With the last placed side in the ITM Cup's top division facing automatic relegation, this was a crucial win for Andre Bell's Wellington side.
Shields was fantastic, giving the region at least one ray of hope as it contemplates a new Super 15 future minus a fleet of departing stars.
The match trend was set in the first half with Southland scoring tries and Wellington kicking goals.
Wellington scored the best try of the half, with giant wing Julian Savea, Shields and Jeremy Thrush making charges in an 80 metre move finished by Apoua Stewart.
Sopoaga kept banging over the goals, unlike Southland kickers James Wilson and Robbie Robinson. The Stags had to rely on tries through Josh Bekhuis and Matt Saunders.
Southland threatened the line a third time in the spell but the move was cut short by TJ Perenara.
Southland scored early in the second half with superb work from halfback Scott Cowan sending Saunders to the line for his second try, with Robinson again missing the goal.
When Sopoaga nailed another penalty, Southland found themselves one point behind, despite having scored three tries to one. Southland edged back into the lead but Wellington finished stronger and Shields' second try helped settled the issue.
Wellington 30 (Bradley Shields 2, Apoua Stewart tries; Lima Sopoaga 3 pen, 3 con)
Southland 25 (Matt Saunders 2, Josh Bekhuis, Tony Koonwaiyou tries; Robbie Robinson con, Marty McKenzie pen). HT: Wellington 13-10
