C:\Program Files (x86)\World of Warcraft\Data\Sound\Spells\FishingBobber_ver2_1.oog
C:\Program Files (x86)\World of Warcraft\Data\Sound\Spells\FishingBobber_ver2_2.oog
C:\Program Files (x86)\World of Warcraft\Data\Sound\Spells\FishingBobber_ver2_3.oog
but when i fish it doesn't use them, i can play all 3 and they work
I'm not sure when exactly the sounds stopped working because i haven't been fishing daily lately but i know they worked after pandaria released.
A post on http://www.curse.com/addons/wow/fishping has a user stating that theirs stopped in 5.0.4 but i can't seem to find any documentation as to the new spell names or if they disabled this functionality.