Risk of crayfish plague stifles search for water contaminants

The investigation into koura deaths at Oraka Stream was left in tatters.
FAIRFAX NZ

The investigation into koura deaths at Oraka Stream was left in tatters.

Investigators into a possible contamination of a South Waikato stream were left guessing after a bureaucratic tug-of-war over three tiny aquatic critters.

Waikato Regional Council's search for answers into the deaths of hundreds of freshwater koura at the Oraka Stream, Putaruru, was ruined by a slack ministry response to a potential biosecurity disaster,  investigations and incident response manager Patrick Lynch told the Environmental and Services Performance Committee last Wednesday.

A trout fisherman discovered the dead and dying koura on December 20, 2016. Council contacted the Ministry for Primary Industries (MPI) on the same day but Lynch said they failed to attend.

Water samples were gathered from Oraka Stream in Putaruru following the discovering of dying koura.
LUKE KIRKEBY/ FAIRFAX NZ

Water samples were gathered from Oraka Stream in Putaruru following the discovering of dying koura.

"By early to mid-January, we got contacted by the MPI," Lynch said. "We actually phoned them on the 20th of December and they elected not to attend."

READ MORE:
Droves of dying koura float down stream
Freshwater stream's dying crayfish

An overseas scientist, made aware by media interest, pointed out to the ministry the deaths could be a result of crayfish plague - a disease not found in New Zealand that would have triggered a quarantine and forced the alert of trade partners, Lynch said.

"There was a tug-of-war over a couple of days between me and MPI because we only had these three koura," Lynch said.

Lynch said although the number of koura collected by regional council staff was small, it satisfied its level of investigation.

MPI investigators had no koura samples to test and were "completely reliant" on council's work.

But the increased risk of crayfish plague forced council to hand over it's three samples. They did so on the proviso the koura digestive tracts were retained so an analysis could be done to try and pinpoint what had killed the them.

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The MPI dissection of tiny animals, at an animal health laboratory in Wellington, found no trace of crayfish plague and left very little else to be tested - less than one gram of koura remained. The minimum sample for council's analysis was 20 grams.

"Unfortunately, the remains of the koura was such that there was not enough to carry out a chemical analysis," Lynch said.

Further examination of the stream gave it the all clear.

"We're surmising that there has been a single strike incident in a tributary upstream and a colony of koura that have been impacted."

The Ministry did not respond to emails but in a February statement said it relies on local authorities, communities and individuals to support its investigations.

 

 - Stuff

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