---
title: "Greenland Institute of Natural Resources Greenland halibut survey NAFO Divisions 1C-1D; Tarajoq debuts with Bacalao 476 gear"
sdDatePublished: "2026-08-08T14:34:00Z"
source: "https://www.nafo.int/Portals/0/PDFs/sc/2026/scr26-012.pdf"
topics:
  - name: "fishing"
    identifier: "medtop:20000561"
  - name: "scientific research"
    identifier: "medtop:20000735"
locations:
  - "Canada"
  - "Greenland"
---


Greenland Institute of Natural Resources Greenland halibut survey NAFO Divisions 1C-1D; Tarajoq debuts with Bacalao 476 gear

Results for Greenland halibut survey in NAFO Divisions 1C-1D for the period 1997-2017, 2019 and 2022-2025

Northwest Atlantic Fisheries Organization

www.nafo.int
Serial No. N7731

NAFO SCR Doc. 26/012

SCIENTIFIC COUNCIL MEETING –JUNE 2026
Results for Greenland halibut survey in NAFO Divisions 1C-1D for the period 1997-2017, 2019 and
2022-2025
Henrik Christiansen1, Rasmus Nygaard1
1Greenland Institute of Natural Resources, Box 570, 3900 Nuuk, Greenland

CHRISTIANSEN, H., & NYGAARD, R. 2026. Results for Greenland halibut survey in NAFO Divisions 1C-1D for
the period 1997-2017, 2019 and 2022-2025. NAFO Scientific Council Research Document, SCR Doc. 26/012: 1-
44.

Abstract
Greenland initiated a survey series in 1997 covering NAFO Divisions 1CD at depths between 400 and 1500 m.
The survey has been conducted with RV Paamiut, using an Alfredo III gear. In 2017, RV Paamiut was retired
and no survey has been conducted in 2018. In 2019, the annual trawl survey was conducted with a chartered
vessel, the CV Helga Maria. All standard gear from RV Paamiut was used in order to make the 2019 survey as
identical as possible to the previous year’s surveys, but the gear was working different at depths > 700m. No
vessel has been available in 2020 and 2021 to conduct the survey. In 2022 the survey was carried out with a
new vessel owned by the Greenland Institute of Natural Resources: RV Tarajoq, using also a new trawl gear,
Bacalao 476. Comparative trawling between RV Paamiut and RV Tarajoq was not possible. The survey was
designed as a Stratified Random Bottom Trawl Survey aimed primarily at Greenland halibut (Reinhardtius
hippoglossoides) and roundnose grenadier (Coryphaenoides rupestris). Here, biomass and abundance
estimates, and length frequencies from the survey are provided for Greenland halibut, roundnose grenadier,
roughhead grenadier (Macrourus berglax), and deep-sea redfish (Sebastes mentella) together with a list of
recorded fish species. In 2025, 69 valid hauls were conducted.
Introduction
During 1987-1995 the Japan Marine Fishery Resources Research Center (JAMARC) and the Greenland
Institute of Natural Resources (GINR), jointly conducted 12 bottom trawl surveys at depths down to 1500 m
(O. A. Jørgensen, 1998a) and four pelagic surveys (O. A. Jørgensen, 1997) at West Greenland, in 1BCD,
as part of a joint venture agreement on fisheries development and fisheries research in Greenland waters.
The bottom trawl surveys were aimed primarily at Greenland halibut (Reinhardtius hippoglossoides) in NAFO
Div. 1B-1D. In 1997, GINR continued the bottom trawl survey series with the institute’s own vessel, RV
Paamiut, which had been rigged for deep-sea trawling. Unfortunately, no calibration experiments between
the Japanese research vessel Shinkai Maru and RV Paamiut were performed, making comparisons between
both vessels impossible. The Paamiut survey traditionally covered NAFO Div. 1CD, but in 2001 the survey
area was expanded to include Div. 1A (to 74 °N) and Div. 1B, and in 2004 the northernmost part of Baffin Bay
(73° N-77°N) (Div. 1A) was also surveyed. In 2010, Div. 1A was surveyed to 75.30 °N (SCR 11/010). In 2013,

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the survey only covered Div. 1D. In 2018 no survey was undertaken due to the retirement of RV Paamiut and
the survey in 2019 was conducted with the chartered CV Helga Maria. All standard gear from RV Paamiut
(such as the Alfredo III trawl along with doors, bridles, etc., and the Marport sensors used on doors and
headlines) was used to make the 2019 survey as identical as possible compared to previous years (Table 1).
However, comparative studies of gear performance between the vessels showed that the gear has been
working differently at depths > 700m (A. Nogueira and Treble, 2020). In 2022, the new vessel owned by
GINR, RV Tarajoq with a Bacalao 476 trawl, began a new survey series.
Methods
Stratification
The survey covered NAFO Div. 1CD between the 3-nm and the mid-line to Canada at depths between 400 and
1500 m. The survey area was stratified within NAFO divisions in 6 depth strata: 401-600, 601-800, 801-1000,
1001-1200, 1201-1400, and 1401-1500 m. The depth stratification was based on Greenland Geological
Survey’s 10 m depth contour maps, Canadian maps and depth soundings made during previous surveys. The
area of each stratum was measured using “MapInfo Version 4.0”. A list of the number of valid hauls per strata
and area is given in Tables 2, 3, and 4.
The survey was planned as a Stratified Random Bottom Trawl Survey with a total of 70 hauls. A minimum of
two randomly placed hauls were conducted per stratum (Bishop, 1994). From 1997 to 2019, the remaining
hauls were allocated to strata based on the stratum area and on predictions of catch variability from past
surveys, in order to minimize standard error of the total survey biomass estimate of Greenland halibut, given
the predicted stratum variance. This method was reviewed in 2020 and realized that because biomass over-
represents larger Greenland halibut, it is not optimized for multiple size classes, and small Greenland halibut
in particular. That resulted in insufficient coverage in shallow strata where small-sized Greenland halibut are
found. It was decided to change the station allocation for a more equitable distribution of stations across
strata (A. Nogueira and Treble, 2020). From 2022, the number of stations is proportional to the total
area (1/750km2), and the survey is planned with 71 hauls. In 2004, the placing of stations independently and
randomly was replaced by buffered random sampling. This method combines the use of a minimum between-
stations distance rule (buffer zone) with a random allocation scheme (Kingsley et al., 2004). Because the
seabed in Division 1D stratum 601-800 m is muddy and soft, and generally not suitable for trawling, stations
are fixed in that stratum.
Vessel and gear
From 1997 to 2017, the survey was conducted by the 1084 GT trawler RV Paamiut. However, in the beginning
of 2018, it was decided that RV Paamiut had to be scrapped owing to increasing maintenance expenses. No
survey has been conducted in 2018. In 2019, the survey was carried out with the chartered CV Helga Maria.
All standard gear has been maintained (Table 1). The survey used an Alfredo III trawl with a mesh size of 140
mm and a 30-mm mesh-liner in the cod-end. The ground gear is of the rockhopper type. The trawl doors are
Greenland Injector weighing 2700 kg. The Injector otter doors replaced the Greenland Perfect doors that have
been used until 2003. The average net height was, in 2014, 20 cm higher with the new doors compared to the
old, but the difference was not statistically significant (95% level), and it was concluded that the net
performance has not changed by the introduction of the new doors. Further information about trawl and gear
is given in Jørgensen (1998b). The effect of the vessel change on the 2019 survey was examined by looking
at gear performance variables [e.g. net height and door distance; A. Nogueira and Treble (2020)]. Data
reviewed for the 1CD survey suggests the change in vessel in 2019 had an effect on the performance of the
Alfredo III trawl gear at depths > 701 m, where Greenland halibut are known to be abundant. Therefor,
indices must be compared with caution. In 2022, RV Tarajoq (2896 GT) began a new survey series using a
Bacalao 476 trawl with a mesh size of 136 mm and a 30-mm mesh-liner in the cod-end (Table 1). The same
doors as on RV Paamiut are used on RV Tarajoq.

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Swept area calculation
A MarPort net sonde mounted on the head rope measured net height. MarPort sensors measured the distance
between the trawl doors. Wing spread, taken as the distance between the outer bobbins, was calculated as:
𝐷𝐵𝑂𝐵= 10.122 + 𝐷𝐵𝑇𝐷∗0.142
where DBOB is the distance between outer bobbins, and DBTD is the distance between trawl doors in m. This
relationship was estimated based on flume tank measurements of the trawl and rigging used in the survey (O.
A. Jørgensen, 1998b).
In 2022, the gear was changed to a Bacalao 476 trawl. The wing spread for a tow was calculated from the
mean door spread and the geometry of the trawl as if the shape would be a triangle. V has been calculated as
follows; Where the trawl and the trawl plus bridles are assumed to form two similar triangles, bridles and
wings making a straight line:

and the lengths of the bridles (s) and the trawl wings (t) are known. The wingspread V is then calculated as:
𝑉= (𝑡𝑙∗𝐿)/(𝑡𝑙+ 𝑠𝑡)
where L is the distance between the doors (door spread). The trawl wing is 26.83 m and the length of the
bridles is 129 m. Because the shape of the Bacalao gear is not a triangle, a constant based on sensor
measurements during the Canadian survey at the same depths was applied. Scanmar sensors measured wing
spread during the deep Canadian survey in Subarea 0A. The difference between our estimation and the
sensor measurements in each depth stratum has been added as a constant in our wingspread calculations.
Bottom temperature
Near-bottom temperature was measured, by 0.1 °C, by a Seastar sensor mounted on one of the otter doors.
Trawling procedure
Trawls were towed for 30 min at a speed of 3.0 knots. However, hauls > 15 min are considered acceptable.
Trawl distance was estimated from the start and end positions of the haul. Trawling takes place day and
night.
Handling of the catch
The catch of each haul was sorted, weighed, and recorded by species. Total length (TL) of all fish species was
measured to 1.0 cm below. Grenadiers were measured as pre-anal fin length (AFL) to 0.5 cm below from 1997

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to 2008 and in 2019, and 1.0 cm below from 2009 to 2017 and 2020 to present. In case of large catches,
subsamples of the catch were measured.
Biomass and abundance
Biomass and abundance estimates were obtained by applying the swept area method (trawled distance *
estimated bobbin spread), assuming a catchability coefficient of 1.0. All catches were standardized to 1 km2
swept area prior to further calculations.
In strata with one haul, the standard deviation (SD) was estimated as:
𝑆𝐷= 𝑀𝑒𝑎𝑛𝑐𝑎𝑡𝑐ℎ
𝑀𝑒𝑎𝑛𝐶𝑉
∗100
Results and discussion
A total of 69 valid hauls were made (Figure 1). Haul-by-haul information on catches of Greenland halibut,
roundnose grenadier, roughhead grenadier, and deep-sea redfish is given in Appendix A Table 17. The
distribution of hauls by strata is given in Table 3 and 4. Date of completion of the survey is given in Table 2. A
total of 81 fish species were recorded (Appendix B Table 18).
Greenland halibut (Reinhardtius hippoglossoides)
The Greenland halibut stock in Subareas 0 and 1 is considered part of a biological stock complex, which
includes Subarea 2 and Div. 3KLMNO. Abundance and biomass indices are available from research vessel
surveys by Canada in Subarea 0A South (1999, 2001, 2004, 2006, 2008, 2010, 2012, 2014-2019, and 2022-
2025); Canada in OB (2000, 2001, 2011, 2013, 2014, 2015, 2016, and 2022-2025), Greenland in Divisions
1CD from 400 to 1500 m (1987-1995, 1997-2017, 2019, and 2022-2025), and Greenland in Divisions 1A-1F
offshore, from 100 to 600 m (1988-2020, and 2022-2025).
From 1979 to 1994, the assessment included SA 0+1, including Div. 1A inshore. In 1994, it was decided to
conduct a separate assessment for the inshore part of the stock in Div. 1A and for SA 0-1 Div. 1 offshore + Div.
1B-F based on tagging experiments. The TAC has been increasing since then (Treble and Nogueira,
2018). In 2020, based on historical catches and tagging experiments, it was also decided to separate, the
stocks inshore from Div.1B-F, in three separate management uni