General information
Icelandic slope beaked redfish (Sebastes mentella) is a redfish species which is similar in appearance to golden redfish (Sebastes norvegicus). There are some characteristic features that distinguish those two species apart, and the depth is one of them, with Icelandic slope beaked redfish inhabiting deeper waters (>400 m). Around Iceland the species is mainly found in the warmer waters in the western, southern, and south-eastern parts of continental slope. Beaked redfish is a slow growing, long-lived, and late-maturing species.
Icelandic slope beaked redfish on the continental shelf and slope of Iceland (the Icelandic waters ecoregion, which is defined to be within the Icelandic 200 NM EEZ and includes ICES Division 5.a and part of ICES Subarea 14), is treated as distinct biological stock and management unit. Mainly fish larger than 30 cm are found in Icelandic waters. The East Greenland shelf is most likely the main nursery area for the Icelandic slope stock.
Scientific data
The Icelandic autumn survey (IS-SMH) on the continental shelf and slope in Icelandic waters covers depths down to 1500 m. Data on Icelandic slope beaked redfish are available from 2000–2023. The survey was not conducted in 2011.
Survey indices
The total biomass and abundance indices were highest in 2000 and 2001, declined in 2002 and have, since then, fluctuated at that level without clear trend (Figure 1). The biomass index of fish 45 cm and larger has, however, increased from the lowest value in 2007 to the highest one in 2021 but has since then decreased (Figure 1). The abundance index of fish 30 cm and smaller (recruits) has been at very low level since 2010. No fish smaller than 30 cm was observed in the 2021 and 2022 surveys and very little in 2023 (Figure 1).
Distribution
Icelandic slope beaked redfish from Icelandic autumn survey is caught along the south-east to the west slope of the Icelandic continental shelf (Figure 2) but is most abundant south-west along the Reykjanes ridge and west of Iceland (Figure 3). Icelandic slope beaked redfish is mainly caught at depths between 400–800 m (Figure 4).
Length and age
The length of the Icelandic slope beaked redfish in the autumn survey is between 25 cm and more than 50 cm (Figure 5). Since 2000, the mode of the length distribution has shifted to the right or from 36–39 cm in 2000 to about 42–45 cm in 2012–2023. During this period the mean length of the fish caught has increased from 37.4 cm in 2000 to 43.2 cm in 2023. This is a large increase in mean length for a species which annual growth is around 1–2 cm and where very few individuals larger than 50 cm are observed. This confirms the recruitment failure.
Otoliths from the autumn survey have been sampled since 2000 and otoliths from the 2000, 2006, 2009, 2010, 2014, 2017–2019 and 2021 surveys have been age read (Figure 6). The age reading shows that the stock consists of many cohorts and the age ranges from 5 to over 50 years. The 1985 and 1990 cohorts were large and were still relatively strong in the 2021 survey. No fish 10 years old and younger were observed in the 2021 survey, yet another indication of a recruitment failure.
Information from the fishing industry
Landings
Total annual landings of Icelandic slope beaked redfish from the Icelandic Waters Ecoregion 1950–2023 are presented in Figure 7.
During the 1950–1977 period, before the extension of the Icelandic EEZ to 200 NM, Icelandic slope beaked redfish was mainly fished by West-Germany. The catches peaked in 1953 to about 87 000 t but gradually decreased to about 23 000 t in 1977. After the extension of the Icelandic EEZ in 1978 the fishery has almost exclusively been conducted by Icelandic vessels. Annual landings gradually decreased from 57 000 t in 1994 to 17 000 t in 2001 and were at that level until 2010. Annual landings in the years 2011–2023 were between 8 300 and 12 000 t. The total catch in 2023 were 6 676 t, a decrease of 2 781 t from previous year.
Fisheries and fleets
The fishery for Icelandic slope beaked redfish in Icelandic waters is a directed bottom trawl fishery along the shelf and slope southwest and west of Iceland at depths between 500 and 800 m (Figure 8). The total number of boats that account for 95% of fishery have been declining steadily (Figure 9). In 1995 about 50 vessels fished for the stock but were around 20 in 2023.