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From fisher to fish passage innovator

Gerard Manshanden knows a lot about fish behaviour, applying his knowledge to provide safe fish passage at pump stations, worldwide – and soon, in Southland.

Gerard Manshanden, co-founder of Fishflow Innovations, supplier of Southland's new fish-friendly pumps

Gerard lives on the shores of Lake Ijsselmeer, a closed-off inland bay in the central Netherlands covering 110,000 ha. Earlier this year, he travelled to New Zealand, visiting the Stead Street pump station site next to the Oreti New River Estuary (4,100 ha) in Invercargill, and the Mangawhero pump station in the Waikato.

Gerard is the co-founder and CEO of Fishflow Innovations, a company leading internationally in the design and build of fish-friendly pumps and fish protection solutions. Two of Gerard's pumps are being installed in the new Stead Street pump station, replacing the old pumps, which are more than 70 years old and, unlike the new pumps, do not provide safe passage for our native fish.

The story of how Gerard went from commercial fisher to innovator in the Netherlands will be relatable to many in Murihiku Southland. Both regions have an extensive coastline, large lakes, and expansive low-lying land areas susceptible to inundation from flooding, storm surge, and rising sea levels. Fishing and food gathering provide significant cultural, social and economic benefits to the communities and regions.

Gerard was the son of a commercial fisher, "I wanted to be a doctor, but after my father died when I was 16, I had to make money to live. So, I took over the company and became a fisherman instead." "I fished eels, but I also fished bream for a lot of the year, and the fishery was good. So, I know a lot about fish and their behaviour.”

"In the Netherlands, we were always taught that fish were not very smart. But they are much smarter than we think. Bream swim in a school. “When I started to fish Lake Ijsselmeer, I noticed that we caught fish that were 75-80 years old. These old fish must be very smart; otherwise, they would have been caught as much younger fish."

He explains that bream 'school for life', remaining in the same social group, and that their social behaviour is complex. As a diver, he observed some of the subtle ways bream communicate through touch when schooling.

Gerard made other valuable discoveries of fish behaviour when undertaking nonlethal monitoring studies of bream to help better manage the fishery. "When the population size was smaller, you might think the fish would start growing faster because there was more space and food. But they just got skinnier. They didn't do well in smaller groups".

"I stopped commercial fishing in the early 2000s. In Holland (now the Netherlands) and the rest of Europe, the water quality had become so bad, particularly the organic pollution, and the fish stocks collapsed."

One of the new fish-friendly pumps in transit to an Invercargill storage facility.

He then applied his knowledge to rebuilding the fisheries, focusing on fish passage and fish protection around pumpstations.

While water boards in the Netherlands used ‘Archimedes’ screw pumps, they were very inefficient to run and required a lot of maintenance and, therefore, ongoing costs. "Eighteen years ago, the water board where I lived gave me a screw pump to make the channel next to where I lived fish-friendly. When I started it up, the first thing I noticed was that it was very inefficient. So, I began to make improvements. I made a pipe around it. I changed the shape of the blades and made other refinements. Today our pumps are 100% efficient and economical to maintain and run over their lifetime, which exceeds 78 years."

After his initial tinkering with the pump next to his home, Gerard partnered with Marcel Klinge, a fish biologist at Witteveen+Bos Consulting Engineers. Marcel was looking for a solution for a fish passage to safely guide fish around the potentially lethal pumps of pumping stations. Their collaboration led to FishFlow Innovations.

The fish-friendly pumps designed and built by FishFlo Innovations offer many benefits over the conventional axial flow pumps widely used throughout New Zealand. Each pump is basically a screw fixed inside a cylinder. As the cylinder turns, the screw lifts water from the drain and discharges the water over the stop bank through the outlet pipe. Water, fish and vegetation spiral through the pump unimpeded. They are very light, so don’t require a lot of power to operate and they are very simple, requiring much less maintenance. Another massive win is that they don’t require a weed screen that needs regular clearing.

During Gerard's 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, 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."

Stead St Pump Station upgrade

Environment Southland is replacing the Stead Street pump station with a new facility housing two new fish-friendly pumps. The pumps will operate in tandem, are 16 metres long and weigh 22.5 tonnes each.

The pump station is a Resilient River Communities project, which is a joint initiative between Kānoa – the Regional Economic Development & Investment Unit, regional councils, and local authorities focused on developing and upgrading vital river management and flood protection schemes in Aotearoa New Zealand.

To find out more about our climate resilience projects, go to our website www.es.govt.nz.

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