Powelliphanta augusta Recovery Strategy
2015 – 2020
P. augusta Recovery Working Group:
Helen Otley, Planning Team, Hokitika
Kath Walker, Science and Capability (Ecology)
Rodney Phillips, Hokitika Conservation Services Team
Approved by:
Mark Davies
Director, Operations Western South Island Region
March 2016
OIAD-830 Talia P Attachment - Powelliphanta augusta Recovery Strategy 2015
Part A – Background and context
Background
First strategic period: 2007 - 2014
Genetic diversity
Mt Augustus ridgeline rehabilitation
Release sites within original range
Current situation
Development of a new strategy
Figure 1
Figure 2
Part B - Second strategic period: 2015 - 2020
Recovery Strategy 2015 – 2020
Intermediate Outcomes
Management Approach during 2014 – 2020
• Captive Population
• Management of sites where snails currently exist
• Habitat restoration of mine site along A10-A13-A12 ridgeline
• Outcome monitoring
• Information recording and sharing
• Strategy implementation
Part C
File notes of advice
References
Appendix 1 - Predator control
OIAD-830 Talia P Attachment - Powelliphanta augusta Recovery Strategy 2015
Part A – Background and context
Background
Powelliphanta augusta is a species of giant land snail endemic to New Zealand. It is found on
Stockton Plateau, near to Westport, on the West Coast of the South Island. It was discovered in 2004
and found in habitat on Stockton Plateau and Escarpment, part of which was to be removed as part of
an open cast coal mine owned by Solid Energy New Zealand Limited (SENZ). The history of the coal
mine operation and the management of the species at the mine and on the adjacent PCL can be found
in the first Conservation Strategy 2007 – 2012 (docDM-190955). The species was described in 2008
(Walker et al. 2008).
P. augusta is now found in approximately 3ha of original habitat (Site A), in two translocated
populations beyond its natural range (Site B on the north-west corner of Stockton Plateau and the Mt
Rochfort area at the southern end of Denniston Plateau) and the balance of the population is held in
captivity (Fig. 1). It has the highest threat ranking, being ‘Threatened: Nationally Critical’ (K.
Walker, pers. comm.).
Guidance for management is directed by a Conservation Strategy, which now requires updating.
First strategic period: 2007 - 2014
The first Conservation Strategy covered the first five years of the programme (2007 – 2012), that
being after the snails were captured, bought into captivity and half of them then translocated to Site B
and Mt Rochfort.
The strategy had the following three long-term management aims:
1. To prevent the extinction of the taxon.
2. The minimum long-term aim is to secure one self-sustaining population of the taxon in the wild.
3. The optimum long-term aim is to secure one self-sustaining wild population of each genotype in
the wild.
A number of intermediate outcomes and management actions to achieve these intermediate outcomes
were also identified.
As a new strategy was not in place until 2015, management during 2013 and 2014 continued under the
guidance of the 2007 – 2012 strategy.
Genetic diversity
Part of the long-term aim is to secure the species known genetic diversity in the wild. In 2008,
Trewick et al. (2008) showed that on mitochondrial DNA, the two morphotypes were different
genotypes, which are referred to as the “northern morph” (A10 snail) and the “southern morph” (A12
snail). Later genetic analysis using both mitochondrial (mtDNA) and nuclear DNA found the same
split between northern and southern morph snails (Buckley 2015).
Buckley also found that snails at the southern end of the A10 (i.e. snail search blocks 6 and 10 and part
blocks 3A and 5B), which morphologically resembled the southern morph snails (Walker et al. 2008),
based on both mtDNA and nuclear DNA belonged to the northern morph, but were still distinctively
different from the northern morph (Buckley 2015). These snails are referred to as the “intermediate”
snail.
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The snails have always been housed in the captive facility according to their search block they were
found in. The northern morph and intermediate snails have been held in individual breeding groups
according to the snail search blocks they were found in (or where needed to make up a sufficient group
size, with snails from an adjacent search block). Fortunately, the intermediate snails all group together
in particular snail search blocks, and so have not been mixed with the northern morph snails, except
for a few containers where some 5a snails (northern morph) have been mixed with some 3a and 3b
snails (intermediate snails).
In addition, sods with alpine plants that were growing in the snail’s original habitat east of Mt
Augustus were lifted by hand and moved by truck in 2006 to a small site called “Downers Garden”.
Though several empty shells were found there in 2007, no live snails were found or are known to
occur there now.
Mt Augustus ridgeline rehabilitation
When the area occupied by
P. augusta was mined, the land was split into mining blocks. The northern
end of the range is mine block A10, the middle area is mine block A13 and the southern end is mine
block A12 (Fig. 2). The most northern end of Site A, which is now the highest point, is known as
NASA (Fig. 2).
During 2010 and 2011, SENZ rehabilitated the A10 mine block by creating a landform ready for
vegetation to be directly transferred (a process abbreviated as VDT). At the end of 2011, SENZ
indicated that it was planning to place VDT on approximately 4ha of the site. The site was called “Mt
Augustus VDT”. By June 12, 0.81ha had been laid, a further 0.21 ha were laid by October 12 and an
additional 1.42ha by June 2013.
During 2013, the exact area of the Mt Augustus VDT site was enlarged to incorporate the south-east
side of NASA. The most recent polygon of the Mt Augustus VDT site supplied to DOC in May 2015
is 4.1ha in size. By May 2016, SENZ had completed VDT placement to the extent indicated and
committed in 2011 (4.1ha) (Fig. 2, ‘Mt Augustus VDT’). A small area of the planned VDT area was
not completed as there is no further suitable vegetation planned to be disturbed at Stockton Plateau.
This area will be rehabilitated by hand planting nursery raised seedlings of species compatible with the
altitudinal setting and surrounding native vegetation (Fig. 2, ‘Mt Augustus hand planted rehab’).
The A12 site was the highest point in the southern ridgeline prior to mining, but lowered by
approximately 20-30m by mining, and is now a small flat triangular shaped area of exposed coal floor
and is considered by SENZ to be completely rehabilitated.
The northern end of A12 drops off steeply and there is a distance of 200m to meet the southern end of
the Mt Augustus VDT. This is mine block A13 and SENZ has not completed mining of this block,
and no detailed rehabilitation plan has been designed by SENZ until final ground profiles are clear.
We understand that there is no further suitable vegetation planned to be disturbed at Stockton that
would enable creation of any further snail habitat at the Mt Augustus site.
Release sites within original range
In the absence of a current strategy that directed where snails could be released within the species
original range, the Recovery Working Group made the decision to translocate the three genetic groups
back to the same geographic positions (i.e. from north to south, northern morph, intermediates and
southern morph snails).
OIAD-830 Talia P Attachment - Powelliphanta augusta Recovery Strategy 2015
The captive north morph population had sufficient rates of breeding and survival of all age classes in
2013, 2014 and early 2015 that some one and two year old snails were translocated to the northern
portion of Mt Augustus VDT, and into the central-southern end of Site A (Fig. 2). The captive
intermediate snail population also had sufficient rates of breeding and survival of all age classes that in
May 2015 some two year old snails were translocated to the southern end of Site A (Fig. 2).
Current situation
After eight years of intensive management of
P. augusta, there is now:
• six wild populations of northern morph snails – one natural population and five translocated
populations (three populations established using wild snails, one with captive hatched snails and
one using translocated habitat)
• one wild population of intermediate snails – a population of wild and translocated (captive
hatched) snails
• one wild population of southern morph snails – one shell of an adult snail was found in March
2014
• a population of northern morph snails held in captivity and managed to maximise both survival
and breeding (although in the latter years more for survival than breeding)
• a population of intermediate snails held in captivity and managed to maximise both survival and
breeding (although in the latter years more for survival than breeding)
• a captive population of A12 (southern-morph) snails held in captivity and managed to maximise
both survival and breeding
There are wild populations at six locations:
• Site A - Natural and translocated population. Northern section all wild, except some captive
born eggs released in northern corner and some young snails into the central-south area, all
northern morph. Southern section wild and translocated 2015 (captive reared snails), all
intermediate.
• Mt Augustus VDT - Snail habitat that was mined and then rehabilitated. Northern section
translocated snail population (captive reared snails) 2013 - 2015, northern morph. Southern
section reserved for intermediate (no releases as yet)
• A12 - Natural population on escarpment only. No releases. Southern morph.
• Site B - Translocated snail population (wild snails held briefly in captivity) 2006. Northern
morph.
• R6 VDT - Snail habitat translocated to new site 2006/07. Snails translocated with habitat.
Northern morph.
• Mt Rochfort Summit and Basin - Translocated snail population (wild snails held briefly in
captivity) 2007. Northern morph.
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Development of a new strategy
In 2012, we began the process of developing a new strategy for the programme. By late 2013, we had
identified that we needed to have senior managerial support for some of the key management
approaches and that this direction would then allow the strategy to be fully developed. This was
primarily around the management approach in the first strategy of not establishing additional
translocated populations unless the current populations in the wild appeared to be failing.
As Director - Conservation Services Northern and Western South Island Region, in March 2014 Mike
Slater approved the recommendation to continue to have this management approach in the new
strategy. The discussion and decision can be found at Part A: Background material:
DOCDM-
1105816 and Part B: Recommendations:
DOCDM-1142379. In October 2014, a first full draft of the strategy was present to SENZ for their comments. SENZ
registered disparate views, principally in relation to the strategy’s strict adherence to limiting release
of captive snails to just the area in which the snails were originally found.
OIAD-830 Talia P Attachment - Powelliphanta augusta Recovery Strategy 2015
Fig. 1 Geographic locations of the sites where P. augusta exist
OIAD-830 Talia P Attachment - Powelliphanta augusta Recovery Strategy 2015
Fig. 2 Geographic locations of the sites within the original snail habitat where P. augusta exists
OIAD-830 Talia P Attachment - Powelliphanta augusta Recovery Strategy 2015
Part B - Second strategic period: 2015 - 2020
Recovery Management Aim
The long-term management aims identified in the first Conservation Strategy are considered relevant
and are appropriate aims for the second strategic period and are therefore restated below with minor
modification to clarify terms that caused some uncertainty, and with the addition of an explicit desired
evolutionary trajectory.
The long-term recovery aims:
1.
To prevent the extinction of the species.
2.
To secure one self-sustaining population of the species in the wild, with allelic diversity not too
dissimilar to what it might have been without the mining disturbance.
3.
To ensure genetic diversity within the species is protected, with each distinctive genotype and
phenotype represented in the wild population.
The allelic diversity is one that is not too dissimilar to pre-mining disturbance. This assessment of
diversity was contained in the first strategy, but not explicitly so (i.e. it was described in the rationale
section but was not stated in the long-term recovery aims).
Definitions
A population will be considered self-sustaining and secure when:
- the population trend is stable or increasing;
- there is an effective breeding population, productive enough to replace each generation;
- at least 50% of the adult breeding population were themselves reared on the site
The genetic diversity of the species will be considered protected when there is a self-sustaining
population of each genotype/phenotype.
In the New Zealand threat-ranking system, population trend is assessed over either a ten year or
three generation time period, whichever is larger (Townsend et al 2008). One generation is the time
between an egg being laid and the middle of the snail’s sexually mature adult life (R. Hitchmough
pers. comm. 2014). Based on the
P. augusta captive population, the timeframe for three generations
is estimated at a minimum of 30 years.
What is the timeframe for assessing the long-term recovery aims?
Given how population trend will be defined, the absolute minimum timeframe at which population
trend should be first assessed is ten years, and which is 2019/2020 as the monitoring programme
began in 2009/2010. The second strategy will thus bring the species work programme up to the point
in time when the long-term recovery aims can be assessed.
The 2015 – 2020 strategy is limited to five years because management decisions will depend on
whether the snail populations at the release sites are assessed in 2020 as being self-sustaining and
secure.
OIAD-830 Talia P Attachment - Powelliphanta augusta Recovery Strategy 2015
Recovery Strategy 2015 – 2020 Intermediate Outcomes
Outcomes to be achieved by 2020 are:
• The species has not become extinct.
• There is an insurance population of the northern morph and intermediate snails held in captivity
and the populations are mixed age and self-sustaining. Only releases of surplus snails have
occurred.
• There is an insurance population of the southern morph snail held in captivity and it has increased
in size, is mixed age and is self-sustaining. No releases of the southern morph snail have
occurred.
• Much of the area that snails occupied when the species was discovered in 2004 has been
appropriately rehabilitated, and is gradually returning to a condition able to support snails beyond
100 years.
• The population of A10 snails in Site A
is stable or increasing.
• Monitoring has occurred and there has been a 10 year trend assessment of population
abundance/density, size class distribution and recruitment in the wild populations.
These outcomes are relatively similar to the intermediate outcomes identified in the first strategy, but
reflect the situation as of 2015 and how we have advanced since 2007 towards achieving the long-term
management aims.
Definitions
In terms of the captivity outcomes, ‘self-sustaining’ is defined as being a population that maintains
its population size and structure through the egg production by captive adults, rather than needing
to add snails from a wild population
OIAD-830 Talia P Attachment - Powelliphanta augusta Recovery Strategy 2015
Management Approach during 2015 – 2020
The management approach consists of five streams of work:
• Captive Population
• Management of sites where snails currently exist
• Habitat restoration of mine site along A10-A13-A12 ridgeline
• Outcome monitoring
• Information recording and sharing
How the strategy should be implemented is also discussed in this document.
The strategy’s timeframe extends beyond the 10-year financial legal responsibility of SENZ to
P.
augusta (the 2015/16 financial year being the final year of funding). SENZ indicated in 2014 that any
financial support beyond 2015/16 would not be possible, except for potentially undertaking some site
management actions (e.g. predator, weed, people control on Stockton Plateau).
The management approach does not include any large-scale releases and the captive management
actions should not lead to high rates of egg production. However, during the life of the strategy, some
captive northern morph and intermediate eggs and snails may become surplus to the aims of the
captive population. Where these snails should be released is detailed in the captive population section.
Iwi involvement
P. augusta is a taonga species and Stockton and Denniston Plateaux is within the rohe of Ngāti
Waewae. They were consulted in June 2015 about the draft strategy and they requested to be
consulted about any potential plans to remove or relocate the species.
OIAD-830 Talia P Attachment - Powelliphanta augusta Recovery Strategy 2015
Captive Population
Northern morph snails and Intermediate snails
Actions
1) Maximise survival, with a particular focus on the health and survival of sub-adult and adult
snails.
2) Keep snails separate to prevent new matings.
3) Snails that are considered surplus (e.g. eggs and recently hatched snails produced post June 2015)
should be released.
4) The release sites for the northern morph and intermediate snails will be identified when the need
arises. The potential release sites for the northern morph snails are Site A northern section, Mt
Augustus VDT northern section, Site B, R6 VDT and Mt Rochfort Summit and Basin sites. The
potential release sites for the intermediate snails are Site A southern section and Mt Augustus
VDT southern section.
Rationale
We have assessed that an insurance population of northern morph and intermediate snails should have
at least 500 snails of mixed age and be self-sustaining. During 2014 and 2015, we had a surplus of
northern morph and intermediate snails, and therefore, we undertook a number of releases to reduce
the population size but retaining the mixed age, self-sustaining characteristics of the population.
Therefore, the focus for 2015 – 2020 is on maximising survival, particularly of the sub-adult and adult
snails because there are fewer of these age classes. A mixed age population structure will able
manager to undertake the action of rapidly producing more snails, if this was to be needed in the future
(post 2020).
The potential release sites for the northern morph and intermediate snails are those sites where the
snails already exist.
Southern morph snails
Actions
5) Maximise survival and breeding rates of southern morph population to the extent compatible with
a healthy and secure captive population.
6) Provide “luxury” care to all adults (e.g. 2 snails to a tray) to prolong as far as possible the
breeding potential of adult snails
7) No snails will be released.
Rationale
As of 2015, there are around 130 A12 southern morph snails held in captivity. This is considered to
be an insufficient number to support a wild population with a moderate – high establishment
probability. The future of the population, including release options, will be considered in 2020.
OIAD-830 Talia P Attachment - Powelliphanta augusta Recovery Strategy 2015
General captive population actions
•
Best practice snail captive procedures are followed at all times. These are documented in a ‘Best
Practice for
P. “Augustus” Captive Management’ document (DOCDM-499357, requires
updating). This is a live document that is updated as required.
•
Best practices procedures for care and production of worms for feeding are followed at all times
(document to be produced). This will be a live document that is updated as required.
•
The conditions under which the snails are held (e.g. light and temperature levels, container size,
feeding regime, number of snails per container) will be managed primarily to maximise
survival, and secondly to allow for sufficient egg production for the northern morph and
intermediate snail populations to be self-sustaining and for the southern morph population to
increase.
•
The three age classes of the three types will be spread across the three storage units.
•
The storage units are kept under 24hr surveillance (via the temperature-cell phone alarm
system).
Action
Responsibility DOC Resources/year
DOC Group
Maintain the captive
DOC
$51,000, but see memo
NWSI opex, with
population as three separate
2304923
external funding/
genetic populations
partnership sought
The resources required are calculated as follows:
General running costs (regardless of captive population size) = $11,000
Labour costs of $35/yr/snail for 500 northern morph snails, 500 intermediate snails and 150 southern
morph snails (includes time in lab and time to manage lab, lab staff and data) = $40,000.
OIAD-830 Talia P Attachment - Powelliphanta augusta Recovery Strategy 2015
Management of sites where snails currently exist
Management Approach during 2015 - 2020
Sites where snails currently exist will be managed to ensure threats are appropriately addressed and
monitored, and new threats identified.
The following site issues have been identified:
-
Erosion
-
Weeds
-
People
-
Fire
-
Predators
-
Browsers
Denniston Plateau including Mt Rochfort is located on public conservation land. Most of the Mt
Rochfort site is an implemented DOC nationally important ecosystem site, although the
P. augusta Summit and Basin populations are not within the site. However, areas where snails occupy are
important uphill buffer sites (within this nationally important ecosystem site) and need to be managed.
The Mt Rochfort nationally important ecosystem site and adjacent buffer areas is being managed by
the Buller Service team. The top half of the 4WD road to Mt Rochfort is maintained by a
Concessionaire
Erosion
Action
Responsibility DOC
DOC Group
Resources/year
Stockton Plateau
Monitor and maintain effective sediment
SENZ
controls along the escarpment from Site A to
the A12 VDT site to prevent undue impacts on
underlying habitat.
The erosion trapping devices should be
SENZ as
Is unlikely to
removed only when the amount of fresh silt
directed by
occur during
being trapped is minimal and/or when the
DOC
2015 - 2020
benefits of allowing the snails to move
between the plateau and escarpment outweigh
the costs of loss of snail habitat to coal
fines/silt smothering, and a mechanism for
Juncus squarosus weed seed transport, to Site
A.
Mt Rochfort
Reduce road gravel flowing over the lower
DOC
2 days two
Buller Service
Summit snail site at Mt Rochfort by proper
people, $500
team
channel and stormwater control and silt-fence
materials, once
erection on the downhill side of the Mt
during life of
Rochfort tower road.
strategy
Rationale
OIAD-830 Talia P Attachment - Powelliphanta augusta Recovery Strategy 2015
On Stockton Plateau, SENZ has a responsibility has a landowner adjacent to public conservation land
(PCL) to ensure that its activities do not negatively affect the adjoining PCL. This includes ensuring
that silt does not enter PCL.
Weeds Invasive weeds including but not limited to gorse and
Juncus squarossus are controlled to zero density
in the sites where
P. augusta is found.
Action
Responsibility
DOC
DOC Group
Resources/year
Stockton Plateau
There is at least annual surveillance for
SENZ, but see
weeds at snail sites.
note below
Where significant weed infestations are
SENZ, but see
present, effective control is undertaken
note below
using methods that considers the effects
on snails (spot-spraying versus
broadcast) and limits the creation of
open areas where more weeds may
germinate.
Mt Rochfort
There is at least annual surveillance for
DOC
No new work,
Buller Service
weeds at snail sites to best practice.
covered by
team
implementation of
Mt Rochfort
ecosystem site
Where weeds are present, effective
DOC
No new work,
Buller Service
control is undertaken which removes
covered by
team
weeds without exposing snails to
implementation of
harmful chemicals or creating open
Mt Rochfort
areas where more weeds may
ecosystem site
germinate.
Gravel contaminated with weed seeds
DOC
No new work,
Buller Service
does not enter snail areas by ensuring
covered by
team
water from disturbed ground does not
implementation of
flow into snail areas.
Mt Rochfort
ecosystem site
In bare areas that need to be
DOC
No new work,
Buller Service
rehabilitated, only bare-rooted
covered by
team
seedlings are planted.
implementation of
Mt Rochfort
ecosystem site
Note:
The Stockton Coal Mining Licence (CML) requires SENZ to control noxious weeds within the CML.
With the requirements for weed control under Wildlife Permit, the snail sites on Stockton Plateau and
at Mt Rochfort receive specific weed control. After April 2015, the snail sites on Stockton Plateau
will remain part of the SENZ weed plan, with an annual planning process to identify priority species
and sites across the plateau.
OIAD-830 Talia P Attachment - Powelliphanta augusta Recovery Strategy 2015
Therefore we can expect some base level of weed surveillance and control work at the snail sites. At
the end of 2016/17, the level of work undertaken by SENZ will be reviewed and an assessment made
whether additional work needs to be undertaken by DOC.
People
Action
Responsibility
DOC
DOC Group
Resources/year
Stockton Plateau
Manage snail sites within the CML so
SENZ
as to ensure the only people who enter
the sites do so for necessary purposes
and that trampling effects are minimised
and steps are taken to mitigate the
introduction of weeds.
The narrow board walk at Site A should
SENZ
be retained
Mt Rochfort
Manage people so that they stay on
DOC
1 person day per year Buller Service
established roads and tracks
to surveillance.
team
Potential for costs if
new works or
maintenance works
needed
Rationale
The presence of people within all the snail sites has the potential to cause a number of effects,
particularly treading on snails, damage to the vegetation, depositing general rubbish and toilet waste
(which occurs at Mt Rochfort Summit), introduction of weeds and changes to the watershed (e.g.
tracks becoming water channels).
At Mt Rochfort summit, the focus needs to be on the public as this area has open access and is situated
beside a viewing spot at the end of a popular scenic road. Around the Mt Rochfort tower, people are
now confined to a single track by fences (erected in 2011).
At the snail sites on Stockton Plateau, the focus needs to be on mine workers, contractors, and visitors,
with constant re-assessment and reduction where possible of the scale of management staff access to
the snail colonies SENZ currently manages people at the various sites with a number of methods.
For example, the R6 site is a closed area and there are signs at the site stating this. Site A should also
be identified as a closed area.
Predator control
Action
Responsibility DOC Resources/year
DOC group
Ground control of rats and
DOC
4 person days per
NWSI opex for
possums – traps and bait stations
service, 12 times/year
contractor, with
volunteer help sought
for Mt Rochfort
Ground control of rats and
DOC
Unlikely to be used,
OIAD-830 Talia P Attachment - Powelliphanta augusta Recovery Strategy 2015
possums –hand laid toxins
not costed
Aerial 1080 control rats and
DOC
Likely to be nil (if
NWSI opex
possums
DOC has to pay for the
1,000ha, then $15,000
(@ $15/ha) potentially
twice during 2015 –
2020)
Monitoring
- trend monitoring of rats
DOC
5 lines is 8 person days NWSI opex for
2 times/yr (4 times/yr
contractor
if mast year detected
or predicted)
- result monitoring through
2 person days in 2019
S&C
identification of cause of snail
and 2020 (when doing
death via damaged shell
snail monitoring)
examination
The details of the predator control programmes are found in Appendix 1.
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Hares
Action
Responsibility DOC Resources/year
DOC group
Visual assessment of hare pellet
DOC
Nil, completed as part of
abundance and browse damage at
predator trap checks
NASA and Mt Rochfort
If browse levels are high, night
DOC
Four days 1 person
Buller Service
shooting of hares at NASA and Mt
team
Rochfort
Rationale
The small remaining area of good natural snail habitat in Site A at NASA, and the best snail habitat on
the slopes just north of Mt Rochfort are a bit more fertile with deeper soils than the remainder of the
sites now occupied by
P. augusta. As a consequence, taller and more palatable tussock and herbs
grow at these sites, but these are being browsed heavily by hares. The quality of the vegetation is
important for
P. augusta as intact plants retain more moisture, provide better shelter from both adverse
climate and predators, and increase earthworm abundance from the ready decay of their leaves.
There is no best practice for hare control, but as both affected sites are small and accessible, night-time
shooting would our best guess as to the best form of both control and hare population trend
monitoring. This could be supplemented by handlaid toxins around the boundaries of the tall tussock
area if necessary.
This threat is considered a medium to low priority.
Fire
Action
Responsibility DOC Resources/year
Any fires started at or near to snail sites should be stopped
DOC
No new costs
as soon as possible.
On the Stockton Plateau, the bare ground (access road) on
SENZ
the eastern boundary of the A10 VDT snail release area
should be retained (otherwise, un-vegetated areas should be
avoided because they can become weedy).
Rationale
Although, the sites where the snails live are not highly susceptible to a fire, an extended period of dry
weather will increase the risk and the VDT sites could be drier and more susceptible to fire than
natural sites, at least for newly established VDT areas (Marshall 2013).
DOC is the rural fire authority is the Westport region and would assess whether to respond to a fire at
the sites on Stockton Plateau and at Mt Rochfort
OIAD-830 Talia P Attachment - Powelliphanta augusta Recovery Strategy 2015
Site surveillance
Action
Responsibility DOC
DOC group
Resources/year
Annual visual checks of all sites to identify
DOC
2 days, 2 people
Project officer
issues that are or could be a threat to site
and S&C
quality
. Things to be on the look out for:
-
pooling of water, drainage issues
-
erosion (in places not identified in erosion
section)
-
bare patches
-
existing gaps not becoming
filled/growing in size
-
slips
-
edge crumbling
-
plants in VDT dying or having very slow
growth
-
hand-planted plants dying or having very
slow growth
Undertake works to remedy identified issues
Depends on
Depends on
as advised by technical experts
issue
issue
Rationale
We have identified in this Conservation Strategy all the current and potential processes that may
threaten the species at the current sites. However, we may not have identified all current threats,
and/or we may have under-estimated some threats, and new threats may occur in the future.
Therefore, it is important to undertake regular visual surveillance of the snail sites to identify any other
threats not currently recognised in the strategy.
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Habitat restoration
Mt Augustus VDT
Action
Responsibility DOC
DOC group
Resources/year
On-going progressive rehabilitation of Mt
SENZ
Augustus VDT area and the A13 block
should be undertaken as mining continues
and allows
Advice should be first sought from DOC
SENZ to seek
SENZ plans
Project officer
before devising/implementing a
advice and
no/limited new
and S&C
rehabilitation/restoration plan for a new
DOC to
rehab work, so
area.
provide advice
DOC resources
unknown
The general rehabilitation techniques (as SENZ
below) should be followed.
Vegetation
monitoring
of
the
Mt SENZ to DOC
Project officer
Augustus VDT should not occur without
approval of DOC.
General rehabilitation techniques
• Where any major ground works are still to be undertaken, landforms should be flat sections rather
than rounded surfaces
• Granite may be laid prior to VDT, as available, going on
• The new landform should be compacted prior to any VDT being applied, to try and permanently
retain the high soil moisture levels, and a low open vegetation preferred by
P. augusta
• Applying VDT sods (where it is available):
- No use of fertilisers, biosolids etc
- Match topography / exposure / soil depth in VDT source area and rehabilitation areas
- Place lower quality source VDT around the perimeter of the VDT rehab area not the central
rehab area (lower quality VDT = plants >2 m in height, VDT with broken sods / rocky
ground)
- avoid gaps between sods (which traps snails, ponds water and is an open area available for
weed invasion) by pressing down on the sod edges, even if that destroys woody vegetation in
the sods.
• Due to the diminishing nature of available suitable VDT, nursery raised seedlings compatible
with the altitudinal setting and surrounding native vegetation will be used for any future
revegetation efforts.
Rationale
SENZ has effectively completed rehabilitation (to the extent it committed to) of the Mt Augustus VDT
site.
OIAD-830 Talia P Attachment - Powelliphanta augusta Recovery Strategy 2015
The next highest priority area is the A13 mining block, but this area is still being actively mined and is
unavailable for rehabilitation present.
SENZ considers that the A12 ridgeline is fully rehabilitated, although it contains some bare exposed
coal floor. As the escarpment below the A13 mining block is very rocky and has limited suitable
habitat for
P. augusta, the connection point between snail populations at Site A and at A12 escarpment
would have to be the A12 ridgeline.
Therefore, the currently bare A12 ridgeline ideally should be vegetated. It is understood that there is
no/little suitable VDT left and it would be very difficult get the trucks that carry VDT up to the site.
Placement of soil and then seed scattering and planting of bare-rooted seedlings is the recommended
option. A potential restoration plan is described in Lloyd (2015).
Restoration plans for NASA and A13 mine block are described in Lloyd (2015). These plans should
be used in providing advice to SENZ.
No monitoring of the Mt Augustus VDT should be undertaken without approval from DOC, due to the
potentially harmful effects on both the translocated vegetation and
P. augusta snails recently released
there. Before any further vegetation monitoring is undertaken there, the potential costs and benefits
would need to be weighed up carefully.
Area between Site B and R6 snail populations
Action
Responsibility DOC Resources/year
Currently bare areas within Site B should not be re-
DOC
None
vegetated as the bare areas are natural and re-vegetation
works carry a risk of introducing new weeds etc.
If inbreeding or loss of some small populations occurs in
DOC
No work planned during
Site B, consideration should be given to moving snails by
2015 – 2020.
hand between sites, or to re-starting failed colonies by
internal site B translocations. Trigger for considering this
work would be the results of the 2020 mark-recapture
monitoring.
Rationale
It is important to improve the connectivity between sites because this should improve the likelihood of
species survival in the long-term. Alternative ways of providing gene flow between the snail
populations there should be sought as attempts to plant land that is naturally rocky or dry are likely to
fail whilst increasing the chances of weed invasion by disturbing the ground.
It should be noted that northern ends of Site B and R6VDT are unlikely to have continuous snail
habitat because of the topography and drainage of the land that exists there.
OIAD-830 Talia P Attachment - Powelliphanta augusta Recovery Strategy 2015
Outcome monitoring
Action
Responsibility DOC
DOC group
Resources/year
Mark-recapture monitoring is
DOC
125 person days
To be determined closer
undertaken at the ten monitoring
(team of five
to 2019/20. Options
sites in 2019/2020.
people for 25
include NWSI opex and
nights)
external funding/
partnership
DOC standard plot monitoring (10m
DOC
36 person days
To be determined closer
x 10m grid search) is undertaken at
(team of four
to 2019/20. Options
all sites in March 2020.
people for 9
include NWSI opex and
days)
external funding/
partnership
Rationale
Mark-recapture monitoring was implemented in 2009 in order to provide robust trend data about
abundance, density, apparent survival, and population structure and growth rates. The method is
financially costly to undertake due to the high number of monitoring sites and the need to re-search
each site on six separate occasions, and appears to have quite high costs to the snail population as it
increases the chances of snails being accidentally trampled as it involves multiple nocturnal searches
when snails are most likely to be on the surface.
During 2009 – 2014, it has been completed every few years at the ten sites. As it was last completed
at all sites in 2015/16, it should next be completed in 2019/2020 to provide a ten year period of data.
The DOC standard diurnal plot monitoring, which involves sites being searched just once, is less
sensitive to population trends especially where densities are low. However, because it is undertaken
when snails are least active on the surface, it probably has smaller negative impacts on survival of the
monitored snails. As a result of the reduced sensitivity of diurnal plots, many plots need to be
established. However, in total, it is considered less costly than the mark-recapture method, so is more
financially sustainable long-term. While mark-recapture can more accurately establish population
trend, diurnal plots have the benefit of collecting more shells for assessing cause of death.
In order to transition from assessing population persistence using mark-recapture to the DOC plot –
based system, plot monitoring commenced in March 2015. To ensure statistically usable results
within a reasonable time frame, at least 15 – 20 snails need to be found in combined plots at each site
(P. Alspach, pers. comm.). We established 15 plots at Site B, 10 plots at Site A and 10 plots at Mt
Rochfort. Although less than 15 snails in total were found at some sites, it was assessed that there
were no more areas within the sites where monitoring plots could be located (especially in higher
density snail areas).
Plot monitoring should occur every five years in line with DOC’s monitoring programmes for other
Powelliphanta species in the Northern and Western South Island region. The plots monitored in 2015
will be monitored again in March 2020.
OIAD-830 Talia P Attachment - Powelliphanta augusta Recovery Strategy 2015
The person days required for monitoring are calculated as follows:
Mark-recapture monitoring
Standard diurnal plots
Current number of plots
10
26
Number of searches required per plot
5
1
Plots searched per day/night
2 per night
3 per day
Hours per shift
7 to 8 hours
9 to 10 hours
Team size
5
4
Minimum number of person days/nights
125
36
Cost at $30/hr
$30,000
$10,800
OIAD-830 Talia P Attachment - Powelliphanta augusta Recovery Strategy 2015
Information recording and sharing
Action
Responsibility DOC
DOC group
Resources/year
Information is recorded, collated, analysed and
DOC
10 person days
Project
reported on, so that it can be shared with others.
Officer
There should be a proactive approach to sharing
DOC
5 person days
Project
information with the scientific community and
Officer
general public.
Rationale
Media stories over the last five years have shown that there is interest in the
P. augusta conservation
programme. However, these stories have been mostly generated from the media or picked up through
the update provided to the Conservation Board (which is sent to the local media). It would be
beneficial if we were more proactive in generating our own media stories at various stages in the
programme.
We are gaining much technical knowledge about the species, and about how to hold it in captivity,
how to conduct robust monitoring, how to improve restoration and VDT techniques. This information
is relevant to other people and other conservation programmes.
We also have to make decisions about how to manage a narrow range endemic species, and other
conservation managers may be interested to know how we have chosen our management approaches
and where we saw the appropriate balance between various costs and benefits.
OIAD-830 Talia P Attachment - Powelliphanta augusta Recovery Strategy 2015
Strategy implementation
Action
Responsibility
DOC
DOC group
Resources/year
The Department will ensure that it provides staff DOC Services
10 person days
Project
and operating costs to implement the strategy
and S&C
Officer
and the identified actions.
The Department will work with SENZ to
DOC Services
5 person days
Project
identify and agree roles/responsibilities for
Officer
SENZ
The Department will seek to establish new
DOC Services
10 person days
Project
partnerships where necessary to achieve full
and Partnerships
Officer
implementation of the strategy.
Rationale
This strategy is a Department of Conservation document. The legal obligations that SENZ has to the
conservation of the species according to the two Wildlife Act authorities it holds will cease at the end
of April 2016. Accordingly, this strategy has been prepared as a Department of Conservation
document, which will be implemented by the Department for the full term of the strategy and by
SENZ until April 2016 for the actions that it is committed to undertaking.
The Department, particularly the Northern and Western South Island Region, will need to look at the
resource implications of the strategy. This is discussed further in the memo associated with this
strategy (2304923).
OIAD-830 Talia P Attachment - Powelliphanta augusta Recovery Strategy 2015
Part C
File notes of advice
August 2013 – minimum age of VDT for snail release. Email. Has advice from Jane Marshall and
Kath Walker. docDM-1404208.
References
Buckley T. 2015. An assessment of genetic structure of
Powelliphanta augusta within a recently
developed coal mine – 09/01/15. Landcare Research, Auckland.
Lloyd K. 2015. Rehabilitation of
Powelliphanta augusta habitat on the Stockton Plateau, Westland.
A report to Department of Conservation. Wildlands Consultants, Dunedin.
Marshall J. 2013. Memo - Fire on Mt Augustus. Science and Capability Group, Department of
Conservation, Hokitika. docDM-1130327.
Trewick SA, Walker KJ and Jordan CJ. 2008. Taxonomic and conservation status of a newly
discovered giant landsnail from Mount Augustus, New Zealand. Conservation Genetics 9: 1563–1575.
Walker KJ, Trewick SA and Barker GM. 2008.
Powelliphanta augusta, a new species of land snail,
with a description of its former habitat, Stockton coal plateau, New Zealand. Journal of the Royal
Society of New Zealand 38: 163-186.
OIAD-830 Talia P Attachment - Powelliphanta augusta Recovery Strategy 2015
Appendix 1
Management of sites where snails currently exist
Predator control – detailed actions
Target pests
Possums and rats
Results target
– No collected snail shells show sign of possum or rat predation
– Rat tracking tunnel index rate in forest immediately adjoining the release sites no greater than 5%
– Possum residual trap catch rate no greater than 1% (or if using wax tags, use Bite Mark Index of
~5%)
Methods
1. Maintenance control - Ground control every year, year round
A. Trapping and bait stations
• Rats
Victor professional rat traps placed at 25m intervals along the current lines. Lines cover snail
areas and adjacent vegetated areas.
Mt Augustus control area has 153 Victor professional rat traps.
Mt Rochfort control area has 121 Victor professional rat traps.
DOC 200 traps are placed at 100m intervals along the current lines.
Mt Augustus control area has 25 DOC 200 traps
Mt Rochfort control area has no DOC 200 traps
• Possum
Sentinel kill traps placed at 50m spacing along the current lines.
Mt Augustus control area has 93 Sentinel possum kill traps
Mt Rochfort control area has 76 Sentinel possum kill traps
Traps are serviced monthly.
• Bait stations
One line on along Stockton Plateau edge, and some in North East and R6 (57 bait stations).
Around Mt Rochfort Basin and a few at Mt Rochfort Summit (23 bait stations)
These locations are linked to areas with high rat capture rates
Placed at 50m intervals.
MBC has consent for 1080 bait. 1080 is preferred as higher uptake rate.
If there are high capture rates, then bait stations are activated and serviced fortnightly whilst there
is uptake and high catches in traps.
The current lines run through Site A, but these traps should not be activated and serviced, except
during mast years when rat captures are high.
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B. Hand laying of 1080 pellets
MBC holds a consent to hand lay 1080 pellets anywhere within the 180ha control site on Stockton
Plateau and 199ha site at Mt Rochfort.
This method could be used when capture rates/bait uptake is high, e.g. as result of a small mast event.
2. Managing the threat of beech mast induced rat irruptions - Aerial laying of 1080 pellets
Triggers for rodent control to protect fauna species are currently being developed by DOC. Managing
rodents in lowland mixed beech forests is subject to South Island wide experimental programmes and
specific prescriptions have not yet been developed. The minimum size for an aerial 1080 operation for
P. augusta would be 1,000ha because of the rate at which rats move when food supplies are low and
when they reinvade poisoned areas. The 1,000ha needs to cover the snail areas and the surrounding
forested areas.
TBFree New Zealand holds a consent to do an aerial operation over 23,000ha of Buller North, and
which covers the escarpment and lower lands around Stockton Plateau and the Denniston Plateau and
their escarpments. The trigger for the operation is possum numbers and last occurred in early 2015.
Elevated rat numbers would be the trigger for an aerial 1080 operation for
P. augusta, and which
would be detected by monitoring rat numbers on the escarpment and coastal foothills.
We are yet to determine the exact operation boundary for future years. Our aspiration would be that
an operation for
P. augusta would be part of a larger operation across Stockton Plateau and Denniston
Plateau. This would appear in theory possible as both Buller Coal and SENZ have Access
Arrangements with DOC and Resource Consents that require them to fund aerial 1080 operations over
Denniston Plateau and the southern half of the escarpment of Stockton Plateau, including up to the
A12 escarpment area. The 1,000ha area for
P. augusta would represent a very small addition to the
treatment area required under the two consents.
If the triggers for an aerial 1080 operation for
P. augusta or at the other sites on Buller Coal Plateau
were met, DOC would work with the various committed partners to determine what area should be
treated and how it should be funded. DOC is planning to obtain a 10 year resource consent for a 1080
aerial operation to cover the entire Buller Coal Plateau and adjacent lands, and therefore the
P.
augusta snail team itself does not need to obtain a resource consent.
The monitoring data would need to be collated, and advice would then be sought from rat control
experts within the DOC Science & Capability team to predict rat population increases, and these levels
would then be used to judge the need for, and the timing and intensity of an aerial operation.
3. Trend monitoring and results monitoring
Standard possum trap catch index monitoring and rat tracking tunnel monitoring will be used to
monitor possum and rat numbers. A higher emphasis is placed on monitoring rat numbers than
possum numbers because few snail shells show possum predation.
Standard possum trap catch index monitoring data from adjacent sites will primarily be used. This
includes the TBFree NZ trend monitoring data within their Buller North control area, Stockton No. 2
South area (SENZ), Cypress area (SENZ) and Denniston Plateau (DOC/Buller Coal Ltd). If the
OIAD-830 Talia P Attachment - Powelliphanta augusta Recovery Strategy 2015
possum trap catch index becomes elevated or possum predation sign is detected on the snail shells, or
otherwise, once a year (could be in February or August, but best to choose one of these months and
stick to it), possum monitoring in the
P. augusta control area will occur in conjunction with the rat
monitoring, with wax tags placed along the rat tracking tunnel lines. Ideally, the wax tags should be
deployed for seven nights but if there are budget restraints, the wax tags could be left out for the same
period as the tracking tunnels (usually one night) and the resulting index will be specific to the site.
Rat tracking tunnel monitoring will be undertaken following DOC best practice. Five lines will be
established on the escarpment and coastal hills below Mt Augustus. During 2013/14, only two of the
potential line locations were suitable (in terms of health and safety) but the area was badly damaged
by a cyclone in Easter 2014 and therefore the lines are likely to have been damaged and otherwise it is
too dangerous to enter the area. Data from five rat tracking tunnel lines run on the western escarpment
of Denniston Plateau and western escarpment by DOC will also be used.
Rat monitoring will occur in February and August in non-mast years and also in May and November
in mast years and/or as alerted by modelling predictions.
DOC also conducts seedfall monitoring on Denniston Plateau with some sites in the forest on the
western escarpment. This data would also be used to identify the size of a beech masting event and
help us decide if a large-scale control operation is needed to control a rat irruption.
Snail shells will be collected as encountered during snail monitoring, and assessed by DOC to
determine the cause of death. The data will be collated on the Excel spreadsheet docDM-1250043.
The trend and result monitoring reports will be produced annually and cover the period July to June.
OIAD-830 Talia P Attachment - Powelliphanta augusta Recovery Strategy 2015