Why am I playing a duel at a fishery I don't have any lures for?

The system may draw any fishery from your unlocked fisheries, it includes those which you have just unlocked and haven't managed to earn lures for. 
After you open a new fishery by levelling up, it is advisable to complete all of its quests before you start or resume playing duels. It will provide you with almost every lure for that fishery so there will be little chance for you to play a duel with lures you don't have yet.
You can also get lures for new fishing spots by purchasing special offers.