Hundreds of dead crayfish in Waikato stream a mystery

Hundreds of crayfish washed up in a Waikato stream, and the regional council is struggling to figure out why.

Local man Erin Hampson-Tindale reported seeing the dead crayfish in Oraka Stream, Putaruru, about 1pm last Tuesday.

Hampson-Tindale told the Herald he was at the stream for a swim with his daughter, 10, and son, 13.

"I had to say 'You can't get in the water guys'.

"It was incredible. I compared it to the motorway in Auckland. It was a one-way exodus, everyone evacuated.

"To go down and witness that, it was hideous."

He was at the stream for about two-and-a-half hours and the crayfish kept coming.

Hampson-Tindale had fished for trout in the stream for the past couple of years.

Several people were still swimming in the river.

"Am I going to take my kids down there? No."

Waikato Regional Council staff returned to the stream for five consecutive days to gather water samples and search the area. They also spoke with a number of businesses upstream.

"It appears a single acute event has killed the koura," said incident response team leader, Derek Hartley.

What a Sad buzz! Remember guys we are the Caretakers - Words from ol mate and Waikato Local Erin Tinsdale "Please share this post. A most terribly sad day for me, the locals of Putaruru, nz and most of all, the awesome little guys that used to populate the Oraka stream bellow my house. Took my kids down to the Oraka river near the Waihou and was mortified to witness thousands (no exaggeration) of poisoned Koura rolling downstream hour after hour! Have enjoyed catching and releasing trout in this beautiful spring fed stream. Feel like i am mourning a lost friend to see this. Its has killed the lot! Will take decades or more to recover. Regional council have arrived to do testing. Bit by bit we lose more and more of beautiful nz".

Posted by Toa Hunter Gatherer on Tuesday, 20 December 2016

"However, the good news is that other aquatic life has been seemingly unaffected by it."

Scientific analysis of the water samples revealed nothing that clearly identified a likely cause of death.

"While it's good news that there have been no further deaths of koura, we're continuing this week to eliminate potential causes as part of our ongoing investigation," Hartley said.

He encouraged anyone with information on the possible cause of the koura deaths to contact the council on 0800 800 401.