Hedges and Christiansen data available for Greenland halibut stock in NAFO Subarea 0+1 offshore; SPiCT model accepted for stock status.

Hedges and Christiansen data available for Greenland halibut stock in NAFO Subarea 0+1 offshore; SPiCT model accepted for stock status.

Data available for the Greenland Halibut Stock Component in NAFO Subarea 0 + 1 (offshore)

Serial No. N7749

NAFO SCR Doc. 26/029

SCIENTIFIC COUNCIL MEETING –JUNE 2026

Northwest Atlantic Fisheries Organization

www.nafo.int Data available for the Greenland Halibut Stock Component in NAFO Subarea 0 + 1 (offshore) K.J. Hedges1 and H. Christiansen2 1Fisheries and Oceans Canada, Freshwater Institute, 501 University Cres., Winnipeg, Manitoba, Canada R3T 2N6 2Greenland Institute of Natural Resources, Box 570, 3900 Nuuk, Greenland

2026-06-10 Hedges, K.J. and Christiansen, H. 2026. Data available for the Greenland Halibut Stock Component in NAFO Subarea 0 + 1 (offshore). Scientific Council Research Document, SCR Doc. 26/029: 1-33. Abstract

The paper presents the data available for Greenland halibut in Northwest Atlantic Fisheries Organization (NAFO) Subareas 0 and 1 (offshore) that can be used for stock assessment. Since 1995, catches have been near the Total Allowable Catch (TAC). Until 2022, catches increased in step with increases in the TAC. However, catches decreased in 2023, following advice from the NAFO Scientific Council. Greenland and Canada have conducted buffered random stratified bottom trawl surveys in Divisions 0A and 1CD since 1999 using the same vessel and the same gear. Surveys were not conducted in 2018, 2020 or 2021, and the 2019 survey was conducted with a charter vessel which after review of gear performance measures was not considered comparable to previous surveys. In 2022, a new time series started with a new vessel, RV Tarajoq, and a new gear, the Bacalao trawl. Starting in 2022 Divs. 0B has been surveyed annually. An index of abundance of age 1 Greenland halibut from a shallow survey in Divs. 1AF was calculated for 1991 to 2025 (no survey was conducted in 2021). A standardized index produced using a delta-GAM with exploitable biomass > 35 cm fork length from the shallow survey in Divs. 1AF and the deep surveys in Divs. 0AB and 1CD, and commercial harvest data were used as inputs for a Stochastic Surplus Production in Continuous Time (SPiCT) model. In 2024, the SPiCT model was reviewed and accepted for use in providing advice regarding stock status and harvest levels. 1 Description of the Fishery, Catches and TAC 1.1 TAC Regulation Greenland halibut in Subarea 0+1, including 1A inshore, came under quota regulation in 1976 when a TAC of 20,000 t was established (Fig. 1). The TAC was increased to 25,000 t in 1979. In 1994, analyses of tagging and other biological information led to the creation of separate management areas for inshore Div. 1A and Subarea 0 + Divs. 1A (offshore) + 1B-F. The portion of the TAC allocated to SA 0 + Divs. 1A (offshore) + 1B-F was 11,000 t and the TAC remained at this level from 1995-2001, during which the TAC was fished almost exclusively in Divs. 0B and 1CD. A series of surveys took place from 1999-2004 in areas of Divs. 0A and 1AB

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www.nafo.int that had not been surveyed before. This new information on biomass in the stock area resulted in increases in the overall TAC of 4,000 t in both 2001 and 2003 and 5,000 t in 2006 that were allocated to Divs. 0A and 1AB. From 2006 to 2009 the advised TAC in Divs. 0A + 1AB was 13,000 t and the TAC for Divs. 0B + 1C-F remained at 11,000 t. Based on an observed positive trend in the Divs. 1CD survey index, the TAC for Divs. 0B + 1CD was increased by 3,000 t in 2010. The overall TAC for SA 0 + 1 (offshore) remained at 27,000 t from 2011 to 2013. In 2014, the TAC for Divs. 0A + 1AB was increased by 3,000 t to 16,000 t based on positive trends in the survey indices. The overall TAC of 30,000 t for the SA 0 + Divs. 1A (offshore) + 1B-F stock remained through 2016. In 2016, an index-based harvest control rule (HCR) was accepted as the basis for TAC advice and an increase of 2,300 t was advised for the SA 0 + Divs. 1A (offshore) + 1B-F stock for 2017 and 2018. Scientific Council advised that the increase be allocated equally between Divs. 0A + 1A (offshore) + 1B, and Divs. 0B + 1C-F. In 2018, the HCR was used to advise an increase of 4,070 t for the whole SA 0 + Divs. 1A (offshore) + 1B-F stock, with allocation of the increase among divisions left to the managers. In 2020, separate management areas were established for inshore fishing areas in Divs. 1B-F, and the TAC was maintained at 36,370 t for the resulting SA 0 + 1 (offshore) stock in 2021 and 2022. In 2022, considering that survey indices were not calculated in 2018-2022 because the survey vessel (RV Paamiut) was retired in winter 2018 and a contract vessel used in 2019 fished differently below 700 m (A. Nogueira and Treble, 2020), it was advised that the TAC for 2023 and 2024 be reduced to the mean level during 2013-2017 (29,640 t), a recent period when the stock was stable. Half of the advised reduction was applied, and the TAC was set at 33,005 t in 2023 and 2024. In 2024 a Surplus Production in Continuous Time (SPiCT) model was accepted for assessing stock status and providing TAC advice for the SA 0 + 1 (offshore) stock (B. Nogueira A. and Boje, 2024). The SPiCT model used commercial catch data (1991-2023) and a combined index that incorporated data from fishery-independent surveys (1991-2023) as inputs. The combined index (Berg and Nogueira, 2024) used a delta-GAM to combine data from deep water surveys in Div. 0A (1999-2023), Divs. 1CD (1999-2023), and a shallow survey in Divs. 1A-F (1991-2023) into a single annual index for the entire stock area. Based on the SPiCT model results, in 2024 it was advised that the TAC be reduced to 90% of the 2023 TAC (29,974.5 t) for 2025 and 2026. The advised TAC reduction was not applied and the TAC for the SA 0 + 1 (offshore) stock was set at 33,005 t in 2025, and new advice was requested for 2026 and 2027. In 2025, NAFO SC provided a risk table in accordance with the NAFO Precautionary Approach Framework to support risk-informed decisions by resource managers. TACs for 2026 and 2027 were set at 35,328 and 34,078 t, respectively, representing increases from the 2025 TAC (33,005 t).

Figure 1. Catches and recommended TAC for SA0+1 (offshore) Greenland halibut.

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www.nafo.int Here, we review data available to assess NAFO SA 0+1 (offshore) Greenland halibut and assessment model results incorporating 2025 survey (Christiansen, 2026) (Hedges, 2026) and commercial harvest data to monitor stock status. 1.2 Catches in Subarea 0 + 1 (offshore) Catches of Greenland halibut were first reported in 1965, rising to 18,303 t in 1975 before declining to 187 t in 1986 (Fig. 1). Catches then increased to 17,888 t in 1992 due to a new trawl fishery in Div. 0B with participation by Canada, Norway, Russia, and the Faroe Islands, as well as expansion of the Divs. 1CD fishery with participation by Japan, Norway, and the Faroe Islands (Tables 1 and 2). Catch declined from 1992 to 1995 primarily due to a reduction of effort by non-Canadian fleets in Div. 0B. Since 1995 catches have been near the TAC, increasing or decreasing in step with the TAC (Fig. 1). The TAC was set at 33,005 t from 2023 to 2025. Fisheries and Oceans Canada does not include the J-cut, tail off product in its list for Greenland halibut, but an interim conversion factor (CF) of 1.48 was provided in at-sea observer manuals and used by vessel operators and observers from 2007 to 2020. In 2021, at the request of the Canadian fishing industry, the CF for J-cut, tail off product was lowered from 1.48 to 1.4. Based on a review of at-sea observer experiments conducted in SA 0 the appropriate value to estimate round weight from J-cut, tail off, dressed weight is 1.5 (round weight = J- cut weight x 1.5), which is comparable with J-cut, tail off CF values used by other countries that fish in the SA 0 + 1 (offshore) stock area (Treble and Hedges, 2022). In 2021 the difference amounted to the removal of an additional 1,129 t (round weight) of Greenland halibut (DFO statistics indicated 87% of Arctic Region catch and 90% of Newfoundland Region catch was processed as frozen, gutted, head and tail off, which describes J-cut product). Catches from SA 0 since 2021 have been adjusted accordingly (Table 1). Inshore fisheries in the fjords of Divs. 1A-F and in Cumberland Sound in Div. 0B are managed separately. However, there is no way to differentiate or separate inshore from offshore catch in the totals reported for these divisions in STATLANT21A statistics. Therefore, it is necessary to rely on the Greenland and Canadian authorities to determine total offshore catches for SAs 0 and 1. Table 1. Greenland halibut catches (metric tons) by year and country for Subarea 0, 1987 to 2025. Based

on STATLANT, with information from Canada used to exclude 0B inshore catch. Year 0A-CAN 0A- OTHER 0A- TOTAL 0B-CAN 0B- OTHER 0B- TOTAL SA0- TOTAL 1987

388 388 388 1988

2 1022 1024 1024 1989

180 907 1087 1087 1990

844 8909 9753 9753b 1991

395 8350 8745 8745 1992

2624 10164 12788 12788 1993 681 681 592 6605 7197 7879c 1994

402 4274 4676 4676 1995 82 82 1859 1292 3151 3233 1996

576 576d 2354 1678 4032 4608 1997 3 3 3868 452 4320 4323 1998

3924

3924 3924 1999 517 517 4267

4267 4784 2000

5438

5438 5438e

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www.nafo.int Year 0A-CAN 0A- OTHER 0A- TOTAL 0B-CAN 0B- OTHER 0B- TOTAL SA0- TOTAL 2001 2628 445 3073 5034

5034 8107 2002 3561 3561 3910

3910 7471f 2003 4142 4142 5059

5059 9201 2004 3751 3751 5771

5771 9522 2005 4209 4209 5789

5789 9998 2006 6634 6634 5585

5585 12219 2007 6173 6173 5318

5318 11491 2008 5257 5257 5175

5175 10432 2009 6627 6627 5622

5622 12249 2010 6390 6390 6941

6941 13331 2011 6365 6365 6814

6814 13179 2012 6365 6365 7257

7257 13622 2013 6314 6314 7352

7352 13666 2014 7934 7934 7003

7003 14937 2015 7922 7922 7491

7491 15413 2016 7559 7559 6402

6402 13961 2017 8458 8458 7932

7932 16390 2018 8408 8408 7563

7563 15971 2019 9708 9708 8619

8619 18327g 2020 9429 9429 8489

8489 17918g 2021 10061 10061 9033

9033 19094gh 2022 9582 9582 9033

9033 18616i 2023 8522 8522 7796

7796 16318i 2024 8572 8572 7885

7885 16457 2025 9273 9273 7567

7567 16840j a Other countries may include Faroe Islands, Poland, Russia, Estonia, Latvia, Japan, or Norway. b Norwegian catch double reported. c The Russian catch is reported as area unknown, but has previously been reported from Div. 0B d Caught under a Canadian charter. e STACFIS estimate f Excluding 782 tons reported by error g STATLANT 21A data are not available h STACFIS estimate using 1.5 conversion factor for J-cut, tailed product; 1,129 t increase over reported catch. i Logbook data j STACFIS estimate using 1.48 conversion factor for J-cut, tailed product; results in over reported catch.

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www.nafo.int Table 2. Greenland halibut catches (metric tons) by year and country for Subarea 1 from 1987 to 2023,

not including inshore areas. Based on STATLANT, with information from Greenland used to

exclude 1A-F inshore catch. Year 1AB- GRL 1AB- RUS 1AB- FRO 1AB- TotaL 1CF- GRL 1CF- RUS 1CF- FRO 1CF- EU 1CF- NOR 1CF- JPN 1CF- Total SA1- Total 1987

1646

855 2501 2501 1988

605

1576 2181 2181 1989

540

1300 1840 1840 1990

841

54

985 1880 1880 1991

933

123 611 673 2340 2340 1992

191

151 2432 2895 5669 5669 1993

186 5 128 46 2344 1161 3