Greenland Institute of Natural Resources biomass and abundance of demersal fish stocks in Nuuk and Ameralik fjords; Halibut, cod, redfish biomass
Biomass and Abundance of Demersal Fish Stocks in the Nuuk fjord and Ameralik fjord derived from The GINR Shrimp and fish inshore (SFI) survey.
Northwest Atlantic Fisheries Organization
Serial No. N7732 NAFO SCR Doc. 26/013
SCIENTIFIC COUNCIL MEETING – JUNE 2026
Biomass and Abundance of Demersal Fish Stocks in the Nuuk fjord and Ameralik fjord derived from The GINR Shrimp and fish inshore (SFI) survey. By Rasmus Nygaard and Henrik Christiansen. Greenland Institute of Natural Resources, Box 570, 3900 Nuuk, Greenland NYGAARD, R., & CHRISTIANSEN, H. 2026. Biomass and Abundance of Demersal Fish Stocks in the Nuuk fjord and Ameralik fjord derived from The GINR Shrimp and fish inshore (SFI) survey. NAFO Scientific Council Research Document, SCR Doc. 26/013: 1-25. Abstract In 2015, the Greenland Institute of Natural Resources initiated a trawl survey in the inshore area of NAFO subarea 1D. The fjords surround the capitol of Greenland, Nuuk and supports several fisheries including Cod and Greenland halibut. The survey is performed with the 458 GT and 32m long research vessels RV Sanna, equipped with a 1440 mesh bacalao trawl. The survey is based on a depth stratification of the fjords using fixed stations where bottom conditions allow bottom trawling. This paper includes biomass and abundance estimates for the Nuuk fjord and Ameralik fjord for Greenland halibut, shrimp, cod, American plaice, deep-sea redfish and Golden redfish.
Northwest Atlantic Fisheries Organization
www.nafo.int 2 Introduction The survey area The survey initially covered 3 fjord areas in NAFO division 1D located in West Greenland (Fig. 1). Nuup Kangerlua (the Nuuk fjord or Godthåbsfjorden) is the larger of the fjords. It is connected to the Davis trait through a narrow channel in the western part and bottom temperatures are influenced by influx of warmer water from the Davis strait. The fjord branches in 3 channels that meet again in the eastern part of the fjord. An icefjord is located in the North-eastern part of the system with 3 smaller iceberg producing glaciers. Glacier activity and tidal currents allows exchange of water masses with the Davis strait and the fjord is known to be highly productive, with both a spring and autumn bloom supplemented with secondary blooms driven by glacier activity. The Ameralik fjord is a long narrow and fjord branching in two shallow areas in the eastern part. Ameralik is about 7 times smaller than Nuup Kangerlua. It is connected to the Davis strait through a shallow archipelago in the western part. Ameralik is generally colder than the Godthåb fjord. Large amounts of highly silty glacier water flows into the fjord in the eastern part partly limiting primary production. The Qarajat fjord is a more open coastal zone or archipelago surrounded basin south of the other larger fjords. The area was only surveyed in the first years, as bottom conditions and kelp debris makes bottom trawling difficult in the area. However, the few stations in the area revealed higher numbers of juvenile one and two-year-old Greenland halibut in the area. The few initial year stations from Qarajat are omitted from the survey indices in this document. Materials and Methods Survey design, stratification and area coverage The survey area is divided into primary strata (fjord) and secondary strata (depth). The survey primary stratum corresponds to the fjords. The primary stratum is further subdivided into secondary (depth) strata at 0–200 m, 200-400 m, 400-600 m and deeper than 600 m (Table 1). Survey period and daily sampling period The trawl survey was in 2015, 2017 and 2018 an autumn survey. In 2019 the survey shifted to the spring but returned to autumn in 2024 (Table 2). Trawling is carried out in the daytime. It takes 4- 5 days to complete the survey every year. Towing time is 30 min on most stations, but hauls down to 10 minutes are accepted. Towing speed is about 2-2.5 knots. Survey vessel, gear and trawl. The vessel used is the 458 GT and 32m long and 10 m wide research vessel RV Sanna (GINR). Since RV Sanna was built in 2012, the vessels has gone through several equipment updates. In 2015, no trawl sensors were installed on the vessel and tow start was estimated from vessel movement and skippers experience (vessel speed and wire vibration). In 2017, Sanna was equipped with marport trawlsensors, 3 Simrad EK80 eccosounders and a Seabat T50 sidescan zonar (Teledyne). The trawl is a 1440 mesh bacalao trawl supplied by Vónin. The bacalao trawl is a fish trawl with an overhanging headrope but modified with a finer meshed codend and bell for scientific purposes to also select shrimp and juvenile fish.
Northwest Atlantic Fisheries Organization
www.nafo.int 3 Swept area calculation Nominal swept area for each tow is calculated as the straight-line distance between its GPS start and end positions multiplied by the wingspread. The distance between the trawl doors is recorded up to 5 times during each tow; provided it was recorded at least 3 times, wingspread for a tow was calculated from the mean door spread and the geometry of the trawl. For the year without trawl censors a modelled door spread is calculated based on depth and door spread in 2017-2019 trawl survey. The length of the bacalao 1440 mesh trawl is estimated to 32m and the length of the bridles (30m), chains and front wings 41,7m. (see appendix I) Biomass estimation The catch in each haul is divided by the estimated swept area calculated from wingspread and track length to estimate a biomass density. Mean stratum densities were multiplied by the stratum area (table 1) to calculate stratum biomass, and a corresponding error variance for the stratum biomass estimate was also calculated for strata with two or more accepted hauls. For strata with only one accepted haul, an average error of variance for all strata was assigned. If a strata has no stations in a given year, the nearest depth strata with stations in that year is geographically enhanced to include the un-surveyed strata. This way the total area surveyed is kept constant across years. Both the abundance and biomass estimate for the initial survey year in 2015 had high CV and the index from the initial year is somewhat uncertain. Biological sampling The catch is sorted by species for each tow and a total catch weight and a length distribution for each species is registered. Otoliths are collected from redfish, Cod and Greenland halibut. Results The survey timing, trip number number of valid hauls by year and strata are listed in table 2. Valid hauls by depth strata is given in table 3. Although the survey is based on fixed stations, some stations have been moved or cancelled every year due to bottom conditions, ice or active commercial fishing gear. Only hauls in the Nuuk fjord and Ameralik were used in the biomass and abundance calculations and in the length frequencies. The Qarajat stations were only completed in the initial years, and therefore not used in the indices. For illustrative purposes, the biomass and abundance densities from Qarajat were included on the maps. Bottom temperatures in Amaralik is about 2 to 3 degrees Co colder than in both the Nuuk fjord and in the Qarajat area (Table 4). Greenland halibut (Reinhardtius hippoglossoides). The abundance and biomass index has been stable since 2017, although apparently decreasing in 2024 (table 6 and 7, figure 2). Distinct cohords can be seen in the length distributions (figure 8.) Greenland halibut larvae (age 0) were present in the autumn survey in 2015, 2017 and 2018, but not in the spring surveys (2019-2021) or the autumn survey in 2024. one-year old recruits are larger in the autumn surveys (14-18 cm in 2019-2023) than in the spring surveys (12-16 cm, 2015-2018 and 2024). Age 2 typically has a mode around 23-24 cm and age 3 around 30 cm. In 2019 high numbers of Greenland halibut from 28-38 cm were found (3 and 4 year old) also present in the 2017 and 2018 survey as (2015 and 2016 YC). The higher than usual numbers of age 2 (14-18cm) and 3 (22-28cm) in 2023 was not seen in the 2024 survey or the 2025 survey .
Northwest Atlantic Fisheries Organization
www.nafo.int 4 Greenland halibut are found in all areas of the fjords but higher biomass densities are found in the deeper areas near Sardloq (figure 13 and 14). Although Ameralik is colder than Nuup Kangerlua all areas are within the temperature optimum for Greenland halibut of -2 +8 CO (figure 24). Cod (Gadus morhua) Cod are in the fjords are known to migrate to shallow water during the summer and to swim pelagic in the area year around and are therefore not easy to survey with bottom trawl in the area. The fishery for cod in the fjord are several times greater than the survey index, any conclusion based on cod indices are tentative. Juvenile cod is surveyed with gillnets during the summer along the beaches and during the wintertime a pelagic survey and acoustics survey is also conducted by RV Sanna. Cod abundance (Table 8) and biomass (Table 9) indices have gradually increased since 2020 (figure 3). Annual growth increments are around 10 cm per year for younger ages. Length frequencies reveal apparently good recruitment from 2017-2019 but apparently missing yearclasses from 2020-2023 (figure 9). In all years, cod were in the south eastern part of the Nuuk fjord (towards the Kapisillit settlement) and in the north eastern branch of Ameralik mainly from 200-400 m (figure 15 and 16). Juvenile redfish (S. Norwegicus or S. mentella) Until 2020, no juvenile redfish were observed in the survey. (This is in agreement with similar surveys from both East Greenland (ices NWWG, anon) and West Greenland indicating poor redfish recruitment from 2010 to 2019 (Nygaard and Nogueira 2020). Since 2021 increasing numbers of juvenile redfish have been observed. Previously juvenile redfish smaller than 20 cm were not identified at a species level and just registered as Sebastes sp. In 2022, DNA tissue samples were collected from 72 juvenile redfish. All of these (72/72, sizes from 7-17 cm with 55 individuals between 11 and 12 cm) were genetically assigned to S. mentella (personal communication with Ian Bradbury DFO in 2024, unpublished). In the 2023 survey all juveniles were visually identified as S. Mentella with the size of the eye mainly being used to determine species. S. mentella clearly has a larger eye diameter/head height ratio compared to S. norvegicus. Based on these findings all juvenile redfish are now identified at a species level and the survey juvenile estimates of biomass and abundance is now included in the species indices. Deep-sea redfish (Sebastes mentella). Both the abundance index and the biomass index of deep-sea redfish fluctuate without a clear trend from 2015 to 2020 (table 10 and 11, figure 5). Length frequencies reveal deep-sea redfish in the size range from 25 to 44 cm in all years corresponding to old redfish close to Lmax (figure 10). New yearclasses can be seen in the most recent years with clear modes of age 1 redfish below 10 cm and dominated by a strong 2020 yearclass (figure 10). The same cohords are identified in the similar offshore surveys where strong recruitment of redfish has been identified in the recent years. Adult deep-sea redfish around 40 cm are seen in all survey years corresponding to old outgrown deepsea redfish that has reached their Lmax. Deepsea redfish are yearly found on the same shallower stations in the south eastern parts of the Nuuk fjord towards the settlement kapisillit and in the north-eastern branch of the ameralik fjord (figure 17 and 18). pregnant females with live larvae are observed in the spring surveys in march april and may. Golden Redfish (S. Norvegicus) Very few golden redf