The Act
Under
Information
Released
Official
The Act
Under
Information
Released
Official
2
CONCLUSIONS:
• High concentrations of 1080 in possum stomachs are to be expected shortly after a
control operation. Even after 13 days the carcasses represented a hazard, e.g., a dog
eating 100 g of liver from a dead possum (with a liver concentration of 8.4 µg/g) would
receive a lethal dose.
• Bait size and integrity were unaffected by aerial sowing.
• The risk from 1080 baits to non-target species, humans, and pets was minimal after
1 month.
• There was no measurable contamination of surface or ground water on Rangitoto Island
after the sowing of 1080 possum baits.
RECOMMEND A TIO NS
• Public concern over the use of 1080 was highlighted by this operation. Analysis of baits
from the control area was obviously essential to ensure the safety of the public. Analysis
of biological samples or water will not be necessary for all future operations. However,
they should be considered if there are unique environmental features or special concerns
are raised by the public in an area designated for large-scale control.
The
• It is recommended that the care and attention to detail shown by DOC staff, which were
Act
the hallmark of both the Rangitoto and Waipoua ( 1990) operations, become standard for
all large-scale possum control. Careful planning, quality assurance, environmental
impact assessment, and the anticipation of public concerns contributed to overall success,
Under
both in terms of% kill and the high standard of DOC's accountability to the public in the
Auckland region.
• FRI has applied for Ministry of Research and Science Technology (MORST) funding to
investigate more thoroughly the fate of 1080 in soil and water. We recommend that this
research be done in conjunction with DOC possum management control operations
Information
during 1991-92.
• Bait-size distribution after sowing does not warrant routine assessment unless the
integrity of the bait is suspect or new methods of aerially sowing bait are being used.
Released
Official
The Act
Under
Information
Released
Official
4
4.3 Persistence of 1080 in baits
Baits were collected from three sites on five occasions over a period of 1 month following the
operation.
Approximately 150-g sub-samples of bait from each sample were homogenised. Sub-samples
(1 g) of these were assayed for 1080 concentration using the alkali digestion-fluoride electrode
method (C.L. Batcheler and D. Batcheler unpubl. data). Assessments were in duplicate, and a
1080 reference standard of known concentration was included in all the assays.
4.4 Ground and surface water analysis
Water samples were taken before and twice during the first month after the bait drop. Further
samples were collected monthly for a total of 6 months (November 1990 to May 1991). Four
sampling points on Rangitoto Island (Causeway, Raupo Swamp, a drinking fountain, and Wharf
bore) were sampled. Water samples from the causeway and Raupo Swamp were representative of
surface water. Samples from the drinking fountain and the wharf bore were ground water from
the water table beneath Rangitoto Island.
The
After derivatisation, 1080 concentrations were assessed using GC-ECD.
Act
5. RESULTS
5.1 Concentration of 1080 in poisoned animals
Under
The highest concentrations of 1080 were found in the stomach of animals immediately after the
control operation (Table I). Animal tissues were still highly toxic 13 days after the operation.
Extrapolating from the highest concentration found on day 13, a medium-sized dog (approx.
10 kg) would only have to eat 100 g of liver to receive a lethal dose.
Information
TABLE 1. 1080 concentration in poisoned carcasses (µg/g).
Released
Date, species, and source of sample
Concentration of 1080
Stomach Liver
Leg
Official
Day 1 (7/11/90)
1) Possum, Yankee Wharf
9.1
1.5
0.5
2) Possum, Whites Beach
26.4
6.6
1.5
3) Possum, Whites Beach
18.1
3.7
0.9
4) Wallaby, Coastal Road
13.3
1.8
2.3
Mean
16.7
3.4
1.3
Day 13 (19/11/90)
1) Possum, bush
5.4
8.4
0.3
2) Possum, bush
2.0
l.5t
0.2
3) Possum, open scoria
*
*
4) Possum, open scoria
0.5
Mean
2.6
5.0
0.25
* The only material obtained from this possum was skin and a leg bone so no analysis was carried out.
t Kidney sent instead of liver
The Act
Under
Information
Released
Official
The Act
Under
Information
Released
Official
The Act
Under
Information
Released
Official
The Act
Under
Information
Released
Official
