From takahē arrival to fish mysteries, no two days are the same in conservation

Conservation is complex work that rarely comes with a neatly packaged ‘How-To’ guide. This month alone we celebrated the arrival of a new pair of takahē to Zealandia while also trying to unpack a ‘whodunnit’ of epic proportions beneath the surface of our waters.

An eagle-eyed Zealandia volunteer spotted a pied shag making light work of a rather large pinky coloured fish in Roto Kawau, the lower reservoir.

For those who know Zealandia’s story, you will recall we undertook the world’s largest eradication of an introduced fish (Eurasian perch) from Roto Kawau just two years ago. Since then, we have spent hours staring into the depths of the reservoir checking to make sure there are no redfin perch remaining.

One of our volunteer skippers valiantly managed to snap two pivotal—but rather blurry—photos of the shag with its catch.

At a glance the photos told us that the fish clearly wasn’t a perch. But what it was is less clear. On one hand, it could be a gold fish or koi carp (a noxious species). On the other hand, it could be a marine fish that the pied shag regurgitated or flew here.

When faced with such mysteries our first port of call is the great many experts in our community. Te Papa and DOC experts rapidly offered their opinions, and the fantastic people at Wilderlab offered to carry out eDNA analysis to see whether we could detect traces of any unwanted fish. (eDNA is the analysis of environmental DNA – samples of water are scanned for genetic markers of all sorts of species.)

So far even these experts are split – around half think it is a goldfish, the other half a marine species. The eDNA hasn’t shown any evidence of goldfish or koi carp at this stage either.

Now, we are back to the drawing board and will need ongoing detective work to make sure we have no noxious fish in the waterway.

This is conservation in action. No easy answers, and any wins are hard won. So, we’ll celebrate the arrival of takahē pair Waitaa and Bendigo this week and continue working to unravel this fish mystery. Zealandia is very pleased to be at the leading edge of finding solutions to our greatest challenges to help Aotearoa reverse the loss of biodiversity, working alongside our wonderful volunteers, community and supporters.

E kore tātau e mōhio ki te waitohu nui o te wai kia mimiti rawa te puna.
We never know the worth of water until the well runs dry.

Photo credit: Kāruhiruhi - Scott Langdale