How IMO member states want a future biofouling convention to look
With MEPC 83’s decision to pursue IMO biofouling regulation in the form of a legally binding framework, the question at IMO is no longer whether hull fouling will be regulated, but how and through what kind of instrument. PPR 13 will be the first real test of that ambition. PPR 13 will be the first real test of that ambition.
Three submissions to PPR 13 – from Japan and Norway jointly, from Norway alone, and from a group led by the Republic of Korea with the United Kingdom, the World Coatings Council and BEMA – give us the clearest view so far of what might be coming. Read together, they sketch out both the emerging areas of convergence and the fault lines that still need to be resolved.
The first point of discussion: where do these rules “live”?
Before anyone argues over specific inspection intervals or cleaning standards, there is a prior legal question: where should biofouling rules sit in the IMO architecture?
IMO member countries Japan and Norway have submitted their recommendations. Their paper walks through the main options on the table:
- amending the Ballast Water Management (BWM) Convention
- amending the Anti-Fouling Systems (AFS) Convention
- creating a new annex under MARPOL
- or using MARPOL Annex VI, supported by a dedicated “Biofouling Code”.
They point out that the BWM Convention is, on the face of it, the closest conceptual fit. It already deals with the transfer of harmful aquatic organisms, and uses tools – management plans, record books, certification – that would translate well into a biofouling context. But extending BWM to cover hull fouling would not be a simple addition. It would mean substantial changes to the articles, the existing annex and even the title of the convention, plus a more complex structure to allow some parties to sign up to ballast water rules, biofouling rules, or both.
The AFS Convention also looks like a candidate at first glance. Its preamble acknowledges that anti-fouling systems are important both for commerce and for preventing the spread of harmful organisms. However, AFS is fundamentally about the control of hazardous substances in coatings. Turning it into a full biofouling management instrument – with obligations on inspection, cleaning and risk control – would represent a major shift in scope and could blur its original focus.
That brings the discussion to MARPOL. Japan and Norway note that none of the existing MARPOL annexes is directly about invasive aquatic species, but Annex VI already connects hull condition to energy efficiency through the Ship Energy Efficiency Management Plan (SEEMP). The SEEMP guidelines recommend regular hull inspection and cleaning, including in-water options. In their view, that opens the door to an approach where:
- Annex VI would be amended to add a broad requirement for maintaining a “clean hull” as part of efficient ship operation; and
- the technical detail would sit in a Biofouling Code, referenced by Annex VI in much the same way as existing codes are tied to SOLAS.
The attraction of this route is pragmatic. Annex VI amendments use tacit acceptance, meaning they can enter into force relatively quickly and will automatically cover the very large majority of the global fleet.
Crucially, Japan and Norway do not insist on one solution at this stage. Instead, they lay out the trade-offs and flag Annex VI and a code as a particularly efficient candidate, without closing the door on other paths.
Korea, the UK, WCC and BEMA have similar goals, but come to a different conclusion
The joint paper from the Republic of Korea, the United Kingdom, the World Coatings Council and BEMA approaches the same question with a broader comparative lens. It reviews MARPOL, the Hong Kong Convention, AFS and BWM against the objectives of the 2023 Biofouling Guidelines.
MARPOL and the Hong Kong Convention are seen as poor fits because their core focus is on ship-generated pollutants and safe recycling respectively, not biological translocation. AFS, while thematically close to hull condition, is judged too narrowly targeted at harmful substances in coatings to carry the wider suite of biofouling measures without diluting its original intent.
That leaves the BWM Convention as the “least bad” fit if the Organization insists on using an existing instrument. Conceptually, BWM’s aim of preventing the spread of invasive aquatic species aligns with the biofouling agenda. But the co-sponsors then spend much of their paper explaining why, in practice, that alignment doesn’t go far enough.
They underline that the management regimes for ballast water and biofouling are fundamentally different. Ballast water management deals with a contained volume of water that can be sampled, treated and monitored. Biofouling, by contrast, is about the condition of exterior surfaces and niche areas exposed continuously to the marine environment, with complex decisions about when and how to clean.
They also highlight scope. Effective biofouling control, in their view, must regulate not just ships but also in-water cleaning systems, service providers and the reception of captured material in ports. The BWM Convention is not built for this wider ecosystem.
On top of that sits a practical concern: BWM is already in the middle of a comprehensive review, based on experience-building. Folding biofouling into that process could add years of delay and a significant administrative burden, without enough added value to justify it.
Their conclusion is therefore much more definitive than Japan and Norway’s. While they acknowledge that BWM could technically be amended to include biofouling, they argue that the differences in science, practice and stakeholders are strong enough to warrant a standalone legal instrument dedicated to biofouling management. In their view, the benefits of a unified ballast-plus-biofouling regime do not outweigh the complexity and risk of confusion.
Norway’s second paper draws up a first sketch of the future rulebook
While those two papers focus mainly on the legal form and where the rules would sit within the IMO framework, Norway’s second submission takes a different tack. It asks: regardless of where this ends up sitting, what should a legally binding framework for biofouling actually contain?
The proposal is a fairly comprehensive sketch of a future instrument, built explicitly on the 2023 Biofouling Guidelines and the IMO’s goal-based standards methodology.
At the top level, Norway envisages a framework with a clear overarching goal – minimising the transfer of invasive aquatic species via ships’ biofouling – supported by functional requirements, detailed regulations and appendices.
The heart of the proposal lies in operational requirements for ships. Norway suggests that ships covered by the framework should be required to keep a Biofouling Management Plan and a Biofouling Record Book, and to operate an inspection regime designed to keep fouling at or below a defined rating. They explicitly reference the rating logic in the 2023 Guidelines: rating 1 as an acceptable upper limit for normal operation, and rating 2 as the point where more frequent inspection and cleaning are triggered.
From there, the paper branches into three areas where future regulation could have real bite.
First, in-water cleaning. Norway argues that cleaning should be carried out “with capture” when fouling is above the agreed threshold, that cleaned surfaces should be brought back to a low rating, and that cleaning must not visibly damage coatings. They propose functional requirements for in-water cleaning systems, type-approval by administrations and explicit obligations on ports to provide suitable reception facilities for captured material. It is an attempt to move in-water cleaning from a patchwork of local rules into a globally coherent regime.
Second, dedicated “biosafety areas” and contingency measures. Norway suggests that the framework could allow for specially protected zones where more stringent inspection and cleaning expectations apply, and where temporary measures can be activated under special conditions. That could give coastal and port States a tool to respond quickly to emerging risks without rewriting the entire convention.
Third, the interface with anti-fouling and MGPS systems. The paper stresses that cleaning methods have to be compatible with coatings and other anti-fouling measures, and that the combination of technologies should keep fouling within the agreed limits without creating new pollution problems, such as excessive release of biocides or microplastics. It hints at a future where coating specifications, MGPS design and cleaning will all be looked at together through a regulatory lens.
Is there consensus yet?
On the core policy direction, the three papers line up more than they diverge.
All assume that the 2023 Biofouling Guidelines will be the foundation, and that the job now is to convert key elements – plans and record books, fouling rating thresholds, performance-based expectations for cleaning and coatings – into mandatory requirements. All support a goal-based, tiered structure that can evolve with technology. And all – explicitly or implicitly – accept that in-water cleaning and service providers will have to come under clearer international oversight.
Where there is no consensus yet is on the legal form. Korea, the UK, WCC and BEMA come out strongly in favour of a standalone instrument. Japan and Norway carefully map the options and highlight the efficiency advantages of an Annex VI plus Biofouling Code approach, but stop short of a recommendation.
What should the industry read into this?
For owners, operators, ports, coating suppliers and cleaning companies, it is still too early to predict the exact timetable or final shape of a biofouling convention.
But it is not too early to see the outlines of future compliance:
- Biofouling management will move from “best practice” to “obligation”, anchored in documented plans and record-keeping.
- Authorities will have clearer expectations for how clean a hull should be kept, how often it is inspected, and how cleaning is carried out.
- In-water cleaning with capture, and the infrastructure that supports it, is likely to be a central pillar.
For now, the safest assumption is that a ship already operating in line with the 2023 Biofouling Guidelines – with a robust management plan, systematic inspections, documented cleaning and a thoughtful approach to in-water operations – will be closer to future compliance than one that treats fouling as an ad-hoc maintenance issue.
FAQ
Biofouling is the build-up of marine organisms – from slimy biofilm to barnacles, mussels and seaweed – on a ship’s hull and underwater components. It increases drag, can raise fuel consumption and emissions, and can also help spread non-indigenous species between regions.
The International Maritime Organization (IMO) sees biofouling as a dual risk: it contributes to the transfer of invasive aquatic species and it undermines energy efficiency by increasing hull resistance. IMO biofouling regulation aims to address both environmental protection and climate objectives by requiring more systematic management of hull condition.
MEPC is the IMO’s Marine Environment Protection Committee. It is the main decision-making body on environmental issues, including air emissions, ballast water, anti-fouling systems and now biofouling. MEPC decides the overall direction (for example, to pursue a legally binding biofouling framework) and approves or adopts conventions, amendments and guidelines.
PPR is the IMO Sub-Committee on Pollution Prevention and Response. It works under MEPC and handles the technical development of regulations and guidelines related to pollution from ships. For biofouling, PPR has been tasked with developing the detailed building blocks of a possible legally binding framework, which are then reported back to MEPC.
The BWM Convention is an IMO treaty that aims to prevent the spread of harmful aquatic organisms through ships’ ballast water. It requires ships to manage and treat ballast water according to agreed standards, keep a Ballast Water Management Plan and Ballast Water Record Book, and hold relevant certification.
The AFS Convention regulates the use of harmful substances in anti-fouling systems on ships, such as certain biocidal paints. It does not currently set out a full biofouling management regime; instead, it focuses on banning or controlling specific coatings that pose risks to marine life.
MARPOL Annex VI is the part of the MARPOL Convention dealing with air pollution and greenhouse gas emissions from ships. It already links hull and propeller performance to energy efficiency through instruments like the SEEMP. One option discussed at IMO is to add biofouling-related requirements to Annex VI and to support these with a separate “Biofouling Code” referenced from the annex.
A standalone biofouling convention would be a completely new IMO treaty dedicated only to biofouling management. It would have its own scope, definitions, obligations and enforcement provisions, rather than being an amendment to an existing convention such as BWM, AFS or MARPOL.
At the moment, most IMO instruments on biofouling are in the form of non-mandatory guidelines, and local or regional rules fill some gaps (for example, conditions on in-water cleaning or port entry). A future legally binding framework would move core elements of those guidelines into mandatory global requirements.
