It is said that these sharks’ favorite meal are the bite-sized Pygmy Suckerfish. Perhaps a hook in their waters will do the trick. Because of the increased concentration of fish, you have an increased chance to catch a shark from fishing pools. Don't forget, in patch 3.3.0 you never catch trash from fishing pools, regardless of skill.
The derby winner will receive a substantial chunk of experience (or money at maximum level) and gain 5000 reputation with the Kalu'ak. In addition, the champion will be given a choice between two unique rewards:

Dread Pirate Ring
Binds on Account
Unique-Equipped
Finger
+34 Stamina
Requires level 1 to 80 (80)
Equip: Improves critical strike rating by 53.
Equip: Improves hit rating by 29.
Equip: Experience gained from killing monsters and completing quests increased by 5%.

Boots of the Bay
Binds When Picked Up
Feet
Requires Fishing (200)
Equip: Increased Fishing +15.
Use: Whisks you away to the finest drinking establishment in Booty Bay. (1 Day Cooldown)
To keep it interesting, the Achievement "Master Angler of Stranglethorn" has been changed to "Master Angler of Azeroth." This can be earned by winning either the Kalu'ak Fishing Derby or the Stranglethorn Fishing Extravaganza.
Please bear in mind this feature will be undergoing testing on our Public Test Realms and is subject to change prior to the release of patch 3.3.0.