Icelandic slope beaked redfish

Sebastes mentella


Technical report
Published by

Marine and Freshwater Research Institute, Iceland

Published

6 June 2025

Key signals

  • The total biomass and abundance indices have fluctuated about a constant level since 2003.
  • Survey estimates have consistently shown very low abundance of pre-fishery juveniles (< 30 cm) since 2012.
  • Length distributions from surveys and fisheries show a progressive shift toward larger fish over time, reflecting an aging population and a long period (2012–present) with very low recruitment.
  • Spawning stock biomass (SSB) declined from 1990–2000, was relatively stable from 2000–2016, and has since declined to lowest level.
  • Fishing mortality (F) has declined since the mid 1990s and dropped below FMSY in 2024.

General information

Icelandic slope beaked redfish (Sebastes mentella) is a deep-water redfish species, similar in appearance to golden redfish (S. norvegicus) but distinguishable by certain characteristics, notably its deeper habitat (>400 m). Around Iceland, it is primarily found in the warmer waters along the western, southern, and south-eastern continental slope. Like other redfish species, beaked redfish is slow-growing, long-lived, and matures late.

This species is considered a separate biological stock and management unit within the Icelandic waters ecoregion, which encompasses ICES Division 5.a and part of Subarea 14 within the Icelandic 200 NM EEZ. In Icelandic waters, individuals larger than 30 cm are predominantly observed. The East Greenland shelf is believed to serve as the main nursery area for this stock.

Information from the fishing industry

Landings

Total annual landings of Icelandic slope beaked redfish from the Icelandic Waters Ecoregion during 1950–2024 are shown in Figure 1.

From 1950 to 1977, prior to the extension of Iceland’s EEZ to 200 NM, the fishery was primarily conducted by West Germany. Catches peaked in 1953 at around 87  000 t, then gradually declined to approximately 23  000 t by 1977. Following the EEZ extension in 1978, the fishery has been almost exclusively prosecuted by Icelandic vessels.

Landings declined steadily from 57  000 t in 1994 to 17  000 t in 2001 and remained at similar levels until 2010. Between 2011 and 2024, annual landings ranged from 2  500 to 12  000 t. In 2024, the total catch was 2,618 t — a decrease of 4,057 t from the previous year.

Figure 1: Icelandic slope beaked redfish. Nominal landings (in tonnes) from Icelandic waters (ICES Division 5.a and Subarea 14) 1950–2024.

Fisheries and fleets

The fishery for Icelandic slope beaked redfish in Icelandic waters is a directed bottom trawl fishery conducted along the continental shelf and slope southwest and west of Iceland, typically at depths between 500 and 800 m (Figure 2). The number of vessels accounting for 95% of the total catch has declined steadily over time (Figure 3).

Figure 2: Icelandic slope beaked redfish. Geographical location of the bottom trawl catches in Icelandic waters (ICES Division 5.a and Subarea 14) 2010–2024 as reported in logbooks of the Icelandic fleet.
Figure 3: Icelandic slope beaked redfish. 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.

Sampling from the commercial fishery

Table 1 shows biological sampling from the catch of Icelandic slope beaked redfish in the Icelandic Waters Ecoregion during 2000–2024. Both the number of samples and the number of length measurements have declined since 2012.

Figure 4 displays the number of samples collected by month from 2012–2024, clearly illustrating the reduction in sampling over time. This decline is primarily due to reduced sampling effort by onboard observers from the Directorate of Fisheries.

The spatial distribution of sampling relative to the fishery during 2020–2024 is shown in Figure 5 and indicates that most sampling effort occurs where the fishery is concentrated.

Table 1: Icelandic slope beaked redfish. Number of samples and number of fish length measured from the commercial catches 2000–2024.

Year

Landings (t)

No. samples

No. length measured

2000

31393

167

34357

2001

17230

95

18563

2002

19045

177

32500

2003

28478

149

26196

2004

17564

117

19640

2005

20563

596

93465

2006

17208

325

50237

2007

17372

203

30107

2008

24125

192

32535

2009

19429

168

27647

2010

17642

168

28464

2011

11737

138

21239

2012

11963

69

11237

2013

8761

63

9360

2014

9501

93

15380

2015

9314

58

9089

2016

9537

88

13026

2017

8372

45

8570

2018

9996

27

5038

2019

8715

40

7509

2020

11375

29

5508

2021

10589

26

4125

2022

9465

8

319

2023

6675

22

2045

2024

2704

26

3018

Figure 4: Icelandic slope beaked redfish. Ratio of samples by month (blue bars) compared with landings by month (solid black line) 2014–2024. Numbers of above the bars indicate number of samples by year and month.
Figure 5: Icelandic slope beaked redfish. Fishing grounds in the years 2020–2024 as reported in logbooks (contours) and positions of samples taken from landings (asterisks) by year.

Length distribution from the commercial catch

Length distributions of Icelandic slope beaked redfish from the bottom trawl fishery show a noticeable increase in the number of small fish in the catch in 1994 compared to previous years (Figure 6). A distinct peak near 32 cm in 1994 can be traced through subsequent years, showing approximately 1 cm of annual growth from 1996 to 2002.

From 2004 to 2024, the length distribution has typically peaked around 39–43 cm. In contrast, where data are available, the length distribution from the pelagic fishery shows that the fish caught were generally larger on average than those taken in the bottom trawl fishery (Figure 6).

Figure 6: Icelandic slope beaked redfish. Length distributions from the Icelandic commercial landings taken with bottom trawl (blue line) and pelagic trawl (red line) in Icelandic waters (ICES Division 5.a and Subarea 14) 1991–2024.

Catch per unit effort

Trends in non-standardized CPUE (kg/hour) and fishing effort (thousand hours fished) are shown in Figure 7. The CPUE from tows in which more than 50% and 80% of the catch consisted of Icelandic slope beaked redfish declined steadily from 1978 to a record low in 1994. Since then, CPUE has increased consistently, reaching the highest levels in the time series in 2020 and 2021.

Between 1991 and 1994, the decline in CPUE coincided with a substantial increase in fishing effort. Effort has since declined and is now comparable to levels observed in 1980. CPUE and effort data are not available for 2022.

Figure 7: Icelandic slope beaked redfish. CPUE and effort from Icelandic trawlers 1978–2021 where beaked redfish catch composed at least 50% of the total catch in each haul (black line), 80% of the total catch (red line) and in all tows where beaked redfish was caught (blue line). The data for 2022 was not available.

Discard

Although no direct measurements are available, discarding of Icelandic slope beaked redish is believed to be negligible.

Scientific data

The Icelandic autumn survey (IS-SMH), conducted on the continental shelf and slope in Icelandic waters, covers depths down to 1  500 m. Data on Icelandic slope beaked redfish are available for the period 2000–2024, except for 2011 when the survey was not conducted.

Survey indices

The total biomass and abundance indices were highest in 2000 and 2001, declined in 2002, and have since fluctuated around that level without a clear trend (Figure 8).

The biomass index of fish ≥45 cm increased from its lowest point in 2007 to a peak in 2021 but has declined since then (Figure 8). In contrast, the abundance index of fish ≤30 cm (recruits) has remained very low since 2010. No fish smaller than 30 cm were observed in the 2021 and 2022 surveys, and only very few were observed in 2023 and 2024 (Figure 8).

Figure 8: Icelandic slope beaked redfish. Survey indices in the autumn survey in ICES Division 5.a 2000–2024. The survey was not conducted in 2011. The figure shows the total biomass index, total abundance index, biomass index of fish 45 cm and larger and abundance index of fish 30 cm and smaller.

Distribution

Icelandic slope beaked redfish in the Icelandic autumn survey is caught along the continental slope from the south-east to the west of Iceland (Figure 9), with highest abundances observed southwest along the Reykjanes Ridge and west of Iceland (Figure 10). The species is primarily caught at depths between 400 and 800 m (Figure 11).

Figure 9: Icelandic slope beaked redfish. Spatial distribution in the Icelandic autumn survey in 2000–2024. The survey was not conducted in 2011.
Figure 10: Icelandic slope beaked redfish. Spatial distribution of the total biomass index from the Icelandic autumn survey 2000–2024. The survey was not conducted in 2011.
Figure 11: Icelandic slope beaked redfish. Depth distribution of the catch from the Icelandic autumn survey 2000–2024. The survey was not conducted in 2011.

Length and age

The length of Icelandic slope beaked redfish observed in the autumn survey ranges from 25 to 55 cm (Figure 12). Since 2000, the mode of the length distribution has shifted to the right — from 36–39 cm in 2000 to approximately 42–45 cm during 2012–2024. Over the same period, the mean length of sampled fish increased from 37.4 cm in 2000 to 43.2 cm in 2024.

This is a substantial increase in mean length, particularly given that the species grows slowly (approximately 1–2 cm per year) and that individuals over 50 cm are rarely observed. The absence of smaller size classes and this shift in size structure are consistent with a recruitment failure.

Figure 12: Icelandic slope beaked redfish. Length disaggregated abundance indices (blue area) in the Icelandic autumn survey 2000–2024. No survey was conducted in 2011. The black line is the mean of 2000–2024.

Otoliths from the autumn survey have been collected since 2000, with age readings completed for 10 survey years (Figure 13). The results show that the stock is composed of many cohorts, with ages ranging from 5 to over 50 years. The 1985 and 1990 cohorts were particularly strong and remained relatively abundant in the 2021 survey.

Signs of recruitment failure are evident in the age distributions, with very few individuals aged 10 years or younger observed since 2018.