IN THE MATTER of the Resource Management Act 1991

Transcription

1 BEFORE THE TASMAN DISTRICT COUNCIL IN THE MATTER of the Resource Management Act 1991 AND IN THE MATTER of an application by the TASMAN DISTRICT COUNCIL (ENGINEERING DEPARTMENT) for resource consents for land use activities, discharges, water diversion, river control structures within rivers and the coastal marine area for river management, erosion control and flood protection works. STATEMENT OF EVIDENCE OF PETER DOUGLAS GAZE Dated 25 September 2015 INTRODUCTION 1. My full name is Peter Douglas Gaze. 2. My evidence is given on behalf of the Tasman District Council (Engineering Department) (Applicant) in relation to an application for resource consents to undertake river management activities. Qualifications and Experience 3. I have had a lifetime career in wildlife ecology specialising in the conservation of birdlife. 4. My early years of employment were with Ecology Division of Department of Scientific and Industrial Research (DSIR). This was followed by 25 years with Department of Conservation (DoC) in an advisory role, specialising in the management of birdlife and herpetofauna. During my time with DoC, I spent five years leading major work to 1

2 conserve black-fronted tern nesting on the Wairau River. This work included a key role in the various court hearings related to the Trust Power application and hence a close connection with the management of birds on braided rivers throughout the country. In this official capacity, and privately, I have become familiar with the birdlife on the rivers within this application area. For the last three years I having been working on privately funded wildlife conservation projects. My Role 5. I was engaged by the Applicant to review the Assessment of Environmental Effects (AEE) from the perspective of a wildlife specialist specialising in bird life, to provide comment on the AEE and the proposed mitigation measures and the potential adverse effects on threatened bird life as a result of the proposed river management activities. I have been asked to present evidence at the resource consent hearing to address these matters. I have not been involved the preparation of the application and the AEE. 6. I am familiar with the area covered by the application as I have lived in Nelson for 35 years. In particular I am familiar with rivers covered by this application. Code of Conduct 7. I have read and agree to comply with the Environment Court s Code of Conduct for Expert Witnesses contained in the Environment Court Consolidated Practice Note My qualifications and experience as an expert are set out above. I confirm that the issues addressed in this evidence are within my area of expertise. I have not omitted to consider any material facts known to me that might alter or detract from the opinions expressed. Scope of Evidence 8. My evidence: (a) (b) Reviews the AEE with respect to its description of the birdlife on the rivers covered by the application and the habitat. I provide additional material on threatened bird species using the rivers and also outline the relevant provisions of the Tasman Resource Management Plan (TRMP) which relate to bird life along the rivers Addresses the activities for which consent is sought and their potential impact on bird life; 2

3 (c) (d) Describes measures that can be undertaken to avoid, remedy or mitigate the impact of river management activities on bird life; and Addresses the conditions of consent, particularly in terms of measures I have described which can be employed to avoid, remedy or mitigate the impact of the activities on bird life. 9. In preparing my evidence I have read the AEE, all of the submissions made on the application and the section 42A report. The submissions and section 42A report do not raise any matters that directly relate to my area of expertise and therefore I do not address these documents in my evidence. 10. The scope of my evidence is limited to bird species which have been classified as threatened with extinction as these are the ones inevitably most vulnerable to environmental change. In doing so no bird species has been omitted from consideration that, in my opinion, might be adversely affected by the proposal. REVIEW OF THE ASSESSMENT OF ENVIRONMENTAL EFFECTS Introduction 11. Braided riverbeds are a feature of the South Island of New Zealand and a range of fauna has adapted to and become totally dependent on this habitat. This environment is most evident with the large rivers draining eastward from the Southern Alps through Canterbury, Otago and Southland. Within the application area shingle braids occur in the headwaters of the larger rivers where there is a high sediment loading from the mountains and a relatively low altitudinal gradient. This landform is well represented in the upper Buller and Matakitaki Rivers and to a lesser extent in parts of the Motueka and Aorere Rivers. The bird species which are most threatened are those which are obligate users of this braided river environment and it is no coincidence that in this region they are now confined to the best examples of it. In particular I refer to the nesting of black-fronted tern and black-billed gull in the upper reaches of the Buller and Matakitaki Rivers. 12. The river management activities and works proposed in this application, and described in Mr Lowe's evidence and the AEE, are likely to affect the braided and meandering nature of rivers and the associated birdlife, where applied within this habitat. I refer particularly to: 3

4 Beach raking/ripping - a technique to mobilise stable sediments and restore a more confined river channel. Tree planting/layering/trenching - if this were to occur within the active bed of a braided river this would restrict the ability of the channels to meander, creating islands for nesting habitat and also has the potential to restrict the extent of bare open shingle bed which is vital for nesting. 13. In addition to these possible works in braided riverbeds, similar work is anticipated within single channel riverbeds. My evidence addresses the birdlife which uses all of these rivers and the potential impact of the proposed work within the constraints given. 14. These concerns are addressed to some extent by the AEE. Section of the AEE suggests that the ability of birds to re-lay and the fine timing of works would provide significant mitigation. Section 5.5 describes the benefits of root raking in removal of vegetation but there is also a potential for adverse impacts in mobilising the substrate. Section 5.12 does not recognise the potential for loss of bird nesting habitat through planting programmes. 15. These same concerns are, however, recognised and more effectively managed within proposed conditions 27 to 30 which requires the preparation of an Environmental Management Plan (EMP) and provision of site specific environmental management plans (SSEMPs). The exclusion of headwater catchments in condition 1 effectively excludes most blue duck habitat from the application. A review of threatened bird species using the rivers 16. A number of threatened bird species use the river habitat affected by this application and some breed within it. The application describes this accurately but rather briefly and the following section sets out this information in more detail. Banded dotterel 17. Banded dotterel are likely to be found in all six of the major catchments referred to with the larger and more aggraded rivers providing better habitat. They are not common or predictably present in any other than perhaps the upper Buller and Matakitaki Rivers. Some birds may be present throughout the year but an influx can be expected over s summer months with coastal birds moving considerable distances inland to breed. 4

5 18. It is interesting to note that a survey of all river birds in the main stem of the Motueka River, which I organised in November 2010, detected only seven banded dotterel and they were all in the Kohatu - Wangapeka stretch. Riverbed surveys in the Matakitaki and upper Buller Rivers detected higher numbers (Steffens 2007). 19. Banded dotterel are unlikely to flock in these rivers, more often being seen as a single pair and somewhat inconspicuous. They will forage along the river edge and in backwaters, preferring the finer sediments. Solitary nests are in a small scrape in an open area of riverbed that has little or low-lying vegetation. It is the choice of this nest site which will provide the best protection from fluctuating river levels, mammalian predators, and human disturbance. 20. Unlike the other species of concern it is not possible to predict where banded dotterel may be present. A guiding principle for river management should be based on awareness that less exposed river bed is likely to mean less available habitat. Given the much reduced population of banded dotterel this loss of feeding habitat will be less significant than the loss of potential breeding sites. Pied stilt 21. The application describes riverbeds within the Waimea, Takaka and Aorere River catchments as providing habitat for this 'declining' species. Pied stilts will forage in finer sediments where there is low flow or preferably a swampy backwater. Stilts are only likely to use this where it is adjacent to more extensive habitat in the form of estuaries or poorly drained farmland. These riverbeds are even less likely to be used by pied stilts for breeding habitat. 22. Steffens (2009) recorded pied stilt in the upper Buller riverbed during four summer surveys (range 2-6) and in the upper Matakitaki riverbed (range 2-24) during the same period. A survey of the Motueka riverbed in 2010 (pers. obs.) recorded a total of 35 pied stilts from Kohatu to the coast. South Island pied oystercatcher 23. This species is mentioned occasionally in the application. It breeds in very low numbers in the more aggraded riverbeds - particularly the Aorere, upper Buller and Matakitaki Rivers where there is good foraging on adjacent pasture. The high numbers of this species breeding successfully on the Canterbury riverbeds and the very few pairs which choose to breed within the affected area would make it a species of least concern. 5

6 Black-billed gull 24. With a conservation status of 'nationally critical' this species deserves the utmost attention of river managers. The species is another that spends the winter in the coastal environment and moves inland in spring to nest in colonies on braided riverbeds. These colonies are relatively 'tight' and traditional in the site chosen. This should provide the benefits of both safe nesting and abundant feeding opportunities over pasture, however, predation and other factors have caused a major decline in recent decades. Most black-billed gulls breed on riverbeds in Southland where numbers have decreased by more than 80% in the last 30 years. 25. As the AEE describes, within the Tasman District, black-billed gulls have only been known to breed in the Buller and Motueka River catchments. The Motueka River colonies have been on that stretch of the main stem between Kohatu and the Wangapeka River mouth but I am not aware of any colonies here, or elsewhere on the Motueka River, over the past 20 years. 26. Black-billed gull colonies have been present on the upper Matakitaki River most years. The size of these colonies has increased (Steffens 2007) which is in dramatic contrast to national trends. A colony is also usually present in the upper Buller River near the confluence with the Howard River. In at least one year a colony established on the Buller River near Murchison. 27. These colonies are incredibly valuable not only because of the species' critical conservation status but because, for whatever reason, these colonies are successful in raising young. Black-fronted tern 28. In many ways the life habits, habitat preferences and threats to the conservation of black-fronted tern mirror that of black-billed gulls. The major difference is that the terns take all their food aerially - terrestrial and aquatic invertebrates. A study of this species on the Wairau River has seen colonies repeatedly affected by flooding and predation with fewer birds coming back to breed each year. 29. The AEE mentions that black-fronted terns breed on the Motueka River and are present on the Waimea River. Like the old black-billed gull colonies on the Motueka River, I doubt that the black-fronted tern has bred in the Kohatu-Wangapeka stretch for many years. 6

7 Birds do congregate at the Motueka highway bridge each breeding season, and some may nest, but these are likely disrupted by the presence of white baiters. While the black-fronted tern may have been seen feeding over the lower reaches of the Waimea River I doubt they have bred. 30. On the Buller River black-fronted tern usually nest, in one or more colonies, near the confluence with the Howard River. On the Matakitaki River, the colonies are usually up-river of Mammoth Flat. These are the same two sites that have been identified as vital for the black-billed gull. Whio 31. Whio are present and breeding in the upper reaches of all six catchments. In contrast with the other species addressed in my evidence, this duck requires a degraded riverbed where increased gradient does not allow sediment to accumulate and where invertebrate fauna can establish in a relatively stable environment. This environment is generally in the Schedule 1 rivers listed in Buller and Motueka River Water Conservation Orders and are outside the scope of this application. Coastal species 32. A range of species make good use of the lower reaches of these rivers in that zone where there is some tidal influence. These include oystercatcher, stilt, herons, egrets, crakes and rails. This habitat is all within the coastal marine area (CMA) and I understand that where any work is proposed in the CMA in relation to the maintenance or extension of the structures, a SSEMP is required (condition 30v). Relevant provisions in the TRMP relating to bird life 33. The concerns I express over potential impacts on birdlife have to a large extent been addressed in principle by the TRMP and are referred to in the AEE. I refer here to: the avoidance/mitigation of adverse impacts on birdlife (Objective ); Schedule 30A specifically identifies the sites where birdlife is most vulnerable to disturbance; and the precautionary approach in the TRMP where values may not have been specifically identified (Policy ). 7

8 POTENTIAL IMPACT OF RIVER MANAGEMENT ACTIVITIES ON BIRD LIFE 34. The greatest potential for an adverse effect on bird conservation is with black-billed gulls and black-fronted terns at the two traditional nesting sites that I describe above. The river works anticipated in this application could impact on the braided habitat which is essential in providing invertebrate food and safe nesting sites. In addition, there is the possibility that new colonies may attempt to establish at sites not specified and hence unprotected by the provisions of this application. 35. As already highlighted in paragraph 13 above, the river works that have the potential for this impact are those that would remove the mulit-channelled character and the associated expanse of exposed shingle riverbed. These activities are described in the application and elaborated on in the evidence of Messrs Giles and Griffiths. Two examples of this work are beach raking or ripping which is designed so as to mobilise sediments which impede river flow and tree planting/layering which would remove exposed open gravel areas within the riverbed. MEASURES TO AVOID, REMEDY OR MITIGATE IMPACT OF RIVER MANAGEMENT ACTIVITIES ON BIRD LIFE 36. The AEE sets out a number of measures to avoid or mitigate the potential adverse impacts and these are referred to below: Section 1.4 and condition 1 excludes the rivers which contain whio or whio habitat; Approval is not being sought for new works within the CMA; Maintenance or extension work within the CMA will be subject to a SSEMP which will be developed in consultation with stakeholders such as DoC and will need to be approved by the consent authority before the works are undertaken; Condition 4 requires works to be planned to take into account the nesting season and the location of native birds; The traditional nesting sites of black-billed gull and black-fronted tern have been accurately described in Schedule 30A of the TRMP and condition 30 requires that any work in these areas during the breeding season be subject to an SSEMP. 8

9 37. There are two weaknesses in these conditions: There is no provision for the protection of any black-billed gull or black-fronted tern colony which may attempt to establish outside of the traditional sites listed in Schedule 30A; and There is no assurance that works outside of the breeding season will not compromise river features that make these successful breeding sites for the two species. 38. Given that little or no river management work has occurred in recent times in the areas that I consider most sensitive to birdlife, I consider that the chances are low that these areas will be affected. However the value of this nesting habitat is of such importance that these hypothetical weaknesses should be addressed. 39. In addition it is appropriate that the applicant seek ways in which the existing habitat values can be actively enhanced. This enhancement is anticipated within Objective of the TRMP. I suggest ways that this might be accommodated below under the heading Conditions of Consent. An example of this enhancement has been provided in other braided river systems where nesting islands have been raised to give protection from small flood events and channels better defined to offer more of a barrier to predators. CONDITIONS OF CONSENT 40. I recommend that the following matters are addressed in the conditions of consent or in the content of the EMP which applies to how activities are planned and undertaken: That the EMP sets out that work shall not proceed at any site where blackbilled gulls or black-fronted terns are nesting. This could be ascertained by a brief survey of any braided riverbed prior to work commencing during the breeding season of October to February. That condition 30 is not restricted to the breeding season only, hence allowing the SSEMP provisions to ensure nesting habitat is not compromised. 9

10 That the EMP requires consideration of the potential to create an enhanced nesting environment on the Buller and/or the Matakitaki Rivers following works on these rivers. This could be achieved by the EMP including this matter as a specific best practice method in relation to in-stream works in these rivers. This will alert the Applicant to address this matter in the planning of works and record its consideration of whether enhancement is appropriate in the context of the works proposed and the site. It will also alert the stakeholders (primarily DoC) to assess this matter in relation to the SSEMP process when this is triggered for works in specific sites during sensitive nesting periods. I consider that this recommendation is consistent with Policy (c) of the TRMP. 41. These matters provide an additional level of assurance that the river management activities will avoid potential harmful impacts on birdlife and open the possibility of a net benefit. CONCLUSIONS 42. The consent application is for works that could have the potential to adversely affect some bird species. The key species are black-billed gull and black-fronted tern which are threatened with extinction and which nest in the braided river beds of the Buller and Matakitaki Rivers. 43. The potential for this adverse effect is limited by the requirement for SSEMPs in identified sensitive areas at sensitive times and by the restrictions already imposed by Water Conservation Orders to exclude prime habitat (in the headwaters of the Buller and Motueka River catchments) from the scope of this application. Further conditions and amendments are suggested that would add to my confidence in these provisions and a possibility for a net environmental benefit for these birds. Peter Gaze 25 September