HERRING

Clupea harengus


Technical report
Published by

Marine and Freshwater Research Institute, Iceland

Published

12 June 2026

Key signals

  • The spawning-stock biomass (SSB) was high around 2007, but declined steadily until 2017 due to additional mortality from the Ichthyophonus infection and a series of below-average year classes recruiting to the stock.

  • The strong 2017–2020 year classes contributed to an increase in SSB after recruiting to the fishable stock. Since 2023, SSB has declined again as these cohorts have become older and subsequent recruitment has been weaker.

  • The total acoustic biomass index from the 2025/2026 surveys was 597 kt, corresponding to 2.2 billion individuals. This is lower than the record-high estimate in 2024/2025 and closer to the long-term average.

  • The juvenile survey was reinstated in 2025 after several years without a survey. The resulting age-1 index was above average and is used in the assessment, reducing uncertainty around recent recruitment.

  • Fishing pressure has been variable over the time series, with high values in the late 1980s followed by a general decline. The current harvest rate is within the range expected under the management plan.

  • Retrospective patterns are moderate in the current assessment, and Mohn’s rho values do not indicate major concern. However, recent peels for SSB and Fbar(5–10) should continue to be monitored.

General information

The Icelandic summer-spawning herring (Clupea harengus) is a pelagic fish that can be found all around Iceland. It lives in a wide range of depths from the surface down to a depth of 400m and at temperatures from 1-15°C (Jakobsson 2000). Its main wintering grounds have been either shallow or deep east or west of Iceland or shallow in the south (Jakobsson 1980, Óskarsson et al 2009). Herring spawns in July, and its spawning grounds can be found along the south and southwest coast of Iceland (Óskarsson and Taggart 2009, Jakobsson et al. 1969). After hatching of eggs at the bottom, larvae reach the north of the country by currents and the main nursery areas are found in fjords northwest and north of the country (Guðmundsdóttir et al. 2007).

Fishery

The total catch in the 2025/2026 season was 104 591 tonnes (Table 4, Figure 2). This also includes the by-catch of herring in the mackerel and Norwegian spring-spawning herring fisheries in June - November 2025. The recommended TAC for 2025 and the TAC (Regulation No. 672, 2 July 2020) was 103 367. Traditional catches in wintering grounds west of the country in September-December amounted to 73 644 tonnes while 30 776 tonnes were caught as bycatch in the mackerel and Norwegian spring-spawning herring fishery in the east in June-November (Figure 1).

Landing trends

Figure 1: Icelandic summer spawning herring in 5a. Seasonal total landings (in thousand tonnes) during 1947–2025, referring to the autumns, by different fishing gears from 1975 onwards).
Figure 2: Icelandic summer spawning herring in 5a. Seasonal total landings (in thousand tonnes) from 1947, referring to the autumns, by different fishing gears from 1975 onwards.

Spatial and temporal patterns

The herring fishing season has changed slightly in the last three decades as detailed in the stock annex. All catches in the year 2025/2026 were caught in pelagic trawls (Figure 2). In the seasons 2007/2008 to 2012/2013, most of the catch (~90%) was caught in Breiðafjörður (Figure 3), but before that it was mainly caught off the south, southeast and east coasts. During the 2013/2014 fishing season, this pattern began to change, with a smaller proportion of catch in Breiðafjörður; and since 2014/2015, most of the fishing has taken place in the west of the country. To protect juvenile herring (27 cm and smaller) in the fishery, area closures are enforced based on a regulation on herring fishing issued by the Ministry of Fisheries (No. 376, 8 October 1992). No closure was enforced in this herring fishery in 2025/2026. Normally, the age of first recruitment to the fishery is age-3, which corresponds to lengths of approximately 26–29 cm.

Figure 3: Icelandic summer spawning herring in 5a. The distribution of the fishery (in tonnes) for the period 2004-2024.

Data and sampling

The assessment of the age composition of the catch is based on samples from the catch of fishing vessels collected at sea by fishermen and catch information. An overview of the sampled otoliths is shown in Table 1. The geographical location of the catch and sampling in 2025/2026 is shown in Figure 4. This year, the calculations were accomplished by dividing the total catch into two cells confined by season and area. Weight-at-length relationships derived from the length and weight measurements of the catch samples were split using the same structure. Based on differences in length-at-age between the summer and winter months, two length-age keys were applied. Catch at age and total landings are available from the 1940s, but only those from 1980 are used in the assessment (Table 1). From trends in the catch at age, it is evident that the older age classes have been contributing to the catches in larger numbers since 2008 (Figure 5). The large 2017–2019 year classes entered the catch as 4- and 5-year-olds (Table 2).

Figure 4: . Icelandic summer spawning herring in 5a. Fishing grounds last year as reported in logbooks (contours) and positions of samples taken from landings (crosses).
Table 1: Icelandic summer-spawning herring 5a. Number of samples and otoliths collected from landed catch.
Year Pelagic Trawl Num. stations Pelagic Trawl Num. samples Pelagic Trawl Num. otoliths Purse Seine Num. stations Purse Seine Num. samples Purse Seine Num. otoliths
1981 0 0 0 32 4 237 1 813
1982 0 0 0 43 4 875 2 461
1983 3 562 278 54 11 124 3 280
1984 1 100 100 37 3 562 2 799
1985 1 100 100 35 5 366 2 182
1986 0 0 0 40 4 452 3 226
1987 0 0 0 55 5 743 4 295
1988 0 0 0 46 4 626 4 318
1989 0 0 0 67 8 159 5 485
1990 2 166 23 55 5 404 4 450
1991 0 0 0 95 12 139 5 689
1992 0 0 0 113 19 456 4 528
1993 92 23 489 76 101 18 772 3 501
1994 3 505 23 57 9 812 2 450
1995 0 0 0 66 8 577 4 042
1996 5 668 183 50 5 828 3 463
1997 27 5 398 834 39 3 928 2 883
1998 11 2 031 148 39 6 156 1 443
1999 41 2 101 952 152 15 691 5 710
2000 55 7 943 1 569 129 9 362 5 536
2001 80 9 238 2 702 82 9 565 2 457
2002 83 12 230 1 481 134 22 220 1 834
2003 171 28 389 916 205 37 084 1 841
2004 74 4 093 1 770 291 76 214 3 960
2005 110 7 565 1 853 157 21 847 4 080
2006 44 4 983 1 393 118 20 152 2 217
2007 19 2 211 658 107 14 000 3 219
2008 17 2 724 43 170 18 053 5 252
2009 60 7 043 1 551 123 10 406 8 390
2010 39 4 130 1 539 60 7 471 6 291
2011 148 17 410 1 488 57 4 033 3 067
2012 32 3 887 193 76 6 513 3 519
2013 76 5 466 1 103 67 8 032 1 480
2014 113 10 434 2 432 2 256 200
2015 98 9 165 2 519 4 364 150
2016 133 11 729 3 369 1 50 50
2017 63 4 907 1 585 1 30 25
2018 62 5 334 1 139 0 0 0
2019 87 7 558 1 665 0 0 0
2020 73 7 409 1 400 0 0 0
2021 59 5 773 1 833 0 0 0
2022 79 7 464 2 194 0 0 0
2023 69 4 547 2 215 0 0 0
2024 55 3 340 2 234 0 0 0
2025 108 5 819 4 309 0 0 0
Table 2: Icelandic summer-spawning herring 5a. Catch in numbers (millions) (1981 refers to season 1981/1982 etc).
Age group
Year 2 3 4 5 6 7 8 9 10 11 12 13 14 15
1980 3,147 14,347 20,761 60,727 65,328 11,541 9,285 19,442 1,796 1,464 698 — 110 79
1981 2,283 4,629 16,771 12,126 36,871 41,917 7,299 4,863 13,416 1,032 884 760 101 62
1982 454 19,187 28,109 38,280 16,623 38,308 43,770 6,813 6,633 10,457 2,354 594 75 211
1983 1,475 22,499 151,718 30,285 21,599 8,667 14,065 13,713 3,728 2,381 3,436 554 100 —
1984 421 18,015 32,244 141,354 17,043 7,113 3,916 4,113 4,517 1,828 202 255 260 —
1985 112 12,872 24,659 21,656 85,210 11,903 5,740 2,336 4,363 4,053 2,773 975 480 581
1986 100 8,172 33,938 23,452 20,681 77,629 18,252 10,986 8,594 9,675 7,183 3,682 2,918 1,788
1987 29 3,144 44,590 60,285 20,622 19,751 46,240 15,232 13,963 10,179 13,216 6,224 4,723 2,280
1988 879 4,757 41,331 99,366 69,331 22,955 20,131 32,201 12,349 10,250 7,378 7,284 4,807 1,957
1989 3,974 22,628 26,649 77,824 188,654 43,114 8,116 5,897 7,292 4,780 3,449 1,410 844 348
1990 12,567 14,884 56,995 35,593 79,757 157,225 30,248 8,187 4,372 3,379 1,786 715 446 565
1991 37,085 88,683 49,081 86,292 34,793 55,228 110,132 10,079 4,155 2,735 2,003 519 339 416
1992 16,144 94,860 122,626 38,381 58,605 27,921 38,420 53,114 11,592 1,727 1,757 153 376 —
1993 2,467 51,153 177,780 92,680 20,791 28,560 13,313 19,617 15,266 4,254 797 254 — —
1994 5,738 134,616 113,290 142,876 87,207 24,913 20,303 16,301 15,695 14,680 2,936 1,435 244 195
1995 4,555 20,991 137,232 86,864 109,140 76,780 21,361 15,225 8,541 9,617 7,034 2,291 621 235
1996 717 15,969 40,311 86,187 68,927 84,660 39,664 14,746 8,419 5,836 3,152 5,180 1,996 574
1997 2,008 39,240 30,141 26,307 36,738 33,705 31,022 22,277 8,531 3,383 1,141 10,296 947 2,524
1998 23,655 45,390 175,529 22,691 8,613 40,898 25,944 32,046 14,647 2,122 2,754 2,150 1,070 1,011
1999 5,306 56,315 54,779 140,913 16,093 13,506 31,467 19,845 22,031 12,609 2,673 2,746 1,416 2,514
2000 17,286 57,282 136,278 49,289 76,614 11,546 8,294 16,367 9,874 11,332 6,744 2,975 1,539 1,104
2001 27,486 42,304 86,422 93,597 30,336 54,491 10,375 8,762 12,244 9,907 8,259 6,088 1,491 1,259
2002 11,698 80,863 70,801 45,607 54,202 21,211 42,199 9,888 4,707 6,520 9,108 9,355 3,994 5,697
2003 24,477 211,495 286,017 58,120 27,979 25,592 14,203 10,944 2,230 3,424 4,225 2,562 1,575 1,370
2004 23,144 63,355 139,543 182,450 40,489 13,727 9,342 5,769 7,021 3,136 1,861 3,871 994 1,855
2005 6,088 26,091 42,116 117,910 133,437 27,565 12,074 9,203 5,172 5,116 1,045 1,706 2,110 757
2006 52,567 118,526 217,672 54,800 48,312 57,241 13,603 5,994 4,299 898 1,626 1,213 849 933
2007 10,817 94,250 83,631 163,294 61,207 87,541 92,126 23,238 11,728 7,319 2,593 4,961 2,302 1,420
2008 10,427 38,830 90,932 79,745 107,644 59,656 62,194 54,345 18,130 8,240 5,157 2,680 2,630 1,178
2009 5,431 21,856 35,221 31,914 18,826 22,725 10,425 9,213 9,549 2,238 1,033 768 406 298
2010 1,476 8,843 22,674 29,492 24,293 14,419 17,407 10,045 7,576 8,896 1,764 1,105 672 556
2011 521 9,357 24,621 20,046 22,869 23,706 13,749 16,967 10,039 7,623 7,745 1,441 618 785
2012 403 17,827 89,432 51,257 43,079 51,224 41,846 34,653 27,215 24,946 15,473 13,631 2,556 236
2013 6,888 46,848 24,833 35,070 17,250 18,550 19,032 21,821 15,952 15,804 10,081 9,775 6,722 2,486
2014 — 3,537 53,241 50,609 70,044 34,393 22,084 22,138 13,298 17,761 7,974 4,461 2,862 1,746
2015 89 6,024 29,890 53,573 43,501 43,015 15,533 10,760 8,664 8,161 6,981 2,726 2,467 1,586
2016 72 10,740 25,575 29,908 41,952 25,823 24,925 9,516 7,734 6,088 4,284 7,154 3,108 826
2017 1,262 5,236 31,855 18,113 10,239 15,506 10,223 8,830 5,676 3,399 1,616 2,220 1,533 1,596
2018 — 8,911 19,642 34,284 16,847 12,376 17,161 6,978 7,379 3,482 1,713 1,153 2,159 489
2019 461 4,601 15,845 12,970 16,084 12,244 6,944 9,531 6,165 4,732 2,983 2,808 2,200 1,866
2020 384 23,603 15,956 22,572 16,333 19,385 11,071 7,098 6,241 3,035 3,359 4,505 1,567 1,129
2021 12,440 21,018 88,992 37,291 37,244 17,231 21,230 13,155 11,781 7,270 5,213 3,549 2,771 1,583
2022 — 23,108 90,765 86,093 26,757 25,604 11,495 14,534 6,998 6,916 4,226 3,817 2,711 1,651
2023 — 8,178 75,892 90,608 56,330 26,617 29,872 11,921 16,204 9,236 8,009 4,399 3,936 2,219
2024 — 1,623 23,825 55,317 70,855 62,492 16,547 16,852 13,537 7,271 7,138 4,593 5,159 4,016
2025 — 26,730 28,952 67,405 86,278 72,227 53,318 18,418 14,638 7,411 7,514 4,058 2,706 1,619
Figure 5: Icelandic summer spawning herring in 5a. Catch at age from commercial samples. Bars are coloured by year class.

Weight at age

Mean weight at age in the stock is shown in Figure 6. As stated in the stock annex, the mean weight-at-age of the stock is derived from catch samples and therefore represents both stock and catch weights. Stock weights of the older year classes have been generally decreasing in recent years.