"After conducting a population genetic analysis of toheroa in order to map the dispersal of their larvae on ocean currents, initial data suggests that the toheroa of southern New Zealand may be historically derived from northern populations which led to the line of enquiry that toheroa were transplanted to locations outside their natural distribution, possibly prior to European settlement."
Paphies ventricosa, or toheroa - which means 'long tongue' in Maori, is a shellfish endemic to New Zealand and of significant cultural importance to Maori. A close relation of the tuatua and the pipi; the toheroa was once an abundant shellfish in Northland, Kapiti-Horowhenua and Southland. Intense commercial and recreational harvesting over the first half of the 20th century resulted in toheroa populations declining to levels where their harvest was no longer viable.
This research challenges the idea that species distributions are largely a consequence of natural processes and recent human activity, said Dr Ross. "It will be the first study in New Zealand to look at what is effectively aquaculture by indigenous people shortly after the first colonisation of a land mass. It's also the first study to examine the impact of early Māori on the distribution of marine invertebrates and their genetic diversity."
A number of relevant Maori groups in toheroa regions (Northland, Kapiti-Horowhenua and Southland) will be participating in the study. Toheroa were an important food resource for Maori until their commercialisation and increased popularity as a recreational harvest resulted in the collapse of fisheries in the 1960s and 70s. Despite the fishery being closed more than 40 years ago, toheroa have failed to recover, the reasons for which remain unknown.
Although not the main focus of the study, research will also address questions about the failure of toheroa to recover from historic and present-day exploitation and will contribute important information that will aid the future restoration, management and cultivation of toheroa and other culturally and ecologically important species, says Dr Ross.
"Restoration of the toheroa fishery is desirable from an ecological perspective but is also important in terms of the ability of coastal iwi and hapu to live sustainably by harvesting locally sourced natural resources. This research will improve our understanding of the life history of toheroa and help identify life history bottlenecks preventing toheroa recovery. Ultimately it may contribute to the recovery of toheroa and Maoridom's reengagement with this taonga resource."
Dr Ross is a marine ecologist working at the University of Waikato's Coastal Marine Field Station in Tauranga. His marine research is focused on understanding how communities of sea creatures respond to and recover from disturbances, particularly man-made disturbances. For the last few years his research has looked at the ecological effects of the MV Rena grounding on Astrolabe Reef.
Overall, four University of Waikato research projects were awarded Marsden funding, totalling more than $1.3million over three years.