Frequently asked questions

Frequently asked questions

The following is a selection of questions that come up most frequently. All questions are covered in more detail in the documentation section.

Which species are covered?
This is a model of commercially fished species under quota management. Because of this focus, which aligns with the focus of policy, there are smaller changes in BEMEF to fleets that primarily target non-quota species. While it is not specifically analysed in BEMEF, there are likely to be similar impacts of MSY as stock assessments of inshore species show similar patterns of low biomass and high mortality (Cefas, 2011; ICES, 2014; eftec, 2015).

The 25 species covered in BEMEF are as follows: anchovy, anglerfish, atlantic salmon, blue whiting, cod, dab, haddock, hake, herring, horse mackerel, lemon sole, mackerel, megrims, northern prawn, norway lobster, norway pout, plaice, pollack, saithe, sandeel, skates and rays, sole, sprat, turbot, whiting.

Which waters are covered?
The areas covered match those under quota management, which is primarily in the North Atlantic and Baltic Seas. Similar impacts are likely to be seen in the Mediterranean where stocks are severely depleted (Cardinale & Osio, 2013;Merino et al, 2015) but may not be the case in the Black sea which has experienced less historical pressure (Goulding et al, 2014).

To only include fleets fishing in the North Atlantic and Baltic Seas, a rule is used in BEMEF to remove any fleet from analysis with less than 50% of its landings occurring in these waters.

What is MSY?
MSY, the maximum sustainable yield, is the highest level of fishing that can be sustained for an indefinite period. The concept of MSY has a long history in natural resource economics and was recently enshrined as the goal of the European Union’s Common Fisheries Policy. Although MSY is often framed as a policy goal, fisheries scientists are clear that it is more appropriate to hold MSY as a limit (European Parliament, 2015). As MSY is a yield it is associated with a necessary level of biomass (BMSY) and fishing mortality (FMSY).

There are related concepts to MSY, like maximum economic yield (MEY), but the same principle of sustainable stock levels holds and it is MSY that is the law in the EU’s Common Fisheries Policy. For this reason it is MSY that is simulated in BEMEF, although in reality fishing below the limit is necessary in a variable system (Froese et al., 2014).

Even in its most simple form there exists uncertainty about these estimates. Some of this is due to the lack of historical experience with low fishing pressure (below Fmsy). There are also issues about the density-dependence effect (Ohlbeger et al., 2014;) and how this interacts with low fishing pressure (Svedäng & Hornborg, 2014;).

Can MSY be achieved for all species simultaneously?
No, MSY cannot be achieved simultaneously for all species because species are not independent. Most significantly, species interact through predator-prey relationships and through competition for food. These interactions will matter even more as fishing pressure decreases as fish stocks are rebuilt. Drawing

When these interactions are estimated, the MSY estimates for species in an ecosystem also change, and new frameworks are being established for this form of assessment (Rindorf et al., 2013).

Within a system an MSY arrangement decisions need to be made about what outcome is being optimised. The result may be an unequal distribution of benefits across Member States (Voss et al., 2014).

BEMEF uses multi-species estimates where available and will continue to update as estimates improve. One promising development is the MyFish project that is due to report on targets and limits while incorporating these concerns in October, 2015.

Where do the MSY estimates come from?
As explained in the documentation section, the estimates come from a variety of sources and maintain a hierarchy of multi-species estimates, single-stock estimates and current landings in that order. These estimates are from ICES, academic journals and current quota from the European Commission.

As new robust figures are published the estimates will be replaced. Currently, however, management decisions are being made and it is important to inform those decisions with the best available data and knowledge about MSY.

When can MSY be reached and how long is the transition period?
The issue of transition is a very difficult modelling question as it involves the constant interactions between fishing pressure, industry changes, economic drivers, stock abundance and ecosystem dynamics. There are also critical issues relating to policy and management decisions. To a large degree the issue of when MSY can be reached and what the transition period looks like comes down to these decisions. Ecosystem dynamics aside, the smaller the fishing pressure on a stock the more rapid the transition to MSY.

The Common Fisheries Policy aims to restore and maintain fish populations above levels capable of producing the maximum sustainable yield (Bmsy). The MSY exploitation rate (Fmsy) is to be achieved by 2015 where possible and by 2020 at the latest for all stocks. In overfished waters this will occur at a later stage as the system returns to an equilibrium with the reduced mortality rate.

Shouldn’t sustainable fishing mean catching less fish rather than more fish?
It depends on how far the fish stock has been depleted. For many stocks in EU waters the biomass level has been depleted so far that the stock is overfished and the yield is smaller than its potential. Historically for these stocks there was a period where yields were artificially high by sacrificing the biomass and replenishment rate of the stock, but in the majority of cases the MSY yield is expected to be higher than current landings.

Certainty the transition period to MSY will require reduced catches. While BEMEF can not model this period in its current form, other research from NEF has focused on this difficult question.

Why do some fleets and countries benefit more than others?
Different fleets target different stocks. The more depleted the stocks the more a fishery will benefit from reaching MSY. As countries typically have fleets targeting similar stocks, this effect is echoed at the country level.

Aren’t forecasting models highly inaccurate?
Models with a forecasting component, particularly economic models, are subject to widespread criticism for their failure to reflect reality. Indeed, we have noted before that economic forecasts are correct slightly less than half the time. For a profession with a great deal of hubris there is little evidence that even the best forecasters rely on anything more than luck. But while macroeconomics is infamously marred with poor forecasting, there is reason to believe we have a more realistic understanding of the key pressures and behaviours of fishing fleets. Furthermore, while the model is robust, the purpose of BEMEF is not to produce one specific result but rather to achieve four broader objectives.

What does BEMEF assume about fisher behaviour?
Modelling fisher behaviour involves theories of decision making in economics. There are different school of thought as to whether human behaviour follows a set of axioms used in classical economic theory. As BEMEF is a simulation model that projects from a historic base period, the most significant assumption is that fishers will behave much in the same way that they did in that period. This is in contrast to some bio-economic optimisation models that model fisher behaviour so as to achieve an overarching objective. These models can offer insights into certain optimisation scenarios but there also needs to be a link to actual fisher behaviour for policy-relevant implications. This is particularly important as optimisation models are often orientated for profit maximisation but some empirical evidence shows fishers do not fish to maximise profits (Holland & Sutinen, 2000; Eggert & Tveterås, 2009; Cambiè et al, 2015). Because of these issues with more formalised decision making theory BEMEF does not use an optimisation function and instead uses a projected simulation from the base period.

What is the brief summary of BEMEF’s resolution and structure?

Why is there no quota allocation scenario for ecosystem impacts?
As BEMEF operates at the fleet level, any criteria must have historic data across 221 fleets. This is a limiting factor so criteria for quota allocation were selected from what is already reported in the AER database. While some gear types and fisheries have a larger ecosystem impact than others, this is not systematically quantified or reported at the fleet level.

Outside of this data limitation there is evidence of reduced ecosystem impacts in the deep-sea from longline fishing compared to trawling (Pham et al., 2014), gillnets compared trawlers for cod in the UK (Crilly & Esteban, 2013), otter trawl and new Queen scallop dredge compared to traditional Newhaven dredge (Hinz et al., 2009) and longliners or pots compared to trawlers in the US west coast sablefish fishery (Jenkins & Garrison, 2013).

Studies in the US (Morgan & Chuenpagdee, 2003) and Canada (Fuller et al., 2008) have attempted to rank all gear types by ecosystem impacts, although these rely on expert ranking rather than fleet level data and the extent to which these ranking can be transferred to the EU is questionable.

Is it realistic to allocate quota between very different fleets?
The quota allocation scenarios should not be seen as a policy proposal. In reality quota allocation will take into account historic share to maintain some stability in the industry and rather than one single indicator it is likely best to use a suite of indicators in unison. Yet as this important issue has not been analysed in depth before the type of economic analysis BEMEF provides can move the discussion forward.

There are also questions about how much quota can shift give the capacity (current or future) of different fleets. Pinning down the amount of quota than can be shifted given a particular level of capacity is not an issue analysed in the model, although it is important to note that given the very small amounts of quota current allocated to some fleets (mainly smaller, inshore vessels) even a small change to quota is a significant marginal increase.

To address capacity issues in part, BEMEF calculate where fleets historically fish and what species they land at port before allocating quota. Only fleets that currently fish in a quota area are compared on the different indicators used. Fleets that land less than 50 kg of a species are not considered at all. The consequence is that quota for deep water fishing (eg. haddock in I,II) is only available to the large vessels that currently operate in this fishery.

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