Sea fisheries

Fish stocks

Healthy fish populations are a naturally renewable resource, providing long-term fishing opportunities for the sea fishing industry and natural food for consumers, as well as being of great importance to our marine ecosystems.

It is important to live within environmental limits to ensure that fish stocks are kept healthy to provide a resource for future generations and to safeguard the diversity of the marine ecosystem on which they depend.

Marine Scotland scientists provide the highest quality science to inform decisions and negotiating priorities, taking into account wider policy objectives, public attitudes, socio-economic implications and the precautionary approach. This helps us to manage stocks effectively.

We encourage eco-labelling schemes too, such as that of the Marine Stewardship Council (MSC) as it recognises that such schemes have a valuable role to play in promoting sustainable fisheries and fish consumption.

West of Scotland

The geologically complex fjordic coastline of Scotland's west coast, along with the interaction of currents, provides a highly diverse and productive environment for marine life. The diversity of habitats includes numerous sea-lochs, the continental slope and shelf, Rockall Trough and seamounts. This is a very different environment to the North Sea.

With fishing communities ranging from Campbeltown to Kinlochbervie, the area supports sea anglers as well as fisheries using trawls and creels. The West of Scotland fishery is worth 36% by value of the overall Scottish fleet. A wide range of fish species are targeted, including demersal and benthic species (e.g. cod and monkfish), pelagic species (e.g. herring and sharks), and shellfish (e.g. crabs and lobsters).

The Nephrops fishery is particularly important to the West of Scotland; worth approximately £45 million, the fishery is the mainstay of small (under 10 m) vessels and is the main species targeted by 40% of large vessels. Two West of Scotland Nephrops fisheries have already been accredited by the Marine Stewardship Council, with more to follow.

The harvesting of some species is considered to be sustainable (e.g. recent scientific assessments showed a 40% increase in monkfish biomass over the last 5 years), however in the last two years concerns have grown about the sustainability of three West of Scotland stocks: cod, haddock and whiting. Following these concerns, the European Commission and Scottish Government agreed to adopt a suite of measures to ensure the sustainability of these whitefish stocks whilst, wherever possible, allowing fleets to pursue other sustainable fisheries.

West of Scotland management

Following concerns about the state of cod, haddock and whiting stocks on the West of Scotland, the European Commission and Scottish Government agreed to adopt a number of changes to gear and catch composition requirements have been implemented in 2009 in the area East of the French Line in ICES division VIa. These include:

Gear requirements:

  • The minimum mesh size in the cod-end or extension piece has increased from 70mm to 80mm.
  • Vessels targeting whitefish that are 15m or below must use at least 110mm gear, whilst those that are above 15m must use at least 120mm gear.
  • Vessels targeting whitefish must also have a 3m long Square Mesh Panel (SMP) fitted 12-15m from the codline. The mesh 110mm or 120mm dependant on whether the vessel is below or above 15m respectively.

Catch-composition requirements:

  • For vessels targeting Nephrops (also known as Norway lobster, langoustine and prawns), the catch must contain at least 30% Nephrops and no more than 10% combined of cod, haddock and whiting.
  • For vessels targeting whitefish, the catch must contain no more than 30% combined cod, haddock and whiting.

A West of Scotland Task Force, whose membership includes policy officials, industry representatives and net suppliers, was created in January 2009. The group was tasked with considering the implications of the management measures for the West of Scotland fishery and coastal communities, including the most appropriate way to take things forward.

One of the West of Scotland Task Force's recommendations was for a joint science forum to be established to share expertise relevant to the state of the West of Scotland fish stocks, and improve scientific knowledge. Members of the science forum include skippers, industry representatives, scientists and representatives from environmental organisations. The forum have been allocated £200,000 to improve existing surveys and scientific knowledge.

Stock assessment

Every year, scientists undertake a programme of work to assess the state of fish stocks in European waters. Marine Scotland scientists at the Marine Laboratory in Aberdeen collect data on stocks in the North Sea and the west of Scotland. This information is combined with data from other European nations who fish in these waters, and is then considered by the International Council for the Exploration of the Sea (ICES).

ICES estimates the current state of the stock, and forecasts what is likely to happen in the future. This process, known as stock assessment, aims to provide fishery managers in the Scottish Government and European Commission with the necessary information on which to base decisions on how much fishing should take place.

Data collection

Information on the fish stocks is collected from three main sources:

  • statistics on the quantities of each species landed are collected in fishing ports by officers of Marine Scotland compliance.
  • biological data on the size and age of the fish caught are obtained by sampling catches directly. Marine Scotland scientific staff regularly visit fish markets around Scotland, and sail on more than 60 commercial voyages each year.
  • research vessel surveys are conducted to determine the abundance of fish, including those too small to be caught by fishermen. Special surveys are also organised to examine the abundance of pelagic fish such as mackerel, sprats and herring and shellfish such as Norway lobsters ( Nephrops) and scallops.


To determine the 'health' of a fish stock, scientists estimate the following levels:

  • fishing mortality - a measure of the proportion of a fish stock taken each year by fishing
  • spawning stock biomass - the total weight of mature fish (capable of spawning) in the population, and the minimum weight of mature fish required to ensure a sustainable fishery
  • recruitment - the number of young fish produced each year which survive from spawning to enter the adult stock and the fishery, and
  • landings - the total annual tonnage of fish taken from the stock and landed by the fishing fleet

Additional information

Additional information is collected relating to when fish spawn, how long they live, what they eat, and changes in the marine environment that may affect fish stocks. The information required to carry out a stock assessment comes from a number of sources including:

  • Market Sampling - information on the length and age of fish is collected at fish markets, along with details of catches of the fishing fleets
  • Discard Sampling -  to provide length and age information on fish that are caught that never reach the market. Discard sampling, in addition to market sampling, provides a more complete picture of the effects of fishing on the stocks, and
  • Research Vessel Surveys - these provide information on the numbers of young fish (recruits) which are too small to be caught and landed by commercial vessels. They also provide information on changes in the distribution and abundance of the adult stock.

ICES management advice

ICES provides fisheries advice that is consistent with the broad international policy norms of maximum sustainable yield (MSY), the precautionary approach, and the ecosystem approach. ICES recognises that the fisheries for which it provides advice have not, in general, been managed with MSY as an objective, and that current European Commission policy does not call for fisheries to be managed in accordance with MSY until 2015. Therefore, the nature of ICES advice is evolving, including options for a 'transition process' to attain full implementation of the MSY approach by 2015.

Within the Precautionary Approach framework, ICES continues to define reference points in terms of spawning stock biomass (the total weight of mature fish in the sea capable of spawning) and fishing mortality (a measure of the rate of removal of fish by fishing). Stocks are classified in terms of reproductive capacity in relation to spawning stock biomass and sustainable harvest in relation to fishing mortality.

Spawning stock biomass and fishing mortality reference points are defined individually for each stock, and consist of limit reference points which signify stock conditions to be avoided, and precautionary approach reference points which give a high probability of avoiding the limit reference points.

Further information and detailed advice on stocks is available on the ICES website.

Briefings given to industry stakeholders on ICES fish stock estimations.

Management approach

Total Allowable Catches (TACs) have been a principal management tool for many years. Technical measures to help control the size composition of catches are also employed. While TACs and quotas based on pre-agreed allocation keys can be helpful in establishing upper limits on landings and stability in the sharing out of fish resources, they have proved less satisfactory in controlling fishing mortality. Part of the problem is that TACs refer to the landed component of a catch which means that once a TAC is exhausted, additional fish taken during a fishing trip have to be disposed of by, for example, discarding over the side.

In recent years, management of effort through a European Days at Sea scheme has also been in operation in an attempt to control mortality more directly by limiting fishing activity itself. Days fishing to be applied across different types of fleet (large meshed trawlers, beam trawlers, etc.) is agreed at the Council of Ministers and operated within each Member State. There have been some signs that this approach, along with significant decommissioning schemes (such as in Scotland), have had some effect in reducing fishing mortality for some species, including Cod. With continued reduction in time at sea, however, there is an increased possibility of more targeted effort through changed fishing behaviour.

Since 2009, Scottish fishermen have been taking part in a Catch Quota Scheme aimed at avoiding Cod. This allows fishermen to land all the Cod they catch, provided they carry cameras on board and stop fishing altogether in the North Sea when they reach their Cod quota. Catch Quota is only one management tool available but this, along with the use of selective gears and Juvenile Real Time Closures, can make a real difference. It is hoped that measures to encourage and reward avoidance behaviour will help reduce Cod fishing mortality further.

Sustainability certification

Independent Sustainability Certification Schemes Including the Marine Stewardship Council (MSC)

The Scottish Government believes that independent sustainability certification schemes, such as that of the Marine Stewardship Council, can be a useful tool in helping consumers decide which sources to buy their food from. The MSC blue eco-label provides assurance that the product comes from a sustainable fishery. There are a number of certification schemes around the world but the Scottish Government is particularly involved with two: those of the Marine Stewardship Council and the Responsible Fishing Scheme.

The Marine Stewardship Council (MSC) is an independent, global non-profit organisation which acts as an independent accreditation body and operates the MSC certification scheme which is a voluntary fisheries eco-label. If a fishery is successfully certified to the MSC Standard then products from that fishery are eligible to bear the blue MSC eco-label.

Marine Scotland is making great progress on certifying fisheries in Scotland, with five fully-certified fisheries (almost 4% of the global total) and a further 10 in the full assessment process.

During 2008-11, the Scottish Government funded two key posts to support Scottish fisheries seeking independent sustainability certification: MSC's Scottish Outreach Officer and Seafood Scotland's Environmental and Technical Manager. We continue to work closely with both MSC and Seafood Scotland. This support highlights the Scottish Government's firm commitment to Scottish fisheries and to ensuring they are well managed, sustainable and profitable.

Marine Scotland supports the vessel-based Seafish Responsible Fishing Scheme (RFS) both in its own right and as a stepping stone to accreditation. The RFS is an independent, audited assessment of good practice by a vessel skipper and crew in their fishing operations. It covers four key areas:

  • Fishing practises
  • Vessel criteria (such as hygiene, fish storage facilities, safety etc.)
  • Crew competence
  • Environmental considerations

You can read more about the Responsible Fishing Scheme on the Seafish website.

Certified fisheries

The following Scottish fisheries are certified by the Marine Stewardship Council:

  • Scottish Pelagic Sustainability Group (SPSG) - North Sea herring

  • SPSG West of Scotland - Herring pelagic trawl

  • SPSG - Western component of North-East Atlantic mackerel

  • SPSG - Atlanto-Scandian herring

  • Scottish Fisheries Sustainable Accreditation Group (SFSAG) - North Sea haddock

  • SFSAG - Northern shelf saithe

  • Shetland and mainland Scotland - rope-grown mussel enhanced fishery

  • Shetland Shellfish Management Organisation (SSMO) - inshore Brown crab, Velvet crab and Scallop

The fisheries listed below are in full assessment for Marine Stewardship Council Certification:

  • Mackerel Industry Northern Sustainability Alliance (MINSA) - North East Atlantic Mackerel

  • PFA, DPPO, KFO, SPSG and Compagnie des Peches St Malo – North East Atlantic blue whiting pelagic trawl

  • SPSG, DPPO, PFA, SPFPO and KFO – Atlanto-scandian purse seine and pelagic trawl herring

A number of other Scottish fisheries are interested in pursuing MSC certification, and some are already in the (confidential) pre-assessment process.

Responsible Fishing Scheme

Growing numbers of vessels in Scotland are signing up to the scheme and to date over 100 Scottish vessels are now fully certified.


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