SAITHE

Key signals

Catch has been below the TAC every year since 2013, with discards negligible (~0.1%) and only ~60% of the 2023/24 TAC taken.
Harvest rates remain consistently below all reference points (HR_MGT, HR_MSY, HR_pa).
Spawning stock biomass (SSB) is currently above all key thresholds (B_lim, B_trigger, B_pa).
Fishery composition is dominated by bottom-trawl effort, with minimal gillnet and other gear use; 2024 landings fell below 40 kt—the lowest annual catch since 2001.
Distribution has shifted northward over the past decade: in 2017–18, over 50% of saithe landings occurred northwest of Iceland.
TAC is set as C_y/y+1 = 0.2 × B₄₊, where B₄₊ is based on stock weights; this harvest-control rule was evaluated against the recent survey variability.

General Information

Saithe in Icelandic waters is managed as a one unit, though tagging studies have shown that in some years saithe migrates from distinct waters into Icelandic waters and vice versa. Saithe is both demersal and pelagic. They can be found all around Iceland, and most common in the warm waters south and southwest off Iceland. In the last decade the distribution has gradually become more northerly and in 2017 and 2018 more than 50% of the catches were taken northwest of Iceland. Less is known about the spawning of saithe than other gadoids in Iceland. Spawning is thought to take place in shallow water (100–200 m) off the southeast, south and west coast of Iceland. The main spawning area is considered to be south/southwest off Iceland (Selvogsbanki, Eldeyjarbanki). Spawning was believed to be earlier than for cod but observations from the gillnet survey conducted in early April show substantial spawning of saithe later than expected from earlier studies. Spawning seems to take place in February–April and the timing of spawning seems to be variable. The larvae drift clockwise around Iceland and in mid-June, juveniles can be found in many coves, bays, and harbours, at about 3–5 cm in length. At age 2, they move to deeper waters in winter.

Saithe become mature at age 4–7. According to available data, approximately 115 thousand saithe were tagged in the NE Atlantic in the 20th century, most of them in the Barents Sea with total returns just under 20 thousand (Jónsson, 1996). Around 6 thousand saithe were tagged in Icelandic waters in 1964–65, the recapture rate being 50% (Jones and Jónsson, 1971). Based on recaptures by area, approximately 1 in 500 of tagged saithe released outside Icelandic waters were recaptured in Icelandic waters, and 1 in 300 released in Icelandic waters were recaptured in distant waters (Jónsson, 1996). For comparison, cod long-term emigration rate from Icelandic waters is 1 in 2000 tagged fish (Jónsson, 1996), a rate almost an order of magnitude lower. Other evidence of saithe migrations do exist, albeit of a more circumstantial nature. Sudden changes in average length or weight at age and reciprocal fluctuation in catch numbers at age in different areas of the NE Atlantic have been interpreted as signs of migrations between saithe stocks (Reinsch, 1976; Jakobsen and Olsen, 1987; Jónsson, 1996). Since mean weight at age decreases along an approximately NW to SE to NE gradient, migration of e.g. northeast arctic saithe to Icelandic waters will, theoretically, be detectable as a reduction in size at age in the Icelandic saithe catches. Catch curves from some year classes, from different areas show some reciprocal variations. Inspection of the data based on the above indicate that the most likely years and ages for immigration are as follows: Age 10 in 1986, age 7 in 1991, age 9 in 1993 and the 1992 year class as age 7 saithe in 1999 and 8 in 2000. Currently only the migration of age 7 in 1991 is included in the assessment but it is the largest migration, estimated around 10 million individuals or 35 thousand tonnes. The other potential migrations are smaller and not significant if estimated on “normal scale”. A tagging program was conducted in Icelandic waters in 2000–2004 from which ~1750 of ~16000 tags released have been returned. The number of returns from areas other than the Icelandic EEZ has now reached 10 or around 2.5% of the recaptures outside the management area of the stock. Most were tagged at eastern localities and recaptured in Faroese waters, with a pulse of tags recovered in early 2006. Other foreign returns have come from areas west of Scotland and east of Greenland.

Fishery

The number of boats accounting for 95% of the total saithe catch has declined from 200-300 boat in 1994–2001 to around 100 boats after 2000 (Figure 1, Table 1).

In the last two decades, most of the catch was taken by bottom trawl (83% in 2010–2017, 90% in 2018–2023), with gillnet and jiggers taking the majority of the rest, 5% for each fleet (Figure 2, Table 1). The share of the gillnet fleet was larger in the past, 26% in 1987–1996 compared to 8% in 1998–2020. Reduction in the gillnet fisheries is caused by general reduction in gillnet boats that are mostly targeting cod and increased mesh size in gillnet fisheries targeting cod. The catch by foreign vessels before 1978 was nearly all taken by bottom trawl.

The reduction in the gillnet fleet was driven by boats changing from gillnets to longlines, a change driven by cod and haddock fisheries. For saithe fisheries, it is important to note that saithe is rarely caught by longliners, so the fleet has become much less directed toward saithe fishing than before. The share of longlines increased gradually from 0.8% before 2000 to 2.2% in 2013–2016 reducing to less than 1% in 2021 and 2022. The share of longline increased slightly in 2023, but the catch remained similar.

The fleet using demersal trawl can be divided in two parts, those that freeze the catch and those that land it fresh. The trend in the last decade has been an increase in the trawler fleet that lands the catch fresh. Freezing trawlers have taken large proportions of the catch of saithe and redfish but much less of cod and haddock. The main reason for this is relative price of frozen vs fresh fish for each species. Mixed fisheries issues, like avoiding redfish when catching fish to be landed fresh, can be a factor, as redfish spines damage the catch. The same vessels are catching redfish and saithe in the same area but not in the same hauls. Redfish is mainly caught during daytime and saithe during the night.

Most of the saithe is caught by bottom trawl at 100-200 m depth (Figure 3). Other gears include gillnets that catch saithe at 50-200 m depth and Danish seine and handline that catch saithe at depths less than 150 m.

The spatial distribution of the saithe fisheries changed greatly from 2002–2014 (Figure 4, Figure 5). Before 2002 most of the saithe was caught south and west of Iceland, but since 2012, 40–50% of the catch has been taken northwest of Iceland. Comparable percentages before 2002 ranged 3–8%. Similar increases can be seen for golden redfish, but redfish and saithe have for a long time been caught by the same vessels, not necessarily in the same hauls, rather as a night versus day fishery. The area where saithe is caught now has since the beginning of the 20th century been the most important cod fishing ground for trawlers.

Figure 1: Saithe. Number of vessels (all gear types) accounting for 95% of the total catch annually since 1994. Left: Plotted against year. Right: Plotted against total catch. Data from the Directorate of Fisheries.

Figure 2: Saithe. Landings in tons and percent of total by gear and year

Table 1: Saithe. Number of Icelandic vessels landing saithe, and all landed catch divided by gear type.

Year	Bottom Trawl		Gillnets		Other gears		Total
Year	Number of boats	Catch	Number of boats	Catch	Number of boats	Catch	Catch
2000	157	25 936	258	4 308	90	980	31 224
2001	138	24 586	308	4 549	65	757	29 892
2002	131	35 606	281	3 311	66	942	39 859
2003	123	45 096	246	2 214	72	1 097	48 407
2004	124	55 394	250	2 254	87	1 347	58 995
2005	130	59 947	210	2 996	84	1 399	64 342
2006	124	65 698	165	3 790	81	1 448	70 936
2007	120	56 092	135	3 919	103	1 312	61 323
2008	103	59 385	129	6 199	131	1 359	66 943
2009	109	46 731	135	9 380	127	1 440	57 551
2010	107	43 903	163	4 483	142	1 166	49 552
2011	104	40 991	157	3 451	129	1 487	45 929
2012	99	41 183	166	3 664	111	1 643	46 490
2013	102	48 813	145	3 109	98	1 383	53 305
2014	96	39 294	145	2 368	78	1 037	42 699
2015	95	41 358	141	2 425	96	1 197	44 980
2016	89	43 176	130	2 521	84	921	46 618
2017	85	44 748	109	1 350	73	977	47 075
2018	79	61 507	94	1 717	84	987	64 211
2019	69	58 836	96	1 425	65	1 461	61 722
2020	79	44 141	88	2 583	59	990	47 714
2021	84	53 482	105	2 979	74	1 201	57 662
2022	79	53 760	89	2 642	82	1 476	57 878
2023	79	36 430	96	1 335	78	937	38 702
2024	79	35 123	81	940	57	552	36 615

Figure 3: Saithe. Depth distribution of saithe catches from bottom trawls, longlines, trawls and demersal seine from Icelandic logbooks

Figure 4: Saithe. Changes in spatial distribution of saithe catches as recorded in Icelandic logbooks.

Figure 5: Saithe. Spatial distribution of catches by all gears for selected years.

Landing trends

Information on landings of saithe exist since 1905 (Figure 6). From 1905–1938 most of the catch was taken by foreigners, and also from 1950–1975 when foreigners, mostly Germans, accounted for 60% of the saithe landings (Figure 6). Mean annual catch of saithe has been 65 thous. tons since 1955, 73 thous. tons before 1980 but 60 thous. tons after 1980. In the last five years, the catch by foreigners has always been less than 300 tons and 0.5%, of which nearly all the catch has been taken by Faroese vessels. In 2024, landings were 38 538 tons. It is almost 10% reduction from 2023, when landings were 42 114 tons, which was far from the set quota, 66 114 tons for 2023/2024 and 66 705 tons for 2024/2025. Landings of Icelandic saithe in 2024 are estimated to have been 38,736t (see also Figure 6).

Figure 6: Saithe. Recorded landings since 1905. Note: “Other” represents mostly German landings.

Data available

The samples used to derive catch in numbers are both taken by observers at sea and from shore samples (Figure 7, Figure 8). The trawlers that freeze the catch account for the majority of sea samples, while all shore samples are from fresh fish trawlers. In addition, relatively few fishes from sea samples are sampled for otoliths but the age-length keys are similar between sea and shore samples even though the length distributions differ. The bottom trawl sampling covers mostly covers the trend of the landings well.

Length distributions from sea and shore samples show some difference, where the shore samples show usually more of large fish.

Figure 7: Saithe. Ratio of samples by month (bars) compared with proportion landings by month (solid black line) split by year and main gear types. Numbers of above the bars indicate number of samples by year, month and gear.

Figure 8: Saithe. Fishing grounds last year as reported in logbooks (contours) and positions of samples taken from landings (crosses) by main gear types.

Discards

Discarding is not considered to be a problem in the Icelandic saithe fisheries, with an estimated discard proportion of 0.1% (Pálsson 2005, 2008; Sigurðsson et al. 2016). Recently, the fleet does also seem to have difficulty in catching the set TAC, making discards more unlikely.

In 1999–2005, substantial fisheries of blue whiting were conducted within Icelandic and Faroese jurisdictions. From 2003–2005, bycatch of saithe in those fisheries was estimated to be 1500-4000 tons per year, less than half of that within Icelandic jurisdiction (Pálsson 2005). Since 2007, blue whiting fisheries in Icelandic jurisdiction have decreased significantly compared to 2000–2005.

Length compositions

The bulk of the length measurements is from the four segments, i.e. trawls, Danish seine, gillnets and hand lines. The number of available length measurements by gear has fluctuated in recent years in relation to the changes in the fleet composition.

Length of saithe caught by nets are in general larger compared to saithe caught by trawl (Figure 9). Length distribution of other fishing gears are similar to trawl.

Figure 9: Saithe. Commercial length distributions by gear and year

Sampling from commercial catch has been revised in recent decades, the number of samples has reduced and also the number of otoliths per sample. Sampling in 2020 was much less than in the years before, the number sea samples and number of age samples was especially low. The main explanation seems to be the COVID-19 epidemic. In 2021 the sampling was back to the level in 2017–2019 but has reduced again in 2022–2024 (Table 2).

Around 90% of the length samples are taken from trawl that accounts for ~90% of the catches.

Length distributions from bottom trawl show a tendency to catch smaller fish from 2003–2017 but again larger fish in 2018–2020. In 2020 the +110 cm group was especially abundant, but proportion of 60-69 cm fish was above average in 2022. In 2024, an increased amount of larger saithe was caught.

Table 2: Saithe. Number of samples and length measurements from landed catch.

Year	Bottom Trawl		Gillnets
Year	Number of samples	Number of length measurements	Number of samples	Number of length measurements
2000	146	21 359	20	2 646
2001	156	23 798	27	3 224
2002	197	30 638	17	2 722
2003	231	36 570	13	1 540
2004	245	38 768	5	588
2005	354	57 381	26	1 806
2006	383	50 122	32	3 794
2007	450	47 544	28	2 845
2008	431	43 666	34	4 039
2009	326	30 414	52	7 248
2010	362	41 688	38	5 020
2011	191	25 150	31	5 248
2012	353	34 757	13	1 833
2013	314	33 966	9	1 331
2014	306	32 654	10	1 036
2015	229	32 599	18	2 044
2016	249	36 940	14	1 382
2017	213	29 646	8	408
2018	143	25 487	6	465
2019	159	28 297	2	14
2020	57	8 182	9	631
2021	159	29 047	2	234
2022	104	15 325	6	707
2023	87	14 295	4	374
2024	86	12 133	6	383

Age compositions

Table 3 summarizes the number of samples and otoliths collected by gear type each year. Over time the number of samples in the gillnets reduced substantially, which is due to the decrease in gillnet fishing in general. In 2024, most of the catch derived from the 2014–2017 year classes (Figure 10). The number of year classes contributing to the catches has increased in recent years; the result of low fishing mortality in recent years and the last year class contributing with more than 1% of total is 11 years old (Figure 11).

Table 3: Saithe. Number of samples and otoliths collected from landed catch.

Year	Bottom Trawl		Gillnets
Year	Number of samples	Number of otoliths	Number of samples	Number of otoliths
2000	146	4 491	20	921
2001	156	4 646	27	1 159
2002	197	4 908	17	500
2003	231	6 462	13	451
2004	245	4 988	5	150
2005	354	5 267	26	71
2006	383	6 267	32	450
2007	450	6 464	28	359
2008	431	6 325	34	800
2009	326	4 687	52	897
2010	362	5 184	38	550
2011	191	4 775	31	299
2012	353	6 292	13	402
2013	314	3 993	9	449
2014	306	2 511	10	250
2015	229	2 426	18	375
2016	249	2 565	14	300
2017	213	1 541	8	82
2018	143	1 659	6	75
2019	159	1 270	2	0
2020	57	850	9	75
2021	159	1 581	2	50
2022	104	1 201	6	100
2023	87	925	4	20
2024	86	983	6	0

Figure 10: Saithe. Catch at age from the commercial fishery in Iceland waters. Bar size is indicative of the catch in numbers and bars are colored by cohort. Note different scales on y-axis.

Figure 11: Saithe. Catch at age from the commercial fishery in Iceland waters. Biomass caught by year and age, bars are colored by cohort.

Weight at age in the catch

Weights of ages 4–6 and 11-14 have been low in recent years, but 7-10 are close to average weight (Figure 12). The large 2012 cohort has the lowest mean weight of all year classes, both in catches and in the survey. This is in line with density dependent growth that has been observed in this stock and can for example be seen for year classes 1984 and 2000 that are both large. Year classes 2013 and 2014 that seem to be above average have higher mean weight at age than the 2012 cohort. The long-term trend since 1980 has been a gradual decline in the mean weight of all ages. Mean weight at age in catches was close to average in 2024 was slightly below average for the older age classes, but otherwise close to the average.

Weights at age in the landings were used to compile the reference biomass (B4+) that is the basis for the catch advice. After the benchmark 2025 (ICES, 2025) it was decided to use stock weights instead of catch weights to compile SSB.

Figure 12: Saithe. Mean weight at age in the catch from the commercial fishery in Icelandic waters. Bars are coloured by cohort.

Natural mortality

No information is available on natural mortality. For assessment and advisory purpose the natural mortality is set to 0.2 for all age groups (ICES, 2025).

Catch per unit of effort from commercial fisheries

Catch per unit of effort data from the bottom trawl fleet shows considerable variability, and has decreased considerably from its peak in 2018 (Figure 13). CPUE in the last three years is the lowest it has been since 2011. Unit effort is here hours trawled and the CPUE index for each year is the median of the CPUE for the selected hauls.

When compiling CPUE indices, deciding which hauls to base the analysis on is not straightforward. All hauls inside a particular area, all hauls with saithe recorded, or all hauls with saithe accounting for more than a defined proportion of total catch could be chosen. The larger the stat-ed fraction, the greater the variability in the CPUE index.

CPUE in the last three years is not low as compared to earlier years, especially if the index is compiled based on all hauls where saithe has been registered. The question is then if data 15 years ago are comparable to modern data, owing to technological advances. However, CPUE indices show considerable similarity to total biomass index from SMB.

Figure 13: Saithe. Catch per unit of effort in the most important gear types. The dashed lines are based on locations where more than 50% of the catch is saithe and solid lines on all records where saithe is caught. Effort data is not available for 2022. BMT = Beam Trawl.

Icelandic survey data

Saithe is among the most difficult demersal fishes to get reliable information from bottom trawl surveys. In the spring survey, which has 500–600 stations, a large proportion of the saithe is often caught in relatively few hauls and there seems to be considerable inter-annual variability in the number of these hauls.

The biomass indices from the spring survey fluctuated greatly from 1985–1995 but were consistently low from 1995–2001 (Figure 14). Since 1995 the indices have been variable but compared to the period 1985–1995 the variability seems “real” rather than noise. This difference is also seen by the estimated confidence intervals of the indices that are smaller after 1995. In 2018 the indices were the highest in the series and had tripled since 2014. Most of the increase was caused by year class 2012 that was strong in the surveys 2015–2018. The index decreased between 2018–2020. It has been variable in last six years, was lowest in 2022 but increased again in the last three years.

The high index in 1986 is mostly the result of one large haul that is scaled down to the second largest haul when compiling indices for tuning. Estimated CV from the survey is often relatively high and many relatively low values appear in the survey matrix, both for the youngest and oldest age groups. The youngest age group (age 3–4 and younger) are considered to inhabit waters shallower than the survey covers and the older age groups are reducing in numbers and could also be pelagic. The high index in 2018 came from relatively large catches in many hauls so the estimated CV was around average.

The autumn survey shows similar trend as the spring survey and the index is at high level in 2017 (2004 and 2018 are outliers due to large CV). The values before 2000 might be underestimated due to stations added in 2000 where large schools of saithe were sometimes found. Excluding these stations leads to a lower but more stable index.

The sample position of both the spring and autumn survey is shown in Figure 15.

Length distributions from the surveys are displayed in Figure 17, and spatial distribution of survey stations is shown in Figure 16.

Age-disaggregated indices from the spring and autumn survey are shown in Figure 18.

Figure 14: Saithe. Indices (total biomass, biomass > 45 cm, biomass > 60 cm and abundance < 25 cm) in the Spring Survey (March) 1985 and onwards (line shaded area) and the autumn survey (point ranges).