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Pork and puha are still on the menu



Pork and puha are still on the menu

By Janette Busch

Dr Shaun Ogilvie, Senior Lecturer in Wildlife Management  at Lincoln University and his team have studied the uptake and persistence of 1080 in watercress and puha; plants that are culturally important to Maori.

Their research showed that there is a negligible risk of humans being poisoned from consuming either puha or watercress plant material that may have taken up 1080 from baits after an aerial 1080 operation.

“To put it in practical terms,” said Dr Ogilvie, “at the maximum levels we found in watercress (in parts per billion) a 70 kg person would need to eat over two tonnes of the affected watercress at one sitting to have a 50% chance of dying from 1080 poisoning.  The puha results were even lower.”

“In fact, the trace levels of 1080 found in the puha and watercress we studied were similar to those naturally occurring in common tea brands.”

A lover of a ‘boil up” himself, Dr Ogilvie, who is of Te Arawa and Ngati Awa descent, worked with local Maori at two experimental sites; the southern side of Lake Waikaremoana for the puha and Kaikoura for the watercress.

The study was designed to replicate the scenario of 1080 baits landing where puha and watercress were growing.

For the puha study, one 1080 bait was laid on the ground at the base of each of eight puha plants with a non-toxic bait below two other plants as controls.  Plants were sampled before and after the baits were laid and analysed for 1080 content. Measurements were taken of rainfall, air and litter temperature and soil moisture at the puha field site.

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For the watercress study, a 100-metre section of a spring-fed stream with watercress flourishing in it was divided into 10 equal sections.  In each section, a plastic mesh cage containing a 1080 bait in it was anchored in the stream bed. Samples were taken for analysis at different times before and after the baits were laid. Air and water temperature, pH, water velocity and rainfall measurements were taken at the watercress field site.

The results showed that both puha and watercress took up 1080 released from the bait. For the puha, the maximum concentration was 15 parts per billion (ppb), three days after the baits were laid and for watercress, the maximum 1080 concentration measured at 63 ppb was on day seven.  No further 1080 was detected after this, indicating that the 1080 was quickly eliminated from watercress. For puha, by the end of the sampling, at day 38, the 1080 concentration had decreased to below detection limits of the method of three parts per billion. 

A closer look at the raw data for puha revealed that 59 samples from a total of 60 had traces of 1080 at amounts near the method detection limit. These 59 samples included those taken from the plants and the controls before the bait was laid, where 1080 had never been applied previously.

“This suggests that puha could naturally contain trace amounts of 1080,”said Dr Ogilvie.

“This finding is important for Maori so we are now looking to undertake a survey of plants throughout New Zealand to see if it occurs in other species.”

This research was funded by the Animal Health Board and undertaken by Lincoln University,  Landcare Research, Lake Waikaremoana Hapū Restoration Trust, Tūhoe Tuawhenua and

Ngāi Tahu (Kaikoura Runanga).


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