The Aleutian Skate (Bathyraja aleutica) is a large deepwater skate (to at least 170 cm total length) known from a widespread distribution across the North Pacific Ocean, from Chiba Prefecture, Japan through to the Sea of Okhotsk and the Bering Sea to California, United States. It has been recorded on the continental and insular shelves and slopes at depths of 15–1,600 m, and generally deeper than 400 m. Across the North Pacific Ocean, skates are bycatch of industrial trawl, longline, and trap groundfish fisheries, and in some areas, skates comprise up to 10% of the total recorded biomass. The Aleutian Skate is a common bycatch of fisheries targeting groundfish, including Pacific Cod (Gadus macrocephalus), Alaska Pollock (Theragra chalcogramma), and Greenland Halibut (Reinhardtius hippoglossoides) and is among the most commonly observed skates in the North Pacific. Across its range, demersal trawl surveys reveal a stable and/or increasing abundance. There is increasing international demand for skate products in countries including China, Japan, and Korea and this increased demand has increased skate retention and interest in developing skate targeted fisheries. There are catch limits set for skates (as a group) in Russian and United States waters. Areas of high skate egg density in the United States Bering Sea and Aleutian Islands are designated Habitats of Particular Concern which allows management intervention where fishing activity is deemed harmful to the habitat. Global population trend is estimated to be stable, and combined with refuge in deep water outside current fishing activities, the Aleutian Skate is assessed as Least Concern.

The Aleutian Skate is widespread across the North Pacific Ocean, from Chiba Prefecture, Japan through to the Sea of Okhotsk and the Bering Sea to California, United States (Last et al. 2016, Grigorov et al. 2022, Orlov and Volvenko 2022).

The Aleutian Skate is amongst the most commonly observed skates in the North Pacific (Ormseth 2020, Grigorov et al. 2022, Tribuzio et al. 2023). Across the North Pacific, catch data from demersal trawl surveys show varying trends in abundance between 1976 and 2021 (Grigorov et al. 2022). In the western Bering Sea, there was a general increasing trend in abundance; in the Sea of Okhotsk, skate catches decreased until the mid-1990s, and have since increased; and in the Northwest Pacific Ocean, skate catches have shown a stable trend since the early 2000s. Overall catch-per-unit-effort (CPUE) trends for the Aleutian Skate in the Northwest Pacific have increased since the 1970s (Orlov and Volvenko 2022). Catches off the Aleutian Islands in Alaskan waters showed a stable and slight increasing trend over time, and in the Gulf of Alaska, skate catches showed some increase until the mid-2000s and have gradually declined since (Grigorov et al. 2022).

Species-specific abundance data are available for the Eastern Bering Sea (EBS) shelf, EBS slope, and the Aleutian Islands over 23 years (2000–2023) based on demersal trawl surveys conducted by the U.S. National Marine Fisheries Service (Ormseth 2020, Tribuzio et al. 2023). On the EBS shelf, survey biomass estimates for the Aleutian Skate increased from 2010–2020 and have since stabilised. On the EBS slope, survey biomass estimates indicate some increases since 2008. Total modelled biomass estimates for the Aleutian Skate in the combined Eastern Bering Sea (EBS) shelf, EBS slope, and Aleutian Islands surveys increased from 25,438 to 43,275 t between 2002 and 2018, with a slight decline to 2023 (Tribuzio et al. 2023). The trend data from each source were analysed over three generation lengths using a Bayesian state-space framework (Sherley et al. 2020, Winker et al. 2020). This analysis yields an annual rate of change, a median change over three generation lengths, and the probability of the most likely IUCN Red List category percent change over three generation lengths (see the Supplementary Information). The trend analysis revealed an annual rate of increase of 5.58% with the highest probability of a Least Concern status.

In the central and western Gulf of Alaska, the mean CPUE for Aleutian Skate in demersal trawl surveys showed an increasing trend from 2003–2015, followed by a decline to levels similar to those first reported in 2003 (Ormseth 2021). The United States West Coast groundfish fishery (operating along the US Pacific Coast from the Washington−Canada border to the California−Mexico border) reported 23.12 metric tonnes of discarded Aleutian Skate between 2002–2014 and no landed catch (Jannot et al. 2021). Global population trend is estimated to be stable based on the abundance data.

The Aleutian Skate is demersal on the continental and insular shelves and slopes at depths of 15–1,600 m, and generally deeper than 400 m (Last et al. 2016, Orlov and Tokranov 2019, Ormseth 2020). It reaches a maximum size of 170 cm total length (TL) (Grigorov et al. 2022). Males mature at ~108–116 cm TL and females mature at 110–115 cm TL (Haas 2011). Size-at-birth is ~12–15 cm TL (Last et al. 2016). Like other skates, the Aleutian Skate is oviparous and ovarian fecundity is higher (7–60 ova) in the Eastern Bering Sea (EBS) than in the Gulf of Alaska (GOA) (3–36 ova) (Haas 2011). Age-at-maturity and longevity are lower in EBS than the GOA, with female age-at-maturity 10.4 years and 13.7 years, respectively and maximum age 17 years and 19 years, respectively (Haas et al. 2016). Thus, in the EBS and GOA, generation length is 13.8 and 16.4 years, respectively.

The Aleutian Skate is a common bycatch of industrial trawl, longline, and trap fisheries targeting groundfish, including Pacific Cod (Gadus macrocephalus), Alaska Pollock (Gadus chalcogramma), and Greenland Halibut (Reinhardtius hippoglossoides). It may be confused with other species and has been reported as part of a complex in the Gulf of Alaska that also includes Bering Skate (B. interrupta) and Alaska Skate (B. parmifera) (Ormseth 2021). It may be retained for the meat of the skate wings with retention rates of up to 30% in some fisheries. Post-release mortality is unknown but was 41% for deepwater Bathryaja species in southwest Atlantic trawl fisheries (Ellis et al. 2017).

In Japan, demersal trawl fisheries operate at depths of 50–500 m and effort has decreased markedly over the last three decades and is continuing to decline with fewer fishers and vessels participating in the fishery (NFMT 2017, S. Tanaka pers. comm. 2019). In Russia, the fisheries usually operate to depths of 600–800 m (Ormseth and Matta 2011). There have been occasional experimental fisheries since 2016 that fish to 2,500 m depth (I.V. Volvenko unpub. data 2019) that may constitute a threat if expanded with the interest in developing targeted skate fisheries in the North Pacific. Skate fisheries in Russia are growing: the average annual skate catch reported to official statistics has grown nearly 3-fold, from 1,650 tonnes (t) in 2004–2008, 3,510 t in 2009–2013, and 4,860 t in 2014–2018; there is no species-specific skate catch reporting (Panchenko et al. 2020). In the eastern Bering Sea, skate egg cases, including the Aleutian Skate, are brought to the surface by commercial demersal trawl and longline fishing vessels targeting deepwater fish including Pacific Cod and Greenland Halibut (Stevenson et al. 2019). The Aleutian Skate is only commercially fished in the upper region of its bathymetric range and has significant refuge at depth from fisheries. The species may be affected by climate change as it appears to have a preferred temperature range (Grigorov et al. 2022).

In Japan, skates are of low value and while there is some domestic consumption, skate wings are most likely exported to the Republic of Korea (H. Ishihara pers. comm. 2019). The meat may be processed into fish meat jelly which is used in some Japanese national dishes (Orlov and Volvenko 2022). In Russia, skates were previously discarded but more recently have been landed for export of wings to China, Japan, Korea, and the British Virgin Islands (Orlov and Volvenko 2022). International demand for skates by Korea is very high and has increased skate retention with Korea a major importer of skates from around the world (Hyun-Su et al. 2013). In the Bering Sea and Aleutian Islands fisheries, 27–51% (average 38%) of all skates were retained from 2011–2023, with larger individuals retained due to the higher market value, and while this may include the Aleutian Skate, there is limited species-specific information (Tribuzio et al. 2023) This species is discarded in the United States west coast groundfish fisheries (Jannot et al. 2021).

There is a Total Allowable Catch (TAC) for skates in Russian and United States waters. In Russian waters, the TAC has changed little since the 1990s and in the 2020s is 11,2000–11,3000 t (Orlov and Volvenko 2022). In the United States Bering Sea and Aleutian Islands (BSAI) regions this species is managed as a skate complex. The BSAI TAC for the complex is based on the age structured model for Alaska Skate (B. parmifera) and the combined other skate survey biomass multiplied by an assumed natural mortality rate and has varied little from 2012–2023 and in 2023 was 27,441 t (Tribuzio et al. 2023). In 2015, six areas in the BSAI region of high skate egg density were designated Habitats of Particular Concern which allows management intervention where fishing activity is deemed harmful to the habitat. The 82 square nautical miles of habitat is split into different areas at the continental shelf/slope break, and aims to protect egg cases of various skate species. Targeted fishing for skates in the Gulf of Alaska has been prohibited since 2005 (Ormseth 2021).

On the United States west coast (Washington, Oregon, and California), ground fisheries are managed by a federal Groundfish Fishery Management Plan. Additionally, in California, a network of at least 29 marine protected areas provide some refuge from trawl fisheries (California Department of Fish and Wildlife 2015). In Japan, management measures have been implemented since the mid-1990s to control fishing effort that include total allowable catches, seasonal closures, and gear restrictions (White Paper 2019). Further research is needed on population size and trends, and life history, and catch rates should be monitored.