You can stick a Wii remote in a guitar shell, a golf club, and, yes, even in the past, a fishing rod. But the way I saw it done today was extra clever.
Here's me holding the Wii version of the controller for this September's Bass Pro Shops: The Strike, a fishing game. It sells for $US40 without the fishing rod shell, $US50 with. You can see the remote embedded. What's interesting is where the nunchuck goes.
In the lower part (I'm sure there's a technical name for it, but I'll just say it's where your line would be coiled), you would find this compartment. It's tricky to see here, but note that circular divot. That connects to the reel you'd turn to reel your line in with your left hand. The top of the nunchuck's control stick is going to nestle in that. So when you're reeling line in, you're actually making full circles with the stick.
See? Nunchuck in compartment.
And here you can see that the C and Z buttons are still press-able via a couple of buttons laid over them by the shell. The C button is used to adjust the amount of drag on the line. The Z button cuts the line if you don't feel like catching the fish you've hooked.
And once it's back together, you're good to go. Snap the controller/rod back and then forward to cast your line — releasing the trigger at just the right time for the perfect cast. It worked for me — at least on the Xbox 360 version today. Using that system's proprietary controller ($60 when bundled with the game), I caught a sparkling magic fish. And a 12-pound bass.