A prominent Long Island businessman was found dead in his car today in an apparent suicide, police sources said.

James Bissett, 48, was found dead in his vehicle in Veterans Memorial Park in Mattituck at 6 p.m. Wednesday night, cops said. His manner of death was not disclosed.

The Mattituck resident was co-owner of the popular Long Island Aquarium in Riverhead and was spearheaded the development of a new Hyatt Hotel nearby.

Active in local Republican politics, Bissett also ran a Holtsville nursery and a Riverhead marina.

The businessman had initially placed his sprawling Mattitucuk estate on the market for $8.9 million but reduced it to $5.8 million on recent months.