Contractors acting for Waikato Regional Council have successfully exceeded their possum control targets during an operation over about 6,200 hectares near Mahoenui in Waitomo district from May till August.
And an investigation into the deaths of two cattle following an aerial 1080 part of the operation in May has found proper aerial control processes were followed by the council and its pest contractors.
The overall operation, by contractor EcoFX Ltd, was carried out by using a variety of bait distribution methods, including the use of bait stations and the aerial 1080 drop.
In post-operation monitoring in the area treated by aerially applied baits there were no possums caught using ground-based traps, compared to a target of a maximum of three per 100 traps.
In two ground control areas, the number of possums caught was also well under the maximum target number.
The possum control will help protect native bird life and plants, and enhance the productivity of farm land.
“This is another excellent result and we thank local landowners for their co-operation with our possum control efforts,” said biosecurity group manager John Simmons.
Meanwhile, an independent investigation into the deaths of two cattle after the aerial 1080 part of the operation has found all 32 resource consent conditions had been complied with and “there was no unlawful discharge of a contaminant to land or water”.
The investigation report says the two cattle, part of a mob of 36 stock, made their way into the area that had been treated with 1080. The stock accessed the bush area through a gate that had been inadequately secured. The stock had travelled several hundred metres from the insecure gate, including crossing the Awakino River, to end up in the 1080 treated bush area. The farmer had been alerted to the 1080 drop before it commenced and advised of the importance of securing his cattle properly to prevent them accessing the treatment area.
The report also says that on the balance of probabilities the cause of the cattle deaths was more likely related to the ingestion of 1080 poison in the treatment area than not but it stressed no definitive conclusion can be reached. The two cattle died within two days of being removed from the treatment area.
“This was an unfortunate incident for all concerned,” said John Simmons, the council’s biosecurity group manager.
“It’s clear our staff and contractors did all the right things but, unfortunately, it seems the cattle were somehow able to force their way through an inadequately secured gate. We will take this into account during pre-operation discussions with landowners adjoining any future treatment areas.”
The investigation into lawfulness of the 1080 drop operation and the cause of the cattle deaths was carried out by the council’s resource use group at the request of the biosecurity group.
On the question of how the cattle got into the treatment area, the report said it could only be assumed that their owner “when placing his cattle behind a fence before the aerial operation, failed to ensure that the No.8 wire latch was adequately twisted to secure the gate and prevent cattle from forcing it open”.