Otago Regional Council took advantage of crystal clear waters brought about by fine weather and equipped a team of divers this week to begin a survey to find populations of invasive Mediterranean fan worm.
Council biosecurity and environmental implementation team leader Robert Win said contractors, headed by a council scientist, were looking at the underside of boats and jetties to find out whether Otago had a significant population of Mediterranean fan worms, which have been in New Zealand for "a while".
Otago has two recent discoveries showing the pest may have made its way south.
He said they were following up with a preliminary survey to make sure there was not a larger infestation.
"This work, hopefully, will be continuing for the next five years, and we're working towards eliminating it.
"However, in saying that, we have boats coming down from all over the place all the time, so we're looking to increase our presence in the biosecurity space, especially around surveillance and monitoring for invasive species in the harbour," Mr Win said.
In the first week, the team of divers had collected two samples, and these had gone to a lab to test whether they were Mediterranean fan worms, or a similar-looking non-invasive species native to New Zealand waters.
He said fan worms native to New Zealand were significantly smaller, growing only to about 3cm or 4cm, whereas the foreign variety were much larger and could grow to about 10cm.
Mediterranean fan worms were usually found living on the underside of boats and tended to overtake the environment they were in.
"If we do find something, we'll probably have to move into a second stage of control, which means ramping up this programme and probably greater investment by the Otago Regional Council to respond to it.
"We would then be looking at support from the Ministry of Primary Industries.
"It’s looking pretty good that at this stage, but fingers crossed."
