It’s encouraging news that New Zealand’s two biggest harbours, the Manukau and Kaipara, were found to be free of new-to-New Zealand pest species, and the Mediterranean Fanworm, in large scale underwater surveys completed in 2019. The surveys highlight the importance of being vigilant whenever we move equipment and boats from the east coast to the west coast.
Mediterranean Fanworm is deeply damaging to our coastlines and has been on the radar of marine scientists since it was first discovered in the South Island over ten years ago. Thousands of individuals can be found in a single square metre and they feed on nutrients and space with native species. It is now well established in a number of east coast North Island harbours, with concerns it will be carried to otherwise pristine locations.
In the Manukau Harbour, the non-indigenous Asian paddle crab Charybdis japonica, nudibranch Okenia pellucida and hydroid Ectopleura crocea were officially detected for the first time.
The Asian Paddle crab is known as an aggressive species that is a strong swimmer and may outcompete native crab species for space and food. It spreads via fouling on vessels, or as larvae in ballast water, where it can live for up to a month.
In the Kaipara Harbour, the non-indigenous colonial tunicates Botrylloides giganteum, Diplosoma listerianum and Eudistoma elongatum, the Australian dog whelk Tritia burchardi and hydroid Ectopleura crocea were officially detected for the first time.
It is recommended that trailer boats, jetskis, canoes, dive gear and fishing gear are washed with freshwater after use and allowed to thoroughly air dry before moving to a new location.
Information and resources for boat owners and operators are available at www.marinepests.nz
About the surveys:
The surveys, which searched both harbours for target marine pests, were the result of a charter agreement between Auckland Council (utilising the Natural Environment Targeted Rate), Northland Regional Council and Biosecurity New Zealand. It is the first charter agreement of its kind between these agencies and enabled efficient management of this multi-agency project.
Baseline surveys for both harbours were carried out in 2006, and since this time over 90 new marine pest species have been discovered in New Zealand.
Following consultation with mana whenua and stakeholders, the surveys were carried out between April and May 2019 by NIWA, with local assistance from Council staff and student volunteers.
The surveys provided information about presence or absence of target (and non-target) marine pest species, which help to inform marine pest management programmes including the Inter-Regional Marine Pest Pathway Management Plan for the Top of the North Councils.
For the results and full reports from the surveys: