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Thousands of nationally threatened native freshwater fish, at-risk lizards and eels have been relocated to allow for restoration work at a Christchurch stream.
The enhancement work at Halswell’s Greens Stream next to to Riverstone Dr involved restoring about 500m of the stream’s banks, installing walking paths and footbridges, and creating habitat for native wildlife.
Freshwater and terrestrial fauna management and relocation was required as the work had potential to disturb, harm, or cause mortality to fish and lizards.
Ecologist Dr Tanya Blakely said 2212 individual fish from five different species were captured and moved to other suitable locations in the stream before the work began.
“Īnanga, which is nationally vulnerable, was the most abundant species, with a total of 2068 individuals captured and relocated. There were also 72 shortfin eels and one longfin eel, plus four juvenile shortfin or longfin eels, 47 common bullies, and 20 upland bullies captured and relocated.”
It was was a surprise to see such high numbers, she said.
“Often people think that freshwater fauna management in-stream may be limited in streams that are regularly dry or have very low flows.
"However, as ecologists we were mindful that Greens Stream is well-connected to Huritini/Halswell River and that even very small waterways can provide important habitat for freshwater fauna. It was neat to find so many īnanga.”
The land bordering the stream and surrounding area are also home to southern grass skinks, which have an “at risk-declining” conservation ranking.
The sleek brown lizards are found in Canterbury and Otago and are often seen out during the day as they bask in sunlit areas.
Traps were set across the project footprint, and 65 lizards were caught by city council herpetologists and then released at a nearby reserve with a suitable habitat.
City council head of three waters Gavin Hutchison said Christchurch and Banks Peninsula have a large network of waterways, including about 2605 kilometres of river tributaries and other smaller streams.
“This work highlights the importance of small tributaries as important habitats for freshwater fish and other fauna, as well as the need for careful fauna management by experts,” he said.
This was the first of two work stages on Greens Stream, being carried out in parallel with the construction of stormwater basins for a nearby housing development. Stage two is planned to start in February next year to avoid the bird nesting period.
As well as improving the waterway and local habitat, the aim of stage one was to increase recreational use of the area by installing two footbridges and removing unused culvert crossings.
The corridor along the stream will be enhanced with appropriate plants and refuges to encourage neighbouring lizards to move back into once the project is completed.
-Allied Media