Contribution to the 2027 Norwegian Red List Assessment for Elasmobranch Fishes

This report provides a brief overview of elasmobranch catch distributions and relative abundance trends from the Institute of Marine Research’s (IMR) data sources. The report is intended to provide supporting information for the Norwegian Expert Committee for Fish’s 2027 assessment of elasmobranch fishes.

Data are provided from IMR’s demersal trawl surveys for species that are sufficiently represented in the surveys. For species with sporadic registrations that are rarely or never caught on surveys, summaries of data collected by the Reference Fleet (consisting of commercial fishing vessels) are shown. Incorrect species identifications may occur in the dataset, particularly in earlier years.

While not presented in this report, IMR has also undertaken research on elasmobranchs that may be considered informative for the Red-List assessment (see References and Further Resources). This includes a dedicated longline survey targeting spurdog (Squalus acanthias) from 2021-2025 (Andrade et al. 2024; Delaval et al. in review). Preliminary analyses suggest spurdog catch rates that are consistent across the five years. Because the survey mainly targets larger individuals, the increased recruitment of juveniles that is apparent in bottom trawl surveys (see Reketokt and ICES spurdog assessments) cannot be seen in the longline survey data.

The survey series that were considered most informative for assessing the catch distributions and relative abundance of sharks, skates, and rabbit fish are presented in Table 1 and Figure 1. Only stations north of 57°N and east of 0°E were included, encompassing the North Sea, Norwegian Sea, and the Barents Sea and spanning the period 2010-2025. Only data collected using Campelen and Alfredo bottom trawl gears were used in this report. We present the raw data from the surveys in the form of catch numbers and biomass, as well as a summary of catch per unit effort (CPUE in kg km^-2) for each survey.

Ten elasmobranch species had sufficient catches in IMR demersal trawls over the 2010-2025 period to produce a reasonable overview of catch distributions and relative abundance trends. For each species, the following is provided:

1. Combined catches across the years 2010-2025 for each of the IMR surveys where the species was observed.

2. CPUE in terms of biomass for each of the selected surveys.

3. Total catch count across IMR demersal trawls from 2010-2025.

4. Total catch biomass across IMR demersal trawls from 2010-2025.

Raw data of elasmobranch catches from the Reference Fleet are also presented as a supplementary source of information, which may aid in filling data gaps for species that are seldom encountered on IMR demersal trawl surveys.

3.1 - Rabbit fish (Chimaera monstrosa)

Norwegian: havmus

3.2 - Spurdog (Squalus acanthias)

Norwegian: pigghå

3.3 - Velvet belly lanternshark (Etmopterus spinax)

Norwegian: svarthå

3.4 - Blackmouth catshark (Galeus melastomus)

Norwegian: hågjel

3.5 - Small-spotted catshark (Scyliorhinus canicula)

Norwegian: småflekket rødhai

3.6 - Thorny skate (Amblyraja radiata)

Norwegian: kloskate

3.7 - Arctic skate (Amblyraja hyperborea)

Norwegian: isskate

3.8 - Round ray (Rajella fyllae)

Norwegian: rundskate

3.9 - Sailray (Rajella lintea)

Norwegian: hvitskate

3.10 - Spinytail skate (Bathyraja spinicauda)

Norwegian: gråskate

3.11 - Occurrence of skates on surveys

An overview of skate species occurrence presented as the number of trawls where a species was reported in IMR demersal trawls is shown in Table 2. The list includes rare species for which abundance data was insufficient for the above analyses, as well as unidentified skates.

We provide a summary of catches of elasmobranchs from the Reference Fleet, which may assist in providing an overview of species that are not well represented in standard IMR surveys (Table 3, Figure 4.1). Data are shown for 2016-2025. Before 2016, the identification of elasmobranchs to species aboard Reference Fleet vessels was less established. Species identification errors may still occur.

The table below shows the number of fishing hauls in which the presence of a species was recorded per year for the entire fleet. The map shows registered catches across the entire period. Note that data are inclusive of all fishing gears, and geographic scope and commissioned vessels vary between years. Data only include waters north of 57°N and east of 0°E.

Albert, O. T., Junge, C., & Myrlund, M. K. (2019). Young mums are rebuilding the spurdog stock (Squalus acanthias L.) in Norwegian waters. ICES Journal of Marine Science, 76(7), 2193-2204. https://doi.org/10.1093/icesjms/fsz156

Andrade, H., Nilsen, T., Vollen, T., Harbitz, A., Junge, C., & Albert, O. T. (2024). A longline survey for spurdog distribution and life history along the Norwegian coast. Fisheries Management and Ecology, 31(2), Article e12676. https://doi.org/10.1111/fme.12676

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Delaval, A., Andrade, H., Nilsen, T., Vollen, T., Lavezza, R. et al. (in review). Distribution and life-history of spurdog (Squalus acanthias) along the Norwegian coast inferred from a five-year fishery-independent longline survey. https://doi.org/10.21203/rs.3.rs-8583209/v1

Delaval, A., Clegg, T., Lynghammar, A., Bruvold, I. M., Tranang, C. A., & Williams, T. (2025). The distribution of skates (Order Rajiformes) along the Norwegian continental shelf and slope. ICES Journal of Marine Science, 82(9). https://doi.org/10.1093/icesjms/fsaf172

Garbett, A., Loca, S. L., Barreau, T., Biscoito, M., Bradley, C. et al. (2023). A holistic and comprehensive data approach validates the distribution of the critically endangered flapper skate (Dipturus intermedius). Journal of Fish Biology, 103(3), 516-528. https://doi.org/10.1111/jfb.15466

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Jac, R., Höffle, H., Albretsen, J., Jakobsdóttir, K., Staby, A. et al. (2022). Of three sharks and one chimaera: varied habitat preferences across a latitudinal range revealed by coastal and offshore surveys. Journal of Fish Biology, 100(3), 660-674. https://doi.org/10.1111/jfb.14979

Junge, C., Ferter, K., Klöcker, C. A., Bjelland, O., Albretsen, J. et al. (2024). Tag attachment innovation on spurdog (Squalus acanthias) reveals year-round coastal association of pregnant females in northeastern Atlantic waters. Journal of Fish Biology, 106(5). https://doi.org/https://doi.org/10.1111/jfb.16000

Klöcker, C. A., Albert, O. T., Ferter, K., Bjelland, O., Lennox, R. J. et al. (2024). Seasonal habitat use and diel vertical migration in female spurdog in Nordic waters. Movement Ecology, 12(1), 62. https://doi.org/10.1186/s40462-024-00498-2

Klöcker, C. A., Bjelland, O., Ferter, K., Arostegui, M. C., Braun, C. D. et al. (2025). Basking sharks of the Arctic Circle: year-long, high-resolution tracking data reveal wide thermal range and prey-driven vertical movements across habitats. Animal Biotelemetry, 13(1), 15. https://doi.org/10.1186/s40317-025-00407-3

Klöcker, C. A., Schlindwein, A., Arostegui, M. C., Bruvold, I. M., Wernström, J. V. et al. (2025). Giants in the cold: Morphological evidence for vascular heat retention in the viscera but not the skeletal muscle of the basking shark (Cetorhinus maximus). Journal of Fish Biology,. https://doi.org/10.1111/jfb.70052

McMillan, M. N., Izzo, C., Junge, C., Albert, O. T., Jung, A., & Gillanders, B. M. (2017). Analysis of vertebral chemistry to assess stock structure in a deep-sea shark, Etmopterus spinax. ICES Journal of Marine Science, 74(3), 793-803. https://doi.org/10.1093/icesjms/fsw176

Nielsen, J., Christiansen, J. S., Præbel, K., Møller, P. R., Devine, B. et al. (2025). Spatial distribution of Greenland shark Somniosus microcephalus (Bloch & Schneider, 1801) life stages across the northern North Atlantic. Ecology and Evolution, 15(7), e71564. https://doi.org/10.1002/ece3.71564

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