After completing Fishing Resort I've moved on to Fishing Master, and I must say I'm enjoying Fishing Master very much. There are many similarities between Fishing Resort and Fishing Master, but Fishing Resort seems more polished and offers more options. Still I like having to fish in different places and trying to complete my fish collection. If you enjoyed this game then check out Fishing Master too.
Fishing Master isn't as good as Fishing Resort, but it shares many similarities. If you like trying to collect all the different fish then you'll like Fishing Master, as it has 100 different fish spread over several areas (each area has four fishing spots, plus a fishing tournament), and there are seasons that affect which fish are available.
The actual fishing mechanism is almost the same as Fishing Resort (aiming, casting and reeling in), and it even has the same jumping fish animation that Fishing Resort has when you catch a fish. There are quests that you get sent on, but they're all of the "catch 2 of this fish" sort. There are different rods and lots of different baits to buy, and you have to figure out which fish like which bait.
On the downside the graphics aren't quite as nice and you can't roam around the areas. There's no side activities like the symbol hunt, submarine watching, changing costumes. I'm about half way through the game and so far there hasn't been any fishing from a boat (well there is but the boat is stationary, you can't move it).
There is a follow up to Fish Master called Fishing Master World Tour, which I assume takes you all around the world (Fishing Master is just based in Japan).