Harvest and Conservation of Sooty Shearwaters (Puffinus Griseus) in the Marlborough Sounds, New Zealand

Customary harvest of wildlife can be an important mechanism through which indigenous people maintain a connection with their environment. Observations built up during harvesting events are also a useful way of monitoring change over time. However, not all traditional societies have lived harmoniously with their environment. Wildlife populations can become depleted quickly if not managed sustainably. Using traditional knowledge interviews, empirical data from two island populations and population modelling, I examined the viability of two island sooty shearwater populations in the Marlborough Sounds and their resilience to resumed, low-level harvest. The biology of the sooty shearwater populations was found to closely resemble that of populations found at higher latitudes. Historic harvest by Marlborough Maori probably had an important influence on the size of present day Marlborough populations. Viability models demonstrated that these populations were experiencing very low or negative intrinsic rates of increase. Population sizes have likely been affected by previous harvest and are not at carrying capacity. The populations are therefore vulnerable to demographic stochasticity, environmental variability and extrinsic factors such as fisheries bycatch. The low and negative growth rates for populations at small sizes not at carrying capacity are of concern where harvesting is proposed. This study provides a basis for ongoing research into the population trajectories of each island population. Harvesting is possible in one population provided an appropriate monitoring regime is established prior to harvest being undertaken, to ensure the long-term viability of Marlborough Sounds' sooty shearwater populations.