Toheroa mātauranga and management in Murihiku

Project objectives

1. Interview Murihiku kaitiaki with recent and past knowledge of toheroa populations, traditional management, and current harvest management.
2. Contrast traditional reseeding methods and with ecological science expectations of optimum methods and places for restoration.
3. Identify threats to traditional harvest areas and what, if any thing, can be done about them.
4. Survey traditional harvest sites for the ongoing presence of Toheroa, their abundance, size distribution and condition; and survey potential sites for reseeding and more active habitat management.
5. Assess viability of toheroa reseeding; if considered likely to succeed, develop a costed plan for reseeding threatened populations and associated potential establishment of mātaitai around restored areas.

Research team

This project will be directed by Ōraka-Aparima Rūnaka Inc.  This is one of the 18 Papatipu Rūnanga, which collectively make up the membership of Te Rūnanga o Ngāi Tahu. We are one of 4 Murihiku based Rūnanga. The Executive of the rūnaka meet weekly and will oversee the day-to-day running and direction of this research project.  Bigger policy issues or take will be brought before the monthly hui attended by members of the rūnaka to find a community consensus on how to proceed.

Our marae is in the process of identifying the areas where we wish to establish mātaitai and it would be sensible to establish mātaitai over the areas reseeded within this project.

The project will be guided by Nigel Scott, Environmental Advisor from Ngāi Tahu’s Toitū Te Whenua, who is working with Ngāi Tahu communities to establish mātaitai and taiāpure. This toheroa project will be the first of many led by the Murihiku kaitiaki within the overall Te Tiaki Mahinga Kai project. Te Tiaki Mahinga Kai is a collective of Tangata Whenua, managers and researchers that aims to improve co-management of mātaitai and taiāpure reserves throughout Aotearoa by conducting research and supporting ecological management directed at enhancing the cultural, economic, social and environmental outcomes for Māori. Science research within Te Tiaki Mahinga Kai is overseen by Henrik Moller, from Kā Rakahau o Te Ao Tūroa. Expert marine ecology will be added by 5 academics from University of Otago and University of Canterbury with decades of experience in the ecology and management of coastal environments. Interviewing to gather mātauranga will be by Simon Lambert.  Rākoa Bull, a member of the Ōraka-Aparima community will be trained and do much of the toheroa surveys.

The need for this research:

NIWA, in conjunction with local iwi, have been active in monitoring toheroa populations in their last remaining strongholds, in Northland and Southland, for the Ministry of Fisheries. Population declines of toheroa in the 1960s resulted in the prohibition of harvesting in 1981, except for Māori customary take and occasional one-day recreational seasons. Surveys at Oreti and Bluecliffs Beaches in Southland have shown a steady decline of toheroa over the last 20 years, particularly at Bluecliffs, with numbers only a small fraction of those in the 1960s (M. P. Beentjes, G. D. Carbines, A. P. Willsman. New Zealand Journal of Marine and Freshwater Research, 2006, Vol. 40: 439–453). Populations fluctuate greatly because of variable recruitment and mass mortality events, but the sustained low abundance is puzzling. Studies of beach profile and substrate at Bluecliffs, commissioned by Meridian Energy pinpointed erosion of fine sand substrates as the likeliest cause of declining toheroa populations there.  Our study using mātauranga is designed to partly test these assessments, but more importantly, help generate a local kaitiaki approach to more actively manage the situation and to combine the knowledge at an early stage of planning a suite of mātaitai in the region. Coupling the available Area Management Tools with protection and enhancement of a taonga species like toheroa is a logical way forward and an excellent way of building the involvement of local kaitiaki in coastal restoration.

Research Methods

The methodology for the project would be:

1. Interview Tangata Tiaki/Kaitiaki with mātauranga of traditional monitoring, reseeding, harvest management methods for toheroa and threats to current populations: Tangata Tiaki/Kaitiaki from all four Papatipu Rūnaka in Murihiku will be interviewed and the methodologies will be documented. Two experienced toheroa harvesters are currently ill, so we urgently want to record their knowledge, but we wish to collect all the mātauranga associated with toheroa in the one go.  Maps and old aerial photographs will be used to guide interviews and identify past changes in habitats and toheroa numbers and current threats to them.
2. Survey current habitats and toheroa population strength (numbers, size frequency distributions and condition) at past and present traditional harvesting sites: Local tangata Tiaki and kaitiaki from the rohe will work with scientists from Te Tiaki Mahinga Kai to score habitats (substrate depth and particle size) in a repeatable non-destructive manner in a stratified random quadrat approach, and count and measure the number of toheroa found.  Distance between high and low tide marks will be used for stratification of the replicated plots and a simulated traditional harvest rate monitoring approach will be designed and recorded for eventual monitoring and management of harvests on any mātaitai created in reseeded sites. A minimum sub-sample of toheroa will be opened to score condition of the shellfish.
3. Consult all other stakeholders and expert scientists to identify potential threats to current toheroa populations and develop a toheroa restoration and management plan for the Oraka-Aparima rohe: a mixture of hui, smaller focus group discussions and written peer review of draft plans will be used to develop a plan that meets the tikanga and goals of the kaitiaki and involves the potential local reserve managers (should a mātaitai be promoted in toheroa reseeded areas).  The primary focus will be on choice of optimum reseeding sites and management strategies in the Te Waewae Bay region.  Preliminary studies of toheroa around Waiau outflow areas is available as a start for this work (funded by ECNZ/Meridian as part of the Manapouri power scheme impact studies) will be consulted for benchmarking and design of the management plan.
4. Preparing a viability assessment and plan for reseeding:

1. Assess overall viability of successful reseeding, based on the results from objectives 1-3. Identify suitable beach areas within the Murihiku for reseeding and active area management: Areas of Oreti beach will be selected as appropriate reference (not re-seeded) areas for monitoring and benchmarking the progress of reseeded and managed areas in subsequent years.
2. Conduct baseline population surveys of the existing toheroa populations on these beaches:  Baseline population surveys will be conducted on the chosen beaches using standard stratified/random transect survey methods to measure abundance, size frequency distributions of toheroa, but also monitored by the less formal traditional methods identified by the interviews.  The sampling will complement that already gathered at Blue-cliffs and Oreti by the NIWA studies but target areas for potential reseeding and active area management.