An investigation into the Murihiku toheroa (paphies ventricosa) : matauranga, monitoring and management
Futter, Julie M.
The value of traditional ecological knowledge and associated traditional practices, or matauranga and tikanga in the New Zealand Maori context, is playing an increasingly important role in the development of effective wildfoods management. Kaitiaki (environmental guardians) in Murihiku (Southland) are concerned about the successful transmission of the matauranga surrounding the ecology, management and threats of the toheroa (Paphies ventricosa). Populations of toheroa, a highly prized endemic surf clam, are found at Oreti, Orepuki and Bluecliffs beaches within Murihiku of which numbers are historically low. Bluecliffs Beach has experienced large sand erosion leaving on so% of the original habitat suitable for the toheroa. Twenty-five semi-directive interviews were conducted across a range ofkaitiaki, local experts and scientists. Interviewees identified the main threats, concerns and gaps in the research surrounding the toheroa and dictated the main aims within this present investigation. Discussions surrounding the traditional practice of translocating toheroa revealed the presence of the third colony at Orepuki Beach, Te Waewae Bay. A population a third the size of the 2005 Bluecliffs Beach population has established at Orepuki Beach from translocation efforts by local community members. The maintenance of this population is of great importance to the resilience of the Te Waewae Bay toheroa given the degraded state of the Bluecliffs Beach population. The potential use of translocation as a stock enhancement tool may have broad potential to secure and increase the resilience of the Murihiku toheroa meta-populations. Translocation of adult toheroa to enhance existing stocks density and to establish new populations is considered the most practical option. The destructive nature of the current population survey techniques and its lack of adhering to tikanga lead to the wish for a non-destructive abundance index based on traditional search methods to be developed. The observation and counting of siphon activity (siphon tips and holes in the sand) provided a poor predictor of absolute toheroa density when compared with densities generated from the excavation surveys. However observing siphon activity in relatively warm temperatures (16°C and above) provides a 95% certain rate of detection during one search. Thus siphon activity searching provides a sound means to assess the presence/absence and distribution of toheroa colonies. The main threats to toheroa were identified as beach traffic, mass mortalities, illegal harvesting, predations, pollution and climate change. All of which are poorly quantified. Preliminary investigations provided evidence of beach traffic adversely impacting juvenile (≤ 39 mm) toheroa, particularly those in the softer sand. Injury rates increased with vehicles with large, spaced lugs on the tyre tread and the motorbike test vehicle killed 18% of toheroa exposed to a single passage compared to an average of 3% for the car/utility vehicles. Similarly the Burt Munro Challenge beach race, an annual motorbike event held of Oreti Beach, caused a 72% (95% CI 40- 90%) juvenile mortality rate within a 1-2 km stretch of the beach. Further research into quantifying the risk of beach traffic, along with important biological parameters (i.e age/size and maximum reproductive potential) need to addressed. The results of this present investigation clearly illustrates of how TEK and its associated practices are relevant to the effective management of wildfood resources. Future development into the management of the Murihiku toheroa should encompass an active adaptive management approach.
Advisor: Moller, Henrik; Lamare, Miles
Degree Name: Master of Science
Degree Discipline: Ecology
Publisher: University of Otago
Research Type: Thesis