I see a wildlife programme on this once, they're jumping out the water to catch insects on the wing. I would think the light is attracting the insects so the jumping gets worse.
I saw flying fish for real on a boat trip in the Amphong Marine Park in Thailand last year. Was trying to get a good look at the island we were approaching, when all of a sudden I saw this fish kinda just a skip across the water!
It was very, very cool. Saw quite a few that date, but you never knew where they'd turn up and always so fast so never got pics.