Two such pumps have been included in the new Stead Street Pump Station project next to the New River Estuary/Kōreti (4,100 ha) in Invercargill and at the Mangawhero Pump Station near Waiuku in the Waikato region.
These fish-friendly Archemedes screw pumps, which have come from the Netherlands, offer many benefits over conventional axial flow pumps that are widely used throughout New Zealand. They’re made up of a screw fixed inside a cylinder. As the cylinder turns, the screw lifts water from the drain and discharges the water over the stopbank through the outlet pipe. Water, fish and vegetation spiral through the pump unimpeded. The pumps are very light, so don’t require a lot of power to operate, and they’re very simple, requiring less maintenance.
These pumps now provide safe passage for a range of freshwater species including the New Zealand longfin eel/tuna.
The pumps are made by Fishflow Innovations. Fishflow Innovations CEO and founder Gerard Manshanden worked as a commercial fisherman in the Netherlands prior to establishing the company and had spent a lot of time observing fish behaviour.
"I fished eels and bream for most of my career, so I know a lot about these fish and their behaviour.”
Manshanden recently visited the Stead Street and Mangawhero sites. During his visit to the Waikato, he was able to see the first of his fish-friendly pumps supplied to New Zealand in action.
"The eels like it! We started it up, and the water below the pump was going down a bit, and perhaps the eels panicked … they were sitting in the long grass…and then in the middle of the day, they swam to the pump, and you saw them swimming out the top, and they would go back around and into it again which was good to see.”
While in the south, Manshanden caught up with some local fishers, including those that know a lot about our tuna, or eels, and who are passionate about restoring fish passage.