Expertise
ICES advice on fishing opportunities: What's behind it?
Alexander Kempf, Holger Haslob, Jens Ulleweit, Norbert Rohlf, Matthias Bernreuther, Christoph Stransky, Karl-Michael Werner, Uwe Krumme, Christopher Zimmermann, Sven Stötera, Stefanie Haase, Kristina Barz | 19.11.2024
In its annual reports, ICES provides an overview of the status of exploited fish stocks in the North-East Atlantic and issues advice on total allowable catches. We explain what the recommendations mean for German fisheries and why they are at a certain level.
Every year, the International Council for the Exploration of the Sea (ICES) publishes scientific advice on the state of fish stocks in the North-East Atlantic ("ICES Advice") and proposes sustainable catch quotas for the following year. In the following, we explain the status of the most important fish stocks for German fisheries and the scientific catch quota recommendations based on this.
Fortunately, the status of many fish stocks in the North-East Atlantic and adjacent areas has improved in recent years. Due to the reduction in fishing pressure, the biomass of many stocks is showing a positive trend. From 2003 to 2022, the biomass of stocks with sufficient data increased in the North-East Atlantic by an average of 37 %. However, the range in the development of individual stocks is wide and for some stocks also negative (e.g. cod in the southern North Sea). Many stocks in EU waters are managed sustainably according to the principle of maximum sustainable yield (MSY), even if the MSY target has not been achieved for all stocks. In 2022, 40 out of 65 stocks for which corresponding reference values are available had achieved the MSY criterion. This corresponds to 62 % of the assessed stocks, compared to only 30 % in 2003. The average fishing mortality rate in 2022, averaged over all stocks, was 42% below the MSY values, while in 2003 the reference points were exceeded by 53% on average. This indicates that the level of exploitation has decreased significantly and only individual stocks are still affected by severe overfishing (data source: STECF Report 2024).
Fishing mortality is a measure of the amount of fish or other marine living resource taken by catch from the harvestable portion of a stock over a given period of time.
The recovery of stocks also has positive economic effects. With fuel prices falling again to some extent since 2022, most fleets in the EU member states are expected to be profitable in 2024. Nevertheless, there are individual fleets that face major challenges as they have very high fuel consumption (e.g. beam trawling for flatfish in the North Sea).
Explanations on the ICES advice for 2025
Cod on the northern shelf has been divided into three sub-stocks (southern sub-stock, north-western sub-stock and Viking sub-stock) two years ago. Workshops to clarify the stock structure of cod in the North Sea and west of Scotland have shown that the three sub-stocks differ genetically and/or in their biological characteristics (e.g. growth, maturity). The population sizes of the sub-stocks have also developed differently. In particular, the southern sub-stock has developed worse than the north-western and Viking sub-stocks. For these reasons, ICES considers an assessment based on the sub-stocks to be appropriate.
According to the available stock assessment, all three sub-stocks were fished above FMSY in 2023. While the north-western and Viking sub-stock is within safe biological limits at the beginning of 2024, the southern sub-stock is clearly outside safe biological limits and below the Blim biomass limit. Since the southern sub-stock in particular marks the southern limit of the cod distribution area, it is very likely that climatic changes play a role in addition to fishing.
The calculations based on the three sub-stocks are based on the assumption that the sub-stocks do not mix in the first quarter, as they remain in their respective sub-stock areas during the spawning season (Figure 1). In quarters two to four, however, the sub-stocks mix considerably.
ICES normally gives advice based on the MSY approach. However, recommendations based solely on the MSY approach for each of the three sub-stocks is not possible in this particular case, as there is no (genetic) data available to quantify the mixing of the sub-stocks in quarters two to four. Advice based purely on the MSY approach at the sub-stock level is therefore not feasible for management purposes, as without knowledge of the spatial distribution and mixing of the sub-stocks in quarters two to four, compliance with the recommended catch levels for all sub-stocks cannot be guaranteed.
To account for the problem of unknown spatial distribution and mixing of the sub-stocks, the weakest sub-stock (the southern sub-stock) is therefore protected by the ICES advice. To achieve this, fishing mortality for the north-western and Viking sub-stocks was reduced in the projections to the same extent (by 65%) in a precautionary approach as required by the MSY approach for the southern sub-stock. The resulting advice is a maximum catch for the stock complex (15511 tons for 2025, which is 32% lower than the combined advice given for 2024 (22 691 tonnes) and 50% lower than the agreed total allowable catch (TAC) for 2024). As in the past, this recommendation can be implemented by allocation to the existing TAC areas. Assuming constant fishing patterns, mixing and stock parameters, the recommended maximum catch means that none of the sub-stocks will be overfished.
The other details in the recommendations per sub-stock ("...which corresponds to 9920 tons from the northwestern substock, 3342 tons from the Viking substock, and 2248 tons from the southern substock) serve primarily to explain how the value of 15511 tons is arrived at. According to the ICES advice, these values should not be interpreted as area-specific recommendations due to the mixing of sub-stocks (e.g. 9920 tons should not be set as the maximum catch for the blue area in Figure 1).
To improve the quality of the assessment and prevent the need to apply a precautionary approach and reduce potential catches under the MSY approach, genetic samples and analyses at a high level of spatio-temporal detail would be necessary. This would make it possible to calculate how stocks mix in individual quarters and when catches are made in which areas. This would also allow targeted measures to be taken to protect the southern sub-stock. However, this would require considerable resources and funding.
The explanation of the Northern Shelf cod as a PDF download
Contact: Dr. Alexander Kempf
The stock is estimated to be just within safe biological limits at the beginning of 2024. The stock was exploited minimally above FMSY in 2023. The productivity of the stock is lower in the last 10 years than in previous decades, which suggests unfavorable environmental conditions.
ICES advices a maximum catch of 79,071 tons for 2025 based on the MSY approach. This corresponds to an increase of 7.1% compared to last year. The assessment was benchmarked in 2024 and biological parameters (mean weight, natural mortality, maturity) and reference points were updated. These changes in combination with a slightly higher assessment of the 2019 cohort lead to the moderate increase in the advice.
The explanation of the saithe in the North Sea as a PDF download
Contact: Dr. Alexander Kempf
Due to a sharp decline in fishing effort by the main flatfish fishing fleets since the early 2000s, fishing pressure on plaice has fallen significantly since then. Massive scrapping programs in the Dutch fleet have continued this trend in recent years. Since 2007, fishing pressure has been below FMSY and in recent years even far below. Recruitment has mostly been above average since 2010. The spawning stock biomass has increased significantly in recent decades and in 2014 reached the highest value since data was recorded in 1957. Since then, the stock has fluctuated far above all biomass reference points due to natural variability in the production of young fish.
The ICES catch advice for 2025 based on the MSY approach for plaice in the North Sea and Skagerrak is no more than 176 988 tons. This is above last year's recommendation (+ 14.2%). The total catch in recent years has always been well below the recommended maximum catch, as it does not appear profitable to fish out the quotas. High fuel costs are likely to further worsen the situation for flatfish vessels.
The explanation of Plaice in the North Sea as a PDF download
Contact: Dr. Holger Haslob
Following a high in the early 1990s, the spawning stock biomass of sole in the North Sea showed a generally declining trend until 2005. After this low point, the stock recovered slightly, but remained below the critical reference value Blim for a long time. Due to a stronger 2018 year class, the spawning stock biomass has increased in recent years and the stock is just within safe biological limits at the beginning of 2024. Fishing mortality (F) has decreased overall since 2005, but was well above the FMSYreference value for a long time. Only since 2020 a strong reduction has been recognizable and for 2023 the fishing mortality rate is well below FMSY. This development was also supported by a massive scrapping program in the Dutch fleet.
In the last decade, the estimated production of young fish shows fewer strong year classes than in previous decades. However, as already mentioned, the 2018 year class is slightly larger. This larger year class currently accounts for a large part of the catches.
ICES advices a maximum catch of 10,696 tons for 2025 based on the MSY approach, which is 191% higher than the previous year's recommended maximum catch. The main reason for the sharp increase in the catch recommendation is a more robust assessment after the benchmark in 2024. This means that it is no longer necessary to compensate for bias in the assessment and carry out the forecasts with downward "corrected" values for the numbers at age at the beginning of the forecast.
The explanation of sole in the North Sea as a PDF download
Contact: Dr. Holger Haslob
The spawning stock biomass of North Sea herring has fluctuated between 1.1 and 2.4 million tons since the late 1990s. Since 1996, the spawning stock biomass has been within biologically safe limits and fishing mortality has been consistently below FMSY.
Despite sufficient spawning stock biomass, the number of herring offspring has been below average since 2003. Only in 2013 a stronger year class was produced. Catches of herring larvae at the spawning grounds show that sufficient larvae are still hatching. However, compared to previous times smaller numbers reach the juvenile herring stage. The reasons for this are not fully understood. As a result of the lower productivity, the stock has fallen in recent years, but remains within safe biological limits.
For 2025, ICES recommends a maximum catch of 410,707 tons (of which 401.490 tons are for human consumption) according to the MSY approach. This is 21.3% less than the maximum catch set for the human consumption fleet in 2024 and 22.8% less than last year's ICES recommendation.
In addition to fishing for human consumption (A fleet), there is also an industrial fishery in the North Sea for the production of fish meal and oil (B fleet). As juvenile herring are the main bycatch in sprat fisheries, this fleet segment has its own maximum bycatch limit for herring (9,217 tons for 2025 according to the ICES recommendation). In addition, off the southern Norwegian coast, in the Skagerrak/Kattegat and in the western Baltic Sea, herring stocks from the North Sea and Baltic Sea mix and are caught together. For Baltic herring from the western Baltic Sea, the Skagerrak and the Kattegat, ICES recommends a fishing ban for 2025 due to the poor stock situation. For this reason, the corresponding advice for catch shares of North Sea herring in the areas mentioned (so-called C and D fleet) have also been set to zero.
The explanation of herring in the North Sea as a PDF download
Contact: Dr. Norbert Rohlf
The spawning stock biomass of Northeast Atlantic mackerel has increased substantially since the 2000s to a maximum in 2014, and has been declining since then, but is still estimated to be within safe biological limits. Fishing mortality has declined since 2003 and has been below FMSY since 2016. Some large year classes have developed since the early 2000s. As a result of increased biomass and climatic changes, the stock has substantive expanded its area of distribution to the northwest (Iceland, Greenland) since the late 2000s, especially during the long summer feeding migrations. However, this process does not seem to be continuing at present.
An age-based model is used to assess the stock. This model uses - in addition to commercial data - the triennial mackerel egg survey, which targets the annual egg production, and for several years also a Nordic survey, which focusses on the stock during the feeding migration. In addition, the International Bottom Trawl Survey (IBTS) is used in Q4 and Q1 to provide estimates of juvenile abundance. Norwegian tagging data, using recapture rates to estimate stock size, have also been integrated into the assessment in recent years.
The latest scientific advice specifies a maximum catch of 576,958 tons for 2025, which is 22 percent below the previous year's recommendation of 739,386 tons. In recent years the fishing nations (e.g. EU states, Norway, Iceland, Faroe Islands, Greenland, Russia) have not been able to agree on a common maximum catch and the unilateral quotas and total catch significantly exceed the scientific recommendations. Mackerel is also fished in international waters, which makes management even more difficult.
The explanation on mackerel in the North-East Atlantic as PDF for download
Contact: Jens Ulleweit
As Russian scientists are currently excluded from ICES work, it was not possible to carry out a stock assessment within ICES in recent years. Instead, a joint Russian-Norwegian Expert Group determines the stock status. According to their assessment, the biomass of this stock is declining further, but remains above the MSY reference point. Fishing mortality remains stable and within the target range of the agreed management plan.
The explanation of cod in the East Arctic as a PDF download
Contact: Dr. Matthias Bernreuther
The German fleet mainly fishes for redfish on the Greenland Shelf and, until 2020, in the Irminger Sea. Two redfish species, the beaked redfish (Sebastes mentella) and the golden redfish (Sebastes norvegicus, formerly Sebastes marinus), occur in several stocks there. The status of these stocks varies. The two species are also caught together on the East Greenland Shelf. It is often difficult to distinguish between golden redfish and beaked redfish, resulting in misreporting between the co-occurring species or both species being reported together as "redfish". This complicates the assessment and management of stocks.
The golden redfish stock on the East Greenland Shelf is part of the stock largely found on the Iceland Shelf. The spawning stock biomass has been within safe biological limits since 2003 and has been fished according to the MSY principle since 2006. The ICES catch advice of no more than 46 911 tons for 2025 is 14% above the recommended maximum catch for 2024 and follows the ICESMSY approach. In the medium term, however, the production of young fish is a cause for concern, as it has been low since 2014. It is expected that the spawning stock biomass will decrease in the future as a result.
The exact status of the beaked redfish stock on the Greenland Shelf cannot be accurately assessed. The stock has declined sharply since 2010 and has not improved in subsequent years. As the most recent values for the biomass index of the Greenland Shallow Water Survey have been close to zero in recent years, ICES recommends zero catches of this stock for 2025 and 2026.
In the neighboring Irminger Sea, there are two other beaked redfish stocks that are caught with pelagic trawls. These two stocks have also declined so sharply that ICES has recommended zero catches for the shallow stock since 2010 and for the deep stock since 2017. In 2021, the stock status of the shallow beaked redfish stock in the Irminger Sea was assessed again for the first time since 2013. The result of the survey was slightly more positive, as the resulting biomass index showed the highest value since 2005, but remains at a low level in historical comparison. Despite the slightly more positive assessment, the recommendation of a zero catch remains, as this result must first be confirmed in the next scientific survey. The deep stock (> 500 m water depth) has been fished since the 1990s with a fishing mortality rate well above FMSY. The results of the above-mentioned survey in 2021 show the lowest biomass value for the deep stock since the beginning of the survey. While Russia, for example, continues to fish for these stocks, the EU currently does not allow fishing for either stock.
The explanation of redfish in the Greenland/Irminger Sea as a PDF download
On the Norwegian shelf, in the Norwegian Sea and in the Barents Sea, there are also two redfish species of commercial importance: the beaked redfish (Sebastes mentella) and the golden redfish (Sebastes norvegicus).
The beaked redfish stock is very likely in good condition. The spawning stock biomass increased steadily between 1992 and 2005 and has since stabilized at a high level. As Russian scientists are currently excluded from ICES work, it has not been possible to assess the stock within ICES in recent years.
In contrast, the golden redfish stock (Sesbastes norvegicus) found on the Norwegian shelf and in the Barents Sea is currently in a poor state. The spawning stock biomass has declined continuously since the late 1990s and is at the lowest level in the time series below critical biomass reference points. ICES therefore recommends zero catches for the years 2025 and 2026. In addition, ICES recommends minimizing bycatches of golden redfish in other fisheries, such as for cod and saithe. Nevertheless, over 10 000 tons per year were caught internationally in 2022 and 2023.
The explanation of redfish in the Norwegian Sea/Barentssea as a PDF download
A benchmark in 2023 used new genetic information to divide the cod stock complex off Greenland into three stocks.
The western coastal stock lives in the extensive fjord systems and is divided into a northern and southern stock component. In the offshore stocks, a distinction is made between a West Greenlandic and an East Greenlandic-Island offshore stock based on genetic stock assignments. Historically, the heyday of cod fishing off Greenland in the 1950s and 1960s was associated with a very large western high seas stock, while the recovery since 2000 is due to a strengthening of the eastern high seas stock and/or increased exchange with the Icelandic stock. Overall, the stocks in Greenland waters mix during different life stages. It is therefore difficult to attribute catches from the fishery directly to a stock. Only a subsequent genetic analysis can provide more clarity.
After the collapse in the early 1990s, there was a 10-year period of very low population densities. After a moratorium until 2005, fishing was permitted again in 2006.
For the East Greenland stock, a solid stock calculation is currently not possible, as seasonal migrations between East Greenland and Iceland prevent separate calculations. Mixing with the Icelandic stock probably explains why the majority of catches in East Greenland currently come from Dohrnbank, which is located in Greenlandic territorial waters between East Greenland and Iceland. Due to a lack of information, the recommendation of an annual maximum catch of 23,518 tons for the years 2024 to 2026 is only based on a reduction of 20% (precautionary buffer) compared to the observed catch in 2022.
The West Greenlandic deep-sea stock is at a low level, but above the critical biomass limit. Fishing pressure is too high based on the MSY concept. The catch advice for 2025 based on the ICESMSY approach is 3,238 tons.
The two components of the West Greenland coastal stock are not targeted by Germany. Both components are overfished in relation to the MSY concept, but are within safe biological limits.
The explanation of cod around Greenland as a PDF download
Contact: Dr. Karl-Michael Werner
For Greenland halibut as a deep sea stock, no single scientific research cruise is available covering the large assessment area of the Faroe Islands, Iceland and East Greenland. Accordingly, the stock dynamics are estimated to a large extent from commercial catch data in addition to a combined research index, whereby the results depend on the weighting of the individual input parameters.
A scientific stock assessment is available. The stock has declined slightly in recent years and is now outside safe biological limits. The stock is also overfished. According to the ICES advice for 2025, the annual catch should not exceed 17,890 tons. This corresponds to a reduction of 9% compared to the previous year's recommendation and a reduction of 17% compared to the maximum allowable catch set for 2024.
The explanation of Greenland halibut as a PDF download
Contact: Dr. Karl-Michael Werner
The directed fishery for cod in the eastern Baltic Sea has already been closed since mid-2019. In EU waters, only a bycatch quota in the mixed flatfish fishery is still in effect. The bulk of the remaining catch is taken by Russia. Although fishing pressure is now very low, the stock shows no signs of recovery. Natural mortality is considered more than ten times higher than fishing mortality. The lack of oxygen in the deep basins of the eastern Baltic Sea is particularly critical. As a result, important spawning and feeding areas are lost. In addition, eutrophication leads to a trophic lengthening of the food web. As a result, there is less energy available for cod.
ICES again recommends the closure of the fishery for 2025 based on the precautionary approach. The EU has so far translated this into a bycatch quota of 595 tons and closed all recreational fisheries. The management objective is now no longer to rebuild the stock to sustainable levels, but to conserve what remains of that stock in order to allow for a recovery once the environmental conditions become more favourable.
The explanation of cod in the Eastern Baltic Sea as a PDF download
Contact: Dr. Uwe Krumme
This small but formerly very productive cod stock has been overfished since the early 2000s, that is fishing pressure has not been adjusted to the reduced production of offspring. Despite several warnings, politicians failed to adjust the management plan in force between 2007 and 2016 - mainly because the European Parliament and the Council of Ministers disagreed on who was in charge for this adjustment.
In 2015, however, the stock produced only 10% of the average amount of recruits: it collapsed. At this point, policymakers took the right measures, reduced the commercial catch drastically and involved recreational fisheries, which account for a significant share of the total harvest, in the recovery of the stock.
The following yearclass of 2016 appeared to be stronger, but did not contribute to the stock recovery as much as expected. Since 2023, the stock assessment is indicative of trends only and results are presented in relative terms. Due to a lack of reliable data, fishing mortality cannot be calculated. The relative harvest rate presented instead indicates that fishing pressure is now very low and has almost no influence on stock development anymore. Spawning biomass shows a slight increase in 2024, but remains far below the limit value. The reason for continued poor recruitment since 2017 has not yet been conclusively explained, but there are indications that the influence of environmental conditions is now much more important than that of fishing. Cod is apparently heckled by rising temperatures in the surface waters and a lack of oxygen in deeper waters in summer. The whole water column can only be used again from late fall. Under these conditions, a recovery of cod in the Baltic even in the medium term seems unlikely.
Since 2022, the directed fishery is closed, and a small bycatch quota has been set to keep the remaining fisheries open in the western Baltic Sea (489 tons for 2023, 340 tons for 2024). The recreational fishery has been closed in 2024. For 2025, ICES follows the standard approach for data-limited stocks and recommends a catch of only 24 tons (including angler’s catches) as in the previous year.
The fishery reports that cod can no longer be caught in this area; therefore, the larger German trawlers, which largely targeted cod, have therefore been scrapped.
The explanation of cod in the Western Baltic Sea as a PDF download
Contact: Dr. Uwe Krumme
Western herring is the most important target species of the German coastal fishery, especially on the coast of Mecklenburg-Western Pomerania. Since about 2004, recruitment has been steadily declining and it took some time before catch levels were sufficiently adjusted to this situation. One main cause of the declining recruitment has been largely elucidated in 15 years of directed research: Later and warmer winters cause a mismatch between herring larvae and their most important food; most of the larvae starve to death.
As a result, the stock has declined sharply, and temporary was only half the limit reference value. ICES has therefore advised for the closure of the fishery for many years. For the Western Baltic management area, this recommendation was largely followed: Total allowable catches were reduced by 94% between 2017 and 2021. In contrast, in the northern part of the range (Kattegat and Skagerrak), where herring stay to feed in summer and fall, legal catches remained far too high: They were only reduced by 57% between 2017 and 2021. As a result, the German coastal fishery was deprived of its basis, but total outtake from the stock still remained so high that the stock could not recover. Only for 2022, Germany, Sweden, Denmark and Norway were able to agree on further drastic cuts in catches in the Kattegat and Skagerrak area as well. More than 80% of the catch is now taken in the eastern North Sea (under the North Sea Herring quota), and less than 10% in each of Kattegat/Skagerrak and the western Baltic Sea, respectively.
The stock remains far below the limit value, but has increased over the past three years. Fishing mortality has continued to decline in 2023 and is now sufficiently low to allow the stock to recover. This may take several years, and even then the stock can only provide half of the catch that could be sustainably fished in the 1990s. ICES maintains its recommendation for 2025 to close the fishery throughout its range.
The explanation of herring in the Western Baltic Sea as a PDF download
Contact: Dr. Christopher Zimmermann
Five flatfish species are commercially exploited in the Baltic Sea: plaice, flounder, dab, brill and turbot. Only plaice is limited by a quota. In the past, flatfish were mainly by-catch in the cod fishery; there were only small directed fisheries, for example for turbot. Since the closure of the two cod fisheries, flatfish have become one of the few exploitable target species in the western Baltic Sea.
The two plaice stocks seem to be doing well, benefiting mainly from the much lower predation pressure due to the poor condition of the cod. Recruitment is strong, ICES could therefore recommend an increase in catches for many years - catches of more than 20,000 tons are possible for 2025 in the Baltic Sea (SD22-32). However, the catches include discards, the vast majority of which have been illegal since 2017 and still account for over 20% of the catches from the area. The allowed plaice catch is not nearly fished out, partly due to a very uneven distribution of national quotas: Denmark is entitled to three quarters of the catch, the other nations share the rest.
Since 2022 the plaice caught are becoming thinner, that is their corpulence factor is deteriorating. Whether this is a density effect or a consequence of changing environmental conditions, as is the case with cod, is unclear at this point. However, the it is increasingly difficult to sell these catches and thus the harvesting of plaice becomes even less attractive.
The other flatfish stocks in the western Baltic Sea are also in good condition. However, the income achievable from flatfish fishing cannot come close to compensating for the catch losses of herring and cod.
The explanation of flatfish in the Baltic Sea as a PDF download
Contact: Dr. Sven Stötera
Sprat is one of the beneficiaries of the changed environmental conditions in the Baltic Sea. The biomass of this currently largest fish stock in the Baltic Sea (just under 700,000 tons of spawning biomass) has been well within the green zone for many years. However, fishing pressure has been somewhat too high over many years, and now offspring production reduces remarkably: The three latest yearclasses belong to the four weakest in the long time series. The outlook is therefore rather pessimistic. ICES advises for 2025 on the basis of the multi-annual plan to reduce catches by a third (compared to the TAC 2024) to max. 164,947 tons. This figure includes the Russian autonomous quota of about 45,000 tons. The stock calculation is now more uncertain because Russian data are no longer be submitted, after Russia has been suspended from ICES
The German fishery exploit this resource with two large (about 50 meters long) and a few smaller trawlers, mainly for the production of fish meal and fish oil.
The explanation of sprat in the Baltic Sea as a PDF download
Contact: Dr. Stefanie Haase
A comprehensive overview of the status of most marine fish stocks of importance to the German market is provided on the German website Fischbestände online.
