"She was cutting them into pieces and literally hit the pin. What kind of sicko does that?" he said.
The incident was referred to the Ministry for Primary Industries and the police.
The Pak'N Save store removed the strawberries, from a North Island grower, from its shelves as a precaution.
By Friday morning the store was selling a different brand of strawberries on special.
A Foodstuff spokeswoman said the affected product had been removed but the supermarket had multiple suppliers.
"All our stores have a robust protocol for issues like these and follow this strictly with the assistance of MPI and the police. The matter is now in their hands."
An owner of the affected North Island grower referred all questions to the Ministry of Primary Industries.
The incident has drawn the ire of a Tauranga grocer, who feared publicity around the issue was inspiring "copycats".
He said he felt sorry for the grower, who he understood was "gutted" by the incident, as was the wholesaler.
The implications were widespread, he said.
"It's going to affect those businesses, and it will make people dubious about eating strawberries, though I can't understand why."
He said incidents should be reported to the store and to authorities rather than media, but also appreciated there was a public interest in knowing about the finds.
The discovery was the latest in a string of disturbing incidents involving needles in fruit, including a needle in a capsicum purchased from Countdown on Cameron Rd in Tauranga last month.
Foreign objects in fruit and vege
December: Pin found in strawberry brought at Pak'N Save Cameron Rd
November: Needle found in a capsicum bought at Countdown Bureta
November: Needle found inside a punnet of strawberries purchased at a supermarket in the South Island in November
September: Three needles found in three strawberries in one imported punnet of Australian Choice brand strawberries at Countdown St Lukes in Auckland
New Zealand Food Safety advice:
If you see something out of the ordinary, please take it to your retailer or give us a call on 0800 00 83 33.