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Planning for Whitebait Spawning Sites
- 1. Planning for Whitebait Applying vulnerability assessment to īnanga spawning sites Shane Orchard, Mike Hickford & David Schiel
- 3. Resilient Shorelines project Estuarine rivermouths Low-lying shoreline ecosystems > susceptible to sea level rise
- 4. Novel opportunity Post-quake adaptation scenario Quantify change Evaluate impacts / management responses Inform policy for future events Hydrodynamics effects similar to changes expected under sea level rise Earthquake changes as a natural experiment
- 5. Īnanga - a much loved species • Īnanga (Galaxias maculatus) > • High cultural importance • Iconic recreational fishery > 70-100% of whitebait catch • Conservation status ‘declining’* Conservation biology • Spawning a critical life stage • Short life cycle (1-2 years) No eggs, no whitebait! * Goodman et al. (2014). Conservation status of New Zealand freshwater fish, 2013. New Zealand Threat Classification Series 7. Wellington: Department of Conservation. 12pp.
- 6. Spawning habitat – what do we know? • Spatially confined areas at rivermouths • Close to limit of saltwater intrusion • In riparian vegetation inundated on spring tides • Habitat susceptible to ... > loss of vegetation cover > disturbance > channelisation > hydrological changes > sea level rise? Key management questions • How to best protect the habitat? • Are threats changing for better / worse?
- 7. 1. Has īnanga spawning habitat shifted? 2. Have threats and vulnerabilities changed? 3. Are management changes needed in the post-quake scenario? 4. If yes, what are the best options? Applications post-quake waterways management natural resource policy & planning inform adaptation to climate change Research questions Īnanga spawning habitat study
- 8. Study site Avon River / Ōtākaro Heathcote River / Ōpāwaho Avon Heathcote Estuary / Ihutai LEGEND
- 9. Quantify spawning habitat at catchment scale • Census style egg survey > 15 km of riverbank > 7 months of survey (2 spawning seasons) > spatial data + environmental variables > dataset = 309 records from 142 natural sites • Applied artificial habitat (straw bales) as detection tool > placed in degraded areas > up/downstream of natural extent & in gaps Methodology
- 10. Results
- 11. Results by month Heathcote / Ōpāwaho Imagery: LINZ
- 12. Results by month Avon / Ōtākaro Imagery: LINZ
- 13. How important are these sites? 2015 = 12,000,000 eggs (4 months) VERY! 0 1 2 3 4 5 6 7 8 February March April May Eggproduction(millions±SE) Heathcote/Ōpāwaho Avon/Ōtākaro Total
- 14. Has spawning habitat shifted? Heathcote / Ōpāwaho Pre-quake ~ 20m2 habitat YES Post-quake ~ 60m2 habitat Imagery: LINZ Opawa Road site
- 15. Avon / Ōtākaro Pre-quake ~ 50m2 habitat Has spawning habitat shifted? YES Post-quake ~ 90m2 habitat Imagery: LINZ Avondale site
- 16. Has spawning habitat shifted? YES And expanded! • New sites are exposed to a variety of unmanaged threats Have threats and vulnerabilities changed? YES ?
- 17. Vulnerability assessment Current threats • Reserves management • Flood management • Bank stabilisation • Pest plant control Heathcote River / Ōpāwaho ~100% spatial overlap Īnanga eggs on reed canary grass (Phalaris arundinacea)
- 18. Post-quake scenario 1. Has īnanga spawning habitat shifted? YES 2. Have threats and vulnerabilities changed? YES 3. Are management changes needed? YES The good news > Spawning habitat was resilient to earthquakes Not so good news > Unlikely to be resilient to changed pattern of vulnerability due to known threats in the post- quake landscape 4. If yes, what are the best options? Management solutions > Address current threats > Manage future risks Conclusions
- 19. Evaluating the post-quake landscape as an adaptation scenario • Effectiveness of current (statutory) protection tools? Finding solutions • Stakeholder perspectives on issues / opportunities for responses • Compare vulnerability outcomes with different management options Current work
- 20. Future work Measures, R. & Bind, J. (2013). Hydrodynamic model of the Avon Heathcote Estuary. Model build and calibration. Report prepared for Environment Canterbury. 28pp. Future threat > sea level rise • Scenario modelling approach, linked habitat + process models • Iterate vulnerability analysis steps
- 21. Implications for conservation planning Post-quake landscape sea level rise scenarios The future is now! • Conservation strategies that do not consider ecosystem mobility may contribute to mal-adaptation • Nature-based solutions for climate change need to include spatial requirements of ecosystems • Addressing spatial allocation over time = practical focus for management
- 22. Acknowledgements People involved: Mike Hickford David Schiel MERG & Waterways staff & students Whaka Inaka partners Many community volunteers!
- 23. Resilient Shorelines CONTACT DETAILS: Email: info@resilientshorelines.nz Blog: www.resilientshorelines.nz THANKS!
Editor's Notes
- Focus of the study is on rivermouths which are areas that will undoubtedly be affected by sea level rise. And initially restricting our attention to sandy estuarine type systems that are common and important type in NZ. In this type there are 3 characteristic areas that are we investigating and characterising: - Sand dune ecosystems that are characteristic of entrance Saltmarsh ecosystem, typically found in the middle reaches, and above this the Upper estuarine margins that are the transition area between saltmarsh vegetation These reaches are extremely important for inanga. as the spawning habitat. Our study is defining and characterising the habitat and this is the focus for this presentation. LONG VERSION: Focus on rivermouths Rivermouths are unique features of the coastline that with undoubtedly be affected by sea level rise They a support a wide range of ecological values, and are also popular with people as places for urban settlement activities such as farming on flood plains. Shorelines at rivermouths are often areas of high interest that may include competing demands. The study sites for this project are sandy estuarine rivermouth systems a common type in NZ They can be small and relatively wild such as the Punakaiki River or much larger and heavily urbanised such as the Avon Heathcote Estuary / Ihutai in in Otautahi Christchurch
- So why the focus on inanga? Hopefully many of you were here for Dr Mike Hickford’s presentation that outlined some of fascinating aspects of inanga biology and conservation. When we look closer at the people aspects we come to the conclusion that inanga is a much loved species, or many reasons. Therefore, threats to inanga are not only a biodiversity issue, they are atural resource management issue. Inanga are a resource that provides benefits to people in many different ways The most obvious of these is the whitebait fishery. This is of high cultural importance to Maori as a kay mahinga kai species. Not ony were the whitebait juveniles harvested but also the adult inanga at a different time of the year. The fishery is also a major recreational resource for all New Zealand. It has considerable commercial value, is an aspect of local food security., and is a drawcard for visitors in several parts of New Zealand. Conservation status is current declining, and there are now many New Zealanders actively engaged in inanga protection, mainly at the level of restoring or protecting spawning habitat. Who knows, there maybe tourism value in being able to proudly display the healthy natural habitat of such flagship species to visitors, and this is already an important consideration for supporting tangata whenua values in relation Manaakitanga and Rangatiratanga which are affected by the availability and condition of local natural resources.
- Census style egg survey at catchment scale designed to quantify spawning site extent, pattern, and productivity 15km reach length to be surveyed Habitat suitability classification based on vegetation survey (3 classes) > used to optimise egg survey effort Criteria: G3 – 100% cover, 0.5cm root mat G2 – 100% cover, <0.5mm root mat G1 – everything else Systematic searches consistent survey effort applied Subjective (spot) searches applied to all other reaches 2 spawning seasons over 7 months > Feb-May 2015, Feb-Apr 2016 Suite of environmental variables recorded for all occurrences
- Census style egg survey at catchment scale designed to quantify spawning site extent, pattern, and productivity 15km reach length to be surveyed Habitat suitability classification based on vegetation survey (3 classes) > used to optimise egg survey effort Criteria: G3 – 100% cover, 0.5cm root mat G2 – 100% cover, <0.5mm root mat G1 – everything else Systematic searches consistent survey effort applied Subjective (spot) searches applied to all other reaches 2 spawning seasons over 7 months > Feb-May 2015, Feb-Apr 2016 Suite of environmental variables recorded for all occurrences