Now that I have played for awhile...
Farming skill and crafting skill advancement seems well balanced: I'm about level 10 in each.
Exploration skill, however seems overpowered: I'm already at level 25. In addition, the drop rates could use some improvement, a least for "common" items.
Fishing skill levels are okay in balance (I am about level 12 there), but the game mechanics are very difficult...
First, I have to be quick to move my pointer and click on a fish; But the click sometimes does not register, is delayed in registering, and/or it ends up being a "click and drag" instead of just a click. This is more of a problem outside your control, depending on the both the OS load and browser load (All the JS running, especially with multiple pages open, may slow it down a bit).
Second, I have to quickly move my pointer to the second area and click on the marker moving back and forth. This has the same problems as above -- Clicks being missed or not registering and triggering until after the marker has zoomed beyond that point. Worse, if the first step turned in to "click and drag", it would drag the fish on top the marker, and before I could click to release and then click again to hit the marker, it is too late. The marker itself sometimes moves too fast, and/or does not stay on screen long enough to "correct" these issues and properly hit it.
I would suggest the first part lasts a little longer to give the player a chance to try re-clicking on the fish. Eliminate the second part entirely, or make it appear closer to where the fish is/was. Another option is simply "click rapidly enough", so that the "catch" depends on how rapidly the player can click up to ten times (and make it so *too rapid*, such as trying to use an auto-clicker, get penalized...) There are many variations based on the same concept, of course.
Another option wold be (if browsers can do it), click and hold to try catching the fish, and releasing when the marker is near the end area. (And going back towards the start if the player holds too long.)
Most everything else seems pretty well balanced and fun.