Miss Campbell (22) beat Mr Harmer (21) by two points to win the Central Otago Stud Merino Breeders junior judging trophy at Earnscleugh Station near Alexandra.
"I was very stoked," Miss Campbell said.
The pair are a couple and both work as shepherds on Armidale Merino Stud near Ranfurly.
The couple will represent Central Otago in the New Zealand finals at the Wanaka A&P Show next month.
Miss Campbell knew little about merino sheep before starting work at Armidale in April last year.
"They are my favourite — their fleece is amazing and they can carry some big lambs. I think they’re cool."
The couple are set to compete against each other again in Waimumu on Saturday.
This time as Otago Southland regional finalists in the Young Farmer of the Year competition.
Association secretary Simon Paterson, owner of Armidale Merino Stud, said the contest featured 17 competitors, aged between 18 and 25.
The event featured a series of speakers.
His father Allan Paterson talked about the commercial classing of merinos.
Veterinarian Dave Robertson, of Oamaru, spoke about ram health and pre-tup best practice.
Earnscleugh Station owner Alistair Campbell and Will Gibson, of neXtgen Agri, talked about breeding values and what it means.
For the first time, breeding values were part of the competition, recognising its importance as a tool for farmers, Simon Paterson said.
Central Otago was the only association developing breeding values as part of its competition and was working to make it part of the national finals.
The competition had been running since the mid 1980s and provided a way for young people to identify traits which could improve the overall quality of a flock and boost financial returns.
"Being able to visually assess sheep is really important part of farming."
At his ram sale last month, all of the 34 on offer at Armidale sold for an average of $2600 and a top price of $5200.
The industry was in good shape with "fantastic" prices for merino wool and meat.
SHAWN.MCAVINUE@alliedpress.co.nz
