The Mediterranean fanworm has become well established in many parts of the Waitemata Harbour and Hauraki Gulf. It is a pest and can form dense colonies that exclude the settlement of other species, it's a filter feeder that can compete with our native filter feeders for both food and space which can impact the mauri of the moana. In high densities, Mediterranean fanworm is likely to also impact commercially on important kaimoana species including mussels (kuku / kūtai), oysters (tio), and scallops (tipa / tupa).
A great guide for identifying the Mediterranean fanworm, .vs. native fanworms can be found at: https://www.marinebiosecurity.org.nz/assets/Uploads/Sabella-pest-ID-Copy.pdf
Initially MPI tried to eliminate this pest, but in 2010 a decision was made that it was not longer feasible to eradicate this pest, as such MPI are only looking for reports in locations apart from Lyttelton, the wider Waitemata and Whangarei harbours. For more information see: https://www.mpi.govt.nz/biosecurity/marine-pest-disease-management/marine-pest-management-system/ Regional councils take responsibility once a pest has been established.
From the ourauckland website: " If you see evidence of fanworm, please notify Auckland Council’s biosecurity team firstname.lastname@example.org"
The Auckland council plan regarding this pest (and others) can be found here: https://www.aucklandcouncil.govt.nz/plans-projects-policies-reports-bylaws/our-plans-strategies/topic-based-plans-strategies/environmental-plans-strategies/docsregionalpestmanagementstrategy/rpmp-section-7.7-regional-marine-programmes.pdf
By all appearances the plan is to make sure people don't spread the pest further, by asking people to keep their boats anti-fouled and maintain moorings, docks, etc.
If you would like to learn more see: https://www.nrc.govt.nz/media/a2rniyui/cawthronsabellabackgroundreport.pdf