The world is becoming increasingly connected as human populations grow and international commerce expands. The movement of marine vessels create a complex global maritime network that is now the most significant pathway for the introduction and spread of non-indigenous marine species (NIMS) to coastal ecosystems around the world. Understanding the connectivity patterns associated with these networks is crucial to inform biosecurity management. Focusing on the New Zealand seascape we performed a suite of network analyses to quantify the potential risk of NIMS introductions and spread via commercial and recreational vessel pathways. Networks were constructed using automated identification systems (AIS), along with recreational boater surveys, and further coupled with life history characteristics of the non-indigenous species of green alga Caulerpa (C. brachypus and C. parvifolia) which poses a serious ecological risk to the New Zealand seascape. Results were used to inform local manager of potential extent of spread and high-risk sites throughout New Zealand in order to limit further spread. This network-based marine biosecurity framework can be adopted in any jurisdiction with access to vessel movement information and used to efficiently identify priority sites for NIMS surveillance and pathway management.