Government expected to publish its response to the consultation on the principles of marine net-gain

This summer the government is expected to publish its response to the consultation on the principles of marine net gain (“the consultation”), which ran from June to September 2022.

This article discusses the concept of marine net gain, provides a summary of the principles put forward in the consultation, and considers the next steps in the implementation of such a regime.

Background to marine net gain In 2018, the UK Government consulted on making biodiversity net gain mandatory for new development on land, and respondents suggested that net gain principles should be extended to marine developments. In its 2019 response, the UK government noted that more work would be needed to define an approach to net gain that was appropriate to the marine environment. The consultation took forward this work and considers how best to introduce a net gain approach to infrastructure and projects in the marine environment. The consultation opened on 7 June 2022 and ran until 13 September 2022.

The consultation sets out the Government’s aims and proposed core principles for its net gain policy for the marine environment and development within it. The consultation then sought views on whether to mandate net gain for marine developments, and, if so, the scope of marine net gain, and how marine net gain could be applied.

In March 2023, the government published a summary of the responses received and stated that it expects to publish its response to the consultation in summer 2023.

How is marine net gain different from biodiversity net gain? 

It is important to acknowledge that marine net gain will not merely be an extension of the land based ‘biodiversity net gain’ regime in the marine environment.

Under the Environment Act 2021, land developers across England will have to deliver a mandatory at least 10% “biodiversity net gain” (“BNG”) from most development which receives Town and Country Planning Act 1990 planning permission from November 2023. A similar requirement will come into force for Planning Act 2008 consents (regarding Nationally Significant Infrastructure Projects) likely from April 2025. The 10% BNG must be measured using Natural England’s BNG metric. Using the metric, the pre-development biodiversity value of onsite habitats within the redline site boundary will be determined. The biodiversity value attributable to the development must then equate to this value plus an additional 10% (or more if required by local planning policy). 

It is understood by Government that the extension of the land based BNG regime to the marine environment would not be appropriate for a number of reasons.

For example, the dynamic nature of the marine environment means that any biodiversity losses associated with a development, or the benefits from an offsetting or compensatory measure, may not always fall within the boundary of the development. In addition, any account of biodiversity in the marine environment (and its interaction with infrastructure) may also need to take account of highly mobile species, such as certain fish, marine mammals and seabirds. For example, the Atlantic puffin (Fratercula arctica) which nests in England in the summer months spends the winter at sea in the Atlantic, and the Eastern Atlantic bluefin tuna (Thunnus thynnus), which has recently returned to UK waters, is a highly migratory species. Marine net gain is therefore being developed from first principles to ensure that it is appropriate for the marine environment.

There are, however, similarities between the proposed marine net gain regime and the BNG regime: marine net gain will operate alongside existing planning policy and practice; marine net gain will first be achieved by applying the mitigation hierarchy; and any requirement to provide compensatory measures under relevant marine protected areas regulation will be unaffected by the introduction of marine net gain. In addition, Schedule 15 of the Environment Act 2021 gives powers for regulations to be made to apply the land based BNG regime, with or without modifications, to any Nationally Significant Infrastructure Projects to the extent that the development is carried out in the English marine region.

The consultation

The consultation is split into five sections, each of which is made up of several principles.

Defining marine net gain

The first section of the consultation defines marine net gain and considers the types of environmental feature that marine net gain will measure for the purposes of establishing the impacts of development and assessing the value of proposed interventions. Under this section of the consultation, views were sought on the following proposals:

  • Marine net gain will measure impacts on habitats and species. This approach reflects the unique dynamics of the marine environment. Unlike on land, habitats do not make good proxies for species in the marine environment due to high levels of species mobility.
  • Marine net gain should seek to expand on BNG to incorporate a wider environmental net gain approach, but only where these extra benefits are ultimately underpinned by biodiversity protection.
  • Marine net gain assessments will not include potentially positive incidental impacts whose benefits are subject to significant uncertainty.
  • Marine net gain will prioritise a contributions-style approach initially that would operate like a levy on marine development, and which would be a relatively quick and straightforward mechanism to introduce. In this scenario, net gain requirements would take the form of financial contributions which would be used to fund priority environmental enhancement or restoration projects. The consultation states that an alternative approach would be to use the biodiversity metric that has been produced by Natural England to enable measurements of biodiversity in terrestrial and intertidal habitats. The consultation recognises that further work will be needed to understand the technical issues with applying these approaches to the marine environment.

Scope of marine net gain

The second section of the consultation focused on the scope of marine net gain, where it will apply and what it will apply to.

Many marine developments ultimately land onshore and therefore also have terrestrial and intertidal elements. For example, the electrical cabling associated with an offshore windfarm will require components on land where those cables make landfall. The intention is that only one net gain regime will apply to each element of a development, and therefore there will be no doubling-up of net gain requirements. It is proposed that marine net gain will only apply to developments, or infrastructure forming part of development, below the Low Water Mark, and land-based biodiversity net gain will only apply to onshore and intertidal developments, down to the Low Water Mark.  It is also proposed that marine net gain should be a mandatory requirement for new development activities within the marine environment, subject to a limited number of exemptions.

Potential interventions

The third and fourth sections of the consultation sought views on what sort of interventions would be considered valid for the purposes of marine net gain.

The consultation proposed that marine net gain will incentivise both active interventions (for example, restoration measures such as seagrass planting, native oyster restoration and kelp forest restoration) and appropriate pressure reduction mechanisms (for example, removal of marine litter and reduction of ocean noise).

The consultation also proposed that marine net gain will incentivise the delivery of strategic interventions in addition to meaningful site-based interventions and sought views on how both could be achieved. The consultation recognised that site-based interventions may not always be appropriate, and that marine net gain could be a means of delivering defined priority interventions. Strategic interventions suggested by respondents include large scale restoration projects, removal of fishing pressures, reducing bycatch, new no-take zones and establishing new and improving management of existing marine protected areas.

Additionality in marine protected areas

The fifth part of the consultation discussed marine net gain and additionality in marine protected areas and sought views on whether marine net gain should allow for improvements to the designated and non-designated features of marine protected areas to qualify as net gain interventions.

What next? 

The principles of a marine net gain regime are at a very early stage and there remains a lot of work to do should marine net gain become part of development planning in the marine environment. We anticipate that there will be further consultations on specific aspects of the regime as the UK continues to seek opportunities for development in the marine environment.

What is gratifying, however, is that measures aimed at nature recovery on land are now being seriously discussed in the context of the marine environment. The marine environment around the British Isles is under a number of pressures, the effects of which are not fully understood. For example, in the next few years we will lose forever the final remnants of the only orca (Orcinus orca) population which is resident in our waters (known as the West Coast Community, whose members have been sighted around the coast of the whole UK). This population of orca are thought to be unable to reproduce, and indeed, no reports of a calf within the population have ever been made. As a result, the population will likely go extinct in a number of years. From the limited information known about this population, taken from visual sightings and a necropsy of one individual, it is thought that the population is dying due to a lack of prey caused by overfishing, disrupting noise pollution from shipping and offshore installations and the slowly poisoning effects of “forever chemicals” which have leaked into the sea over many decades, and continue to impact these animals even though they are now banned. A focus on marine net gain, along side other proposals by Government to expand the network of marine protected areas in our waters, may give marine species and habitats the opportunity they need to recover.

At Freeths, we have been watching closely as the framework begins to take shape and have been considering implications of such a regime for both developers and those working with and for the marine environment. We have been increasingly navigating other emerging natural capital regimes such as that for biodiversity net gain, and accordingly, we are uniquely placed to consider and discuss how such a regime could apply in the marine environment.

Helen Mitcheson is an associate in Freeths Environmental Law Team. Prior to qualifying as a solicitor, Helen worked as an environmental consultant working with offshore developers and as a marine mammal scientist. Get in touch today.

The content of this page is a summary of the law in force at the date of publication and is not exhaustive, nor does it contain definitive advice. Specialist legal advice should be sought in relation to any queries that may arise.

Get in touch

Contact us today

Whatever your legal needs, our wide ranging expertise is here to support you and your business, so let’s start your legal journey today and get you in touch with the right lawyer to get you started.


Get in touch

For general enquiries, please complete this form and we will direct your message to the most appropriate person.