Minding their own business leaving everyone else the fuck alone.
According to lore I think they aren't supposed to leave Northrend or they die. Temperature thing. But lately we've seen some around Boralus and stuff so "trading, more or less," I think is the answer to what they're "doing". Living, getting the heck away from the Scourge maybe.
Tuskarr don't seem to have much if any goal or agenda beyond fishing. So unless they're fishing up Naga or Jinyu and doing fish-people genocide I don't expect they'd ever get up to much of anything on their own. They had enemies in the Wolvar and Magnataur. So maybe as enemies to a kind of centaur they'd get along with Tauren or hate Night Elf Dryads or hate Faun or Sylvari of Night Fae. Maybe more pertinent to current activity in Northrend next to the realm of death and all... so maybe Tuskarr are waging war on Night Fae and losing. Maybe Tuskarr get butchered. And then their anima fed to the forests, maybe helps stop the anima drought.
theyve been enslaved by the mighty sporeling empire. fhplox and shhhborp are currently in charge i believe.
TO FIX WOW:1. smaller server sizes & server-only LFG awarding satchels, so elite players help others. 2. "helper builds" with loom powers - talent trees so elite players cast buffs on low level players XP gain, HP/mana, regen, damage, etc. 3. "helper ilvl" scoring how much you help others. 4. observer games like in SC to watch/chat (like twitch but with MORE DETAILS & inside the wow UI) 5. guild leagues to compete with rival guilds for progression (with observer mode).6. jackpot world mobs.
Probably just fishing.
Do you hear the voices too?
I remember in WotLK when you quested around Moa'ki Harbor south of Dragonblight (or might have been the village in Borean Tundra), there was one Tuskarr who said they were leaving Northrend and sailing south to get away from the undead. I am not sure what happened to that, if they changed their mind, if they did sail south, and where they went if they did? Would love to know.
I know a few traders have popped up around the world, but the vast population of remaining Tuskarrs I have no idea where they are. Northrend is still in a state of WotLK right now :P