Marine Pathways Project - NNS introduction pathway assessment

Why investigate NNS pathways of introduction and their intensity?

There are a number of pathways by which marine NNS can be introduced into and spread within marine waters. Key pathways include shipping, recreational boating, aquaculture stock movements and natural dispersal. Prevention of introduction and early mitigation following introduction are recognised as the most effective approaches to reducing the potential impacts of NNS. This is especially true in a marine environment where control and eradication may be very difficult or impossible.

Assessment of introduction pathway activity intensity was the focus of recent work by Cefas. By assessing the intensity of introduction pathway activity it is possible to identify coastal areas where NNS may be more likely to be introduced.
The coastline of the UK split into 50k grid squares showing the relative intensity of a pathway activity

Assessment of the intensity of introduction pathway activity

In order to determine where introduction pathways activity is likely to be high data corresponding to each pathway was sought. For the shipping pathways we acquired data corresponding to shipping traffic into and within marine waters around Great Britain (GB) and Ireland, for the recreational boating pathway we used data which provides an indication of the likely recreational cruising routes into and within marine waters around GB and Ireland, for the aquaculture pathway we sought information regarding the import of live shellfish into GB and Ireland. Finally, to gain insight into the likelihood of NNS introduction via natural dispersal we considered prevailing current around GB and Ireland and the proximity to other landmasses.

We split the coastline of GB and Ireland into 50k grid squares and using the data sought, scored each grid based on the relative intensity of each pathway activity. By grading each grid according to the score we created heatmaps which can be used to easily visualise where introduction pathway activity is high compared to others areas and where it is lower compared to other areas.

Marine non-indigenous species monitoring and risk management (external link) (Cefas 2014)

Why is it important to consider introduction pathway activity?

Introduction pathway activity will facilitate the management of NNS for example, by highlighting areas where the likelihood of introduction of NNS may be increased and therefore where monitoring should be focused. Introduction pathways assessment will ultimately aid the prevention of NNS introduction and early detection of NNS following introduction.

Thin strip of image show tree trunk and bark