The number of stranded whales being successfully refloated has plummeted in recent years, new figures show.
The survival rate was 70 per cent in the 1990s, and now it's about 45 per cent, figures released to NZME from the Department of Conservation (DoC) show.
The data follows the death of up to 250 whales that stranded at Farewell Spit last month.
Steve Whitehouse from Whale Rescue said New Zealand is now among the worst in the world at saving whales when it used to be with the best.
But DoC's Golden Bay operations manager Mike Ogle said each case should be treated separately.
He said some information is missing from DoC's records, which go back to the 1800s.
Whale Rescue's Jo Halliday said she believes stranding survival rates will go up if rescues resume at night.
Whales stranded at Farewell Spit last month were spotted at 8pm but rescue efforts couldn't start until daylight.
By that time more than 100 had already died.
Halliday says in the past generators have been used to light up beaches.
"There has been so much focus on namby-pamby health and safety, and I totally get that they need to have health and safety, but it has gone over the top."
But DoC said it had to put people first after some people were severely injured in a night-time rescue in 1993.
Whale Rescue has also raised concerns at the number of animals being euthanised.