The state of Baltic fish stocks should not be compromised –

Let 2018 be the year to fully follow the scientific advice on Baltic Sea fishing opportunities


Dear Sir/Madam, 

We at the Stockholm University Baltic Sea Centre firmly believes that the only way to ensure a long-term sustainable and profitable fishing industry in the Baltic Sea is to apply an ecosystem-based approach to fisheries management and protect the fish stocks from being overexploited. Such an approach requires a management that puts the state of the natural resources first and adjusts fishing effort according to how much the ecosystem can deliver. 

Unfortunately, during too many years, the safe exploitation limits for some of the most ecologically (and economically) important Baltic fish stocks have not been respected, and scientific advice has not been fully complied with in quota setting. Consequently, both the Eastern and Western Baltic cod stocks now are in critical states.

This damaging management has resulted in historically low cod catches in the Baltic Sea and a weakened economy in the fishery as well as an ecosystem without an important class of large sized, predatory fish. 

We stress that the kind of short-term thinking that has characterised the setting of fishing opportunities in the Baltic Sea in recent years now has to stop –for the sake of fish stocks, the economy of the fishing industry, and for the Baltic Sea ecosystem as a whole.

Our recommendations in short:

  • Do not exceed the ICES advised catch limits for the Eastern cod stock (26 071 tonnes).
  • Reduce commercial catches for the Western cod stock to the lowest possible levels, not exceeding ICES advice (between 1376 and 3541 tonnes).
  • Do not follow the EU Commission’s proposal to roll over fishing opportunities of 2017 exploitation levels for the Western cod stock (5597 tonnes).
  • Adhere to ICES advice regarding sprat fisheries in subdivisions 25-26.
  • Decide for a total eel fishing ban in the Baltic Sea, as proposed by the European Commission and advised by ICES.

Eastern Baltic Cod

The situation for the Eastern Baltic cod is especially worrisome since it is not only affected by intense fishing but also restrained by unfavourable environmental conditions.

In their latest advice for the eastern cod stock, the International Council for the Exploration of the Sea (ICES) show how the stock has been overfished during the last period of years[1]. The individual growth has become density-dependent, which constrains the productivity of the stock. We stress that sustainable exploitation levels for Eastern Baltic cod are much more limited than perceived in regular assessments[2].

We urge decision-makers not to exceed the scientific advice of limit 2018 year’s catches to 26 071 tonnes[1], which is also in agreement with the EU Commission proposal[3]

Both Eastern and Western Baltic cod have gone toward more truncated size structures between 1991 and 2016, implying a strong decline in growth[2]. To achieve the commitment of a natural size and age composition of commercial fish stocks in accordance with the Good Environmental Status in the Marine Strategy Framework Directive, ICES has acknowledged that growth patterns improve when fishing mortality is reduced[4]. The way fishing affects the size structure is today partly overlooked, even though it is clear that the fishery leads both to a higher mortality in bigger size groups as well as stunted growth. Today cod starts to reproduce at a size of about merely 20 cm, in comparison with more than the double of that size in the 1990’s[5].

From an economic perspective, it is clear that fishing at lower levels would both generate a better performance of the fishery and less variation in fishing opportunities over longer time periods. In Fig. 1[6] this can be seen specifically for Eastern Baltic cod using the concept “ecologically-constrained Maximum Economic Yield” (eMEY) strategy, taking into account ecological factors as well as short- to medium-term economic costs.

Figure 1. Time-series of “ecologically-constrained Maximum Economic Yield” (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 estimate 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 (from Voss et al. 2017)

Western Baltic cod

The Western Baltic cod might become of the most controversial fish stock when deciding Baltic Sea fishing opportunities for 2018, given the level of disagreement and different opinions on appropriate management actions that exists between stakeholders. We at Stockholm University Baltic Sea Centre emphasize the crucial need to take extraordinary measures for alleviating the poor state of the stock. Even though an increased number of recruits (age 1 individuals) was found last year[7], we stress that this is -  at most - indicative and evidence of a positive stock production certainly has to be based on more than one strong year class.

We recommend that the commercial catch in 2018 should be reduced to the lowest possible levels, and should not exceed the levels that ICES advice, which are between 1376 and 3541 tonnes [7], (depending on which Fmsy range is adhered to in the multiannual plan for the stocks of cod, herring and sprat in the Baltic Sea[8]).

We do not support a rollover in fishing opportunities of 2017 exploitation level as proposed by the EU Commission (5597 tonnes[3]).

Possible to sustain both high stocks and high catches

Adjusting F levels to an MSY level would have been possible already when the revised Common Fisheries Policy (CFP) came into force in 2014. One of the consequences of not having done so can be the reduced stock size that we see today. To illustrate the deviation between how the Western cod stock was actually managed for the period 1994-2015 (Fig.2 first bar from the left), compared with what would have been the stock size (SSB) and catches if an MSY approach would have been adhered to, we have run a basic age-structure model under different constant fishing mortality scenarios. That is: FMSY lower; FMSY and FMSY upper. As illustrated in the figure above, if an MSY approach had been adopted for the period, we would have at least the same catch as observed today or even much higher catches and a much higher fish stock. Thus, our models indicate that a fishery policy sustaining both higher fish stocks and higher catches in the Baltic Sea are possible when adopting a MSY approach. 

Figure 2. Average Spawning Stock Biomass (upper panel) and average catch (lower panel) for the period 1994-2005. From left to right the columns represent: observed values; modelled scenarios on: FMSY lower, FMSY and FMSY higher. FMSY lower and FMSY higher represent the lowest and highest values within the range of FMSY, respectively (Ref EU 2016/1139). 

Special considerations regarding sprat and herring

Cod in the southern Baltic Sea are suffering greatly from limited availability of prey (i.e. sprat and herring). One crucial reason is that most of the sprat and herring are located in more northern/eastern parts of the Baltic Sea, while most of the cod are located in the south. ICES have in recent years recommended that a spatial management plan is developed for the sprat fisheries in subdivisions 25-26 (southern Baltic Sea)[9]. Such restrictions of the pelagic fishery are now highly needed, as the relative catch proportion of sprat in the area where cod are concentrated has increased from 37% to 47% of the total catch between 2010 and 2012-2016[9].

We strongly recommend that ICES advice regarding sprat fisheries in subdivisions 25-26 is finally adhered to, as part of the clear aspirations of EU and the Member States to achieve a more ecosystem-based fisheries management.

European eel

European eel consists of one single stock – which is critically endangered. Even under the best of circumstances, it would take decades before the stock recovers. Therefore, the European Commission propose a total eel fishing ban in the Baltic Sea during 2018 [3]. The proposal is part of the European Union's approach to adjust the levels of fishing to long-term sustainability targets, or maximum sustainable yield (MSY) by 2020, as agreed by Member States and the European Parliament in the CFP. It is also in line with the policy intentions expressed in the Commission's Communication on Fishing Opportunities for 2018 and ICES latest advice[10], confirming that “when the precautionary approach is applied for European eel, all anthropogenic impacts (e.g. recreational and commercial fishing on all stages, hydropower, pumping stations, and pollution) decreasing production and escapement of silver eels should be reduced to –or kept as close to –zero as possible".

We urge responsible Ministers to pursue the recommendations given by the EU Commission, and decide for a total eel fishing ban in the Baltic Sea.

The European eel is threatened and it is listed as critically endangered by IUCN[11]. Glass eels entering continental waters has declined over the last 30–50 years and according to the latest assessment conducted by the ICES, eel catches are at their lowest point ever recorded[10]. The European eel belongs to those species that are easily over-exploited due to their high age at maturity. The Baltic Sea still is an important feeding area for eel. Spawning migrating silver eel on their way out of the Baltic is traditionally harvested along the shores, making countries like Sweden and Denmark some of the major marine eel fishing nations in Europe. Baltic migratory eel hence represents a vital part of the potential spawning biomass that still can be found in the distribution area of the European eel. It has been suggested that the fishing mortality is insignificant in the Baltic Sea[12]. However, Svedäng &Cardinale (2015) has found no evidence for that[13]. On the contrary, observations from the fishery and tagging studies rather suggest high fishing mortality and a low eel biomass.


Presently, and only a few years after the latest CFP reform, we see several positive trends in the European fisheries. Although the MSY-concept is not entirely adhered to, many commercial fish stocks are growing to more sustainable levels in several European waters. One good example is the North Sea, where the cod stock finally shows a long-awaited recovery[14]. This lack of a similar success story is largely a result of implementing needed reductions in fishing pressure, reflected both in reduced fishing capacity (fishing vessels) and lower fishing quotas (TACs). 

The Baltic Sea can still become the next positive example. That, however, will require that we follow the scientific advice. 

Yours sincerely,

Tina Elfwing

Director, Stockholm University Baltic Sea Centre

Christoph Humborg

Scientific Director, Stockholm University Baltic Sea Centre

For further information about Baltic cod, please contact:

Henrik Svedäng, researcher at Baltic Eye, Stockholm University Baltic Sea Centre,

Gustaf Almqvist, marine ecologist and researcher at Baltic Eye, Stockholm University Baltic Sea Centre,

Maciej T. Tomczak, marine ecologist and researcher at Baltic Eye, Stockholm University Baltic Sea Centre,

For further information about European eel, please contact:

Henrik Svedäng, researcher at Baltic Eye, Baltic Sea Centre,

Gustaf Almqvist, marine ecologist and researcher at Baltic Eye, Baltic Sea Centre,


[1] ICES Advice on fishing opportunities, catch, and effort (Published 31 May, 2017) cod.27.24-32.

[2] Svedäng, H. & Hornborg, S. 2017. Historic changes in length distributions of three Baltic cod (Gadus morhua) stocks: Evidence of growth retardation. Ecology & Evolution 7:6089–6102.

[3] European Commission-Press release - Commission proposes Baltic Sea.!tx93pC

[4] ICES Special Request Advice Northeast Atlantic Ecoregion sr.2017.07. EU request to provide guidance on operational methods for the evaluation of the MSFD criterion D3C3 (second stage 2017). 

[5] Friedrich W. Köster, Bastian Huwer, Hans-Harald Hinrichsen, Viola Neumann, Andrei Makarchouk, Margit Eero, Burkhard V. Dewitz, Karin Hüssy, Jonna Tomkiewicz, Piotr Margonski, Axel Temming, Jens-Peter Hermann, Daniel Oesterwind, Jan Dierking, Paul Kotterba, Maris Plikshs, Handling editor: Howard Browman; Eastern Baltic cod recruitment revisited—dynamics and impacting factors, ICES Journal of Marine Science, Volume 74, Issue 1, 1 January 2017, Pages 3–19, 

[6] Voss R, Quaas MF, Stoeven MT, Schmidt JO, Tomczak MT and Möllmann C (2017) Ecological-Economic Fisheries Management Advice—Quantification of Potential Benefits for the Case of the Eastern Baltic COD Fishery. Front. Mar. Sci. 4:209. doi: 10.3389/fmars.2017.00209

[7] ICES Advice on fishing opportunities, catch, and effort (Published 31 May, 2017) cod.27.22-24.

[8] U. 2016. Regulation (EU) 2016/1139 of the European Parliament and of the Council of 6 July 2016 establishing a multiannual plan for the stocks of cod, herring and sprat in the Baltic Sea and the fisheries exploiting those stocks, amending Council Regulation (EC) No 2187/2005 and repealing Council Regulation (EC) No 1098/2007. Official Journal of the European Union, L 191/1.

[9] ICES Advice on fishing opportunities, catch, and effort Baltic Sea Ecoregion (Published 31 May 2017) spr.27.22-3.

[10] ICES Special Request Advice. EU request to provide advice on fisheries-related anthropogenic impacts on eels in EU marine waters (Published 8 May, 2017).


[12] Westerberg and Wickström (2015. Stock assessment of eels in the Baltic: reconciling survey estimates to achieve quantitative analysis. ICES Journal of Marine Science, doi: 10.1093/icesjms/fsv049).

[13] Svedäng, H., and Cardinale, M. Comment on stock assessment of eels in the Baltic by Westerberg and Wickström (2015): do we need more unknowns? – ICES Journal of Marine Science, doi: 10.1093/icesjms/fsv246.

[14] ICES (2016) Advice on fishing opportunities, catch, and effort Greater North Sea and Celtic Seas ecoregions; Cod (Gadus morhua) in Subarea 4, Division 7.d, and Subdivision 3.a.20 (North Sea, eastern English Channel, Skagerrak) update Nov 2016; Book 6 Section 3.3