those few hundred resses after killing a fish might be great loot for a townhall1 player but now in th4 I just avoid those "obstacles" since they only cost extra time for zero gains. That is all.
What iam trying to say is to adjust the rewards in singleplayer to the current townhall. My upgrades cost way over 100k of resses each now and it just doesn't make sense to waste minutes on the singleplayer map to kill a fish just to get rewarded with some hundred resses.
It's not as fruitless as you think. Bigger monsters, ships a and pirate bases yield bigger rewards and bigger rewards for explore quests and uncovering daily spawns can only be gotten by higher PH, needed for bigger further travelling higher lvl ships. You can also make a lot of resources regardless of level by constantly sailing circles in calm waters,( the lightest blue water), which are only 6 second to sail each square, without a guild perk. Roughly 3k each resources and 2-3 gems in can be found in 3-4 rounds. Making for pretty fast farming. For that reason alone, it's worth your time. However you should be doing this anyways as you're going to need multiple thousands of explorer points to upgrade stuff later.