Guest blog: Troubled waters? Enforcement of fisheries and vessel conflicts in post-Brexit seas

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This guest blog is authored by Professor James Harrison from the University of Edinburgh Law School. James has previously written guest blogs on ‘the UK as an international fisheries actor’ and ‘Unpacking the legal disputes over Rockall’ and SPICe briefings on UK-EU fisheries negotiations and the UK Fisheries Bill.

As with all guest blogs, what follows are the views of the author, not those of SPICe or the Scottish Parliament.


At the end of the transition period at 11pm on 31 December 2020, the UK will become responsible for policing fisheries in its surrounding waters as an independent coastal state.  But what does this mean exactly?  What powers does a coastal state have to enforce its fisheries law and regulations and which agencies are responsible for enforcement in Scottish waters?  These questions are complex, requiring an appreciation of a variety of international treaties and domestic statutes. This blog discusses the legal framework for fisheries enforcement that will apply after the transition period, regardless of a deal on a UK-EU future relationship being agreed or not.

What powers does a coastal state have to enforce fisheries regulations within its exclusive economic zone (EEZ)?

In accordance with the 1982 United Nations Convention on the Law of the Sea (UNCLOS), a coastal state has sovereign rights for the purpose of conserving and managing the natural resources within its EEZ, which extends from the edge of the territorial sea up to 200 nautical miles from baselines drawn around the land territory of a state or to the maritime boundary with a neighbouring coastal state (see map below). 

The image shows a map of the British Isles and surrounding waters of the northeast Atlantic. A bold line shows the extent of the UK's Exclusive Economic Zone. This extends from off the coast of southwest England, through the English Channel and north through the middle of the North Sea. It extends to the northwest north of Shetland between the Faroe Islands and Norway and Westwards 200 nautical miles off the west coast of Scotland until it meets the lands border of Northern Ireland.
The bold line represents the boundary of the UK Exclusive Economic Zone (Source: UK Parliament)

This means that any fishing within that area can only be carried out with the consent of the coastal state, which has the power to take enforcement action where there is evidence of a violation of its fisheries regulations.  For these purposes, enforcement action includes boarding, inspection and ultimately the detention of a vessel and prosecution of the suspects.  As a matter of Scots law, instead of prosecution, the matter may also be dealt with by a fixed penalty notice.

However, a coastal state cannot completely prevent foreign fishing vessels from entering its EEZ.  This is because UNCLOS confers a right of freedom of navigation on all foreign vessels in the EEZ and coastal states have an obligation to give due regard to this freedom in exercising their enforcement powers.  This means that a foreign fishing vessel may lawfully pass through the waters of a coastal state unhindered, providing that it is not fishing. 

This legal position is reflected in UK legislation in the Fisheries Act 2020, which provides in section 12 that a foreign fishing vessel may enter British fishery limits ‘for a purpose recognised by international law’ but that if it does so it ‘must return outside British fishery limits as soon as the purpose has been fulfilled.’ 

In practice, this means that any foreign fishing vessel should proceed through British waters without interruption – any stopping or delay could be reasonable grounds for suspecting the foreign vessel of fishing, justifying the UK authorities to board and inspect the vessel for evidence of illegal fishing.

Which agencies are responsible for enforcing fisheries regulations at sea in Scotland?

Whilst Police Scotland may in principle be able to exercise their enforcement powers in relation to fisheries offences, this is a task that is principally undertaken by Marine Scotland Compliance, a department of the Scottish Government.  Marine Scotland Compliance operates 18 local fisheries offices around the country and it also has three marine protection vessels and two aircraft at its disposal to facilitate the detection of fisheries offences at sea.  Two small rigid inflatable boats (RIBs) have recently been added to the fleet in order to carry out inshore patrols and to free up the larger craft for offshore duties. 

Operational staff at Marine Scotland Compliance are warranted British Sea-Fishery Officers (BSFOs) conferred with the range of enforcement powers under Part 3 of the Aquaculture and Fisheries (Scotland) Act 2013, which includes the power to board, inspect and ultimately detain vessels, as well as the power to inspect and seize objects used in connection with commercial sea fishing. 

Image showing the marine Scotland fisheries protection vessel the MPV Hirta. The vessel is pictured at sea. The vessel is around 80 metres in length and is painted in grey paint.
Marine Scotland fisheries protection vessel, MPV Hirta

However, Marine Scotland Compliance officers are not the only BSFOs.  In accordance with section 7 of the Sea Fisheries Act 1968, all commissioned officers on Her Majesty’s ships and any persons in command or charge of any aircraft or hovercraft of the Royal Navy, the Army or the Royal Air Force are also automatically designated as BSFOs and they may therefore exercise enforcement powers within British fishery limits.  Indeed, the Royal Navy Overseas Patrol Squadron (previously the Fisheries Protection Squadron) has recently been increased in size to eight vessels, which have a role in policing fisheries legislation in UK waters, alongside other operational tasks around the UK and overseas territories.  It was reported in December 2020 that up to four patrol vessels could be involved in fisheries enforcement in UK waters from January 2021.

In practice, the role of the Royal Navy in fisheries enforcement in recent times has been limited to English, Welsh and Northern Irish waters, where it operates alongside other agencies, such as the Marine Management Organisation and the Inshore Fisheries and Conservation Authorities. Naval vessels do not currently carry out routine fisheries patrols around Scotland.  Nevertheless, Marine Scotland Compliance does coordinate its enforcement activity closely with other government agencies, including the Royal Navy, through the Joint Maritime Operations Coordination Centre and it would be possible for the Scottish Government to request additional assistance from the Royal Navy in relation to fisheries enforcement should it so wish.  

Legal gaps in relation to conflicts at sea between fishing vessels

One of the threats that has been raised in the context of Brexit is a possible increase in tensions between UK fishing vessels and foreign fishing vessels operating within UK waters after 31 December 2020.  This is not a new problem and there have been past reports of conflicts at sea involving UK and foreign fishing vessels, including a recent incident involving the German-flagged Pesorsa Dos and the UK-flagged Alison Kay in the EEZ off Shetland.  Technically, this is not a matter of fisheries regulation, but rather safety at sea.

International regulations on this subject require all vessels to conform to general principles of ‘good seamanship’ and to keep a ‘safe distance’ from other vessels and failure to follow these rules may constitute a criminal offence.  However, in enforcing these principles, coastal states can normally only exercise powers within the 12 nautical mile territorial sea, but not in the EEZ.  For this reason, the Merchant Shipping (Distress Signals and Prevention of Collisions) Regulations 1996/75, which are enforced by the Maritime and Coastguard Agency, only apply to foreign ships whilst they are in the UK territorial sea or internal waters. This has resulted in a gap in the legal framework relating to the prevention of conflict at sea in the EEZ, where BSFOs are limited to ordering the boat to move away and reporting the incident to the flag state for further action

It is possible that the coastal state may be able to exercise additional powers in its EEZ when an incident involves a foreign fishing vessel covered by the 1967 Convention on the Conduct of Fishing Operations in the North Atlantic.  Article 6 of this treaty, to which the UK is a party, expressly requires that ‘all vessels shall conduct their operations so as not to interfere with the operations of fishing vessels or fishing gear.’  Furthermore, it not only requires contracting parties to ensure that their own vessels comply with these rules, but Article 8(2) also provides that ‘within the area where a coastal State has jurisdiction over fisheries, the implementation and enforcement of the provisions of this Convention shall be the responsibility of the coastal State.’  

Because UNCLOS confers jurisdiction over fisheries to the coastal state in the EEZ, the UK could potentially enforce these treaty provisions in its waters. However, the treaty would need to be given effect in domestic law before any such action could be taken.  Safety of fishing vessels and the prevention of harassment at sea was an issue taken up by Alistair Carmichael MP during the passage of the Fisheries Act 2020, but his amendments were ultimately not adopted and so the legal gap remains.  However, it could be filled rather easily either by the adoption of an order under section 5 of the Sea Fisheries Act 1968 which permits the Scottish Ministers to regulate the conduct and safeguarding of fishing operations in Scottish waters or through the adoption of appropriate conditions in licences granted to foreign fishing vessels under section 17 of the Fisheries Act 2020.

The legal framework discussed in this blog will apply whether the UK and EU agree a future relationship deal or not.  It remains to be seen how the outcome of negotiations will affect the risk of escalating tensions between vessels at sea in 2021 and beyond.

James Harrison,

Professor of Environmental Law, University of Edinburgh Law School