Blue whiting

Main results

Icelandic vessels caught a total of 286 760 tonnes in year 2025. Most of this catch (76%) was taken in the Faroese exclusive economic zone (EEZ), 16% in the Icelandic EEZ and 7% in international waters, mostly west of Ireland.
Sampling of the catch was thorough, with one sample on average taken for every 2784 tonnes caught.
Blue whiting in the catch were larger on average in 2025 than in 2024. This is because the large year classes from 2020 and 2021 still make up most of the catch, about 60% of the catch in 2025, down from about 70% in 2024.

General information

Blue whiting (Micromesistius poutassou) is a wide-ranging oceanic, pelagic and mesopelagic fish species belongin to the cod family. It ranges from Svalbard and the Barents Sea in the north to the Iberian Peninsula in the south (Monstad 2004). Most blue whiting mature at 2-4 years of age (ICES 2022). Adult fish usually live at depths of 300–500 m. Their distribution depends mainly on sea temperature, and they are rarely found in water colder than 3°C. Blue whiting spawn mainly along the shelf edge west and northwest of the British Isles, at the Rockall, Rosemary and Porcupine banks, and as far north as the Faroese shelf in early spring. The spawning grounds have shifted in recent years, and studies show that ocean currents play a role in where the fish choose to spawn. After spawning, blue whiting migrate into the Norwegian Sea, which serves both as a nursery area and as their main feeding ground. Blue whiting play an important role in the mesopelagic and pelagic ecosystem. They prey on zooplankton and smaller mesopelagic fish, and are prey for larger demersal fish and marine mammals.

Around Iceland, blue whiting are found all around the coast, but mainly off the southeast, south and southwest coasts, though density varies from year to year (Bjarnason et al. 2021). The number of age-1 blue whiting around Iceland are closely linked to strong year classes entering to the stock. This appears to be the main factor driving their distribution around Iceland, more so than environmental changes in the area. For further information on blue whiting see: https://www.hafogvatn.is/is/sjavardyr/kolmunni-1

Fisheries

Icelandic vessels began fishing blue whiting in the mid-1990s. Since then, the total annual catch has ranged from about 1 thousand tonnes to just over 500 thousand tonnes (Figure 1). In 2011, direct fishery for blue whiting was closed, becasue to low stock size, and the limited catch recorded that year was taken as bycatch. The fishery initially took place mainly within the Icelandic EEZ, but the main fishing grounds soon shifted to the Faroese EEZ, where they have remained since.

Figure 1: Blue whiting. Landed catch of Icelandic vessels by area and year according to the catch registration system of the Directorate of Fisheries from 1997 to 2025.

In the early years, fishing took place along and on the ridge between Iceland and the Faroe Islands (Figure 2). In 2005-2008, the main fishing ground shifted to the shelf edge south of the Faroe Islands, where it has remained since.

Figure 2: Blue whiting. Distribution of catches of Icelandic vessels in 1997-2025 according to logbooks.

At the start of the Icelandic fishery, when fishing took place mostly southeast of Iceland, the main fishing season was over summer and into autumn (Figure 3). As the main fishing grounds moved south of Faroe Islands the main fishing season shifted from the second half of the year to the first half of the year. Since 2005, approximately 2/3 to total annual catch is taken in the first half of the year.

The catch in winter (Nov.-Mar.) depends on two things: the total allowable catch of blue whiting, and the annual capelin quota. The smaller the capelin quota, the more blue whiting catch from January through March. Almost all blue whiting (> 99%) are caught with pelagic trawl.

Figure 3. Blue whiting. Estimated proportion of the catch of Icelandic vessels by month and year in 1997-2025 according to logbooks.

The multinational blue whiting fisheries began in the 1960s and grew rapidly in the mid 1970s, when the annual catch first exceeded 100 thousand tonnes (Figure 4). Since then, the total annual catch has fluctuated considerably, ranging from about 100 thousand tonnes to almost 2.5 million tonnes.

Figure 4: Blue whiting. Reported catch for all countries in all areas for the years 1963-2025 according to the ICES catch database.

Sampling

Sampling from the catch of Icelandic vessels for the Marine and Freshwater Research Institute was representative of the distribution of cathces in 2025, with samples well distributed across the main fishing areas (Figure 5). The number of samples, length measurements and age readings has been good since organised sampling from the fishery began in 1998 (Table 1). No catch samples were taken in 2011, because directed fishing for blue whiting was restricted that year.

Table 1: Blue whiting. Number of samples from the catch, number of fish measured, number of fish aged and total landed catch by year. No catch samples were taken in 1997 and 2011.

Year	Number of samples	Number measured	Number aged	Catch (t)
1998	11	1035	249	68681
1999	72	6676	1648	160425
2000	137	12151	2623	260938
2001	83	6863	3628	365099
2002	96	7918	4654	286430
2003	150	12808	7396	501496
2004	76	5801	3716	422078
2005	118	9094	5387	265515
2006	127	10807	6190	314768
2007	92	8090	4455	237854
2008	56	4985	2745	163793
2009	67	5667	3237	120202
2010	45	4035	2127	87908
2012	44	2559	1628	63056
2013	44	3598	2053	104918
2014	57	4910	2467	182879
2015	82	7569	2021	214870
2016	60	5215	1480	186914
2017	89	7960	2231	228935
2018	90	7507	2237	292952
2019	101	8208	2411	268351
2020	100	7665	2470	243725
2021	74	5740	1762	190147
2022	59	4734	1435	191813
2023	84	6843	2056	292853
2024	109	8694	2553	321572
2025	103	8348	1717	286760

Catch composition

The length distribution of blue whiting from the catches since 1998 is shown in Figure 6. The annual mean length fluctuates between 24 cm and 30 cm. The catch each year is made up of a few year classes, and when large new year classes enter the fishery, the mean length decreases. This happened in 2022 and 2023, when the large 2020 and 2021 year classes entered the fishery. The mean length then increased again in 2024 and 2025, as these same year classes continued to dominate the catch.

Figure 6: Blue whiting. Length distribution (blue area) from the catch of Icelandic vessels for the years 1998-2025 together with the mean of all years (black line). Mean lengths (cm) and the number of fish measured per year are shown in the upper right corner. No catch samples were taken in 1997 and 2011.

The age composition of the catch from 2010 to 2025 shows how large the 2014, 2020 and 2021 year classes are compared with other year classes (Figure 7). The 2020-2021 year classes have been prominent in the fishery since 2022, both in numbers and in weight (Figure 8), and they still dominate the catch in 2025.

Figure 7: Blue whiting. Catch at age of Icelandic vessels for the period 2007-2025, except data from 2009 are missing. Bars indicate catch in numbers by age and are coloured by year class. No catch samples were taken in 2011.

Figure 8: Blue whiting. Estimated composition of the total annual catch by year class for the period 2010-2025. The catch in 2011 was just under 6 thousand tonnes and is not shown in the figure.

References

Monstad, T. Blue whiting, in: The Norwegian Sea ecosystem, edited by: Skjoldal, H. R., Tapir Academic Press, Trondheim, 2004.

Sigurvin Bjarnason. 2021. Kolmunni (Micromesistius poutassou). In Guðmundur J. Óskarsson (ed.), Staða umhverfis og vistkerfa í hafinu við Ísland og horfur næstu áratugi. Haf- og vatnarannsóknir, HV 2021-14. https://www.hafogvatn.is/static/files/2021-sidur/hv2021-14.pdf

ICES. 2022. Stock Annex: Blue whiting (Micromesistius poutassou) in subareas 1- 9, 12, and 14 (Northeast Atlantic and adjacent waters). ICES Stock Annexes. Report. https://doi.org/10.17895/ices.pub.21105808.v1