Collection

Managing harbour porpoise bycatch in English waters

The Marine Management Organisation (MMO) is working collaboratively with the fishing industry, conservation organisations, and other marine stakeholders to reduce the accidental capture (bycatch) of harbour porpoise in English waters.

From:
Marine Management Organisation
Published
11 July 2025

The MMO is particularly considering new measures for two Marine Protected Areas (MPAs) designated for harbour porpoise:

  • Southern North Sea MPA

  • Bristol Channel Approaches MPA

We also want feedback on how wider management measures might apply across the harbour porpoise Management Units (MUs) in the North Sea and the Celtic and Irish Seas

Why action is needed 

Harbour porpoises are highly mobile marine mammals found throughout the cold and temperate seas of Europe, including English waters. They play a vital role in regulating fish populations and maintaining healthy marine ecosystems. 

Bycatch, when porpoises become entangled in fishing gear such as gillnets, can lead to: 

  • Internal and external injuries 

  • Long-term health issues 

  • Physical and psychological stress 

  • Reduced life expectancy 

  • Drowning and death 

Current levels of bycatch in the UK may be unsustainable, particularly in the MPAs identified above. Evidence gathered to date suggests that bycatch from gillnets is above sustainable levels in both MPAs.

We understand that porpoise bycatch is an accidental and entirely unintentional activity. Fishers do not want to harm protected marine wildlife and have a vital role to play in addressing this issue for the future. This includes sharing evidence, their views on potential management options, and using their knowledge of working at sea to shape management approaches. By working together, our approach will reflect both our conservation priorities to protect harbour porpoise, and consider the practical challenges fishers face at sea

What our proposals may include 

We are considering six broad bycatch management options. These could be applied within the MPAs or more widely across the relevant Management Units: 

  1. Time-area closures. Seasonal or year-round restrictions on gillnets in high-risk areas. 

  2. Effort limitation. Limiting the total amount of fishing activity. 

  3. Dynamic closures. Temporary closures in response to real-time data, such as porpoise presence or bycatch risk thresholds. 

  4. Mandatory acoustic deterrent devices (ADDs). Requiring all gillnet vessels to use ADDs to reduce porpoise bycatch. 

  5. Voluntary gear modifications. Promoting alternative fishing methods through voluntary codes of conduct and support schemes. 

  6. Bycatch monitoring and reporting. Introduce dedicated bycatch monitoring and reporting as part of an adaptive risk management plan and/or supporting tool.

These options are not decisions, they are potential options under active exploration. MMO welcomes input at this early stage to help shape more formal proposals going forward. We are keen to work with the fishing industry and other stakeholders to ensure any measures are proportionate and practical, whilst still fulfilling our legal duties to achieve the conservation objectives of MPAs. Formal proposals will be presented at a later date.

How you can help 

We want your early views on these potential management options before we move to a formal consultation. Please read the harbour porpoise bycatch management options document and / or the handouts that summarise the main topics of the document here: Harbour Porpoise Bycatch Management Options

We also want your help filling bycatch evidence gaps. While we have collected and reviewed the best available evidence on harbour porpoise bycatch and gillnet activity in UK waters, a number of evidence gaps still remain. Information you could provide, such as the location, time of year, and gear in use when you have experienced bycatch, could provide additional context to determine an appropriate management option and the appropriate spatial scale and circumstances at which management options could be applied (for a more detailed list of evidence gaps please see the Harbour porpoise bycatch management options document). 

The primary bycatch evidence gaps are: 

  • Bycatch hotspots or coldspots, any areas and times of year with high or low risk of porpoise bycatch; 

  • Bycatch across gillnet fisheries, any metiers/fisheries with high or low risk of porpoise bycatch; and 

  • Location of gillnetting effort by vessels under 12 m in length. 

We are asking stakeholders to: 

  • Consider the six potential management options and review our current evidence in the Harbour Porpoise Bycatch Management Options document and / or its handouts.

  • Comment on the feasibility, benefits and challenges of each management option. 

  • Share additional evidence or insights on harbour porpoise bycatch. 

  • Provide feedback on bycatch from different gear types, different regions, and different seasons. 

Marine protected areas - Stage 4 impacts evidence - GOV.UK 

Harbour Porpoise Bycatch Management Options

Marine Protected Areas - Stage 4 Interactive Maps

Get involved 

Your feedback will help us shape management measures that are both effective and practical. 

Once this engagement process ends, we will review all feedback and provide information on next steps, including any future formal consultation. 

Upcoming Workshops 

There are currently no upcoming workshops. Future workshops updates will be published here.

Background 

This work supports Stage 4 of our assessment and management of fishing in marine protected areas (MPAs) offshore of 6 nautical miles (nm) from the coast in English waters. 

Stage 4 considers the impacts of fishing on offshore MPAs designated for highly mobile species: harbour porpoise and marine birds.  

MMO ran a call for evidence to assess the impacts of fishing in Stage 4 MPAs from 5 Dec 2023 to the 13 Feb 2024. 

We have since updated our evidence documents and continued to draft site level assessments. During this process we have identified that fisheries management is likely required to reduce harbour porpoise bycatch.

Further guidance 

Read current advice on reducing bycatch and complying with existing regulations: Reduce dolphin and porpoise bycatch – GOV.UK 

Find out more about MMOs role in assessing and managing activities in England’s marine protected areas.

Collection

Updates to this page

Published 11 July 2025
Contents