Nygaard and Christiansen present commercial Greenland halibut data in Upernavik area; three CPUE indices from logbooks and landings.
Commercial data for the Greenland halibut fishery in Upernavik.
Northwest Atlantic Fisheries Organization
www.nafo.int Serial No. N7737
NAFO SCR Doc. 26/018
SCIENTIFIC COUNCIL MEETING –JUNE 2026 Commercial data from the Greenland halibut fishery in the Upernavik area Rasmus Nygaard1, Henrik Christiansen1 1Greenland Institute of Natural Resources, P.O. Box 570, 3900 Nuuk, Greenland
NYGAARD, R., & CHRISTIANSEN, H. 2026. Commercial data from the Greenland halibut fishery in Upernavik area. NAFO Scientific Council Research Document, SCR Doc. 26/018: 1-14.
Abstract
Although the commercial fishery for Greenland halibut inshore in West Greenland started around 1910, the first available catch statistics from the Upernavik area are from the 1960s. The fishery is traditionally performed with longlines from small open boats, small vessels, or from dog sledges through a hole in the sea ice. This document presents catch statistics and data from the commercial catches collected from the fishery targeting Greenland halibut in the fjords in the Upernavik district. The document includes statistics of commercial sampling effort collected by the Greenland Institute of Natural Resources (GINR), i.e., length frequency calculations of mean size in the landings and preliminary catch-at-age (CAA). Also provided are three commercial CPUE indices. Two CPUE indices are based on logbook data (one for longline logbooks and one for gillnet logbooks) and one CPUE index is based on factory landings data (from longline catches).
Introduction
The first available catch statistics from the Upernavik area are from 1964. The area consists of deep branching fjords separated from Baffin Bay by a shallower archipelago. The fishery is traditionally performed with longlines from small open boats, small vessels, or through a hole in the sea ice and transported with dog sledge. Gillnets are also allowed in certain areas and during the winter. License requirements were introduced in 1998 and in 2008 TAC and quota regulations were introduced for the inshore fishery. Logbooks have been mandatory for vessels larger than 30ft since 2008. In 2012, the TAC was split in two components with ITQs for vessels and a shared quota for open boats. The ITQ system currently does not specify catch to a certain district which causes a discrepancy between the ITQ and total quota set for each district. In the 1980s, small vessels entered the fishery and the use of gillnets increased in the following years. In the late 1990s, the first regulations limiting areas open to gillnet fishery were introduced, limiting gillnet fishery to the winter season. Authority to regulate seasons and areas open to gillnet fishery, was transferred to municipalities in 2004, and areas open to gillnet fishery have expanded since. In 2017, the minimum mesh-size in the Greenland halibut gillnet fishery was reduced from 110 mm to 95 mm, which enables catches of Greenland halibut as small as 50 cm with a maximal selection in the interval 55-70 cm. The inshore stock in division 1A is considered to mainly recruit from the stock in Davis Strait, although adults appear somewhat resident in the fjords, possibly isolated from the offshore spawning stock due to the shallower banks in between.
Northwest Atlantic Fisheries Organization
www.nafo.int 2 Materials and methods
Recent catch statistics (factory landing and logbooks) are available from a centralized database managed by the Greenland Fisheries and Hunting Control Authority (GFJK). Both logbook (haul by haul) and factory landings (daily individual landings) are reported as individual fishing events containing dates, field code or position, effort, sorting categories and more.
Commercial sampling
Commercial samples are collected by the Greenland Institute of Natural Resources (GINR). During surveys or sampling campaigns, factories are visited and the size of the landed fish by species and gear is registered. However, due to the logistic challenges in Greenland (size of Greenland and mainly transport by air or sea), sampling catch is challenging. In this regard, Upernavik poses a special challenge due to the many settlements with factories in the area. Factories are located in Upernavik Kujalleq, Upernavik, Aappilattoq, Inarsuit, Tasiusaq, Nuussuaq, and Kullorsuaq. Fish landed to the different factories are, however, often taken in the same areas leading to biased sampling locations being a smaller problem. Only Kullorsuaq is rarely or never visited. To ensure sufficient length information from the commercial catches is available, GINR used to conduct commercial length measurements in factories during the winter fishery. Factories are also visited during the gillnet survey conducted with the GINR research vessel RV Sanna. If individual fish weights from automated sorting machines (graders) are available these data are preferred to the opportunistic sampling from factories. In recent years many of these factories have installed graders (a sorting machine weighing each individual fish), providing a valuable data source for fish stock assessment. However, no data has been provided by the industry since August 2023. Due to low survey activity with the old and now sold research vessel RV Adolf Jensen (effort directed to Disko Bay and Uummannaq) a gap exists in the sampling around 2002 to 2007. Individual weights collected by Upernavik seafood from 2001-2014 have now been recalculated to length frequencies and it is thus now possible to complete the data for this period.
Age-length key (ALK)
Age information is occasionally obtained from commercial landings, but most otoliths in the area are collected through biological surveys with GINR research vessel RV Sanna during summer gillnet surveys. No otoliths are available from 2002 to 2007.
Logbook CPUE calculation
Three different commercial CPUEs are calculated for the inshore stocks. A general linear model (GLM) with year, month, and boat as factors is applied to the longline and gillnet fishery logbook data since 2010. Only longline sets with more than 200 hooks and gillnets with catches between 0 and 1000 kg/gillnet are included to omit obvious outlier values and limit the influence of potential data errors on the analysis. CPUE observations are log-transformed prior to the GLM analysis. Least-mean square estimates were used as standardized CPUE series. Lastly, a longline CPUE based on factory landings catch data is calculated using the same procedures as for the logbook CPUE (see details in Riget and Nygaard, 2018 & Bjare and Nygaard, 2022).
Results
Catches
The first available catch statistics from the Upernavik area are from 1964. Total catch remained at a low level until the beginning of the 1980s (Fig. 1, Table 1). Catches decreased from 1998 to 2002, but gradually increased until 2019. Factory vessels receiving catch from small boats have occasionally supplemented the factories located in settlements to increase the factory capacity and increase competition and prices in the area. Total catch reached a record high of 8,955 t in 2019. Since then, catches have decreased and in 2025 only 4,329 t were caught in the area.
Northwest Atlantic Fisheries Organization
Typically, around 90% of the catches are from longline fishery and 10 % from gillnet fishery. The catch statistics are aggregated by gear (longline or gillnet) and month (Table 2). Official databases often lack sufficient area or gear information prior to 2012. The catch by gear and month is used to calculate mean size in the landings and estimate catch-at-age (CAA). The Upernavik area consists of several large ice fjords, but the main fishing grounds are the deep Ikeq fjord (Upernavik Icefjord) and Gulteqarffik (Gulteqarffik is the Inuit word for “where the gold is collected”). Since the large icefjords are often not accessible due to glacier ice, the fishery is sometimes restricted to the shallower fjords near Upernavik and the settlements in the area or less active icefjords like Tasiusaq Bay located between Gulteqarffik and Ikeq (Fig.2). A breakdown of catch by gear and month is provided in Table 2.
Length information
Due to the logistical challenges in Greenland commercial length information is not available for all months or even years (Table 3). Grader data from the area is available in 2020 and 2021 and can replace the lacking data in these years. In 2022 and 2023 grader data was used as part of the CAA calculations, but no data has been received by the industry since October 2023.
In Upernavik there is little difference between summer and winter fishing grounds and only small differences in the summer and winter length distributions are observed. Mean individual length in the commercial landings decreased from 1993 to 1998 (Fig. 3). From 1999 to 2012 the mean length in the longline fishery remained constant with little change from year to year. However, a decrease in the size of the landed fish has been observed gradually since 2013 (Fig. 3). Length distributions of the landed fish are shown in Fig. 4. It should be noted that the estimates of mean length and the length distribution was based on only 1,245 Greenland halibut in 2024 and 2,694 Greenland halibut measured during surveys in August 2025.
Age-length key (ALK)
Age reading of Greenland halibut was suspended from 2011 to 2017 at GINR due to low quality of the age readings and lack of an internationally agreed method. However, age readings have since been reinitiated and an ALK is currently being constructed back in time. Until 2020 CAA was created with an ALK constructed using age readings from whole frozen otoliths from all three inshore areas collected from 2008, 2009 and 2010. From 2021 CAA was constructed with individual year’s ALK from otolith readings from Upernavik supplemented by the other inshore areas as a backup of missing length and age combinations. Although the CAA should be treated with caution due to uncertainty in the age readings, the CAA indicates a shift in the age composition of Greenland halibut in the area. From 2008 to 2011 the fishery was based on older Greenland halibut (ages 7- 11) (Fig. 5). After 2020 the fishery is dominated by younger fish between 5 and 9 years. The CAA estimates for 2024 and 2025 may be influenced by poor length information and lack of grader data in these years.
Factory landings CPUE (longline)
The CPUE based on factory landings data consists of more than 10,000 observations in all years and covers all longline fishery and >90% of the yearly catch (Table 6). The CPUE shows a decrease since 2012 (Fig. 6).
Logbook CPUE (longline)
Longline CPUE based on logbooks from vessels >30ft show a gradual decrease from the beginning of the timeseries (Table 7 and Fig. 7). In 2020 the CPUE decreased but returned to previous levels in 2021. However, in 2025 the logbook CPUE decreased again. Although the CPUE is based on only the larger vessels and a different data source, the CPUE shows an almost identical trend as the factory landings longline CPUE.
Logbook CPUE (gillnet)
The gillnets CPUE gradually decreased from 2009 to 2019 with a sudden drop in 2013 and 2014 (Table 8 and Fig. 8). However, the index may be influenced by a shift in the minimum allowed mesh size in the gillnets from
Northwest Atlantic Fisheries Organization
www.nafo.int 4 110 mm gillnets to 95 mm in 2017. The reduction in mesh size in the gillnets should, however, lead to a greater overlap with the stock and therefore an increase in fishing efficiency. And yet, the gillnet CPUE decreased substantially since 2009, and even more pronounced since 2019.
Discussion The catches have decreased since 2021, although they are generally high in the past decade compared to earlier. T