The 20-year-old Burling was in a positive mood ahead of the regatta, saying: "We are going there relatively confident, hopefully we can get on the podium.''
Tuke said after the race: "We were hoping to get on top of the podium but things didn't really go our way this week so it's a good way to finish the regatta.''
The regatta has been plagued by shifty, inconsistent winds but the finals day produced more typical Perth conditions. The "Fremantle doctor'' came up in the afternoon, blowing a 15 knot breeze which the sailors appreciated.
Aleh and Powrie did extremely well to finish third after a mix-up at the start which saw them over-shoot the line.
They had to perform a penalty turn which put them well back but they made up good ground on the first leg to get back into the hunt and finish behind Spain and Great Britain.
"We were pretty far back in the first leg so we were just stoked to do so well,'' Powrie said.
"We just came here with the aim of qualifying the class so we're thrilled to get the bronze medal.''
The pair, who won silver in last year's world championships, will now be favoured to get the nod for selection to London.
The battle between Ashley and Tobin, which has been raging for years, continued last night.
Ashley is the defending Olympic champion and the man who has denied Tobin a place in the last two Games. Much selection weight was thought to have been placed on this World Championships, with Ashley likely to have the edge now that he has finished ahead of Tobin.
Ashley qualified for the final race in sixth, just five points and one place ahead of Tobin.
In the final race, the men's Laser class, New Zealander Murdoch finished behind Tom Slingsby of Australia and Great Britain's Nick Thompson for bronze.
Result of the 49er class gold medal race:
Australia (Nathan Outteridge and Iain Jensen) 1, NZL (Peter Burling and Blair Tuke) 2, Denmark (Emil Nielsen Toft and Simon Nielsen Toft) 3.
Result of the women's 470 class:
Spain (Tara Pacheco and Berta Betanzos) 1, Great Britain (Hannah Mills and Saskia Clark) 2, NZL (Jo Aleh and Olivia Powrie), 3.
Result of the men's RS:X windsurfer class:
Dorian van Rijsselberghe (NED) 1, Piotr Myszka (POL) 2, Nimrod Mashich (ISR) 3. Also: JP Tobin (NZL) 5, Tom Ashley (NZL) 6.
Result of the men's Laser class:
Tom Slingsby (AUS) 1, Nick Thompson (AUS) 2, Andrew Murdoch (NZL) 3.