Ernslaw is undertaking a major trans-location programme in its South Island forests waterways to protect rare and threatened species, using a relatively new technology…e-DNA

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e-DNA (Environmental DNA) is genetic material shed by organisms as they move in, through and around their environment.  

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e-DNA sampling kits quickly and effectively identify species in waterways, which may otherwise be missed during conventional sampling.  

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John Hollows, Aquaculture Manager at Ernslaw One, says as early adopters of this new technology it has enabled a much more accurate assessment of life in its forest’s streams and forms a major part of operational planning. “We have previously conducted fishing surveys with spot lighting, electric fishing and netting but it has not been foolproof. With the e-DNA kits it’s either there or it’s not – the fish can’t hide.

“The result is we’ve got confidence when planning our harvest operations that we’re not affecting fish or their spawning areas,” says John.

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Using e-DNA technology Ernslaw has identified more than 20 fish species in its South Island forests. Through water testing, brown trout were identified above a culvert where Pomahaka galaxiids were also present.  Ernslaw approached Otago Fish & Game for help to remove the trout.

“In the first run just before Christmas, we moved about 70 trout downstream below the culvert.  We will keep removing trout until e-DNA testing reveals there are no more above the culvert,” said John.

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The West Otago area has some of the most diverse galaxiid species in New Zealand.  

“Some turn into whitebait – the adults lay eggs under rocks with the larvae drifting out to sea before returning as whitebait, whilst others can spend their whole life in a small stretch of stream,” said John.

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Otago has15 non-migratory galaxiid species, of which 14 are threatened.  With careful management streams within Ernslaw’s forests can become galaxiid refuges.

“There are a whole lot of native species that can be found in a small distribution area so it’s important to know what we’ve got and where,” said Hollows.  “We are building a database of what is found where so we can continue to protect them as part of our environmental work.”

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