FISHERIES MANAGMENT can be undertaken through a variety of technical conservation measures (TCMs). Examples are changing mesh size, imposing size limits on fish retained, closing fishing areas for a time, limiting the duration of fishing operations etc. The commercial industry invariably resists the introduction of any of these and any attempt to impose regulation is usually met with a cold response.

MSY is a blanket term which could be described as a “desirable outcome” rather than a methodology. Any or all of the above TCMs – and more – might be used to secure the desirable outcome.


THE THEORY UNDERLYING MSY is appealing in its simplicity. As illustrated in the accompanying diagram, the exploitation of a fish stock can be visualised in terms of fishing effort and yield. As the effort (which may be expressed as the number of vessels, length of net, engine power etc.) increases, along the base line, so does the harvest (tonnage of fish) removed from the stock, shown on the vertical.graph test

In the early stages the relationship between the two is linear – one boat fishing for one day lands one tonne of fish, ten boats in ten days land one hundred tonnes etc – but eventually, as the limits of the stock are approached, the yield begins to decline – one hundred vessels fishing for one day harvest only 80 tonnes etc. As the effort continues to climb, the landings per boat decline further.

MSY is the point, marked with the red vertical arrow in the diagram, at which “equilibrium” is reached. Harvested fish are replaced by adequate supplies of young on-growing individuals to sustain production. Provided the effort does not move any further to the right of the line, the stock will remain productive. Or so the theory goes.

Of course nothing is that simple. Fish do not reproduce at the same rate every year and many stocks are maintained by irregular recruitments. Thus, in practice, there is no fixed point of exploitation at which stability is achieved and the calculation of MSY is a movable feast. Even if there were however, fish stocks are not exploited in a standardised way. The majority in the seas around us are fished by a variety of gears which have various impacts on different stages of the life cycles of a variety of species. It is simply not possible to manage a single species by a fixed, unwavering rule under these conditions, unless the fishing effort is placed very far to the left of the vertical red line.

The appeal of this management mechanism is its apparently clean, logical approach. A calculation is done and everybody abides by its outcome. But that is not the way fisheries operate. A decision on MSY is no more easy to put into effect than a proposal to close an area to trawling or the introduction of a new gear regulation or the imposition of a size limit. Everywhere, whether expressly allowed for or not, the commercial fishing industry will push boundaries to capture a greater than recommended harvest. Within the terms of the Common Fisheries Policy scientifically established limits to fisheries regulation may be pushed aside where social and economic conditions warrant doing so[i]; in practice, that is what generally happens.


PREDICTIONS OF THE CONSEQUENCES of over-population and resource shortage multiplied in recent years. The publication of A Blueprint for Survival [ii] in 1972 presented an over-view of world problems which galvanised widespread interest. It preceded the first environmental summit: the Conference on the Human Environment held in Stockholm, Sweden later that year. The summit was deemed to be successful and has been revisited at ten year intervals since. In 1982 it took place in Nairobi, Kenya and a decade afterwards in Rio de Janeiro, Brazil by which stage it had changed its title to the United Nations Conference on Environment and Development and was known for short as the Earth Summit.[iii]

During the twenty years since the first world summit, data from a variety of sources confirmed the anticipated trends, if not all the details, of global environmental disimprovement. There was concern and 178 countries represented by between 20 and 30 thousand individuals from governments, NGOs and the media attended. Resource depletion, inequitable distribution and their end products which ranged through poverty, war and pollution focused minds on finding a sustainable alternative.MSY history

The resulting Rio Declaration enunciated 27 principles of environment and development (intended to be an Environmental Bill of Rights), to be known as Agenda 21, for which there was general approval so that they were adopted by consensus. Unfortunately, the 27 principles were non-binding. Two of those are the Polluter Pays Principle and the Precautionary Approach, both of which are admirable but flawed and often ignored.

The 1992 Rio summit was followed by the World Summit on Sustainable Development in Johannesburg, South Africa, in 2002. Fleshing out Agenda 21 further, the principle of Maximum Sustainable Yield (MSY) was adopted as a means of rescuing wild capture fisheries which were observed to be in rapid decline. The latest revision of the European Union’s Common Fisheries Policy coincided with the Johannesburg summit and the Commission in Brussels incorporated MSY as a long term management system.[iv]

MSY was described in Commission documents as “designed to ensure the exploitation of living marine resources in sustainable economic, environmental and social conditions”, a phrase which contains more than enough imprecise terms to render it meaningless. But claims for the advantage such a management regime could bring did not end there: …“several scientific studies have shown” that MSY could “restore 80% of European fish stocks affected by overfishing”. We were not told to what level they might be restored. Further possible advantages would include a decrease in fish imports to the EU.[v]

In keeping with commitments made at the Johannesburg Summit in 2002, member states also promised to bring stocks to levels compatible with the principles of MSY by 2015 at the latest.Mug 1

MSY was enthusiastically received everywhere and it was incorporated into the Common Fishery Policy of the EU in 2002 so it is appropriate to inquire what it achieved there since. Did EU fish catches increase? According to Eurostat, the total catches of the EU27 in 2002 were 8.2 million tonnes (mt); in 2013 they had declined to 4.7 mt, a decrease of 42%.[vi]Imports of fish and fish products rose to a maximum in 2006 during the period 2002-2014 but have tended downwards since.[vii]

Despite its obvious failure to live up to its promise there has been unquestioning support for the principles of MSY although the deadline for its full implementation has crept into the future. The consultation on fishing opportunities within the EU for 2015 stated that the MSY objective “is to be achieved by 2015 where possible and on a progressive, incremental basis at the latest by 2020 for all stocks”.[viii]

So, what has MSY achieved? Obviously it did not secure the objective of improving catches or reducing imports to any significant extent but it provided reassurance that some corrective measures had been adopted to halt the decline in fish stocks. Thus, the policy deflected criticism away from the Commission and scientific agencies responsible for the rational management of fish stocks while their decline continued, unabated.


cOMPOSITE xxxxxxPROBABLY BECAUSE THE prospects for marine fisheries are so dire, MSY was eagerly accepted as a solution to   intractable problems. When the regulatory bodies and their agencies adopt a simplistic solution, the only scrutiny must come from non-governmental organisations with an environmental brief (ENGOs). A number of those expressed their enthusiasm for the mechanism on a celebratory mug. MSY, it proclaims, is associated with more fish and larger ones too. GreenpeaceBirdLife InternationalOceana, the World Wildlife Fund and Ocean 2012 are all under the same misapprehension.
In fact, MSY is a moveable feast, which is why it appeals to those whose regulatory role is so unrewarding. The accompanying diagram illustrates an all-too-common pattern of decline; it refers to an increasing number of fish species. The orange line describes the reduction in biomass (total tonnage) over perhaps a comparatively short period of time, say twenty or thirty years. MSY can be applied at any stage of the stock’s deterioration. From an administrative point of view MSY has considerable advantages: if it were applied, for example, at the blue line and the stock further declined, it could be “re-established”, temporarily at the red one etc. Thus, the declining stock could be said to be “at MSY” even as it virtually disappears.

Mug 2




[i] Communication from the Commission to the European Parliament and the Council: Concerning a consultation on fishing opportunities for 2015 under the Common Fisheries Policy. Brussels 26.6.2014 Com (2014) 388 final.

[ii] By Edward Goldsmith, Robert Allaby et al, The Ecologist 2: 1

[iii] United Nations Conference on Environment and Development (UNCED), Rio de Janeiro, Brazil Accessed on 19 February 2015

[iv] Maximum Sustainable Yield Accessed on 19 February 2015

[v] Additional claims stated that MSY would bring about a reduction in the cost of fishing activity and an improvement in the quality of catch (by a reduction in discards).

[vi] Catches in all fishing regions Accessed on 21 February 2015

[vii] These figures have come directly from Eurostat. There are other, slightly different, interpretations of the data.

[viii] COMMUNICATION FROM THE COMMISSION TO THE EUROPEAN PARLIAMENT AND THE COUNCIL Concerning a consultation on Fishing Opportunities for 2015 under the Common Fisheries Policy /* COM/2014/0388 final */ Accessed on 21 February 2015