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Freshwater ecological survey identifies several species


Freshwater fish are surviving in Alexandra Stream, according to an ecological survey undertaken as part of the Te Hōnonga a Iwi Restoring Rosedale Park project.


Whitebait Connection Programme Coordinator Briar Broad, together with the water quality leaders and students from Kristin School, recently undertook the analysis on the area of stream running through Rosedale Park.


“When combined with the data collected through ongoing water quality monitoring, this gives a deeper understanding of the state of the local freshwater environment and a baseline to monitor change over time,” Briar says.


The freshwater ecological survey confirmed the presence of banded kokopu (a whitebait species), common bully (freshwater fish) and sizable short and long fin eels.



“Given the highly developed nature of the catchment that feeds into Alexandra Stream, with large industrial areas, impervious surfaces and high stormwater flows, it was a great sign to see these freshwater fish surviving here.


“These species are commonly found in our streams as banded kokopu and both our eel species are fairly resilient to the environmental pressures, such as high flows and low water clarity, that occur in urban environments.”


Briar was pleased to find juvenile banded kokopu as it demonstrates that repopulation is taking place and there are no barriers to their movement upstream.


“Ideally, we would like to identify the presence of a range of ages including mature adults, however the absence of adults in our survey does not mean they are not in the stream. It just means they are not in that particular reach of the stream or were not active that night.


It would be good to do surveys further upstream to identify the presence or absence of adult banded kokopu in the upper catchment, Briar says.


“We know that inanga (the smallest whitebait species) are present further downstream, which is to be expected as they tend not to migrate as far up the waterway.”


The survey also found gambusia (mosquito fish) in the stream.




“Gambusia can survive in water temperatures that are too warm for our native freshwater fish species, and they are very tolerant of pollution, meaning that they thrive in our degraded urban streams. They produce live young all year round, so reproduce at a much faster rate than native species, outnumbering them quickly. They are primarily a threat to our native species through competition for resources (food and habitat) in streams that are typically already of low quality.


The Whitebait Connection, part of the Mountains to Sea Conservation Trust, is a non-profit action-based community conservation education programme offering concrete and specific ways in which all New Zealanders can come to understand and become involved in the future health of local streams, rivers, lakes and wetlands.


“We have a range of funding sources. My support for the Rosedale Restoration is part of an Inanga Spawning Project funded by the Upper Harbour Local Board, with the support of Healthy Waters - Auckland Council.”


This project aims to identify spawning areas across the Upper Harbour area and engage the local community to connect with their local waterways. New Zealand whitebait species utilise different parts of the stream at different stages of life, from the upper catchment all the way down to where the freshwater meets saltwater, and out into the sea. This means it’s crucial to protect the entire length of stream environments, from the mountains to the sea.


“Working with Te Hōnonga a Iwi provides a wonderful opportunity to work with passionate and engaged members of the community, which will lead to wider knowledge about the importance of freshwater environments, the current threats they are experiencing, and ultimately improved health of the waterways across the catchment as a whole,” says Briar.


Projects such as the Rosedale Park restoration create positive change in how people view their relationship with the local environment, including their local awa.


“This will hopefully create behaviour change in how people use the land and dispose of waste (such as rubbish, chemicals, and sediment), resulting in less pollution entering the stream through the stormwater system. This is one of the biggest threats in this catchment as pollution events can flow through the aquatic environment quickly, resulting in the death of multiple species in its path.”


The planting that is taking place will create a better relationship between the water and the land, providing more shade, leaf litter, and bank stabilization, as well as habitat for the invertebrates that live their life both within the freshwater and the terrestrial environments, Briar says.


If you would like to find out more about the work Whitebait Connection does, head to whitebaitconnection.co.nz

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