Lagarosiphon lakeweed found in Frankton Marina

by Lauren Pattemore - Oct 20, 2023

Frankton Marina has undergone "urgent and proactive" weed control works earlier this month after dangerous lake weed Lagarosiphon was found in isolated patches in the pristine water of Lake Whakatipu. 

The weed forms thick, dense beds and can grow up to five metres tall, shading out native aquatic plants, impeding water flows and also impact recreational activities.

That's why a hard and fast approach has been used by the Toitū Te Whenua LINZ team, and the Lake Whakatipu Aquatic Weed Management Group who are carrying out the control programme. 

Biosecurity lead Tracey Burton says their efforts will help avoid the lagarosiphon "infestation" that has occurred in Lake Dunstan's waters.

Lagarosiphon can also “The Frankton Marina is a high-risk site and the Marina owners are now working with the weed management group to reduce the risk of weed fragments dispersing from here to the rest of the lake."

This identification of lagarosiphon and control programme comes after a team of LINZ divers has been undertaking surveillance in Lake Whakatipu, Ms Burton says. 

The Otago Regional Council environmental implementation manager Libby Caldwell says the weed can spread easily via stem fragments by currents, boats, fishing gear, aquariums and pond escapes.

She says those heading out on the water to check, clean and dry their gear as it plays a "major role" in stopping lagarosiphon's spread, especially important if users are moving between different waterways.

In mid-October, ORC council staff attended the World Jet Boat Marathon held in Otago and Canterbury rivers to educate attendees on the importance of 'Check, Clean, Dry' and how these steps protect Otago’s waterways from biosecurity threats including lagarosiphon.

The Queenstown Lakes District Council (QLDC) General Manager Community Services, Kenneth Bailey is encouraged with the progress made to control the weed, and is continuing to support the control programme carried out by Toitū Te Whenua LINZ and the Lake Whakatipu Aquatic Weed Management Group.

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