Well, I guess it comes down to realism to how much fun you want them to have, having a high fishing skill being ((82+8=90)=I know what fish I'm more likely to catch with this bait!) it's not realistic there but...
Well, in my case I'd tend strongly towards fun, both because it tends to be more, well, fun, and because it tends to be
simpler. Unless fishing or labors in general are a particularly central and vital part of the game, it's probably just not worth it to get all weird and complicated regarding exactly how you catch fish or smooth stone.
Hmmm.
Well, what if a fishing skill was a compilation of different minor skills plus your own knowledge? Like high foraging would get you better bait because you would know the appropriate skills to doing so.
Most labour things like that rely on you getting better means only that you figure out better ways of doing the job you want to do, it's less granular.
Well, why?
More importantly, though, wouldn't this run into recursion problems? Your Fishing skill is really just your Foraging, Topography, Birdwatching, and Tracking skills... but presumably each of those is also a labor where knowledge is more important than raw talent, so wouldn't each of those be a combination of things in turn? At some point you'd just end up with a probably fairly long list of attributes and a probably fairly complex list of formulae for translating them.
Which isn't necessarily a bad thing, but seems awfully elaborate unless you've got a specific plan for it.
So for fishing compared to masonry, you being better at fishing involves finding shortcuts to get more and better kinds of fish while masonry is just a straight level up bar giving you a 1+.
Aghhhh, it's hard to explain.
Getting a sunfish compared to a rockfish would Not depend on how steady your hand is, it requires knowledge of the bait, the area where sunfish live and understanding of a sunfishes habits.
Labours compared to crafting favour different people with different traits because crafting isn't that fluid, you think of something to make, and you make it, how well you make it depends on your basic skill level on doing it (visualisation, being steady with your hand etc, etc.), it improves only with practice.
Fishing is another story, it isn't just practice (though you do want a lot of patience), it comes from knowledge of how to do it.
I still don't understand the practical difference you're getting at, here. Leveling up fishing gives you +2 Fish or +1 Fish Tiers. Leveling up Masonry gives you +1 Furniture Level or +2 Crafting Power. Does getting there by different in-universe explanations matter for the raw outputs?
AHHHHHHHH HOW DO I EXPLAIN THIS.
Alright, perhaps the player could be rewarded for their intelligence in solving where to fish and with what, how long to wait before you give up.
It isn't a skill, it's a big puzzle that the real life player with help from the GM must solve, E.G.
Alright, so fishing here doesn't work, so far I've only seen about 2 Sunfish, so they sure live here, perhaps it's the bait that isn't working? Or perhaps the name could be the clue?
Is this helping? At all?
Couple problems here. One, why? Sounds pretty complicated just to do for the hell of it or because it's "realistic."
Secondly, the problem with puzzles is that once they're solved, they're solved. If gaining skill in labors is a matter of figuring out IC knowledge OOC, it basically loses any connection to the individual and becomes more of a party-wide thing. Initially, you have no idea where to fish or how, then someone experiments a bit or gets some hints and realizes that Dusk Eels can only be caught at sundown, and now anybody can catch as many Dusk Eels as they like. It's more of the fortress learning to feed itself than any individual character gaining anything.
Crafting skills usually assume that higher monetary worth is of more value than lower monetary worth; thus, it's better to make high quality goods than lower quality (since in this DF-related example you get multiplier bonuses from decorations and things you would not get from just having a whole lot of low quality goods.) Since the point of the skill is to convert raw materials into fungible goods, you want to spend a lot of time and effort to maximize the profit column.
On the flip side, labor skills usually assume that volume of work is more important than strict monetary worth; thus, it's better to catch enough fish to feed the fort for a year than it is to catch the one delicious salmon in the river. Since the point of the skill is to perform functions necessary to the survival of the fort, there is much less benefit for doing those functions beyond the necessity of survival. To put it another way, the fort wants X food units (FUs) to survive for a year; a low skill fisher has to spend all of his time and actions meeting that X requirement, while a high skill fisher could get X FUs in six months and then have the rest of the year for leisure time (or for optimal play, for pursuing more lucrative Crafting skills for profit.)
Given this, how you handle such things depends on the nature of the game. If the point is to struggle to survive and then maybe scrape together some goods to purchase what you couldn't produce yourself, then labor skills would be emphasized in importance. If the point is to maximize profit, then crafting skills will be more emphasized, particularly if survival is quite likely.
For the artifact aside, I'd assume that a mini-artifact is roughly equivalent to a Masterwork in terms of "crafting crit." Labor crits would be a significant reduction in action/time/resource consumption to accomplish the stated goal, or in a profit-motivated game it would be more along the lines of "get the quota of fish + make some scrimshaw."
Interesting.
However, what about when relatively pointless player pride or greed comes into play, or if the wealth of an item can have uses beyond commerce? Even if it's identical in function, and even if that function is nothing, I suspect many players would rather own or produce a single masterwork item than several items of lesser quality but equal combined value.
More generally, this is a nice mechanical analysis, but I was concerned in large part with "satisfaction." Even if it's a vital service to the fortress, is a Fisherdwarf really going to feel as important and fulfilled hauling in X FUs as a Gem Cutter is occasionally producing Ruby Dragon Figurines studded with Gold and bearing an image of two swans in Jet?