| Year | Number of samples | Number measured | Number aged | Catch (t) |
|---|---|---|---|---|
| 2007 | 21 | 298 | 285 | 36489 |
| 2008 | 26 | 758 | 668 | 112353 |
| 2009 | 60 | 2238 | 1945 | 116160 |
| 2010 | 115 | 4821 | 4759 | 122034 |
| 2011 | 191 | 8031 | 4760 | 159263 |
| 2012 | 244 | 11421 | 5604 | 149366 |
| 2013 | 180 | 7733 | 3505 | 151234 |
| 2014 | 155 | 6276 | 3201 | 172960 |
| 2015 | 160 | 7195 | 3425 | 169336 |
| 2016 | 113 | 4889 | 2767 | 170374 |
| 2017 | 108 | 4261 | 2431 | 167367 |
| 2018 | 77 | 3403 | 1907 | 168331 |
| 2019 | 125 | 5652 | 3081 | 128076 |
| 2020 | 112 | 4896 | 2755 | 151534 |
| 2021 | 109 | 5070 | 2637 | 132127 |
| 2022 | 98 | 4055 | 2381 | 129979 |
| 2023 | 96 | 3635 | 2238 | 141369 |
| 2024 | 64 | 2381 | 1476 | 89638 |
| 2025 | 100 | 3869 | 2375 | 129628 |
Key findings
The catch of Icelandic vessels in 2025 was 129 628 tonnes, of which 30% was taken within the Icelandic Exclusive Economic Zone (EEZ), and 70% in international waters in the Norwegian Sea.
Catch sampling rate was high with one sample (includes 100 fish) taken for every 1300 tonnes caught.
The catch length distribution shows a decrease in larger fish in 2025 compared with 2024. Mean length was 37 cm in 2025, 1 cm less than in 2024.
Mackerel density in the Icelandic EEZ was very low in 2026 compared with the historical average. It was measured during the International Ecosystem Summer Survey in Nordic Seas (IESSNS). Density was slightly higher than in 2025, which was the record low for the period 2010-2026, making 2026 the second-lowest value in the time series.
General information
Mackerel is a wide-ranging and widely distributed pelagic fish. It is a warm-water species found on both sides of the North Atlantic. In the Northeast Atlantic it is generally regarded as a single stock, and the fishery is managed accordingly. The mackerel stock is one of the most valuable fish stocks for Europe fisheries.
During the last century, mackerel was a rarely seen vagrant in Icelandic waters. In the early 2000s, it began to be observed southeast and south of Iceland during summer as bycatch in the summer fishery for Norwegian spring-spawning herring (Ástþórsson et al. 2012). It was also found in the diet of gannet chicks at Vestmannaeyjar beginning in the summer of 2005 (Vigfúsdóttir et al. 2009).
Mature mackerel follow a seasonal migration pattern between separate summer feeding areas, overwintering areas and spawning areas (Uriarte and Lucio 2001). Mackerel spawn on the continental shelf and shelf edge of mainland Europe from January to July (Trenkel et al. 2014). Spawning begins in the south and moves northwards as the year progresses. After spawning, mackerel migrate northward or northwestward into the Nordic Seas and into the North Sea to feed during the summer months. In autumn, mackerel gather in dense schools in the northern North Sea, which then move southwards as the winter progresses. Over the winter, mackerel are distributed along the European shelf edge and shelf from the coast of Portugal to Shetland. Juveniles remain in nursery areas on the shelf off Ireland, west and north of Scotland, in the Bay of Biscay, and in the North Sea until they mature at 2 or 3 years of age, when they begin their annual migration with the spawning stock.
The summer distribution of mackerel has changed drastically since the early 2000s (Ólafsdóttir et al. 2019). Before then, their summer feeding grounds were limited to the Norwegian Sea, east of 10°W and south of 72°N.
This began to change in 2005 and 2006, when mackerel distribution started expanding westwards from the Norwegian Sea to the east coast of Iceland. By the summer of 2010, results from the IESSNS surveys show that the distribution hab expanded to the west coast of Iceland, almost reaching the median line with Greenland at 30°W. Then, in summer of 2013, mackerel were recorded in Greenlandic waters for the first time, extending into the northern Irminger Sea, with a western limit of 36°W and a southern limit at 62°N.
The expansion later reversed. The distribution of mackerel in Icelandic waters contracted markedly west of the country in the summer of 2019 (Ólafsdóttir and Sigurðsson 2021). In the summers of 2023-2026, mackerel were recorded only off the southeast coast of Iceland, the same area where they were first observed in the early 2000s (ICES, 2026).
Fisheries
Directed fishing for mackerel in Icelandic waters began in the summer of 2007. Since then, the annual total catch by Icelandic vessels has ranged between 36 and 173 thousand tonnes (Figure 1). Almost all mackerel is caught with pelagic trawl (> 99%).
At the start of the fishery, most of the catch was taken within the Icelandic EEZ. This changed in 2017, when fishing in international waters increased. Since then, a large part of the catch has been taken there, ranging from 32% to 84% annually (Figure 1).
In the early years, the fishing grounds were along the shelf edge southeast of the country, and moved west along the south coast in the early 2010s (Figure 2). From 2011 to 2016, the main fishing area was along the shelf edge from the southeast to the Westfjords.
In the summer of 2017, the fishery began to move eastward into the Norwegian Sea, and to decrease west of the country. In the summers of 2021 and 2022, there was almost no fishing along the shelf edge of Iceland and limited in Icelandic EEZ.
In 2023 and 2024, fishing in Icelandic EEZ increased again, but it was limited to the area southeast of the country, not located close to the shelf edge. In 2025, the fishery shifted east again into the Norwegian Sea as observed and approximately 1/3 was caught in Icelandic waters off the southeast coast.
Since 2000, the annual total catch from the stock has fluctuated between 0.4 and 1.4 million tonnes (Figure 3). Catch figures from before 2000 are considered unreliable and are given less weight in the stock assessment than figures from 2000 onwards.
Sampling
Sampling of the catch of Icelandic vessels by the Marine and Freshwater Research Institute was excellent in 2025 (Figure 4). The number of samples, length measurements and age readings has been excellent since the fishery began in 2007 (Table 1).
Catch composition
The length distribution of mackerel in the catch by year is shown in Figure 5. The annual mean length fluctuates from 34 cm to 38 cm. The size composition of the catch has changed over the years, with mackerel size increasing in recent years compared with earlier years.
The age composition of the catch from 2012 to 2025 shows that the proportion of older fish in the catch has increased over time (Figure 6). The 2005-2012 year classes (0-age) have been prominent in the fishery, both in numbers and in weight (Figure 7).
Mackerel around Iceland in the pelagic summer survey
The density of mackerel in the Northeast Atlantic has been measured annually during summer since 2010. In 2010, the distribution of mackerel around Iceland reached the west coast (Figure 8). From 2010 to 2017, mackerel were found along the east, south and west coasts of the country.
In 2019-2020, the distribution contracted rapidly, and by 2020, mackerel were recorded only off the southeast coast. They then migrated west along the south coast again in 2022 and 2023, but since 2024, mackerel have been recorded only east of the country.
The mean biomass index of mackerel in the Icelandic EEZ, in summer 2010-2026, ranges between 0.01 and 3.9 million tonnes (Figure 9). It fluctuated around 1.5 million tonnes in 2010-2014, increased to 3-4 million tonnes in 2015-2017, and decreased to < 0.01 million tonnes in 2025. In 2026 the biomass index was estimated 0.06 million tonnes.
The mean biomass is calculated using 1000 bootstrap replicates. From this, 90% confidence limits for the mean, and the coefficient of variation (CV), are also calculated. In some years, a single station has catches ranging from several to tens of tonnes (Figure 8). Such large hauls increase the uncertainty, seen in the wide confidence limits in 2015-2017, 2022 and 2024.
The CV ranges between 0.2 and 0.8, and has been increasing since around 2020. It is highest in the years most stations catch no mackerel, while a few stations have catches tonnes at a time. This shows that density was most even in 2010-2014, with few stations catching nothing and few catching a lot. In recent years, the difference in mackerel density has increased, many stations not catch nothing, while a few catch a large amount.
RFID tag recaptures
Radio Frequency Identification tags are commonly abbreviated RFID. RFID tags are inserted into the body cavity of mackerel, and RFID scanners in processing plants detect the tags automatically during landing. Three pelagic processing plants in Iceland have RFID scanners: Síldarvinnslan in Neskaupstaður, Brim in Vopnafjörður and Skinney-Þinganes in Höfn í Hornafirði.
Tagging of mackerel with RFID tags began in 2011 (ICES 2020). Since then, a total of 717 665 fish have been tagged (https://smartfishmap.imr.no/). Staff of the Institute of Marine Research in Norway tag mackerel annually west of Ireland and Scotland during the spawning season in May. A total of 702 599 fish was tagged between 2011 and 2026 (Figure 10). Staff of the Marine and Freshwater Research Institute in Iceland tagged 15 066 fish off Snæfellsnes in August, from 2015 to 2019. Mackerel have not been tagged around Iceland since 2019, as little or no mackerel have migrated west of the country in recent years.
The number of mackerel tagged each year varies, ranging 22 792 to 61 135. Most fish were tagged in 2023 and fewest in 2013. The number of fish that could be tagged decreased sharply in 2024-2026 compared to earlier years. This was because fewer fish were caught during the tagging surveys, not because the survey ran for fewer days.
From 2014 to 2026, between 24 and 590 tags have been recaptured annually at Iceland processing plants (Figure 11). Most tags are recaptured in Neskaupstaður, followed by Vopnafjörður, with fewest in Höfn. This reflects differences in catch volume processed at each plant, as more catch means more tags recaptured. No scanning took place in Vopnafjörður in 2025 and 2026 or in Höfn in 2026.
Recaptured tags come from fish that were tagged between 2011 and 2026 (Figure 12). In general, recaptures from a tagging event are highest in the year of tagging and the following two years.
The tagging location has changed over time (Figure 13). From 2011 to 2019, most recaptured mackerel were tagged west of Ireland, with a few fish tagged off Snæfellsnes, Iceland. In 2020, and from 2023 to 2026, most recaptured fish were tagged further north, off the west coast of Scotland. In 2021 and 2022, recaptures were distributed along the west coast of Ireland and Scotland. This pattern reflects changes in tagging location. Taggings were further north, northwest of Scotland, in 2020 and from 2023 to 2026, compared with other years.
Of the 10 915 mackerel tagged around Iceland, 396 have been recaptured as of September 10, 2026. They have been recaptured along the south and east coasts of Iceland, in the Norwegian Sea, in the northern North Sea, and northwest of Scotland (Figure 14). In 2025, four fish were recaptured, and so far in 2026, one fish has been recaptured, in January, west of Shetland. The location of recaptures reflects both the location of the fishery and the location of the plants that scan the mackerel catch for tags.
References
Astthorsson, O. S., Valdimarsson, H., Gudmundsdottir, A., and Óskarsson, G. J. 2012. Climate-related variations in the occurrence and distribution of mackerel (Scomber scombrus) in Icelandic waters. ICES Journal of Marine Science, 69: 1289-1297. https://doi.org/10.1093/icesjms/fss084
Freydís Vigfúsdóttir, Kristján Lilliendahl & Arnþór Garðarsson. 2009. Fæða súlu við Ísland. Bliki. 30: 55-60.
ICES 2020. Stock Annex: Mackerel (Scomber scombrus) in subareas 1-7 and 14 and divisions 8.a-e, 9.a (the Northeast Atlantic and adjacent waters). ICES Stock Annexes. Report. https://doi.org/10.17895/ices.pub.18622763.v1
ICES. 2026. Preliminary cruise report of the International Ecosystem Summer Survey in the Nordic Seas (IESSNS) 29th June - 30th July 2026. Working Document to ICES Working Group of Widely Distributed Stocks (WGWIDE, No. 1), ICES HQ, Copenhagen, Denmark, 26th August - 1st September 2026. 65 pp. https://www.hafogvatn.is/static/files/iessns-cruise-report-2026-preliminary.pdf
Ólafsdóttir, A.H., Utne, K.R., Jacobsen, J.A., Jansen, T., Oskarsson, G.J., Nøttestad, L., Elvarsson, B., Broms, C. and Slotte, A. 2019. Geographical expansion of Northeast Atlantic mackerel (Scomber scombrus) in Nordic Seas from 2007 - 2016 was primarily driven by stock size and constrained by low temperatures. Deep-Sea Research Part II: Tropical Studies in Oceanography, 159: 152-168. DOI:10.1016/j.dsr2.2018.05.023
Anna Heiða Ólafsdóttir og Sigurður Þór Jónsson. 2021. Makríll (Scomber scombrus). Í Guðmundur J. Óskarsson (ritstj.), Staða umhverfis og vistkerfa í hafinu við Ísland og horfur næstu áratuga. Haf- og vatnarannsóknir, HV 2021-14. https://www.hafogvatn.is/static/files/2021-sidur/hv2021-14.pdf
Trenkel, V.M., Huse, G., Mackenzie, B.R., Alvarez, P., Arrizabalaga, H., Castonguay, M., Goni, N., et al., 2014. Comparative ecology of widely distributed pelagic fish species in the North Atlantic: implications for modelling climate and fisheries impacts. Progress in Oceanography, 129: 219–243. https://doi.org/10.1016/j.pocean.2014.04.030
Uriarte, A., Lucio, P., 2001. Migration of adult mackerel along the Atlantic European shelf edge from a tagging experiment in the south of the Bay of Biscay in 1994. Fisheries Research. 50: 129–139.