It is possible to solo fish him up. What I like about him versus the lurker is that it is not an automatic death! Just run up the hill after confirmation of completing the achievement and hearth out.
1 - After doing the background quest and getting a mudskunk lure from Nat Pagle in Dustwallow Marsh,
2 - head into ZG and water walk to the Zulian Mudfish pools and fish 5 up (bring a few water walking pots with you--if you can't solo the groups of alligator's that is--because the fish that live there will attack you from time to time (make sure you can solo a level 60 elite fish) and take off the water walking buff.
3 - after obtaining the 5 fish, water walk to Pagle's Point (just keep following the river north) and apply the lure (you don't have to cast or even have your pole equipped to do this) and congratulations! ... you are now 1 step closer to the Salty title!!!
Caveats:
1) at level 70 this is easy mode
2) I had another person that was with me that did NOT recieve the achievement...this might be due to 1 of 2 factors. a) he did not complete the Gahz quest or b) it only goes to the fisherman who actually fished him up.
3) might as well bring 2 other 70's with you (healer, tank, dps) and farm the Polymorph book :)
4) While not as detailed as fishing Lurker solo, I thought it would be a good idea to make this post for those who have not done Gahz' at 70 and to validate that this is possible.