Key signals
Following a peak in landings from 2008-2013, landings since 2017 have been at historically low levels.
Biomass indices from the Icelandic Autumn Survey declined from 2009 to 2022, and have increased in the past three years.
From 2010 to 2020 recruitment levels were minimal or low. These have since increased to levels seen in early 2000s.
Spawning stock biomass (SSB) has increased since 2020 and is currently at a similar level to 2010.
Biomass levels are expected to increase under current conditions due to improved recruitment.
General information
Blue ling (Molva dypterygia) in ICES Division 5.a and Subarea 14 are assessed as one stock. Blue ling is a deep-water gadoid species primarily distributed along the continental shelves and slopes of the Northeast Atlantic, particularly around Iceland, the Faroe Islands, Norway, the British Isles, and off East Greenland. In Icelandic waters, it is commonly found in deeper regions over soft seabeds in the southeast, south, and west of Iceland, at depths greater than 500 meters. The majority of the population is concentrated between 300 and 800 meters, and it is rarely found at depths shallower than 200 meters. During the winter months, blue ling tends to stay at deeper depths, while in the spring and summer, it ascends to shallower areas.
The blue ling is smaller than the common ling (Molva molva), reaching an average length of approximately 80 cm and a maximum length of around 150 cm, according to the Icelandic autumn groundfish survey. Blue ling is a slow-growing species, living up to 20 years or more. Sexual maturity is typically reached when individuals are 75-90 cm. Sexual dimorphism is notable with females growing faster and reaching maturity at larger sizes and older ages than males. Spawning occurs in the spring at depths of 500-1000 meters or deeper, in waters with temperatures ranging from 5-8°C, outside the continental shelf off the southern coast of Iceland, south and west of the Faroe Islands, west of Norway, and west of Scotland to Northern Ireland. Off Iceland, blue ling spawns from February to April, peaking in March in waters with temperatures of 5-6°C. Known spawning grounds include depths of 600-1000 meters south of the Westman Islands and along the fishing limits of the Reykjanes Ridge (Franshóll). The eggs are pelagic, measuring 1.3-1.5 mm in diameter, and hatch in the upper layers of the ocean. The larvae drift long distances west and north, traveling far into the open sea toward Greenland, where they grow alongside the larvae of cod, herring, capelin, silver hake, and common skates. The juvenile fish settle on the seabed when they reach 8-10 cm in length, typically between August and October (Jónsson and Pálsson (2013))
Fishery
Landings trends
Since 1960, landings of blue ling in Icelandic water have shown three distinctive peaks (Figure 1). In the early 1980s, catches were at a historical maximum, driven primarily by bottom trawl fisheries targeting spawning aggregations near the Westman Islands (Figure 1, Figure 2). In 1993, the Icelandic bottom trawl fleet fished on aggregations of spawning blue ling in a small area on the Reykjanes Ridge at the border between Division 5.a and Subarea 14 (Figure 1, Figure 2). The third peak began in 2008 when the longline fleet started targeting blue ling. Landings peaked in 2010 and subsequently declined to a historic low in 2020. In between these peaks, catches have generally been below 3000 t and blue ling has largely been bycatch in redfish, greater silver smelt, and Greenland halibut bottom trawl fisheries, and tusk longline fisheries.
Before 2008, the majority of the catches of blue ling in 5.a were caught by trawlers (Figure 2) as bycatch. From 2008-2013 there was a substantial change in the fishery as longliners started targeting blue ling and their proportion of catches increased from 7–20% in 2001–2007 to around 70% in 2011 (Figure 2). The trend has reversed and from 2016–2025 the proportion of longline catches decreased to 10–30%.
Historically, landings in Subarea 14 have been small compared to Division 5.a (Figure 1). Total international landings from Subarea 14 have been highly variable over the years, ranging from a few tonnes in some years to around 3700 t in 1993 and 950 t in 2003. Most of the landings in 2003 were taken by Spanish trawlers (390 t). Since then, no further information is available on this fishery. The high landing values in Subarea 14 are very occasional, and in most years, total international landings have been between 50 and 200 t. Preliminary landings in 2025 were 17 t.
Preliminary total landings in 2025 were 640 tonnes of which the Icelandic fleet caught 624 tonnes.
Spatial and temporal patterns
The main bottom trawl fishing grounds are located northwest of Iceland close to the shelf break, and southwest of Iceland at the base of Reykjanes Ridge (Figure 4). Fisheries also operate along the continental shelf south and southeast of Iceland, and directly west of Iceland (Figure 4, Figure 6). Most of the catches by trawlers are taken in waters between 200 m and 700 m (Figure 3). When targeting blue ling, longliners typically operated in waters from 200 m to 500 m (Figure 3), and catches were distributed in deeper waters west, southwest and south of Iceland (Figure 4, Figure 6).
| Year | Nr. Bottom Trawl | Bottom Trawl | Nr. Long Line | Long Line | Nr. Other | Other | Total catch |
|---|---|---|---|---|---|---|---|
| 2000 | 108 | 801 | 44 | 808 | 36 | 25 | 1 634 |
| 2001 | 110 | 597 | 39 | 131 | 48 | 34 | 762 |
| 2002 | 105 | 986 | 41 | 256 | 25 | 23 | 1 264 |
| 2003 | 105 | 883 | 47 | 197 | 33 | 17 | 1 098 |
| 2004 | 112 | 894 | 53 | 145 | 45 | 44 | 1 083 |
| 2005 | 106 | 1 261 | 60 | 108 | 51 | 126 | 1 496 |
| 2006 | 105 | 1 477 | 69 | 151 | 47 | 107 | 1 734 |
| 2007 | 97 | 1 544 | 90 | 374 | 64 | 76 | 1 995 |
| 2008 | 95 | 2 111 | 92 | 1 454 | 61 | 88 | 3 653 |
| 2009 | 89 | 2 242 | 87 | 1 677 | 69 | 211 | 4 129 |
| 2010 | 85 | 2 202 | 96 | 3 978 | 73 | 198 | 6 378 |
| 2011 | 81 | 1 630 | 97 | 4 140 | 58 | 134 | 5 904 |
| 2012 | 79 | 1 449 | 78 | 2 425 | 52 | 332 | 4 207 |
| 2013 | 75 | 1 300 | 72 | 1 420 | 45 | 48 | 2 769 |
| 2014 | 72 | 923 | 74 | 628 | 36 | 43 | 1 594 |
| 2015 | 67 | 821 | 78 | 868 | 36 | 22 | 1 712 |
| 2016 | 66 | 701 | 54 | 213 | 31 | 10 | 925 |
| 2017 | 57 | 436 | 53 | 169 | 26 | 14 | 619 |
| 2018 | 65 | 363 | 60 | 132 | 20 | 7 | 502 |
| 2019 | 58 | 238 | 54 | 161 | 27 | 16 | 415 |
| 2020 | 58 | 264 | 47 | 71 | 21 | 9 | 344 |
| 2021 | 59 | 286 | 41 | 33 | 20 | 4 | 323 |
| 2022 | 55 | 338 | 37 | 86 | 20 | 2 | 427 |
| 2023 | 52 | 304 | 36 | 96 | 20 | 4 | 404 |
| 2024 | 55 | 427 | 28 | 42 | 16 | 3 | 473 |
| 2025 | 52 | 555 | 25 | 43 | 20 | 24 | 622 |
Catch per unit of effort from commercial fisheries
Effort and nominal catch per unit effort (CPUE) data from the Icelandic trawl and longline fleet are given in Figure 8. Due to changes in the fishery (expansion into new areas, fleet behaviour, etc.) and technical innovations, CPUE is not considered a reliable index of biomass abundance of blue ling and therefore no attempt has been made to standardize the series. However, looking at fluctuations in CPUE and effort may be informative regarding the development of the fishery. CPUE from longlines was high from 2008-2013 but has decreased markedly since. CPUE from trawls has been gradually decreasing over time. Effort from bottom trawls peaked in 2009 and has since declined to the same level observed in the early 2000s. Effort from longlines peaked in 2011 but has remained relatively stable since.
Landings and discards
Landings data before 1982 (and foreign landings until 2005) are sourced from the ICES STATLANT database. Icelandic landings from 1982–1993 were collected by the Fisheries Association of Iceland, and from 1994 onward by the Directorate of Fisheries. Foreign landings were recorded by the Coast Guard before 2014 and by the Directorate of Fisheries thereafter.
Discard rates of blue ling are unknown. Discarding is prohibited by law. Management measures, such as inter-species quota transfers and landing flexibility, discourage discarding. To help prevent high grading and quota mismatches, fisheries are permitted to land catches that are exempt from quota deductions, provided that the proceeds from their sale are transferred to a government-managed fund. More information is available at https://www.responsiblefisheries.is/seafood-industry/fisheries-management.
Data and sampling
Commercial data
Fishing areas and sampling locations are shown in Figure 9 and Figure 10. In 2025, 7 samples were collected from bottom trawls and 0 from longlines (Figure 10, Table 2). As of January 2026, the sampling frequencies for blue ling from longline were increased to improve coverage.
