Scottish scientific electrofishery for razor clams trial - biological and ecological goals: progress report

1. Introduction

Razor clams (Ensis sp.) are marine bivalve molluscs commonly found around the coast of Europe, inhabiting sediments from fine sand to soft mud in the intertidal and sub-tidal areas (Breen et al., 2011). Often referred to as “spoots”, three species are widely distributed around Scotland; E. siliqua, E.magnus (also known as E.arcuatus) and E.ensis (Breen et al., 2011). E.siliqua (the “pod” razor) is the razor clam species typically targeted by the fishery in Scotland, and anecdotal information from the Scottish fishing industry suggests there has been a targeted fishery for razor clams for many years.

In Scotland, fishing with electricity was prohibited under EU law (Article 31 of EC Regulation No. 850/98, superseded by Article 7 of Regulation (EU) 2019/1241), with an exception for scientific studies. Electrofishing for razor clams involves towing electrodes slowly over the seabed behind a fishing vessel to create an electric field (Figure 1). The electric field elicits a response from the razor clams, and they emerge from burrows allowing divers to collect marketable clams by hand, whilst small and unwanted clams can re-burrow in the sediment (Fox et al., 2019).

In 2016, following discussion with stakeholders, the Scottish Government (SG) launched a public consultation on electrofishing for razor clams in Scotland (Consultation about electrofishing for razor clams in Scotland - Scottish Government - Citizen Space). Although electrofishing causes minimal disturbance to the seabed and is considered a low impact method of harvesting compared to other conventional methods, such as dredging (Murray et al., 2014), the consultation feedback highlighted concerns about the wider environmental impacts of electrofishing and stock sustainability. In response, the SG agreed to pursue the development of a scientific study designed to a gather further information about electrofishing.

The Scottish Parliament approved a Scottish Statutory Instrument (SSI) (Razor Clams (Prohibition on Fishing and Landing) (Scotland) Order 2017) which prohibits fishing for razor clams in Scottish waters and the landing of razor clams in Scotland except in two specified circumstances:

i. for scientific investigation when authorised by Scottish Ministers; and,

ii. for traditional hand gathering of razor clams from the shore. A person carrying out such non-commercial harvesting will be limited to 30 razor clams per day.

This SSI allowed a trial electrofishery for razor clams to officially start in February 2018, with the end date scheduled for January 2025. Derogations to be part of the scientific trial were issued to 28 fishing vessels, allowing them to fish for razor clams (using electrofishing) in designated areas. Each vessel participating in the trial must abide by the Terms and Conditions (Marine Scotland - Edinburgh VQ.dot (www.gov.scot)) which include being subject to a daily catch limit of 450 kg and an annual effort limit of 110 days at sea. In addition, all vessels require a Remote Electronic Monitoring (REM) system on board at all times, providing details of vessel position and status of the electrofishing gear. The REM system must remain switched on, including when the vessel is transiting or fishing for species other than razor clams. Lastly, the electrofishing gear must operate within the parameters specified by the Marine Directorate.

The goals of the trial cover four categories: (1) biological and ecological,(2) economic, (3) social, (4) best practice and management. This report will focus on the biological and ecological goals of the trial which were:

• to gather local level information on razor clam populations and stocks, including accurate data gathered by trial participants to supplement stock survey work;
• to ensure sustainable harvesting levels; and,
• to gather further information about the impacts of the electrofishing method on target and non-target species.

To help achieve these goals, trial participants were instructed about their responsibility to contribute to monitoring, research, and stock assessments for the trial. These obligations were clearly set out in the trial Terms and Conditions.

The trial is supported by the Health and Safety Executive (HSE) who regulate commercial diving activities, Food Standards Scotland (FSS) who are responsible for food safety regulations in Scotland, and Scottish Association for Marine Science (SAMS) who have undertaken survey work and a PhD study. This trial has been collaborative, and Marine Directorate staff have worked alongside these agencies, Marine Directorate compliance and policy colleagues to produce annual reports (Marine Scotland, 2019, 2020, 2021). This report documents the results and progress for the trial work streams and provides an improved evidence base for management of any future electrofishery for razor clams in Scottish waters