The Ministry for Primary Industries (MPI) has not identified any exotic disease as a cause of the death of more than 80 birds in Lake Wānaka last month.

MPI is leading an investigation into the deaths of 85 dead paradise shelducks and a mallard duck found on the margin of Lake Wānaka and in a nearby paddock on Tuesday April 23.

“Testing to date in our labs has been focussed on identifying possible exotic diseases. None have been found,” an MPI spokesperson told the Wānaka App today (Monday May 6).

“The next step is to determine what substances might have been involved, ie toxicology testing. We are in the process of finding labs with available capacity to do that testing.”

Read more: Unexplained bird deaths on Lake Wānaka

A Wānaka woman who collected about 20 dead birds from Dublin Bay told the Wānaka App she was told by an MPI vet that three birds which she had given him to test had died from “poisoning with organophosphates”.

Organophosphates are an active ingredient in insecticides.

Fish & Game communications officer Bruce Quirey told the Wānaka App he trusted MPI would “do their job to investigate whether the application of an insecticide is related to the incident”.

“Fish & Game is keenly interested to know the outcome and whether poisoning by an insecticide, such as diazinon, is confirmed as the cause of death,” he said.

New Zealand’s Environmental Protection Authority has put in place a timeframe for three organophosphate pesticides to be phased out: fenamiphos and methamidophos are to be phased out by July 2024; and diazinon must be phased out by July 2028.