Top of the South Marine Biosecurity Partnership
Protecting the Top of the South from marine invaders


One of the goals of the Top of the South (TOS) Marine Biosecurity Partnership is to slow the spread of marine pests into or within the top of the South Island. Recreational boats from marina berths and moorings can easily accumulate marine pests and hull biofouling is main ‘pathway’ by which pests established in and around port areas are spread.

Since the summer of 2015/16, we have conducted regional in-water surveys of recreational boats in the TOS region to check for marine pests and assess levels of boat fouling, and to check for pests on adjacent structures like swing moorings an jetties. We also talk to boaters about the importance of keeping their hull clean, and collect basic data on their hull maintenance practices. These web pages provide a summary of the survey work and key findings.

Layout of web pages

You will see five tabs in the bar at the top of the page. These will take you to the detailed information from the surveys, in particular:

Methods: summary of survey methods used, target marine pests and Level of Fouling assessment.

Key findings: provides a summary of the key results from the latest summer survey, with a comparison to earlier years.

Explore data: enables visualisation of the survey results in the form of maps and graphs. In the top right navigation bar you can switch between views of the data for the entire TOS, or separately for each subregion (Tasman, Nelson, Marlborough). The sliding bar allows you to filter the data to time periods of interest. Hovering over map symbols and chart data shows additional information and clicking on their legend entries will show/hide layers. Static outputs and their data can be exported using the top left buttons on the maps (, ) and top right menu buttons on the charts ().

Data for the 2023/24 season was collected using the Marine Vessel Portal (MVP). Please click on this link to view the data.


For feedback on web page content and ideas for improvement, please email us at