The 23-year-old had a standout club season for Taieri last year but has been starved of opportunities at the next level.
The likes of Aleki Morris-Lome, Sio Tomkinson, Michael Collins and Josh Timu, who has been training with the Crusaders this year, have all been preferred ahead of him in the Otago set-up.
That meant the strapping South Otago product received just one opportunity in 2020 after making four appearances in 2019.
A move south to the Stags will mean Whaanga will link up with the likes of Isaac Te Tamaki and should result in much more game time.
Southland coach Dale MacLeod confirmed the Stags were talking with Whaanga when contacted for comment by the Otago Daily Times.
"I’ve got to be careful what I say there until it is all done and signed," MacLeod said.
"I rate him as a player. He has some really good attributes. He’s got power and size and he has got himself in really good shape in the last couple of years.
"I think he has just been very unlucky [not to play for Otago more often]. When you are in a squad, sometimes all it is is one person’s opinion whether you get the starts or not.
"But Otago are very deep with the midfielder talent they’ve got, so he will be a good addition to our group if he signs."
MacLeod said the Stags had a core of about "17 to 19" players sorted but there were still some pressing vacancies.
The departure of Manaaki Selby-Rickit has left a big gap in the locking stocks. He has transferred to Bay of Plenty.
Halfback Logan Crowley is considering returning to his home province, Taranaki, and the Stags are also looking to pick up another loose forward or two.
The front row is looking healthy. Highlanders prop Siate Tokolahi is back for another round as is Ethan de Groot.
Hookers Greg Pleasants-Tate and Flynn Thomas are confirmed for 2021.
Negotations continue with inspirational captain and No8 Tony Lamborn but Matt James and Charles Alaimalo are returning, so the Stags will have the guts of what was a well-performing pack in 2020.
It is unclear whether second five-eighth Ray Nu’u will return for another season but backs Te Tamaki, Rory van Vugt and Tevita Latu, are good to go and fullback Josh Moorby is a firm likely.
There has been some significant turnover, however.
MacLeod said about 16 players had moved on.
"But I believe we’ll have a stronger group ... and we have lined up another outside back who is a bit of a coup for us.
"That will come out in due course."
Could it be Solomon Alaimalo? He has signed with the Higlanders and a move to the Stags would enable him to link up with his brother, Charles.
