Winning the contest is simple ... in theory. Once the contest starts at 14:00 server time, fish in every pool in Northrend you can find until you get a Blacktip Shark. When you get it, bring it back to Dalaran. There's a lot of luck involved, but the contest is definitely winnable, especially now that it's been out for over two years.
The derby offers some pretty sweet rewards. It's the only place in the game where you can obtain an heirloom ring. (You could opt for boots that increase your fishing skill by 15 instead, but who'd ever choose that instead?)
Do you participate in the Kalu'ak Fishing Derby? Have you already won your Dread Pirate Ring prize? Or is the random nature and high competition level of the contest simply not worth your time?