TVNZ won't confirm the future of Survivor New Zealand, following disappointing ratings for last night's finale.

TVNZ2's Survivor lost to rival The Block NZ on Three by a wide margin in its key commercial demographic of viewers aged 25-54.

107,000 viewers tuned in to watch Survivor last night, compared with the 181,700 who watched The Block.

Survivor's ratings mark a downturn from earlier in the season, which saw 136,000 viewers tuning in April.

A Mediaworks spokesperson told the Herald: "A third of the way through the season and The Block NZ continues to grow from week-to-week and continues to beat its competition. It appears the tribe has spoken."

TVNZ hoped to reignite interest in Survivor over its second season after a low-rating season one, which saw an average of  144,000 viewers (aged 25-54) watching each episode.

"Last season the feedback we got was… less talk, more action," series producer Tim Lawry told the Herald in April.

"The contestants are so much more cut-throat than they were last year, and the game is taken to a new level this season in terms of blindsides."

Today, a TVNZ spokesperson told the Herald: "A decision has not yet been made on a season three of Survivor New Zealand."

The disappointing ratings continue a troubled run for TVNZ, following mediocre ratings for its reality dating show, Heartbreak Island.

An average audience of 80,000 viewers aged 18-49 tuned in across Heartbreak Island's first season, lower than TVNZ might have hoped for.

A second season of Heartbreak Island has been confirmed. TVNZ says it plans to adjust the format before its return, based on viewer feedback.

"Listening to audience feedback enables us to bring the very best programme to air. We did this for Survivor season two and Heartbreak Island will be no different. We'll incorporate some viewer tweaks to further strengthen the format for season two."