Mapping stressors in Hawke's Bay

Hawke’s Bay has a diverse coastal marine ecosystem with sandy beaches, intertidal reefs, dunes and estuaries. The region has large river systems, fisheries, productive lands and ocean outfalls that can add stress to the marine system and affect people’s values for the coastal area. 

It is a typical example of the complex issue of seabed degradation across Aotearoa New Zealand’s coasts. Hawke’s Bay Regional Council (HBRC), iwi and community groups are united in wanting to tackle this issue, have a shared vision, and are willing to use our ecosystem-based management (EBM) research findings and tools to inform stressor management. 

The collaborative project is addressing two key stressors that are relevant throughout the country’s coastal ecosystems: land-derived sediment and seafloor disturbance from bottom contact fishing. 

This research is co-developed with the Hawke's Bay Marine and Coastal Group (HBMaC), a multi-stakeholder group that includes recreational and commercial fishers, tangata whenua and government agencies, and is facilitated by HBRC science staff. 

Impact 

The collaboration is trialling real-world application of tools developed by Sustainable Seas:  

• System mapping – to visualise important interconnections and feedback loops between variables (social and cultural as well as ecological) that best explain the behaviour of a system over time. For example, mapping the links between seabed health to kaimoana availability to Abundant kaimoana provides opportunities for whānau to nurture relationships that support identity, wellbeing, and knowledge retention, development and intergenerational sharing of tikanga.
• Seafloor disturbance model – to scenario test potential management actions based on ecological understanding of how disturbances such as bottom trawling or sedimentation impact on resilience and recovery of seafloor invertebrate communities.
• Analogue tool – to place the seafloor model results in the context of the system map, exploring how scenarios that resulted in increases in benthic structure might flow through to social, economic and cultural components of the system map.

“The Sustainable Seas team’s expertise is helping us to untangle the contribution of these stressors and provide advice for the way forward, which is invaluable; especially as solutions for Hawke’s Bay will be applicable to the rest of Aotearoa.” – Anna Madarasz-Smith, Principal Scientist/Team Leader – Marine and Coast, HBRC 

System mapping: complete 

The system mapping identified that the largest gaps between current and desired states were: 

• Sediments entering the marine system from land.
• Benthic structure (how complex the seabed is).
• Loss of connection with Tangaroa.
• Public satisfaction with ecosystem health.

Benthic structure is the most critical gap to address because it underpins seabed health. The health of the seabed was perceived to underpin all ecosystem function, ecosystem services, cultural values, and more. 

The system map and its findings are discussed in this webinar, which was co-presented by the research team and Anna Madarasz-Smith and Becky Shanahan from HBRC. 

 “The mapping highlighted areas that I wouldn’t have considered naturally, particularly around social-ecological interactions in the fishing space, an area I am less familiar with.” – Anna Madarasz-Smith 

Scenario-testing: underway 

The systems map identified how everything is connected and where potential action points are. 

The project team is now working with HBMaC to investigate the likely effect of potential management actions on environmental disturbance and recovery, and whether they might lead to improved ecosystem health. They are using the seafloor disturbance model for scenario testing. For example, they are investigating the potential effect of: 

• Reducing sediment inputs on seabed health.
• Reducing fishing effort, resulting in reduced bottom contact from fishing
• Using spatial closures to fishing, for example customary management zones and rāhui.

The way forward 

This research will provide HBMaC a way to determine the anticipated magnitude of recovery that could occur from different management actions (or combination of actions) to improve benthic habitats, and the associated environmental, cultural and social outcomes. 

For example, if both sediment and bottom contact from fishing are reduced by 10% each, what is the impact on seabed health – and subsequently on fish, jobs, manaakitanga (abundant fish enables whānau to express respect and hospitality to visitors through the provision of kaimoana), and mana of the ecosystem and of iwi/hapū? 

These findings will be applicable to other rohe (regions), Regional Councils and government agencies because issues associated with seabed health degradation are common across Aotearoa. 

Contact 

Carolyn Lundquist [email protected] 

Research organisations 

NIWA, Deliberate, HBRC, Whetu Group