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Commercial Fishing



Battle over Maximum Sustainable Yield. The dangers of one-dimensional fisheries management Within the corridors of Westminster, another battle is raging. This one is over how the principle of maximum sustainable yield should be applied to our fisheries after the UK has left the EU and CFP.

The Fisheries Bill is passing through Parliament and battle is engaged for parliamentarians’ favour in both the Commons and the Lords. On the one side, are fisheries managers, the fishing industry and fisheries scientists, and on the other, the environmental NGOs and their sympathisers, who are pressing a one-dimensional view of fisheries management. If successful this would inadvertently, but inevitably, close down some of our most important fisheries.

MSY: a useful yardstick/a dangerous dogma

MSY is a convenient yardstick to measure whether fish stocks are being fished at sustainable levels. It involves establishing biological reference points for each stock as a rough proxy for the levels fishing which would secure maximum benefits from each stock. The concept, however, was never designed to be applied in mixed fisheries where a range of species, each with different conservation status, are caught together. Useful when used as an aspiration, applied in a dogmatic way, MSY can become an obstacle to sustainable fisheries management.

MSY was adopted as a political objective at the World Summit on Sustainable Development, in Johannesburg in 2005. Since then it has been used as a shorthand yardstick for sustainability. And since 2013, after extensive lobbying by the environmental NGOs, it has been a legal requirement within the CFP, with a deadline to have all harvested species consistent with MSY by 2020. MSY therefore comes into play when quotas for each species are set each year, based on scientific advice produced by the International Council for Exploration of the Seas.

ICES produce single species advice for each stock to meet the European Commission’s request for advice expressed in a memorandum of understanding. The form of that request is important. Even though, since 2000, fishing pressure across all of the main species groups has been falling dramatically and stocks have been rebuilding steadily, scientists when asked what level of catch is consistent with achieving MSY by 2020, for a handful of stocks can only provide one possible answer: zero catch. And that is a problem for mixed fisheries under the landing obligation.

Mixed Fisheries

In the real world of mixed fisheries, fisheries managers are faced with a range of objectives. Management decisions for each stock are always based on the scientific advice but trade-offs between the different objectives require compromises. These include:

  • Building or maintaining the biomass of each stock to MSY, bearing in mind that even without human intervention, the abundance of any given fish stocks will fluctuate in response to different environmental signals: once a stock is at MSY, there is no guarantee that it will stay there, even at low fishing levels.
  • Reducing discards, or as there is now a discard ban/landing obligation, avoiding chokes, where the exhaustion of one quota would close fisheries for other economically important species
  • Maintaining the viability of fishing businesses and fishing communities, often through a staged approach to rebuilding stocks to avoid the worst socio-economic impacts when below average recruitment means that quotas have to be reduced

Setting quotas within this context is complex. Multiple objectives require difficult trade-offs. The introduction of the EU landing obligation, which requires all quota species to be landed unless there is a specific exemption, raises the stakes because of the risk of chokes, when the exhaustion of quota for one species will mean that a vessel cannot retain any more of that species but neither can the species be landed because there is no quota to cover that landing. A classic Catch 22.

In recognition of these kind of management dilemmas, the EU introduced the concept of fishing mortality ranges into their management plans, in the teeth of strenuous opposition from the more purist NGOs and their allies in the European Parliament. F-ranges are not a panacea for chokes, but they do provide fisheries managers with a little more flexibility to set quotas in mixed fisheries. Even the European Commission, the body charged with overseeing implementation of EU fisheries law, has been noticeably reluctant to give full force to the MSY principle in its proposals – because of the consequences of following a one-dimensional path.

MSY in the Fisheries Bill

The central purpose of the Fisheries Bill, currently making its way through Parliament, is to provide UK fisheries ministers with the authority to set quotas and control access to UK waters after the UK departs the EU. It also contains a range of broad objectives, including one to maintain fish stocks in line with the MSY principle. What is missing by contrast with the Common Fisheries Policy, is the requirement to set quotas for all harvested stocks at MSY by 2020.

This has been done for good reason. A hard, legal obligation to set quotas at MSY, irrespective of the circumstances, would tie managers’ hands in dealing with the necessary trade-offs described above. Removing the arbitrary deadline provides fisheries management with a degree of flexibility to manage mixed fisheries whilst still maintain the commitment to set quotas at levels which generate maximum economic benefits.

The NGOs argue that this change represents a dilution of the UK’s commitment to the EU’s sustainability standards. It is a deceptively simple but dangerous argument. Because it is simple – and the counter argument is rather complex – it is gaining traction in Parliament.


The EU landing obligation, which came fully into force on January 2019, requires all quota species to be landed and counted against quota. For fisheries in which the scientific advice for one species caught in a mixed fishery is for zero catch of that species, this poses a dilemma. A species caught as unavoidable bycatch could close the whole fishery prematurely. Applied legalistically, the MSY principle, alongside the requirements of the landing obligation, would mean closing whole fisheries in January for the rest of the year. In concrete terms, had this approach been applied for the quotas set in December 2018, for the 2019 fishery, applying the MSY principle within the context of the landing obligation would mean the immediate closure of:

  • The West of Scotland demersal fisheries
  • The Irish Sea nephrops fisheries
  • The Celtic Sea demersal fisheries.

This drastic action would be required because there is zero catch scientific advice for, respectively, cod, whiting and cod in these fisheries. Put plainly, following a rigid interpretation of MSY at the 2018 December Council would have meant catastrophic social and economic consequences for thousands of fishing businesses and hundreds of fishing communities in Western Waters. The more purist NGOs could perhaps afford to be blasé about such an outcome but clearly ministers baulked at taking responsibility for such carnage. In the event, a difficult compromise was found.

MSY as a slogan

The NGOs would have us believe that all that is needed to achieve sustainable fisheries is political will. The beauty of this formulae is its simplicity. The appeal is to the general public and politicians who, understandably, know little of the complexities of managing mixed fisheries within the context zero catch advice and the landing obligation. But reducing MSY to a slogan is dangerous.

Embedded as a hard, legal, requirement, with an arbitrary timetable, would:

  • Limit fisheries managers’ ability to achieve optimum outcomes,
  • Be impossible to achieve consistently from a biological point of view, as humans cannot control spawning success or the recruitment of young fish to the fishery each year
  • Make international fisheries negotiations dance around a scientifically illiterate legal requirement
  • Carry potentially dire social and economic consequences

None of these would be the intention but they would be the consequences of an inflexible, one-dimensional approach to MSY. The fishing industry has a deep interest in a management system that delivers high average yields of commercial species. ICES science demonstrates that great progress has been made in achieving this objective across all the main species groups. As the UK leaves the EU it makes sense to retain MSY is as a principle, as an aspiration, and as an objective – but the consequences of giving it primacy over all other considerations would be disastrous.