Fish-friendly pump marks milestone in fish passage journey

Tuna (eels) were sighted going through the enclosed Archimedes screw pump at the Mangawhero pump station near Aka Aka, north Waikato, while Waikato Regional Council tested the new pump in operation.

During the successful test run, several tuna went through the pump and pump station outlet, making it to the other side safe and sound.

Pathways to the Sea Project Manager Michelle White says the instalment of the pump marks a massive milestone towards managing fish passage in New Zealand waterways as required by the National Policy Statement for Freshwater 2020.

“The council acknowledges the need for more sustainable use and management of our flood protection scheme assets, and this pump is the start of our mission to provide native fish with safe passage to the sea for spawning,” says Mrs White.

She says the council will be testing the enclosed Archimedes to see how successfully it passes New Zealand native fish species as part of its research into minimising fish mortality through pump stations.

The pump has been sourced from the Netherlands and is the first of its kind in New Zealand. In Europe, enclosed Archimedes screw pumps have proven to be 100 per cent fish friendly.

“We’re looking to see how this kind of pump works with our native eels and if we get the same results,” says Mrs White.

“We’ll be looking at whether tuna avoid the pump, what size tuna are passing through and assessing to see if there is any injury or mortality as a result of tuna passing through.”

The monitoring will take place during the migration season in 2023.

Integrated Catchment Management chair (North) Stu Husband says the pump has benefits other than safe fish passage.

“It operates to support drainage in the catchment, and to transfer water during high rainfall events,” says Cr Husband.

“It rotates very slowly and delivers high efficiency so is cheaper to run, and it’s a simple design that won’t require much maintenance.”

A second site where an enclosed Archimedes screw pump will be installed is Churchill East pump station, near Te Kauwhata.

Waikato Regional Council received $4.48 million from funds administered by the government’s regional economic development Unit, Kanoa – RDU, to support the upgrade of up to five pump stations in the Waikato to enable safe fish passage. Other sites are still being assessed for suitability.

A blessing will be held at the Mangawhero pump station in the coming weeks.