The goal of the International Council for the Exploration of the Seas/ Intergovernmental Ocean-ographic Commission/ International Maritime Organization Working Group on Ballast and Other Ship Vectors (ICES/IOC/IMO WGBOSV) is to provide scientific support to the develop-ment of international measures aimed at reducing the risk of transporting non-native species via shipping activities. This report summarizes the key findings and outcomes in 2019–2021.

A notable product of the group’s work is a comprehensive review paper examining spatial and temporal trends in the transport of aquatic, non-native species over a 50-year period. On average, a new detection occurred every 8.4 days, highlighting the importance of this issue.

WGBOSV developed and submitted four papers to the IMO. These papers provided scientific underpinnings to the discussions at IMO on two of the group’s ToRs: ballast water management (specifically, the verification of compliance monitoring devices, CMDs) and biofouling manage-ment. The synthesis report on biofouling that was submitted to IMO also served as the underly-ing scientific evidence for the first ICES Viewpoint: “Biofouling on vessels – what is the risk, and what might be done about it?”. Further, four peer-reviewed papers offered insight into ballast water management by: proposing a verification protocol of CMDs, considering exceptions and exemptions to ballast water management, and evaluating the availability and suitability of sam-pling ports on ships. ICES science highlights were published to amplify the findings from two of these papers.

Regarding the term of reference on climate change, three peer-reviewed manuscripts that bene-fitted from discussions at meetings were published regarding the risk of invasions in the Arctic.

Finally, addressing the term of reference on the utility of molecular tools—an emerging approach for reliably identifying and quantifying non-native organisms—a manuscript was published. Here, the utility of using high throughput sequence metabarcoding in the context of invasion species was demonstrated. A workshop has been planned to harness the knowledge of interna-tional experts on this topic. The proposed future work will carry on these five priorities and clarify emerging, topical issues within them.