A rare galaxiid fish population in Central Otago is set to benefit hugely from a joint community, council and contractor collaboration which has installed a fish barrier weir to better protect their habitat in Thomsons Creek.

The barrier has been installed in Thomsons Creek in the Manuherekia catchment, to the southwest of Omakau township, which is a tributary to the Manuherekia River.

Dating back more than two years, the $150,000 Thomsons Catchment Project is co funded by the Ministry for the Environment, through a Jobs for Nature grant of $110,000 and an Otago Regional Council contribution of $40,000.

A celebration was held yesterday, 3 April, to mark the completion of the fish barrier. Attendees included members of the Manuherikia Catchment Group, ORC Councillors, Thomsons Catchment Project committee, Fish & Game and the engineers and builders involved.

Thomsons Catchment Project Manager, Nicola McGrouther, says the project grew from a galaxiid survey of the whole catchment in January 2021, in conjunction with the Department of Conservation, Fish and Game and ORC.

The Thomsons Catchment Project’s overall goal is to increase galaxiid numbers, through use of a fish barrier, wetland riparian planting and fencing, to be followed up by fish monitoring, she says.

“Design criteria included installing a robust 1m high weir across Thomson Creek, to stop fish access upstream, but also to allow floods to pass safely over the structure,” McGrouther says.

Thomson Creek was temporarily diverted around the weir site during construction, to allow for suitable foundation material to be installed.

"It wouldn't have been achieved without the fabulous work and support from Mount Aurum, Breens Civil and Central Excavating,” she says.

ORC Chair Gretchen Robertson, who attended the celebration, says “we’re thrilled to be able to get behind the Thomson's Creek project. This is about environmental gains and much needed positive community focus.”

“The fish barrier will protect native fish from predation from trout and perch. Central Otago Roundhead Galaxiids are special native fish with the same conservation status (nationally endangered) as the rare South Island Kaka”, says Cr Robertson.

“Thomson’s Creek is about local people chipping in whatever they can to bring a vision alive.”

“The ORC gets huge satisfaction from seeing the positivity, collegiality, and environmental gains projects like this generate. The buzz is contagious and we're seeing more community-driven environmental projects popping up,” Cr Robertson says.

“The work of the Thomson's Creek Committee, a group of mainly local Manuherikia farmers, undoubtedly inspires others to get involved in making a difference for their special places too”, she says.

ORC Councillors and attendees also got their hands dirty, planting natives donated by the Otago Central Rail Trail Trust for the project. A public Open Day is being planned.

Great example of collaboration

Anna Gillespie, Manuherikia Chair and Thomsons Catchment project executor opened the fish barrier with Chair Robertson.

“It was a really special day, with an incredible turn out from councillors, who were genuinely interested and positive about the project.”

“The fish barrier has been a collaborative process with the ORC and water users and it’s exciting to get the first project finished. This is the first of three major tranches of work, including the constructed wetland, and working with farmers”.

ORC’s Manager Environmental Implementation Libby Caldwell says the community driven project was a “really great example of collaboration across many stakeholders”.

“It’s really exciting to see this work happening to protect our galaxxid populations in Thomson’s creek.

This project’s important as all of Otago’s non-migratory galaxxid species are threatened with extinction,” Mrs Caldwell says.

To better understand what fish species were present, the fish survey identified the presence of the roundhead Galaxias, which is a non-migratory galaxxid, meaning they do not migrate from the waterway from where they hatched, but live in the same section of water for their whole lifecycle.

“The fish barrier will ensure that undesired species of fish, which prey on our native galaxxids are restricted in their access to these fish populations, enabling them to thrive,” Mrs Caldwell says.

When in full operation, electric-fishing will be undertaken to remove any trout of upstream of the gate, which will then be released downstream.

The fish barrier complements other parts of the Thomsons Creek Conservation Project, which includes fencing, planting and wetland enhancement, which together would contribute greatly to protecting galaxxids and reducing the chances of those taonga becoming extinct, she says.

Other ORC support for project

The stages completed to date of the Thomsons project have received financial support from the ORC fund which was established to provide consent processing and compliance funding support to projects. The fund is for projects which have an environmental benefit but require resource consent.

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