Seabirds as Tohu of Ocean State

Abstract

Bioaccumulation and toxicity of heavy metal pollutants has the potential to contaminate marine systems when present in high concentrations. For centuries, seabirds have been used by Indigenous communities to determine the health of marine systems. More recently, Western science has also recognized seabirds as useful indicators to monitor elevated risk of marine pollutants. This project aims to explore the role of seabirds as indicators of ocean state using a ‘tohu’ framework that reflects a kaitiakitanga-based natural resource management. This advocates for a natural resource co-governance model by drawing upon the knowledges, values, and ethics of western and Māori world views. Following a kaupapa Māori based methodology, three customary harvest mutton-bird species (Ōi (Pterodroma gouldi/grey faced petrel); Tītī (Puffinus griseus/sooty shearwater; and Toanui (Ardenna carneipes/flesh-footed shearwater) were investigated using both qualitative and quantitative methods. Semi-structured interviews identified three key themes in resource management of these birds by Māori: harvesting practices, kaitiakitanga, and whanaungatanga. Harvest practices had a bottom-up governance approach creating diverse harvesting techniques that adapt to local environments. Kaitiakitanga identified mana whenua rights in and power-sharing in natural resource management as a requirement for success. Whanaungatanga also identified relationships and collaboration as a vital component. Inductively coupled plasma mass spectrometry (ICP-MS) and laser ablation ICP-MS (LA-ICP-MS) were used to analyse a 22-elemental suite of feather ōi, tītī, and toanui feathers. These were compared against species, sex, age, blood heterophil-lymphocyte (H:L) ratios, feather deposition patterns, and life stage. Compared with tītī and toanui, ōi had the highest levels of Hg whilst toanui recorded the lowest concentrations of Mn and Cu of the three species. As these species forage and migrate to different marine areas, this may reflect marine elemental compositions. In adult ōi, Hg and Se were positively correlated with age. Whereas ōi chicks had the highest Hg feather concentrations compared to fledged chicks and adults. This may have implications for the consumption safety of ōi chicks. Variations in feather metal deposition in mid-to-upper sections of the feather rachis. Thus, clipping samples from these sections is sufficient for sampling which is far less invasive than removing an entire feather. No differences were found between ōi feather elemental composition and H:L ratios and sex. These novel findings inform both conservation efforts and customary harvest practices. Genuine cross-cultural collaboration is imperative to successfully address the health of these birds, marine health, and the communities consuming these birds.