Didymo found in Fiordland

01:31, Jul 24 2013

The Department of Conservation is devastated after finding didymo in remote parts of Fiordland.

A water sample collected by the DOC and Fish & Game confirmed the presence of the invasive freshwater algae in Fiordland's Large Burn valley.

It is the first time that a river west of the divide - located on the Milford Sound-Te Anau highway - has provided a positive didymo sample and is a hugely disappointing result in the battle to keep Fiordland didymo-free.

Fish and Game field officer Bill Jarvie said the organisation was at a loss to how didymo got into the burn which drains into Caswell Sound.

Anglers in Fiordland were strictly required to obtain a "Clean Gear Certificate" before entering the area to fish, Mr Jarvie said.

However, hunters were not subject to the same strict requirements.


The Large Burn was infrequently visited by fishing and hunting parties, he said.

DOC freshwater ranger Lyndsay Murray said the discovery was ''gutting''.

''It's the first confirmed positive sample of a waterway west of the divide," Ms Murray said.

"The geographic barrier of the mountains that helped keep it out of remote Fiordland has been breached." 

DOC and Fish and Game were alerted to the suspicious algal bloom by a helicopter operator.

The operator heard a report from a client dropped into area who believed Large Burn was affected, Ms Murray said.

Western Fiordland remains one of the "last frontiers" of rivers to remain free of didymo in the South Island, despite it being so close to the Waiau River, where didymo was first discovered in 2004.

The incursion into the Large Burn valley is the first positive didymo sample in Fiordland since 2010 where it was discovered in the lower reaches of the Iris Burn River.

A review of the controls implemented for didymo control in Fiordland were taking place as a result of the Large Burn discover, Ms Murray said.

Up until now it was thought that these controls, including the clean gear certificate, were working well.

The Southland Times