Just leaned from serebii.net that there is a new way to chain in pokemon x and y with a fishing rod. Here is exactly what serebii says...
"It turns out that if you manage to get a chain of consecuctive fishing hooks, it will gradually increase the likelihood of finding a Shiny Pokémon, with the exact figures still to come. The higher the amount of Pokémon hooked, the more likely you get a shiny Pokémon, but as with PokéRadar, this is not a guarantee.
There are a few things that will break this consecutive streak, however. If you move from the spot, the streak is broken. If you pull in the rod too early, the streak is broken. If you don't get a nibble, the streak is broken. With the latter being a possibility, it's logical to have a Pokémon with the ability Suction Cups as your lead in order to increase the likelihood of hooking a Pokémon."
I have tested this new way of chaining for myself, and it really works!! It is a lot easier than chaining with the pokeradar, but the only downside is that you can only get the pokemon from fishing. Still an easy way for shinies though.