Edited by: Athanassios C. Tsikliras, Aristotle University of Thessaloniki, Greece
Reviewed by: Fabian Zimmermann, Norwegian Institute of Marine Research, Norway; Katrine Soma, Wageningen University and Research, Netherlands
*Correspondence: Rudi Voss
This article was submitted to Marine Fisheries, Aquaculture and Living Resources, a section of the journal Frontiers in Marine Science
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Fishing is a social and economic activity, and consequently socio-economic considerations are important for resource management. While this is acknowledged in the theory of Ecosystem-Based Management (EBM) and its sector-specific development Ecosystem-Based Fisheries Management (EBFM), currently applied fishery management objectives often ignore economic considerations. Year-to-year management, however, implicitly responds to short-term economic interests, and consequently, regularly resorts to tactical short-term rather than strategic long-term decisions. The aim of this article is to introduce a new way of estimating management advice referred to as an “ecologically-constrained Maximum Economic Yield” (eMEY) strategy, which takes into account ecological criteria as well as short- to medium-term economic costs. We further illustrate what net cost reductions per year are possible applying the eMEY strategy compared with the existing way of setting total allowable catches (TACs). The eMEY approach aims at maximizing the economic benefits for the fishery as well as society (consumers), while safeguarding precautionary stock sizes. Using an age-structured optimization model parameterized for the Eastern Baltic cod case study, we find that application of eMEY advice results in more stability in catch advice. Quantification and visualization of the costs of deviating from eMEY advice offers a transparent basis for evaluating decision-making outcomes. The costs of overfishing are mainly borne by the commercial fishery, while fishing less than optimal is particularly costly for the processing industry and consumers. To foster the uptake of our eMEY approach in current advice given by the International Council for the Exploration of the Sea (ICES) and the EU fishery management system, we suggest an easy-to-implement scheme of providing integrated advice, also accounting for economic considerations.
Overfishing is a major challenge to global future sustainable development (United Nations,
Such a restriction in the interpretation of sustainable fishing is, however, in contradiction to Ecosystem-based Fisheries Management (EBFM). EBFM explicitly includes ecosystem as well as social, cultural and economic considerations, and its further development is high on the international science and policy agenda (ICES,
After the revision of the EU Common Fisheries Policy in 2013, a first Multi Annual Management Plan (MAP) was developed for the Baltic Sea region, which is supposed to act as a blueprint for other European regions. The Baltic MAP mentions social and economic objectives, but actual management is still based only on criteria to meet reference levels of fishing mortality (FMSY) or stock size, i.e., to reach levels at or above BMSY (the stock biomass to produce maximum sustainable yield; EU,
Currently, scientific (ecological) advice on the ecologically and economic important Eastern Baltic cod stock is based on work by the ICES Baltic Fisheries Assessment Working Group (WGBFAS). On a yearly basis, WGBFAS assesses and evaluates stock status and dynamics, and predictions of catch option for the next year are performed. Catch options and advice are drafted and delivered to the EU Commission, which takes the actual catch decision. The Commission is supported in its work by stakeholder input from the Baltic Sea Advisory Council (since 2004). Until 2013 the stock belonged to category 1 (stocks with full analytical assessments and forecasts for catch options). ICES advice was based on the MSY approach, i.e., attaining a fishing mortality rate of no more than FMSY while maintaining the stock above a lower limit biomass (Blim) with at least 95% probability. In this approach, ICES (
Long-term simulations of Eastern Baltic cod development suggest that constant fishing at FMSY probably fulfills at least the ecological objectives (Voss et al.,
The aim of this article is to introduce a new way of estimating management advice referred to as an “ecologically-constrained Maximum Economic Yield” (eMEY) strategy, which takes into account ecological criteria as well as short- to medium-term economic costs. We further illustrate what net cost reductions per year are possible applying the eMEY strategy compared with the existing way of setting TACs.
To this end, we advance the concept of Maximum Economic Yield (MEY). The optimal stock under MEY can be smaller or larger than the MSY stock size: While discounting may lead to the famous result of optimal extinction (Clark,
Our new eMEY concept includes social and economic as well as ecological criteria (related to minimum stock sizes) to produce short-term advice that serves as the basis for achieving long-term targets and thus advice for multi-annual management plans. The recent adoption of fishing mortality ranges as a management goal in the Baltic MAP (EU,
We used an ecological-economic optimization model for a fishery of an age-structured fish stock with eight age-classes, parameterized for the Eastern Baltic cod trawl fishery. The model calculates the economic optimal fishing effort and related TAC to be set in the next year, using a short- to medium-term perspective, and current stock conditions as input. As ecological side condition, the stock size needed to produce MSY (BMSY) has to be safeguarded. Age-based population numbers, survival rates and body weights are obtained from the standard stock assessments (ICES,
Using our ecological-economic model in a hindcast mode, we calculated a hypothetical eMEY advice for the period 1989–2013, i.e., reconstructed economically optimal TACs, while safeguarding ecological criteria. We only used data that had been available in each assessment year: we used the stock structure of the most recent assessment as provided by the ICES Baltic Fisheries Assessment Working Group (WGBFAS) as starting conditions (ICES,
The model also offers the opportunity to illustrate and quantify the economic consequences of TAC setting deviating from eMEY. We first quantified these economic costs for the time-series 1989–2013. Afterwards we performed a sensitivity analysis of duration and degree of deviating from eMEY on economic costs. This analysis provides general insights on trade-offs and cost dynamics. Concerning trade-offs, we consider the direct impact on the fishery (fishery profits) on the one hand, and social benefits generated for consumers as well as the processing industry (user surplus) on the other hand. The costs are summed over a period of 10 years, applying a discount rate of 0%. Short-term, tactical considerations, which lead to higher (or lower) exploitation rates than optimal according to our eMEY concept, will have to be counter-balanced in the future. Therefore, we assume the deviations to occur in the first 4 years. Afterwards management switches back to optimal eMEY management, so that minimum ecological constraints (BMSY stock size) are achieved latest after 10 years. The assumption of switching back to optimal management after 4 years is somewhat arbitrary. In the sensitivity analysis we hence quantify the economic effect of non-optimal eMEY fishing over 1–10 year time-spans, as well as different levels of deviation from eMEY advice.
Using our ecological-economic optimization model we compared TACs derived according to our eMEY strategy with the catch limits historically advised and subsequently set by the EU fishery management (Figure
Time-series of ecologically-constrained MEY (eMEY; 10 years time perspective), ICES advice, politically agreed TAC, as well as actual catches for the Eastern Baltic cod fishery. Up to 2003 a common TAC was set for the Eastern and the Western Baltic cod stocks; we westimate the TAC for the eastern stock only, based on the biomass ratio of both stock components. Error bars on eMEY estimates show the results of a sensitivity analysis concerning economic model parameters.
Summary of model output, comparing different management regimes considered: eMEY management, ICES scientific advice, politically agreed TACs, and classical MEY.
1989 | 24.2 | 179 | 220 | 16.6 | 35.7 | 29.1 | 29.1 | 33.1 |
1990 | 20.7 | 129 | 210 | 14.0 | 33.0 | 27.1 | 27.1 | 30.5 |
1991 | 12.7 | 122 | 171 | 9.0 | 30.7 | 24.4 | 24.4 | 28.7 |
1992 | 17.8 | 0 | 100 | 12.4 | 31.7 | 24.2 | 27.3 | 29.3 |
1993 | 20.9 | 0 | 40 | 14.2 | 33.0 | 25.0 | 32.7 | 30.5 |
1994 | 23.4 | 25 | 60 | 16.0 | 33.7 | 33.7 | 32.7 | 31.3 |
1995 | 23.4 | 80.8 | 120 | 16.0 | 33.1 | 29.1 | 27.2 | 30.7 |
1996 | 19.9 | 76.1 | 165 | 13.6 | 31.6 | 27.1 | 23.2 | 29.3 |
1997 | 14.5 | 130 | 180 | 10.7 | 30.1 | 18.0 | 17.7 | 28.4 |
1998 | 13.5 | 60 | 140 | 10.0 | 29.7 | 24.4 | 19.0 | 28.0 |
1999 | 13.9 | 88 | 126 | 10.6 | 29.8 | 20.7 | 19.8 | 28.3 |
2000 | 11.9 | 60 | 105 | 9.2 | 28.9 | 22.3 | 18.4 | 27.6 |
2001 | 6.2 | 39 | 105 | 6.6 | 25.8 | 17.3 | 6.7 | 26.6 |
2002 | 6.3 | 0 | 76 | 6.7 | 24.2 | 18.5 | 8.4 | 25.1 |
2003 | 5.3 | 29.3 | 75 | 6.7 | 22.2 | 16.0 | 7.1 | 24.2 |
2004 | 7.6 | 13 | 45.4 | 6.7 | 24.0 | 23.6 | 16.4 | 23.7 |
2005 | 8.3 | 0 | 42.8 | 7.7 | 23.6 | 17.8 | 17.6 | 23.6 |
2006 | 9.7 | 14.9 | 49.2 | 9.1 | 24.2 | 23.9 | 18.2 | 24.3 |
2007 | 11.7 | 0 | 44.3 | 10.1 | 26.7 | 19.8 | 22.7 | 26.2 |
2008 | 16.2 | 0 | 42.3 | 13.6 | 27.3 | 20.3 | 25.5 | 26.5 |
2006 | 20.5 | 48.6 | 49.38 | 16.5 | 28.4 | 26.9 | 26.8 | 27.2 |
2010 | 24.6 | 56.8 | 56.1 | 19.2 | 29.7 | 28.3 | 28.3 | 28.2 |
2011 | 23.0 | 64 | 64.5 | 17.9 | 30.8 | 28.4 | 28.3 | 29.1 |
2012 | 29.3 | 74.2 | 74.2 | 22.7 | 32.4 | 30.4 | 30.4 | 30.6 |
2013 | 32.0 | 65.9 | 68.7 | 24.8 | 32.8 | 31.7 | 31.5 | 31.0 |
Mean | 29.3 | 24.3 | 22.7 | 28.1 |
Furthermore, annual fluctuations in eMEY based TACs are much smaller than in the other two management options, and therefore best meet the objective of inter-annual stability of catches, which is often put forward by fishermen and managers (Rindorf et al.,
The eMEY-based advice for next years harvest levels is, however, higher as compared to the classical MEY approach (Table
Typically, MEY management builds up the stock fastest, while stock recovery under TAC management is slowest. Our eMEY solution forms a compromise between the ecological and economic objectives. In years with the special case of zero catch advice (e.g., 1992), the resulting fast stock recovery is economically non-optimal (Figure
In a next step, we quantified the economic costs of deviating from the optimal, integrative eMEY advice for the historic time-series. These costs could have been saved in the past, if the eMEY strategy had been applied. In extreme cases, the costs sum to >1,200 million € over a 10 year period when the historical advice would have been used, and almost 2,000 million € when the realized TAC decisions would have been applied (Figure
Economic costs of deviating from advice: time-series 1989–2013. Costs arising when following standard scientific advice
Due to tactical consideration, politicians often choose to set a TAC, which is not in line with scientific recommendations. Our approach offers the opportunity to project the societal costs of deviating from the ecological-economic optimum, i.e., the effect of setting a higher or lower TAC than scientifically advised according to our eMEY concept. The costs depend on the degree of deviation as well as the duration of the deviation (Figure
Economic costs of over- or under-fishing for the year 1994. Costs for the fishery in terms of foregone fishery profits as well as for the consumers and fish processing industry (user surplus). Costs depend on the degree of deviation from ecological-economic optimal harvest (
After a period of strong decline in stock biomass and associated fishing options, the Eastern Baltic cod stock was assessed to have considerably increased in 1994, partly due to improved environmental conditions. Management decisions at this perceived turning point are particularly interesting, as the objective of further stock recovery had to be traded against increased harvesting prospects. The eMEY advice for 1994 amounts to 30.500 tons (harvest multiplier = 1.0 on x-axis of Figure
In more general terms, the costs of deviations from the eMEY optimum increase non-linearly with both over- and under-fishing the resource (Figure
The impact of a variable duration of the deviation from eMEY advice (between 1 and 9 years) is investigated closer in Figures
Scientific advice on harvest opportunities is currently given on basis of long-term ecological objectives, i.e., the MSY objective. Decision makers are, however, confronted in their daily lives with short-term socio-economic pressures, which they have to account for in their decisions (Voss et al.,
Here, we developed a new way of estimating management advice, which takes ecological as well as economic, short- to medium-term objectives explicitly into account. Using an ecological-economic optimization model of a fishery on an age-structured population we provide additional fishing options, and illustrate and quantify the effect of deviating from the optimum (i.e., setting higher or lower TACs than economically optimal). This kind of information could be used for constructing integrated advice, which is one step forward toward EBFM.
There is a clear need to change the existing management toward an eMEY strategy in order to reach the overall objective of EBFM, which is to sustain healthy marine ecosystems and the fisheries they support, including social and economic benefits (Pikitch et al.,
The political will to proceed to EBFM (including socio-economic considerations) is formulated in the latest reform of the European Common Fisheries Policy (CFP). It not only emphasizes its commitment to pursuing MSY but also that the CFP shall implement an ecosystem-based approach to fisheries management (EU,
The transition from the current management system, which is mainly based on biological considerations, toward a more integrated ecological-economic assessment and advice system seems difficult. However, the request for enhanced stability of fishing opportunities and reduced uncertainty (Rindorf et al.,
We propose a stepwise transition, which offers progress, but still continuity. In the frame of the ICES Workshop on DEveloping Integrated AdviCE for Baltic Sea ecosystem-based fisheries management (WKDEICE) a theoretical framework was established (ICES,
Incorporation of ecological-economic modeling and environmental information in the standard advice process to proceed to a more integrated advice, and ecosystem-based fisheries management.
It is crucial for acceptance of our new strategy (by scientists as well as stakeholders), that the underlying model assumptions, limitations, and uncertainties are communicated. Our results are strongly driven by the estimates of cost and price parameters: We use empirical data, which are specific for the eastern Baltic cod fishery (see Supplementary Material). We allow for a time-trend in the cost parameter, and include the interplay with important potential substitutes, i.e., Northeast Artic cod catches when specifying the demand function. Nonetheless, we provided a thorough sensitivity analysis of the economic parameters to assess how robust our results are. Despite considerable uncertainties (see Figure
As the Baltic ecosystem and its associated fishery, including its socio-economic aspects, are frequently changing due to the influence of various human and naturally induced drivers (Möllmann et al.,
Finally, in a multi-user or multi-species context different management strategies will result in winners and losers (Voss et al.,
RV, MT, and CM chaired the original workshop this paper is based on. RV, JS, MT, and CM designed the work. MQ and MS prepared the economic input data and run the bio-economic analysis. JS and MQ prepared the ecological input data. RV wrote the paper. All authors contributed in interpreting the results and contributed to critically review the text.
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
The authors wish to thank all members participating in the ICES Workshop on DEveloping Integrated AdviCE for Baltic Sea ecosystem-based fisheries management (WKDEICE) for valuable support and discussions.
The Supplementary Material for this article can be found online at:
MT was funded by the BalticEye and DEMO Stockholm University projects. Baltic Eye is partnership between Stockholm University and foundation BalticSea2020 and DEMO—“DEMOnstration exercise for Integrated Ecosystem Assessment and Advice of Baltic Sea cod” was funded by Granholm Stiftelse.