvenile loggerhead sea turtle and hundreds of sharks and other fish, did not have any marker buoys or identifying information required by fisheries regulations, according to court documents.
The entrapment of a loggerhead, a species listed as threatened, is a violation of the federal Endangered Species Act.
It was reeled out of the water in an eight-hour recovery operation that involved a helicopter, two commercial fishing boats, a speedboat, two divers and federal and state agents.
Federal prosecutors said Allman owned two of three boats that were fishing for black tip sharks and set up the net to capture a school of sharks.