”What is the best reference point to make sure that fish stocks are harvested sustainably and yet profitably?”

well, the answer to this question is (practically) free consultancy...

Our new paper considers that topic and contribute significant discussion. Here is the summary:

Froese, R., Coro, G., Kleisner K., Demirel, N. (2014). Revisiting safe biological limits in fisheries. Fish and Fisheries, (in press) doi: 10.1111/faf.12102

"Official fisheries management reference points used for stocks in the Northeast Atlantic were investigated as to the appropriateness of their current levels. In 46% of the stocks the official estimate of the precautionary biomass limit SSBpa was found to be below the consensus estimate of three different methods. The official exploitation limit Fmsy was found to exceed the rate of natural mortality in 76% of the stocks. Selectivity of official gears resulted in an age at first capture that was below the age of full maturity in 74% of the stocks.

The Law of the Sea (UNCLOS 1982), the Marine Strategy Framework of the EU (MSFD 2008), and the new Common Fisheries Policy of Europe (CFP 2013) require that fish stocks shall be rebuilt to and maintained above the biomass level (SSBmsy) that can produce the maximum sustainable yield. In its advice for 2014, ICES did not provide estimates of SSBmsy, which makes it difficult to judge where Europe stands with regard to these commitments (Froese and Proelss 2010). Using the proxy for SSBmsy developed in this study and looking at stock sizes in 2013, 88% were below the level that can produce the maximum sustainable yield, 52% were outside of safe biological limits, and 12% were severely depleted. The rate of fishing mortality in 2013 exceeded the rate of natural mortality in 73% of the stocks and fishing continued also in the severely depleted stocks. Thus, while the new Common Fisheries Policy (CFP 2013) of the European Community is widely regarded as a big step in the right direction, much remains to be done to rebuild healthy fish stocks and fisheries in the Northeast Atlantic."

The whole business of MSY is tricky - we know for mixed fisheries where species also interact that it is impossible to get all stocks to MSY and ICES and STECF have done a lot of work trying to model optimal yields from such fisheries. MSY also has a long history of being discredited - unfortunately I think it sounds politically attractive, who could argue with a promise of maximum yield for ever? and so has ended up being the 'policy' target without real consideration of whether it is realistic or safe. Generally MEY (maximum economic yield) is found at F below Fmsy so it is only because so many stocks are still way below MSY levels that it looks OK to use as a target.

In view of the fact that within one marine fisheries ecosystem live and interact many inter-related species in a prey-predator dynamic and ever changing co-existance in a fluctuating environment; in view that external, marine dynamics and climate-associated factors, as well as various human activities and other environment changes affect target species at various stages of their life-history, and, finally, in view that the data on which "calculations" of MSY, SSB, MEY, etc., etc., are based, are never in true time, hence the persistent gap between the time of the data and time when the recommendations and regulations are applied (for example, while the data might've been processed when still the trend was upwards, while the recommenadations might've arrived when the trend was already downwards) - in view of all this, I don't believe that such "science" can provide reliable information, which in most cases is between highly approximate and outright fallatious.  Sorry for that,   MB-Y

I agree to some extent also with the previous poster - most fisheries approaches we use assume to some extent that the system is in some sort of equilibrium - which of course it rarely is - it is for example clear that stock-recruit relationships can move through productive to less productive periods - and vice versa. Usually our timeseries are too short to definitely see that this has happened or to set up alternate S-R plots for different periods although it has been attempted for North Sea cod for example.

However, fisheries management has to be based on something and "unreliable" science seems to be better than "no science" - as long as we do not kid ourselves about how uncertain or certain it really is.

As I said I think MSY is politically attractive and politicians (and to some extent the wider stakeholders) do not want to know that everything is rather uncertain.

Now I need to go and read Frose et al. new paper!

Hi Clive,

enjoy Rainers paper! If its the one about survey-based assessments, I think the methods looks very promising.

And I agree, our science is not perfect, but in many cases the best basis for advice we have.

Hi Clive, thanks for your comment. You also wrote:

"However, fisheries management has to be based on something and "unreliable" science seems to be better than "no science" - as long as we do not kid ourselves about how uncertain or certain it really is".        And:

"As I said I think MSY is politically attractive and politicians (and to some extent the wider stakeholders) do not want to know that everything is rather uncertain". 

Well, I agree with the last sentence, but as to "the best available science" IMO there's a better science available than the present "management by output" axiome. This is management by input, which requires good knowledge of the target spp. life history, so that fishing can be forbidden at certain times and on certain grounds (protecting spawning and young stages growing up), regulating sorts of gear, and preventing pollution of inshore areas of spawning, roe hatching, larvae rearing, and fingerlings growing. Unfortunately, this requires "field" research, that's going to sea instead of seating comfortably in front of computers and "playing" with numbers. Plenty of other problems, too. You can look up http://benyami3.wix.co,/benyami. Plenty of related stuff there.  Cheers,  MB-Y

Sorry. It's http://benyami3.wix.com/benyami

Wolfgang,

I'm not a great fan of triggers, reference points, quantitative limits and all the rest. They tend to lead to over-simplified, stylized ("paint by numbers") approaches to management, with no place for creative thinking, expertise in managing fisheries or understanding of the ecosystems and the biology of the resources. What we really need is intelligent responses to time-specific situations in each fishery, with the best response varying from fishery to fishery and situation to situation (something that none of our over-centralized fishery-management systems can deliver). In practice, it is sadly true that we often have to enshrine everyone's good intentions into hard limits that can then be applied swiftly to real, specific situations -- particularly when resources are declining quickly. Quantitative triggers have a role then.

They cannot, however, be usefully discussed in the abstract. They are components of management systems and each form of reference point can only really be examined within the context of the system it is embedded in (and, even then, only fishery by fishery as many systems may work well for some of the fisheries to which they are applied but not for others).

At the risk of grossly over-generalizing: ICES is correct that a limit which triggers a management response should not be set at the desired long-term target level. Real fisheries, even if successfully managed over the long term, will always show temporal variability around the target, while the available data will provide variable indications of the true value of whatever is being measured. If every little dip in some number triggers management actions, costs will be incurred (by all parties) with little or no benefit.

Conversely, the optimal long-term biomass target should not (in general) be some biomass in theoretical equilibrium with a harvest of MSY. (And that's without launching into the absurdity of invoking a concept, like MSY, that was discarded decades ago by scientists.) We have known for decades about asymmetries of risk and it is sure that, for most fisheries, we want biomass levels above those expected with MSY fishing. So perhaps ICES should set its triggers at SSB[MSY] and its targets at some higher level.

Which brings us to the underlying question: Who gets to make those decisions? I would suggest that, in any effective governance system, technical experts (e.g. ICES) should provide policy advice to decision-makers (e.g. EU fisheries ministers) but that the policy decisions should be made by executives who can look across issues more broadly than the technical specialists can. Once those decisions have been made, it is the task of the technical people to apply the policies as those have been set, not to manipulate the rules because they know better (even though they often do). That said, I would not suggest the EU as a shining example of effective governance and perhaps ICES is justified in making dysfunctional changes to the directives it is given, balancing other failures of the overall management system. Only someone with intimate knowledge of that particular system could offer reasoned comment on that point and it's not likely that anyone in that position will speak publicly.

Trevor Kenchington

It is evident that the paradigm that large spawning stocks always provide strong recruitment and vice-versa has been wrong all the way, and science should look for the physical and biological reasons for the respectively poor and abundant recruitments that, in different years, don't correlate with SSB levels. On the contrary, stronger recruitment is more probable when the SSB is small, but consists of large, esp., female individuals. In at least 3 cases (Atlantic cod, hadock and saithe), ICES data (2006) show that recruitment correlates with SSB only to a certain stage, but as the latter grows recruitment shrinks. I don't believe that these simple and well-documented facts made any impression on the managemental inertia. Do check. The relevant graphs appear also in Jon Kristjansson's and my papers, (references on request).  MB-Y

Hi Menakhem

I am not sure I follow the relevance of your comments above. MSY is calculated taking into account the density-dependent recruitment of the stock i.e. it does account for the non-linear relationships between recruitment and SSB. The issue of age structure in the spawning population is another complicating factor and only for a few stocks do we have good enough data on the real stock structure to investigate that problem - NorthEast Arctic cod is a good example (certainly not all Atlantic cod stocks).

In terms of ICES advice, in my experience it always tries to provide advice consistent with the policy - so previously the advice was framed within a precautionary framework, now we have moved to MSY. I think these changes have led to some of the potential confusion with the various triggers and reference points now being cited in the advice.

I think the EU CFP reforms also recognise that central control is a blunt instrument which has not worked too well  - hence regionalisation is a key pillar of the reforms - not very clear yet how that will work though.

Hi,

yes, part of the current confusion about MSY implementation is caused by the recent change in the policy (from precautionary to MSY) and the need of time to understand and adapt to the new situation combining both, precaution and MSY. The ICES idea of adding a Biomass trigger is part of this process. Still in the development stage.

Regarding the issue of stock structure, the reproductive value of large fish and its role on MSY reference points I'd like to suggest you this paper:

Cerviño, S. R. Domínguez, E. Jardim, S. Mehault, C. Piñeiro and F. Saborido-Rey. 2013. Impact of egg production and stock structure on MSY reference points. Implications for Southern hake management. Fisheries Research.138: 168-178.

It explains why considering the reproductive value of bigger females does not impact so much on Fmsy. The main source of uncertainty in this case is the type of relationship (Beverton-Holt or Ricker)

In this other paper we adressed the issue of the mixed fisheries MSY with bioeconomic models:

Da Rocha, J-M., Gutiérrez, M-J. and Cerviño, S. 2012. Reference points based on dynamic optimization: a versatile algorithm for mixed-fishery management with bioeconomic age-structured models. ICES Journal of Marine Science, 69 (4), 660–669.

Money is the way to sum up yield of different species. As expected, economic considerations suggest a lower Fmsy.

Should not SSBMSY act as the trigger for what should arguably be the real objective in commercial fisheries management i.e. SSBMEY or perhaps SSBMSEY?

If we were to change over to managing fisheries rationally, aiming to optimize the human benefits obtained by fishing (instead of playing games with arbitrary points on some theoretical curve generated by an unrealistic population-dynamic model), why would we invoke MSY at all?

In response to David Hall's point - the answer is yes, sort of! Where ICES is able to define a biomass target it usually does so but for many stocks the biomass target is highly uncertain. In these cases they tend to default to an estimate of F which should yield MSY over time - this can be based on various ad hoc rules or can be taken from meta-analyses across a larger number of similar stocks or species.

In response to Trevor's point I am not entirely sure what he is suggesting as a better approach - last and previous post.  My impression was that the idea of following science advice with triggers and targets etc was brought in precisely because the previous situation -where EU ministers often set excessively high quotas for national interest reasons got us into this mess in the first place.

At present EU is exploring idea of regionalisation and we will have to see if that works out better than the present centralized approach.

It would be really interesting to hear some examples globally which seem to work better (I'd certainly be interested in terms of the course I teach on fisheries ecology). Pacific halibut springs to mind but is that actually being managed within an ecosystem-framework or following a single-species approach?

Hi Clive, as you're teaching ecology, why don't you suggest to manage fisheries according to the fishes' ecology? Many of the ups and downs in fish stocks have been stubbornly atributed to successful management and  excessive yields, respectively, with ecology  entirely disregarded. Stocks fluctuate, fishing or not, also in result of ever-changing influence of many factors, hardly dependend on the fishing itself. Stocks might've shrunk for any reason, and lay low, in spite of moratoria, reduction of MSYs and other acronyms, because, e.g., other organisms, better fit to the environmental change that might've occurred, fill up the vacant or partly vacant niche. The new dwellers may stick around, until the conditions return to the previous state and the original "owners" return in force, with some manageres publishing a triumphant paper on how their acronyms brought back the fish. Forgive me my style, but I'm a bit exasperated.

Clive: Debate (and I use that term loosely!) about fisheries is often trapped into sterility by conceptions that date back to Huxley's time and even more to the seminal work of Michael Graham in the 1930s. Great men both, but they set us on a course that has failed and yet still shapes the shouting.

For one (amongst many), there is the nonsensical notion that the science of fish is sufficient as a science of fisheries. We (as human societies) harvest fish but we don't do it to benefit the fish. We do it for us (for a seafood supply, for jobs, for profits, for personal satisfaction or whatever combination of those and other factors). Rational, science-based management would use biological advice to define the constraints imposed by fish production but socio-economic advice to define the optimum within those constraints. Both forms of advice could be and should be scientific -- and thus set apart from the agenda-based statements of what various interests wish was true.

Then there is the folly of supposing that fisheries management has to be (perhaps should be) some sort of contest between conservationists and rapacious fishermen, with politicians usually favouring the latter. That has been the pattern in too many fisheries but it wasn't in most until attempts at government-centred management created the problem.

There has to be a better way. At least, I continue to keep faith that there is. If I am wrong, the coming generations will lose much more than merely the fisheries of this tired old planet.

The specifics of EU fisheries management, I will leave to those who are directly involved. Just remember that, in this field if no others, the EU has a long way to go even to catch up with most of the rest of the developed world. And we have further to go before finding a system that makes sense. It will take much more than regionalizing the existing system to create real progress.

Hi Menakhen/Trevor

I do teach fisheries in an ecological framework - the module I lead is called Fisheries Ecology - not Fisheries Management. However, there are some things we can try and control, and others which are out of our control. For offshore fisheries about the only thing you can try and control is the fishing itself (and make use of MPAs to protect spawning areas etc.).

Whether changes in stocks are due to changes in ecosystem productivity or harvest rates actually makes rather little difference to our response  - if over-harvested or productivity is declining we have to cut fishing and if SSB or productivity improves we can allow a higher harvest  - I am really talking here about offshore stocks and not coastal or freshwater where habitat degradation and pollution can be very important - and should of course be controlled.

Perhaps this is getting closer to what Trevor is meaning because it is not assuming there is a long-term stable MSY - which is where this interesting debate kicked off.

Interestingly I think Huxley has been widely mis-interpreted. If you check out his full paper for the Fisheries Exhibition he talks about over-fishing of oysters for example. He does say the offshore stocks appear in-exhaustible, but that was in the context of the fishing technology of the time - I really do not think he can have been expected to foresee the huge technical changes which occurred in the 20th century. Unfortunately he is often lampooned now by modern writers.

I also think we need to be a bit cautious about being too negative about current management. because In many cases where we have reduced fishing mortality we do see stocks rebuild i.e. they do often respond to this control (of course there are some well known counter-examples).

"Just remember that, in this field if no others, the EU has a long way to go even to catch up with most of the rest of the developed world." Specific examples please?

Clive: No criticism of you as an individual. You are repeating the standard wisdom. However, by doing so, you are reinforcing my point.

I was not referring to Huxley's famous comment. (Which was probably incorrect for the North Sea trawl fisheries of his day, though I do not fault him for not realizing that.) My reference was to his _time_. That was the era when scientists were first drawn into marine fisheries questions. (Buckland had undertaken his studies in salmon streams earlier, of course.) The choices made then have shaped fisheries management ever since. One important choice was to give the primary role to a zoologist. Economics and sociology had not been invented then, so perhaps there wasn't much other option. Anyway, as an educated gentleman of his day, Huxley probably had as good a grasp of economic principles as almost anyone else in Victorian England. I suspect, nonetheless, that formulating the problem in terms of resource biology suited a time of laissez faire, when people did not readily take to the notion that government limiting investment might be a good idea. If the offshore fishermen of that era were like those today, they too probably preferred the idea that the problem was with the fish, since that did not involve some outside authority micromanaging their operations.

As to not being negative about current management because the resources can rebuild when mortality is cut: You are again repeating the popular mantra. Of course that happens in most cases. (Why wouldn't it, if F has been anything but negligible?) The only interesting questions on that issue concern the cases where populations do _not_ respond to reductions in mortality rates.

My point is that rebuilding resources (where they have been depleted below some optimum) is merely a small step along a hard road. We achieved that with the Atlantic Canadian groundfish in the later 1970s, aided (as recoveries almost always are) by good recruitment. Then we collapsed the largest sector of the industry in the early'80s, despite the resources being better of than anyone could remember, put that back together by '85 ... then lost the lot in '92-93. Getting fishing mortality down (though sometimes up) to a sensible level is obviously needed. Ditto for biomass. But that is nowhere near enough.

To make the central point again and perhaps more clearly: Managing fisheries to achieve goals defined in terms of the resources is a fundamental policy mistake. We fish to advance human interests (or else we would not fish at all). We need to manage fisheries so as to achieve that advance in human interests -- sustainably (in most cases) and without undue collateral impacts on the rest of the planet but still to achieve the advance. Until management can do that, and maintain it over the long term, it is not meeting the need.

As to the EU's attempts: Compare your own comment about EU Ministers, until recently, setting quotas in terms of national interests against Canada's tight (but ultimately ineffectual) science-based controls from circa 1980, Australia's resolution of the local vs large-scale tension through its offshore constitutional settlement of the early '80s, or New Zealand's thorough ITQ system from the mid-80s. And those are only the second-grade fishery-management nations. I lack the facility with languages that would be needed for definite conclusions but I suspect that the fisheries-management systems in Japan, Norway and Iceland have left all the benighted Anglos in their dust.

This is all getting far away from the theme of this thread, which concerned ICES' use of reference points. Should we create a new thread and continue there? 

Hi Tevor

Yes I think the debate has gone too far from the original question. It would be great to start a new thread and hopefully get some more opinions coming in.

I think what you are saying is that to achieve sustainability goals we need to view fisheries as a complete bio-socio-economic system but I am still a bit hazy about what  an optimal system would look like.

High everybody,

I agree with Clive, I have not seen many management scheme which targets are based on economics rather than on the ecology of the target-stock, and thus it is elusive, how such a system should look like. There may be some small-scale examples from e.g. the US, Australia or other regions of the world and these would be interesting to collate. If the systems from these regions could work in a large-scale political systtem like the EU CFP, I cannot judge. Maybe anyone has some literature on this already?

Anyway, with the original debate about SSb_MSY vs. B_MSY trigger, I cannot find a clear tendency which reference point would be preferred by the people who answered to this thread. My conclusion so far is, that converting Bpa to B_MSYtrigger cannot be the final answer, but instead a limit value for SSB should be derived from a probabilistic distribution of SS_BMSY. This limit value should allow to test whether SSB is significantly lower than SSB_MSY and if so, harvest control rules for F should kick in.

Trevor Kenchington, can you enlighten me please on what you mean by your statement that Canada, New Zealand and Australia were "only the second-grade fishery-management nations"?  I would have thought that these countries led the world in terms of fisheries management.

David: I think each of those three has, at times, led one or another facet of fisheries management. I suspect that, in terms of overall performance, Japan, Iceland and Norway have done better, each in its own way. However, it is very hard to know without deep experience in the management system in question. I have been in or around Canadian fisheries management since 1980, was fully immersed in the U.S. version from 1999 until 2006, but was only briefly (though directly) involved in the Australian one from 1984-87. In that era, we (in Australia) closely watched what was going on across the Tasman Sea. However, I have only once visited iceland and never Norway or Japan. I do not speak or read their languages. I am left with impressions of how their management systems function and what they have achieved but, sadly, I cannot confirm or refute those.

Trevor, I was involved in Australian fisheries since 1981 and in the 1980s was quite involved developing OCS arrangements in several States as well as implementing ITQ management systems and buy-backs with a view towards optimising MEY or MSEY notwithstanding the lack of usable algorithms! While my focus for the last 13 years or so has been on running our fish tag manufacturing business (Hallprint), I recently returned to a "mainstream" fisheries role as a Commissioner with the Australian Fisheries Management Authority which as you would know is now responsible for managing Australia's domestic federally managed fisheries such as shark, trawl and tuna. My observations are that Australia has advanced considerably as a fisheries management nation in this time through the implementation of harvest management, stock rebuilding, by-catch and environmental strategies associated with clearly articulated policies.  My company does supply tags to Norway, Japan and Iceland and our customers there all speak very good English.  I am certainly not convinced that these country's fisheries management systems or record in fisheries management is superior to Canada, New Zealand or Australia's but I probably can't make an objective comparison either as I have not visited Norway, Japan or Iceland either.  For the first time Australia's fisheries were recently assessed by ABARES to have not a single species that was "subject to overfishing".

During the last decades, in most if not all the countries mentioned, management by output (ITQs, catch shares, etc.) had been introduced. It has led inevitably to concentration of fishing rights in the hands of coroporate and other big owners, and to dislocation from the fishery of smaller owners. It might've increased total profits, but on the expense of social benefits and weakening or total demise of coastal communities. There're contradictory reports and opinions about the effect this sort of management has had on the fish resources.

if K is assumed as a constant (a premise for a MSY based on linear approaches combined to the logistic eq.) ... well, the results are always going to be the same, no matter how you go around the question (and how many further concepts you discuss: crunching down signals, underfitting series, omitting memories and __autocorrelated residuals__ ... will always lead you to under-exploiting the stock for the relatively higher abundances and -what is worst- over-exploiting it when it is as most vulnerable, during periods of relatively lower abundances ... long history. Best from Greenland.

I agree with Aldo's point - clearly a constant MSY or any other constant target reference level will not cope with changes in stock/ecosystem productivity - I think what people are struggling with is how and when to trigger a revision in reference points - clearly you do not want to be revising them every year but on the other hand it is difficult to know when a longer-term shift in productivity has occurred as opposed to a short-term change. Be interested in other people's thoughts on this.

We have to make the push for variable reference points [r(t), K(t), MSY(t) ...] and for incorporating (into the models&management) delays, memories, the variability in the data and the combined effects from the environmental forcing and F.

I proposed this at the NAFO SC. A first council to discuss these issues.

I agree with Clive.

Best from Nuuk/Greenland ("Halibut Town" :-)

Aldo: I would be interested to see just what you proposed to the NAFO SC. (I'm sure that it was too advanced and complex to be set out in the format of this discussion board.) However, as you have stated it here, you seem to be merging different kinds of variability.

MSY may be invoked in a reference point (though I could wish that fisheries-management agencies had progressed beyond such foolishness) but r and K are parameters to be estimated on the way to an estimate of the quantitative value of a reference point (amidst other purposes). Data variability is something else again, of course. Meanwhile, the responses of resource populations are to the combined effects of all drivers but there is good reason to treat the effects of F separately from the rest ("the environment") because the point of the modelling is usually to aid management in its attempts to adjust F in order to attain some desired policy goal.

If your proposal is that the environment and the resources' responses to it should not be treated as constant, then I doubt that anyone will disagree with you. I heard the same demand nearly 35 years ago and nobody disagreed with it then. But the people who shouted the suggestion couldn't say how it should be done and those of us charged with doing stock assessments (in my case: for Atlantic Canadian groundfish) knew that we didn't have enough data, even if we made the standard (but absurd) assumption that all of the drivers except F and recruitment were unchanging. If we allowed M, K and W[inf] to change over time, we could not have drawn any conclusions at all -- and that despite making a bunch of other equally absurd assumptions, such as supposing that the biological structure of the resources conformed to the existing management units (mis-named "stocks").

Even back then, I thought that we would have done better to admit that we could not produce any advice at all. It took another ten years for the management failure to become inescapable but, to me, when our groundfish fisheries were managed out of existence, it confirmed that those of us on the science side would have been better to proclaim ignorance than to pretend to a knowledge that we did not have. 

The global fisheries-science community has moved ahead in our understanding through the decades since, of course, but I doubt that the fundamentals have really changed. With a few happy exceptions, we still have neither the background knowledge nor the case- and time-specific data that we would need if the status of resources and fisheries were to be compared against chosen reference levels with useful precision.

We could argue over which fisheries might be amongst the exceptions. For the rest, and as I have said in earlier contributions to this thread, I think we need a radically different approach to fisheries management.

Maybe what matters is less BMSY vs MSYbtrigger than what happens when B falls below the reference point.

Perhaps the most important thing is to make sure there is adequate data to characterise biomass state, rapid reaction if B is too low, and compliance with agreements when F is cut.

See e.g. Thorpe 2019 North Sea multispecies MSY in journal of fish biology where we looked at performance of 238 different harvest control rules.

the consequence of such an approach, everywhere, has been overfishing. if they do not change the "old-timers", they are going to destroy everything. Bayesian approaches, the logistic equation and fixed population parameters are useless.

Interesting discussion. In the US, the absolute biological catch (ABC) levels is well below MSY to account for uncertainty.

For public terminology, I like how MEY (maximum economic yield) states that this level of harvest results in the highest profits for fishers. Mathematically, MEY is below MSY and thus helps add caution. Of course, the practical and management challenge of reducing capacity and effort to levels that can achieve MEY will be challenging and require deep cooperation between managers and fishing communities. Just some thoughts!

Sorry, Holden, but I cannot agree with either of your statements.

US ABC's are set below estimated MSY for various reasons but nowhere near far enough below to account for all of the uncertainties. If they were, most of the fisheries might as well be closed -- and then we would never gather the information needed to reduce the uncertainty. With a few happy exceptions, we have no choice, through the opening decades of this century, but to manage fisheries while carrying a whole lot of risk of failure.

More important: MEY is not and never has been about yielding the highest profits for fishermen. It is a macro-economic concept and (in a theory that lies somewhere between over-simplified and absurd) purports to represent the greatest difference between costs and revenue for a society or nation. Beverton and Holt (1957) came closer to the maximum-profit-for-fishermen (micro-economic) idea when they suggested that only allowing a single boat into a fishery would be maximal. (That is wrong too, as anyone who has tried to operate an industry sector based on a single boat could tell you.)

Which brings us to another problem: Maximizing profits for Fisherman A does nothing for Fishermen X, Y and Z, whose exclusion from the fishery is necessary if A's profits are to be maximized. As most people who chose a fisherman's life would rather fish with little economic return than not fish at all, maximizing anyone's profit without considering how many people get to share in that maximization can swiftly become a pointless exercise. So is maximizing net returns to a nation, if the value of fishing is considered only in economic terms.

The too-frequent misunderstanding of such complexities goes a long way towards explaining the mess that fisheries management fell into through the second half of the last century.