Whitebait fritters are under threat from polluted and vanishing streams
Friday, 3 March 2017
The iconic Kiwi whitebait fritter, could be under threat due to a flow-on effect from worsening urban stream pollution and depletion.
Whitebait is the generic term for kokopu, an endemic fish that lives in New Zealand streams.
Auckland is home to five different species of kokopu, and all but banded kokopu are rare or endangered.
Northcote College science teacher Kit Hustler has been studying the kokopu in the North Shore's Le Roys Bush with groups of his students since 2009.
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Like kiwi, tuatara and fantails, kokopu are native animals; yet, they are the only endemic species to not need a permit to study them, Hustler says.
Kokopu have several unique features: they can launch themselves out of the water for food, juveniles can clamber up waterfalls, and eggs develop out of the fresh water on the banks.
Eggs wash into the sea to hatch, then the juveniles find their way back into streams via a chemical 'signal' released by the adults, which basically says 'there's good habitat here to live in', he says.
It's the babies in the sea that are caught and made into fritters.
'No streams, no adults, no babies, no fritters. It's very simple,' he says
Like real Kiwi kids, kokopu are caught by using marmite bait in minnow fish traps.
After being caught, Hustler records and photographs the individuals, before returning them to the stream.
Surburban streams have been 'hammered' by a number of events,' Hustler said.
Sewerage overflows, sediment from development, building of walkways have contributed to a significant decline in the population.
'I used to catch, roughly, 20 baby fish a year, now its about three,' Hustler says.
Auckland Council's senior regional biodiversity advisor Matthew Bloxham says he also struggles to make people aware of the plight of the kokopu.
'Streams in Auckland vary from awful to glorified gutters,' Bloxham said.
However, Bloxham says that their future will not be as bleak and a better understanding will stop streams from turning into 'concrete swills'.
'We work with engineers to protect streams from development, as well advise Auckland Council and members of the public on how to foster resilient native communities.'
Planting around streams by the public is a powerful way to improve stream health by keeping the streams cool, Bloxham says.
'We can claw back the freshwater ecosystems, by ripping up the concrete, rehabilitating the streams and bartering against stormwater inflow. Back to their original state, as best as possible,' he says.