Invasive ‘undaria’ wiped out
AN invasive seaweed around Stewart Island appears to have been eradicated from a part of its southern coast, an Environment Southland survey said.
Environment Southland found no found no sign of invasive undaria in Broad Bay during a survey last month after it had been identified in the area in 2020.
Divers spent a week where they surveyed Broad Bay, Easy Har bour and a number of key anchorages on the southern coast.
The check on Easy Harbour found some regrowth of undaria, but at a much lower density than when it was discovered in 2022. The regrowth was removed.
Environment Southland biosecurity operations manager Ali Meade said all undaria was removed and no further expansion of the population was identified.
‘‘The reduced number of plants and density is a good sign that our work to eliminate the incursion is on track. Followup removal efforts will be required to ensure elimination from the site.’’
Divers also completed a followup inspection of the incursion discovered in Broad Bay in 2020.
At the time, undaria was removed from craypots.
‘‘This is a great result and shows what can happen with quick efforts to remove the invasive species. Further surveillance will be required to confirm complete elimination over the next few years but it looks promising.’’
The final aspect of the dive trip was to survey key anchorages around the southern coast of Rakiura and within Port Pegasus for undaria, carpet sea squirt and other marine pests.
‘‘No undaria was found at the sites inspected around the southern coast or in Port Pegasus. Some sea squirts were found in very low numbers but were not positively identified as the invasive species, carpet sea squirt.’’
Photographs of the ascidians would be sent away for identification, but they were most likely native, Mrs Meade said.