Lizards are set to be debated at a one-day ecology hearing in front of the fast-track panel today.
A joint witness statement was worked out earlier this week.
Nine expert witnesses had a conference on Wednesday to discuss issues around lizards and little common ground appears to have been found on questions set by the panel.
The nine witnesses could not collectively agree what lizard species were there or not there, the actual number of lizards present, where exactly they all lived, whether the mine would have a permanent or temporary impact on lizard survival and if lizards could be salvaged and identified in an ethical way.
Witnesses representing the same organisation did not always agree on the same thing.
The nine experts were Dr Graham Ussher, Keith Barber and Dr Matt Baber, who all appeared for the applicant; Dr Mandy Tocher, for the Department of Conservation; Trudy Anderson and Rebecca Teele, for the Otago Regional Council; Dr Geoffery Rogers, for Sustainable Tarras, and Matthew Dale and Jade Watkin for Kā Rūnaka.
Five of the witnesses agreed species of McCann’s skink, Southern grass skink and Kawarau gecko were on site. Orange-spotted gecko, Jewelled gecko and Lakes skink were unlikely to be on site.
Dr Baber and Dr Ussher considered it highly unlikely these species were present but their presence could not be ruled out.
Dr Tocher was concerned lizards were misidentified, which led to a flawed values assessment.
"This appears to have affected the information gathered, the assessment of effects, and the range of management options considered," she said.
But Dr Ussher and Dr Baber said to the degree to which some individuals were potentially misidentified was expected to have a negligible bearing on the level of effects assessment assigned to southern grass skink.
Five of the witnesses agreed the site, known as the direct disturbance/development footprint, a 610ha area where opencast and underground mining would take place, had a population of 500,000 lizards.
Dr Tocher said most impacts were adverse or uncertain, and the proposed heavy reliance on adaptive management would place the onus on future ecologists to determine whether the planned on-site actions are effective.
The most numerous species on site were McCann’s skink and Kawarau gecko, followed by Southern grass skink — all three species absolutely protected under the Wildlife Act 1953.
The Kawarau gecko was more vulnerable to extinction, regionally and nationally, than other species.
Dr Ussher said the adverse effects on lizard habitat and numbers of the three species over 480ha of the mine site would be temporary — if temporary was defined as a human generation. The rest of the mine site would constitute a permanent loss to lizard habitat.
Ms Anderson and Dr Tocher considered most impacts within the 480ha of the mine site would be permanent, particularly related to Kawarau gecko and Southern grass skink.
There was reasonable uncertainty around the success of rehabilitation and habitat creation.
Dr Baber and Dr Ussher had high confidence in the ability of native lizards to re-establish on the rehabilitated part of the mine site because McCann’s skink were generalist habitat users and Kawarau gecko were habitat opportunists.
The national population of the Kawarau gecko would be impacted up to 7%, Dr Tocher and Ms Anderson said.
But the impact could rise to affect nearly a third of the national population when the whole area of the wider site was included such as the covenant revocation area and the Ardgour restoration area.
In contrast, Dr Baber and Dr Ussher said just 0.1% of Kawarau gecko could be impacted as they had 400,000ha of habitat, compared to as low as 10,000ha as calculated by Dr Tocher and Ms Anderson.
Dr Tocher said those population estimations were from unpublished calculations with a low level of certainty, its database had identification errors and of the 400,000ha only some of this was actual habitat.
Two of the applicant’s witnesses Dr Ussher and Dr Baber, along with others, said despite the proposed offsetting and compensation, the level of residual effects on the lizard assemblage and, in particular, on Kawarau gecko and southern grass skink, remained significant.
Six of the nine witnesses agreed it was not feasible to salvage all lizards, but outcomes should be optimised for those lizards that are salvaged and relocated.
The current salvage plan did not achieve this, Dr Baber said.
Toe clipping had been used to identify residual lizards, but this was not proposed because of cultural and animal ethics reasons.
To substantially reduce the severity of effects for relocated lizards it would require release into larger scale pest-exclusion-fenced areas with suitable habitat.
Mr Barber said larger pest exclusion fences were a viable solution and practically achievable.
