Applications close for the Wai Māori Scholarship at midday on Monday 22nd September, so we thought we’d share a bit about Phoenix Hale.
Phoenix is undertaking a Masters (Research) in Ecology and Biodiversity at the University of Waikato, focussing on gambusia – a species of pest fish.
Below is an introduction and a quick explanation of the mahi that Phoenix been undertaking.
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Tēnā rā tātau katoa
He uri tēnei o Ngāti Porou ki Hauraki
Nō Harataunga awau, kei Whakatū e noho ana
Ko Phoenix Hale tōhou ingoa
I am currently studying towards a Master of Science in Ecology and Biodiversity at the University of Waikato, focussing on a species of pest fish, known as gambusia.
Gambusia was introduced to Aotearoa under the false assumption it would help control mosquito populations. Unfortunately, this species is now quite widespread throughout parts of te Ika a Māui and is known to outcompete with native fish for food and even eat their eggs.
The core question of this study being how connected individual populations are within a catchment or wider geographical area, focussing on Nelson-Tasman, the only known gambusia populations in te Waipounamu.
This question arose from uncertainties as to the role of heavy rainfall events in spreading gambusia between different creeks that flow into an estuary, and even between large, isolated estuaries. If it can be proven that these populations do not connect or spread during these events, there may be a chance to remove this species from important riverscapes.
Two methodologies have been chosen for this. First, netting surveys were undertaken throughout the year within all streams known to contain gambusia in the Waimea Inlet, where variables like salinity, rainfall, and temperature were captured to determine whether the distribution pattern could be explained by variations in habitat. Second, environmental DNA and tissue samples were taken from 3 catchments in Nelson-Tasman, and a further 5 in te Ika a Māui known to contain gambusia, including the original release site in the Auckland Domain. The genetic information of these samples is currently being analysed to determine whether the genetic variation between sites is enough to suggest these populations do not mix with each other.
The netting surveys were undertaken during a dry year with limited habitat variation between sampling events. The only significant variable that could explain gambusia absence was tide height. Since sampling had finished, Nelson experienced various heavy rainfall events and populations had significantly less gambusia post heavy rainfall than during the study. This suggests that gambusia are pushed out to the estuary during these events, but we will need to wait for the results from the genetics study to see whether it can be confirmed gambusia then spread to other streams or even catchments from there.
